UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Form20-F

(Mark One)

or

or

or

Commission File Number1-15006

(Exact name of Registrant as specified in its charter)

PetroChina Company Limited

(Translation of Registrant’s name into English)

The People’s Republic of China

(Jurisdiction of incorporation or organization)

9 Dongzhimen North Street

Dongcheng District, Beijing 100007

The People’s Republic of China,

(Address of principal executive offices)

Wu Enlai

Telephone number: 8610 5998627059982622

Facsimile number: 8610 62099557

Email address: jh_dong@petrochina.com.cnsunbo05@petrochina.com.cn

Address: 9 Dongzhimen North Street, Dongcheng District, Beijing 100007, The People’s Republic of China

(Name, telephone,e-mail and/or facsimile number and address of registrant’s contact person)

Securities registered or to be registered pursuant to Section 12(b) of the Act.

Securities registered or to be registered pursuant to Section 12(g) of the Act.

None

(Title of Class)

Securities for which there is a reporting obligation pursuant to Section 15(d) of the Act.

None

(Title of Class)

Indicate the number of outstanding shares of each of the issuer’s classes of capital or common stock as of the close of the period covered by the annual report:

Indicate by check mark if the registrant is awell-known seasoned issuer, as defined in Rule 405 of the Securities Act.    Yes  ☒    No  ☐

If this is an annual or transition report, indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934.    Yes  ☐    No  ☒

Note — Checking the box above will not relieve any registrant required to file reports pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 from their obligations under those Sections.

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) or the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.    Yes  ☒    No  ☐

Indicate by check mark whether the registrant has submitted electronically, and posted on its corporate Web site, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of RegulationS-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files).    Yes  ☐☒    No  ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, anon-accelerated filer, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” and “emerging growth company” in Rule12b-2 of the Exchange Act.Act:

Large Accelerated Filer  ☒                AcceleratedFiler  ☐                Non-Accelerated Filer  ☐                Emerging Growth company  ☐

If an emerging growth company that prepares its financial statements in accordance with U.S. GAAP, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards† provided pursuant to Section 13(a) of the Exchange Act.  ☐

Indicate by check mark which basis of accounting the registrant has used to prepare the financial statements included in this filing:

If “Other” has been checked in response to the previous question, indicate by check mark which financial statement item the registrant has elected to follow.    Item 17  ☐    Item 18  ☐

If this is an annual report, indicate by check mark whether the registrant is a shell company (as defined in Rule12b-2 of the Exchange Act).    Yes  ☐    No  ☒

(APPLICABLE ONLY TO ISSUERS INVOLVED IN BANKRUPTCY PROCEEDINGS DURING THE PRECEDING FIVE YEARS)

Indicate by check mark whether the registrant has filed all documents and reports required to be filed by Sections 12, 13 or 15(d) of the Securities Exchange Act of 1934 subsequent to the distribution of securities under a plan confirmed by a court.    Yes  ☐    No  ☐

Table of Contents

i

ii

CERTAIN TERMS AND CONVENTIONS

Conventions Which Apply to this Annual Report

Unless the context otherwise requires, references in this annual report to:

We publish our consolidated financial statements in Renminbi or RMB. In this annual report, IFRS refers to International Financial Reporting Standards as issued by the International Accounting Standards Board.

Conversion Table

Certain Oil and Gas Terms

Unless the context indicates otherwise, the following terms have the meanings shown below:

References to:

FORWARD-LOOKING STATEMENTS

This annual report contains“forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities and Exchange Act of 1934, as amended. Theseforward-looking statements are, by their nature, subject to significant risks and uncertainties. Theseforward-looking statements include, without limitation, statements relating to:

The words “anticipate”, “believe”, “could”, “estimate”, “expect”, “intend”, “may”, “plan”, “seek”, “will” and “would” and similar expressions, as they related to us, are intended to identify a number of theseforward-looking statements.

By their nature,forward-looking statements involve risks and uncertainties because they relate to events and depend on circumstances that will occur in the future and are beyond our control. Theforward-looking statements reflect our current views with respect to future events and are not a guarantee of future performance. Actual results may differ materially from information contained in theforward-looking statements as a result of a number of factors, including, without limitation, the risk factors set forth in this annual report and the following:

You should not place undue reliance on anyforward-looking statements.

PART I

Item 1 —— IDENTITY OF DIRECTORS, SENIOR MANAGEMENT AND ADVISORS

Not applicable. However, see “Item 6 — Directors, Senior Management and Employees — Directors, Senior Management and Supervisors” and “Item 16C — Principal Accountant Fees and Services”.

Item 2 —— OFFER STATISTICS AND EXPECTED TIMETABLE

Not applicable.

Item 3 —— KEY INFORMATION

Exchange Rates

Selected Financial Data

Historical Financial Information

You should read the selected historical financial data set forth below in conjunction with our consolidated financial statements and the notes and “Item 5 — Operating and Financial Review and Prospects” included elsewhere in this annual report. The selected consolidated statement of comprehensive income (except for ADS data) and cash flow data for the years ended December 31, 2014, 20152017, 2018 and 20162019 and the selected consolidated statement of financial position data as of December 31, 20152018 and 20162019 set forth below are derived from our audited consolidated financial statements included elsewhere in this annual report. The selected consolidated statement of comprehensive income data (except for ADS data) and cash flow data for the years ended December 31, 20122015 and 20132016 and the selected consolidated statement of financial position data as of December 31, 2012, 20132015, 2016 and 20142017 set forth below are derived from our audited financial statements not included in this annual report. Our consolidated financial statements were prepared in accordance with IFRS as issued by the International Accounting Standards Board. The financial information included in this section may not necessarily reflect our results of operations, financial position and cash flows in the future.

(2)	Each ADS represents 100 H Shares. The basic and diluted earnings per ADS were calculated with the same method as that used for the calculation of the basic and diluted earnings per share.

(3)	Return on net assets is calculated as “Profit for the year attributable to owners of the Company” divided by “Equity attributable to owners of the Company”.

(4)

(a) The comparative data in the table was restated as if Dalian West Pacific Petrochemical Co., Ltd. was consolidated since the earliest year presented. Please refer to “Item 4 — Information on the Company — Acquisitions and Divestment” and Note 40 to our consolidated financial statements, and (b) We have initially applied IFRS 16 on January 1, 2019 and IFRS 15 and IFRS 9 on January 1, 2018. According to the adopted transition plan, the comparative data has not been restated. For a detailed description of the changes and impacts of these accounting standards, please refer to “Note 3 (aa) New Accounting Standards” in our financial statements.

Risk Factors

Our business is primarily subject to various changing competitive, economic and social conditions. Such changing conditions entail certain risks, which are described below.

Risks Related to Macro Economic Conditions

Our operations may be adversely affected by international and domestic economic conditions. As the oil and gas industry is sensitive tomacro-economic trends, oil and gas prices tend to fluctuate along with changes inmacro-economic conditions. We may experience pricing pressure on our refined products in recessionary periods, which would have an adverse effect on our profitability. In 2016, a weak domestic economy continued toprofitability.Changes in macro-economic conditions can affect the demand for certain of our products. These factors may also lead to intensified competition for market share, with consequential potential adverse effects on sales volumes. Inflation may lead to increase in our operating costs. Notwithstanding the measures taken by the PRC government to control inflation, China may experience an increase in inflation in the future and our operating costs may become higher than anticipated. The financial and economic situation may also have a negative impact on third parties with whom we do orbusiness, and may do, business.impact their ability to perform contractual obligations to us. In addition, other factors that affect the macro economy, such as declining population growth rates, conflicts and wars, trade and tariff policies, and major public health events, such as the recentCOVID-19 pandemic, may have an adverse impact on oil and gas and petrochemical industries, including us. Any of these factors may adversely affect our financial condition, results of operations and liquidity.

Risks Related to Competition

The oil, gas and petrochemicals industries are highly competitive. There is strong competition, both within the oil and gas industry and with other industries, in supplying the fuel needs of commercial, industrial and residential markets. In recent years, with further diversificationthe intensive reform of the market players in China’s petroleum, refining and petrochemical industry,chemical, natural gas, LNG, pipelines and refined oils sales industries, we have been facing increasingly intense competition in the exploration, refinery, chemical, sales, and oil and gas service sectors from privately-owned companies, foreign-invested enterprises and other state-owned enterprises that recently entered the refinery, chemical, sales and oil and gas service sectors.industries. In addition, the rapid development of unconventional oil and gas resources, new energy sources and new products also poses competition with the conventional energy and petrochemical industries. Competition puts pressure on product prices, affects oil products marketing and requires continuous management focus on identifying new trends, reducing unit costs and improving efficiency. The implementation of our growth strategy requires continued technological advances and innovation, including advances in exploration, production, refining, petrochemicals manufacturing technology and advances in technology related to energy usage. Our performance could be impeded if competitors developed or acquired intellectual property rights to technology that we required or if our innovation lagged the industry.

The easternEastern and southernSouthern regions of China have a higher demand for refined products and chemical products than the westernWestern and northernNorthern regions. Although we have strived to increase our refinery capacity in the southernSouthern regions of China over recent years, most of our refineries and chemical plants are located in the northeasternNortheastern and northwesternNorthwestern regions of China. We incur relatively higher transportation costs for delivery of our refined products and chemical products to certain areas of the easternEastern and southernSouthern regions from our refineries and chemical plants in westernWestern and northernNorthern China. We face strong competition from other traditional domestic oil companies, local independent refineries and other competitors. As a result, we expect that we will continue to encounter difficulty in increasing our sales of refined products and chemical products in these regions.

Risks Related to Outbound Investments and Trading

We are subject to various political, legal and regulatory environments in foreign developing countries where we operate, some of which are known to be unstable and differ in certain significant respects from those

prevailing in developed countries. The main factors affecting our outbound investments include unstable political situations, unstable tax policies and unstable regulatory regimes. CNPC, our controlling

shareholder, and its affiliates and subsidiaries may choose to undertake, without our involvement, overseas investments, operations and trading in the oil and gas industry, including certain exploration and production of oil and gas, refining, transportation, trading, engineering construction and transportation, importtechnical services, operations of crude oilpipelines and natural gas, operation of liquefied natural gas, or LNG projects, or other business activities. CNPC’s overseas asset portfolio includes oil and gas development and pipeline projectsactivities in certain countries or with certain entities that are subject to U.S. economic sanctions or are designated as State Sponsors of Terrorism, including Iran, Sudan, Cuba, Syria, Myanmar, Russia and Russia.Venezuela.

In 2018, the United States withdrew from the Joint Comprehensive Plan of Action (“JCPOA”) and reimposed certain sanctions against Iran, which were conditionally lifted in 2015 following entry into the JCPOA. These reimposed sanctions have implications fornon-U.S. companies, including requiring foreign companies to cease participation in projects in certain sectors of Iran (including the energy sector), and, except for eight countries and regions (including China) which were granted a Significant Reduction Exception (“SRE”) to be able to continue to import limited oil, prohibiting or restricting oil imports from Iran. The SREs expired in May 2019, and the United States announced that no additional waivers would be re-issued. Pursuant to section 13(r) to the U.S. Securities Exchange Act of 1934, reporting issuers are required to disclose whether they or any of their affiliates have knowingly engaged in certain activities, transactions, or dealings related to Iran during the reporting period, including activities not prohibited by U.S. or other law. In 2019, our controlling shareholder, CNPC, held indirect interests in certain oil and gas development projects in Iran, namely, (i) the MIS oil fields in which CNPC obtained a 100% interest in 2010, (ii) the North Azadegan oilfield, in which CNPC obtained a 100% interest in 2009 and (iii) the South Pars gas field project. Regarding the South Pars gas field project, CNPC first obtained a 100% interest in 2009. After ceasing participation in the project in 2012, CNPC in July 2017 regained a 30% investment and operating interest in the South Pars gas field project under a new Iran Petroleum Contract (the “IPC”). In November 2018, CNPC took over another shareholder’s interest pursuant to the IPC but the project was on hold. In October 2019, CNPC withdrew from the project. From there-imposition of U.S. sanctions until May 2019, CNPC had been providing minimal support and extraction-related services to the MIS oilfield and the North Azadgan oilfield to recover its investment pursuant to the project agreements and in line with the SRE issued to China. Since May 2019, CNPC has suspended extracting oil from the two oilfields. In 2019 (until May), CNPC transported back to China approximately 1.47 million tons of crude oil that it extracted from the MIS oilfield and the North Azadgan oilfield, of which approximately 0.41 million tons were resold to our company’s refineries. In 2019, crude oil that we processed from the foregoing source accounted for 0.32% of the total oil processed by our refineries and contributed 0.08% of our total revenue.

Since July 2014, the United States has adopted economic sanctions against certain Russian persons and entities, including various entities operating in the financial, energy and defense sectors, such as Rosneft, Gazprom, Transneft, OAO Novatek and Yamal LNG. These sanctions prohibit U.S. persons from transacting in, providing financing for or otherwise dealing in debt issuance by certain of these entities, or restrict exports and transfer of technologies to certain of these entities.

CNPC had certainpre-existing trading and investment relationships with some of these sanctioned Russian entities. For example, CNPC entered into a long-term agreement with each of Rosneft and Transneft to import crude oil from Russia in 2009 and a long-term agreement with Rosneft to import crude oil from Russia in June 2013 and a long-term agreement with Gazprom to import natural gas from Russia in May 2014.2013. CNPC has resold, and will for the foreseeable future resell, all or a substantial portion of the imported crude oil from Rosneft and Transneft under the crude oil agreementagreements to us. In 2014, CNPC signed a long-term agreement with Gazprom to import natural gas from Russia, which was assigned to one of our subsidiaries in 2019. CNPC also indirectly holds 20% equity interest in OAO Yamal LNG and 10% equity interest in Arctic LNG 2, both of which is a subsidiaryare subsidiaries of OAO Novatek, another sanctioned Russian entity. In May 2014, we entered into a long-term LNG import agreement with a subsidiary of OAO Yamal LNG to import LNG from Russia.

In August 2017, the United States imposed economic sanctions against the Government of Venezuela and certain state-owned entities, including Petroleos de Venezuela, S.A. (“PdVSA”). These sanctions prohibit

U.S. persons from transacting in, providing financing for or otherwise dealing in “new debt” issued by these entities on or after August 25, 2017, with certain exceptions for short-term debt. Neither CNPC nor PetroChina purchased such new debt securities issued by the Government of Venezuela or by PdVSA, nor did they provide any assistance to third parties in this regard. In 2019, the United States issued enhanced sanction measures against Venezuela, which included blocking the property of Venezuelan government and its controlled entities, and introducing new restrictions on Venezuela’s oil sector. Under these programs, persons determined to be operating in the oil sector of the Venezuelan economy, or to have materially assisted, sponsored, or provided financial, material, or technological support for, or goods or services to or in support of, any person included on the list of SDNs and Blocked Persons, may also be subject to risk of being designated for blocking sanctions. CNPC has longstanding trading and investment activities in Venezuela. In 2019, we purchased a small amount of oil product sourced from Venezuela for processing and resale, which contributed approximately 0.7% of our total revenue in 2019. CNPC has suspended purchases of oil from Venezuela. In 2008, CNPC Exploration and Development Company Limited (“CNPC E&D”), a joint venture held as to 50% by us and 50% by a wholly-owned subsidiary of CNPC, acquired 40% stake in the Sinovensa block located in Carabobo, Monagas State, Venezuela. The other 60% stake of the block is held by PdVSA, which also serves as the operator of the block. The block produces and sells heavy oil. We also indirectly hold minority interests in a few other small projects in Venezuela. For the year ended December 31, 2019, the share of profit generated from the Sinovensa block and these other projects accounted for approximately 1.4% of our total profit.

We closely monitor the possible impacts of U.S. sanctions against these Russianthe countries and entities which have trading or investment relationships with CNPC or us. We do not believewill continue to manage our risk exposure and to endeavor that our activities nor those of CNPC, with these sanctioned Russian entities are in violation ofdo not violate any applicable economic sanctions administered by the United States. However, we cannot assure you that current or future regulations or developments related to economic sanctions will not have a material adverse impact on our business or reputation. Certain U.S. based investors may not wish to invest and have proposed or adopted divestment or similar initiatives regarding investments in companies that do business with countries and entities that are subject to U.S. sanctions. These investors may not wish for CNPC or us to make investments or conduct activities in the countries or with the entities that are the subject of U.S. sanctions and may divest their investment in us because of our relationship with CNPC and its investments and activities in those countries or with those entities that are the subject of U.S. sanctions. As a result, the trading prices of our ADSs may be adversely affected.

In July 2012, the U.S. Treasury Department’s Office of Foreign Assets Control, OFAC, added Bank of Kunlun Co., Ltd., or Kunlun Bank, an affiliate of our company due to common control by CNPC, to its “List of Foreign Financial Institutions Subject to Part 561”, which was replaced by the list of Correspondent Account of Payable-Through Account Sanctions, pursuant to the Comprehensive Iran Sanctions, Accountability, and Divestment Act of 2010. OFAC reported that Kunlun Bank provided financial services to at least six Iranian banks that were on OFAC’s sanctions list during 2012. These financial services included holding accounts, making transfers and paying letters of credit on behalf of the designated banks. In 2018, Kunlun Bank has discontinued the business activities which are subject to U.S. sanctions. Since November 2018, Kunlun Bank’s settlement business involving Iran has been limited to settlement of humanitarian materials, limited crude oil trade within the framework of applicable SRE exemptions, and other business activities that are not informed us ofsubject to sanctions, and it has ceased business cooperation with the revenue and profit it generated from suchbanks that are subject to secondary sanctions. Beginning in May 2019, Kunlun Bank further ceased involvement in settlement activities in relationrelated to Iran or whether it will discontinue such activities.Iranian crude oil trade. Our company has no involvement in or control over such activities of Kunlun Bank or CNPC and CNPC subsidiaries and affiliates, and we have never received any revenue or profit derived from these activities.

Risks Related to Government Regulation

Our operations, like those of other PRC oil and gas companies, are subject to extensive regulations and control by the PRC government. These regulations and control affect many material aspects of our

operations, such as exploration and production licensing,industry-specific andproduct-specific taxes and fees and environmental and safety standards. As a result, we may face significant constraints on our ability to implement our business strategies, to develop or expand our business operations or to maximize our profitability. Our business may also be affected by future changes in certain policies of the PRC government with respect to the oil and gas industry. For example, on March 19, 2019, the PRC government passed theOpinions on Implementation of the Reform of the Operation Mechanism of Oil and Gas Pipeline Network (the “Opinion”). According to the Opinion, the PRC government will carry out reforms of the oil and gas pipeline operation mechanism. An oil and gas pipeline network operator shall be established, which will have diversified investors with state-owned capital holding the majority stake. The Opinion states that the PRC government would form an oil and gas market system with multi-channel suppliers in the upstream, an integrated pipeline network with high efficiency in themiddle-stream, and a fully competitive market in the downstream, to improve the efficiency of oil and gas resource allocation. On May 24, 2019, a number of Chinese government agencies jointly issued theRegulations on the Fair Opening of Oil and Gas Pipeline Network Facilities, pursuant to which, from May 24, 2019, oil and gas pipeline network operators shall providenon-discriminatory services of oil and gas transportation, storage, gasification, loading and unloading, transshipment to users who meet the accessing conditions; without proper reasons, they must not delay the signing of or refuse to sign service contracts with users who meet the accessing conditions, and must not make unreasonable requirements. On December 9, 2019, the Chinese government established the China Oil & Gas Pipeline Network Corporation (the “National Pipeline Network Company”). The National Pipeline Network Company is in discussions with the Company regarding a possible acquisition of certain pipeline assets from the Company. As at the date of this report, no definitive agreement has been reached. There is no assurance that the definitive agreement, if any, will not bring any adverse effect on the development of our natural gas and pipeline business and our operation results.

Currently, the PRC government must approve the construction and major renovation of significant refining and petrochemical facilities as well as the construction of significant crude oil, natural gas and refined product pipelines and storage facilities. We presently have several significant projects pending approval from the relevant government authorities and will need approvals from the relevant government authorities in connection with several other significant projects. We do not have control over the timing and outcome of the final project approvals.

Because PRC laws, regulations and legal requirements dealing with economic matters continue to evolve, and because of the limited volume of published judicial interpretations and thenon-binding nature of prior court decisions, the interpretation and enforcement of these laws, regulations and legal requirements involve some uncertainty. Because the PRC Company Law is different in certain important aspects from company laws in the United States, Hong Kong and other common law jurisdictions, and because the PRC securities laws and regulations are still at a stage of development, you may not enjoy the shareholders’ protections that you may be entitled to in other jurisdictions.

Risks Related to Controlling Shareholder

As of December 31, 2016,2019, CNPC beneficially owned approximately 86.166%80.41% of our share capital. This ownership percentage enables CNPC to elect our entire board of directors without the concurrence of any of our other shareholders. Accordingly, CNPC is in a position to:

CNPC’s interests may sometimes conflict with those of some or all of our minority shareholders. We cannot assure you that CNPC, as our controlling shareholder, will always vote its shares in a way that benefits our minority shareholders.

In addition to its relationship with us as our controlling shareholder, CNPC by itself or through its affiliates also provides us with certain services and products necessary for our business activities, such as construction and technical services, production services, materials supply services, social services and financial services. The interests of CNPC and its affiliates as providers of these services and products to us may conflict with our interests.

Risks Related to Pricing and Exchange Rate

Our operations are affected by the volatility of prices for crude oil, refined products and natural gas. We set our crude oil median prices monthly based on the international trading prices for crude oil.

Since the second half of 2014,In recent years, international prices for crude oil have declinedfluctuated substantially and fluctuated at a low level in response to changes in global and regional economy, politics and supply and demand for crude oil. We do not have, and will not have, control over factors affecting international prices for crude oil. Fluctuations and volatility in crude oil prices have a significant impact in our results of operations. A decline in crude oil prices may reduce revenues from, and may result in a loss in, our exploration and production segment. For example, since the beginning of March 2020, the international crude oil price has fallen sharply due to a pessimistic outlook on the world economy affected by theCOVID-19 pandemic and oversupply of crude oil in the global market. The decline in international crude oil prices is expected to greatly affect the Company’s upstream business profits and oil and gas import costs, and affect the Company’s downstream business profits through China’s pricing mechanism of refined oil products, thereby adversely affecting the Company’s overall sales revenue and profits. Further, if crude oil prices remain at a low level for a prolonged period, our company haswould be required to determine and estimate whether our oil and gas assets may suffer impairment and, if so, the amount of the impairment. An increase in crude oil prices may, however, increase the production costs of refined products, reduce demand for our products and affect our operating profits.

Since 2008, theThe PRC government has gradually improved its refined oil pricing mechanism. When there is a change in the average crude oil price in the international market during a given time period, the PRC government can adjust refined oil prices. When international crude oil price experiences sustained increases or becomes significantly volatile, the PRC government may increase its control over the refined oil prices. As a result, the regulation on refined product prices by the PRC government may reduce our profit and cause our refining assets to suffer impairment.

We negotiate the actual settlement price with natural gas users within the ceiling of citygate price range permitted by the PRC government. When the domestic price ceiling set by the government is lower than the international natural gas price, the cost of our imported natural gas will be higher than the sales price of our natural gas, which may reduce our revenues and profit, or result in losses, cause our natural gas assets to suffer impairment.

We receive most of our revenues in Renminbi. A portion of our Renminbi revenues must be converted into other currencies to meet our foreign currency obligations. The existing foreign exchange limitations under the PRC laws and regulations could affect our ability to obtain foreign exchange through debt financing, or to obtain foreign exchange for capital expenditures. The value of Renminbi against U.S. dollar and other currencies may fluctuate and is affected by, among other things, changes in China’s political and economic conditions. The PRC government has implemented a floating exchange rate system to allow the value of the Renminbi to fluctuate within a regulated band based on market supply and demand and by reference to a basket of foreign currencies. Because most of our imports of crude oil, equipment and other materials and our outbound investments are settled in foreign currencies, the exchange rates between RMB and U.S. dollars and any other relevant foreign currencies may have an effect on our crude oil purchase costs and our investment costs.

Risks Related to Environmental Protection and Safety Production

Compliance with changes in laws, regulations and obligations relating to climate change or environmental protection and safety production could result in substantial expenditures and reduced profitability from increases in operating costs. In recent years, the PRC government has implemented environmental protection and safety production laws and regulations and has gradually improved refined oil standards which have stricter requirements for our business, and led to an increase in our operating costs. In the future, the PRC government will implement more stringent environmental protection and safety production regulations and impose higher standards on refined oil products. Compliance with these new regulations and standards will increase our costs and expenses.

Our oil and gas exploration and production activities shall comply with relevant PRC environmentenvironmental protection laws and regulations governing abandonment and disposal processes for oil and gas exploration and production activities. We have established standard abandonment procedures pursuant to these laws and regulations. We have included under our asset retirement obligations the costs for these abandonment activities and this asset retirement obligation is based on our best estimate of future abandonment expenditures. In addition, PRC national or local governments may enact stricter environmental protection regulations and our abandonment costs may increase as a result.

In 2014, the PRC Environmental Protection Law and the PRC Safety Production Law were amended. The amended laws imposed stricter requirements on the sectors in which we operate or participate and as a result our operation costs have increased. Since 2015, China has promulgated relevant policies to accelerate the process of gasoline and diesel fuel quality upgrading in China. Since January 2017, the China V Standards have been effective across the country for vehicle-use gasoline and diesel; and as of January 2018, ordinary diesel of China V Standards will be generally supplied across the country. China is expected to implement more strict standards for gasoline, diesel and other products in the future. New governmental requirements to improve oil quality will continue to pose challenges to our refining and chemicals segment and could increase our costs for oil refining.

Exploring for, producing and transporting crude oil and natural gas and producing and transporting refined products and chemical products involve many hazards. These hazards may result in fires, explosions, spills, blow-outs and other unexpected or dangerous conditions causing personal injuries or death, property damage, environmental damage and interruption of operations.

Some of our oil and natural gas fields are surrounded by residential areas or located in areas where natural disasters, such as earthquakes, floods and sandstorms, tend to occur more frequently than in other areas. As

with many other companies around the world that conduct similar businesses, we have experienced accidents that have caused property damage and personal injuries and death.

Significant operating hazards and natural disasters such as earthquake, tsunami and health epidemics such as the currentCOVID-19 pandemic, may cause partial interruptions to our operations and property and environmental damage that could have an adverse impact on our financial condition.

Risks Related toCOVID-19

In January 2020, the World Health Organization declared theCOVID-19 outbreak a “Public Health Emergency of International Concern” and on March 11, 2020 it was declared a pandemic. Between January 2020 and the date of this report, theCOVID-19 disease has spread to many countries, with the number of reported cases and related deaths increasing daily and, in many countries, exponentially. Many countries’ governments have imposed increasingly stringent restrictions to help avoid, or slow down, the spreading ofCOVID-19, including, for example, restrictions on international and local travel, public gatherings and participation in meetings, as well as closures of universities, schools, stores and restaurants, with some countries imposing strict curfews. In China, various forms of restrictions were imposed and continue to be in place, and there can be no assurance that these restrictions will not be extended further on one or more occasions. These measures have led to a significant decline in demand for, and prices of, our refined oil products and natural gas, and the restrictions are expected to have an adverse effect in the short to medium-term on our oil and gas business chains. Globally, these widespread restrictions in various countries across the world are expected to also result in a decrease in demand for oil, thereby also putting pressure on global oil prices.

We continue to monitor developments closely as theCOVID-19 pandemic develops. The impact of theCOVID-19 pandemic on our business will depend on a range of factors which we are not able to accurately predict, including the duration, severity and scope of the pandemic, the geographies impacted, the impact of the pandemic on economic activity in China and globally, and the nature and severity of measures adopted by governments. These factors include, but are not limited to:

As of the date of this report, there is significant uncertainty relating to the severity of the near- andlong-term adverse impact of theCOVID-19 pandemic on the global economy, global financial markets and the Chinese economy, and we are unable to accurately predict the near-term or long-term impact of theCOVID-19 pandemic on our business. To the extent theCOVID-19 pandemic adversely affects our business and financial results, it may also have the effect of heightening many of the other risks described in this “Risk Factors” section, such as those relating to marco-economic conditions, pricing and our liquidity. See also “Risk Factors — Risks Related to Marco Economic Conditions”, “Risk Factors — Risks Related to Pricing and Exchange Rate.” and “Risk Factors — Risks Related to Liquidity”.

Risks Related to Climate Change

In recent years, the oil industry has faced an increasingly severe challenge imposed by global climate change. Numerous international, domestic and regional treaties and agreements that restrict the emission of greenhouse gas have been executed and become effective. China and some other countries in which we operate have adopted, or are considering the adoption of, regulatory frameworks to reduce greenhouse gas emissions. These include adoption of carbon emission quota and trade regimes, carbon taxes, increased efficiency standards, and incentives or mandates for renewable energies. These requirements may lead to a substantial increase in our expenditures, make our products more expensive, lengthen our project time, reduce the demand for hydrocarbons, and shift hydrocarbon demand toward relatively low carbon sources such as natural gas. Current and pending greenhouse gas regulations may also increase our compliance costs, such as those for monitoring or sequestering emissions. As a result, our results of operations and our strategic investment may be adversely affected.

China is a signatory country to the Paris Agreement which has taken effect since November 2016. China is expected to reach the peak level of carbon emissions by 2030 and plans to roll out the national carbon quota trading system in 2017. As a result, a majority of our subsidiaries operating in China may be subject to mandatory requirement with respect to carbon emission quota and trading, which could adversely affect our business and results of operations.

Risks Related to Insurance

Due to the fact that oil industry is susceptible to high andindustry-specific risks in nature, the current ordinary commercial insurance cannot cover all the business areas in which we operate. We maintain insurance coverage against some,liability risks relating to assets that have significant operational risks, auto risks, and third-party liabilities for personal, property, and environmental risks, but not all, potential losses. We may suffer material losses resulting from uninsurable or uninsured risks or insufficient insurance coverage.

Risks Related to Oil and Gas Reserves

The crude oil and natural gas reserves data in this annual report are only estimates. The reliability of reserves estimates depends on a number of factors, assumptions and variables, such as the quality and quantity of our technical and economic data and the prevailing oil and gas prices applicable to our production, some of which are beyond our control and may prove to be incorrect over time. Results of drilling, testing and production after the date of estimates may require substantial upward or downward revisions in our reserves data. Our actual production, revenues and expenditures with respect to our reserves may differ materially from these estimates because of these revisions.

We are actively pursuing business opportunities outside China to improve our international operations. We cannot assure you, however, that we can successfully locate sufficient, if any, alternative sources of crude oil supply due to the complexity of the international political, economic and other conditions. If we fail to obtain sufficient alternative sources of crude oil supply, our results of operations and financial condition may be materially and adversely affected.

Risks Related to Liquidity

We have made best endeavors to ensure an appropriate level of liquidity and financing ability. However, as we are currently undergoing projects construction in responsemaking our efforts to the growth in our oil and gasfind high-quality large-scale reserves,

strengthening capacity building in key areas, constructing new, and expanding some existing, refinery and petrochemical facilities and constructing several natural gas and oil pipelines, we may have to make substantial capital expenditures and investments. We cannot assure you that the cash generated by our operations will be sufficient to fund these development plans or that our actual future capital expenditures and investments will not significantly exceed our current planned amounts. If either of these conditions arises, we may have to seek external financing to satisfy our capital needs. Our inability to obtain sufficient funding for our development plans could adversely affect our business, financial condition and results of operations.

Risks Related to Effectiveness of Internal Control over Financial Reporting

The SEC, as required by Section 404 of theSarbanes-Oxley Act of 2002, has adopted rules requiring every public company in the United States to include a management report on such company’s internal control over financial reporting in its annual report, which contains management’s assessment of the effectiveness of our internal control over financial reporting. In addition, an independent registered public accounting firm must attest to and report on the effectiveness of our internal control over financial reporting. Although our management concluded that our internal control over our financial reporting for the fiscal year endedas of December 31, 20162019 was effective, and our independent registered public accounting firm has issued an attestation report, which concluded that our internal control over financial reporting was effective in all material aspects as of December 31, 2016,2019, we may discover other deficiencies in the course of our future evaluation of our internal control over our financial reporting and may be unable to remediate such deficiencies in a timely manner. If we fail to maintain the adequacy of our internal control over financial reporting, we may not be able to conclude that we have effective internal control over financial reporting on an ongoing basis, in accordance with theSarbanes-Oxley Act. Moreover, effective internal control is necessary for us to produce reliable financial reports and is important to prevent fraud. As a result, our failure to maintain effective internal control over financial reporting could result in the loss of investor confidence in the reliability of our financial statements, which in turn could harm our business and negatively impact the trading prices of our ADSs, H Shares or A Shares.

Risks Related to Audit Reports Prepared by an Auditor who is not Inspected by the Public Company Accounting Oversight Board

As a company with shares registered with the U.S. Securities and Exchange Commission, or the SEC, and traded publicly in the United States, our independent registered public accounting firm is required under the laws of the United States to be registered with the Public Company Accounting Oversight Board, or the PCAOB, and undergo regular inspections by the PCAOB to assess its compliance with the laws of the United States and professional standards. The PCAOB, however, is currently unable to inspect a registered public accounting firm’s audit work relating to a company’s operations in China where the documentation of such audit work is located in China. Accordingly, our independent registered public accounting firm’s audit of our operations in China is not subject to the PCAOB inspection. In recent years, the SEC and the PCAOB have issued a number of joint statements highlighting continued challenges faced by the U.S. regulators in their oversight of financial statement audits of U.S.-listed companies with significant operations in China. As part of a continued regulatory focus in the United States on access to audit and other

information currently protected by national law, in particular the PRC’s, in June 2019, a bipartisan group of lawmakers introduced bills in both houses of the U.S. Congress that would require the SEC to maintain a list of issuers for which PCAOB is not able to inspect or investigate an auditor report issued by a foreign public accounting firm. The Ensuring Quality Information and Transparency for Abroad-Based Listings on our Exchanges (EQUITABLE) Act prescribes increased disclosure requirements for these issuers and, beginning in 2025, the delisting from U.S. national securities exchanges such as the New York Stock Exchange of issuers included on the SEC’s list for three consecutive years. Enactment of this legislation or other efforts to increase U.S. regulatory access to audit information could cause investor uncertainty for affected issuers, including us, and the market price of our ADSs could be adversely affected. It is unclear if this proposed legislation would be enacted.

The PCAOB has conducted inspections of independent registered public accounting firms outside of China and has at times identified deficiencies in the audit procedures and quality control procedures of those accounting firms. Such deficiencies may be addressed in those accounting firms’ future inspection process to improve their audit quality. Due to the lack of PCAOB inspections of audit work undertaken in China, our investors do not have the benefit of the PCAOB inspection of our independent registered public accounting firm’s audit workswork and audit quality control procedures of our independent registered public accounting firm.procedures.

Risks Related to SEC Litigation Against the “Big Four”PRC-based Accounting Firms

On January 22, 2014, Judge Cameron Elliot, an SEC administrative law judge, issued an initial decision suspending the Chinese member firms of the “Big Four” accounting firms, including our independent registered public accounting firm, from, among other things, practicing before the SEC for six months. In

February 2014, the initial decision was appealed. While under appeal and in February 2015, the Chinese member firms of “Big Four” accounting firms reached a settlement with the SEC. As part of the settlement, each of the Chinese member firms of “Big Four” accounting firms agreed to settlement terms that include a censure, undertakings to make a payment to the SEC, procedures and undertakings as to future requests for documents by the SEC and possible additional proceedings and remedies should those undertakings not be adhered to.

IfHad the settlement terms are not been adhered to, the Chinese member firms of “Big Four” accounting firms may becould have been suspended from practicing before the SEC, which could in turn delay the timely filing of our financial statements with the SEC. In addition, it could be difficult for us to timely identify and engage another registered public accounting firm to audit and issue an opinion on our financial statements.statements and our internal control over financial reporting. A delinquency in our filing of the annual report with the SEC may result in the NYSE initiating delisting procedures, which could harm our reputation and have other material adverse effects on our overall growth and prospect.

Risks Related to Employee Misconduct

We may not be able to detect or prevent employee misconduct, including misconduct by senior management, and such misconduct may damage our reputation and could adversely affect the trading price of our ordinary shares and ADSs.

We have gradually reinforced and enhanced our internal control and corporate governance policies and procedures in order to strengthen our ability to detect and prevent employee misconduct. We cannot assure you, however, that we will be able to detect or prevent such misconduct in a timely fashion, or at all. If we fail to prevent employee misconduct, our reputation may be harmed, and the trading price of our ordinary shares and ADSs could be adversely affected.

Risks Related to Cyber Security

Our activities depend heavily on the reliability and security of our information technology (“IT”) systems. If the integrity of ourOur IT systems were compromisedmay suffer disruptions due to technical failure, cyber attack,cyber-attack, computer intrusions and viruses, technical

failure and disruptions, power orand network outages or natural disasters,disasters. We have adopted multi-layer technological measures for prevention and detection of cybersecurity problems, and we also train our activitiesemployees in order to improve their awareness and ability to detect and respond to cybersecurity situations. If our measures prove to be insufficient, the cybersecurity disruptions could damage or destroy assets, could sustain serious damage,compromise business systems, result in proprietary information being altered, lost, or stolen; result in employee, customer, or third-party information or material intellectual property being compromised, cause physical harm to people or the environment, or otherwise disrupt our business operations. We could incur significant costs to remedy the effects of a major cybersecurity disruption in addition to costs in connection with resulting regulatory actions, litigation or reputational harm. As a result, we and our customers, employees, or third parties could be divulged and, in some cases, personal injury, environmental harm and regulatory violations could occur,adversely affected, potentially having a material adverse effect on our business and financial conditions.

Item 4 —— INFORMATION ON THE COMPANY

Introduction

History and Development of Our Company

Our legal name is “ 中国石油天然气股份有限公司” and its English translation is PetroChina Company Limited.

We are the largest oil and gas producer and seller occupying a leading position in the oil and gas industry in the PRC and one of the largest companies in the world. We are engaged in a broad range of petroleum and natural gas related activities, including the exploration, development, production and marketing of crude oil and natural gas; the refining of crude oil and petroleum products, as well as the production and marketing of basic petrochemical products, derivative chemical products and other chemical products; the marketing of refined oil products and trading; and the transmission of natural gas, crude oil and refined oil products as well as the sale of natural gas.

Currently, substantially all of our crude oil and natural gas reserves andproduction-related assets are located in China. Our exploration, development and production activities commenced in the early 1950s. Over more than six decades, we have conducted crude oil and natural gas exploration activities in many regions of China.

We commenced limited refining activities in themid-1950s. Our chemicals operations commenced in the early 1950s. In the early 1960s, we began producing ethylene. Our natural gas transmission and marketing activities commenced in Sichuan in southwesternSouthwestern China in the 1950s.

We have increased our efforts to pursue attractive business opportunities outside China as part of our business growth strategy to utilize both domestic and international resources to strengthen our competitiveness. Since 2005, we have acquired interests in various oil and natural gas assets in several countries, which significantly expanded our overseas operations and effectively increased our oil and gas reserves and production volumes. We are currently assessing the feasibility of making further investments in international oil and gas markets. At the same time, we have been maintaining certain proportion of imported crude oil and natural gas in accordance with our needs. In 2016,2019, we imported approximately 486.1711.0 million barrels of crude oil, as compared to 435.6640.6 million barrels and 488.6684.9 million barrels of crude oil in 20142017 and 2015,2018, respectively.

We were established as a joint stock company with limited liability under the Company Law of the PRC on November 5, 1999 as part of a restructuring in which CNPC transferred to us most of the assets and liabilities of CNPC relating to its exploration and production, refining and marketing, chemicals and natural gas businesses.

On April 7, 2000, we completed a global offering of H Shares and ADSs. In September 2005, we completed afollow-on offering of over 3 billion H Shares at the price of HK$6.00 per share. In October 2007, we issued 4 billion A Shares at an issue price of RMB 16.7RMB16.7 per share. The A Shares were listed on the Shanghai Stock Exchange on November 5, 2007. As of December 31, 2016,2019, CNPC beneficially owned 157,701,211,528 shares in us, which included146,882,339,136 A

Shares and 291,518,000 H Shares indirectlyin us, representing approximately 80.41% of our share capital in aggregate. The H Shares held by CNPC were through Fairy King Investments Limited, an overseas wholly owned subsidiary of CNPC, representing approximately 86.166% of the share capital of us.CNPC.

For a description of our principal subsidiaries, see Note 18 to our consolidated financial statements.

Our headquarters are located at 9 Dongzhimen North Street, Dongcheng District, Beijing, China, 100007, and our telephone number at this address is(86-10) 5998-6223.5998-2622. Our website address is www.petrochina.com.cn.www.petrochina.com.cn. The information on our website is not part of this annual report. Our annual report on form20-F and other reports filed electronically with the SEC can be found on the SEC’s websitewww.sec.gov.

Our Corporate Organization Structure

The following chart illustrates our corporate organization structure as of December 31, 2016.2019.

Acquisitions and Divestment

On November 24, 2015, our board of directors approvedSeptember 27, 2018, we entered into an equity purchase agreement with Total S.A. to acquire the sale22.407% equity interest held by CNPC Exploration and DevelopmentTotal S.A. in Dalian West Pacific Petrochemical Co., Ltd. (“Dalian West Pacific”). On December 6, 2018, we entered into an equity purchase agreement with each of Sinochem Group Co., Ltd. and Sinochem International Oil (Hong Kong) Co. Ltd., to acquire 8.424% and 25.208% equity interests in Dalian West Pacific, respectively. On May 17, 2019, the transaction was completed. Upon the completion of the transaction, together with our existing equity interest, we held a total equity interest of 84.475% in Dalian West Pacific and it became one of our 50%-owned subsidiaries,principal subsidiaries. We have accounted for this transaction as combination of its 50%entities under common control and restated our financial statements and certain of equity interest in CNPC Trans-Asia Gas Pipeline Co.our operating data, including volumes of imported crude oil, production capacity of refineries, production and sales volumes of refined and chemical products, average realized prices of refined products, ect., Ltd. to a wholly-owned subsidiary of Guoxin International Investment Corporation Ltd. for a consideration of US$2.327 billion. This transactionas if Dalian West Pacific was closed inconsolidated since the second quarter of 2016.earliest year presented.

For other material asset disposal,information on capital expenditures, please see “Item 7-Major Shareholders5 — Operating and Related Party Transactions-Related Party Transactions”.Financial Review and Prospects — Liquidity and Capital Resources — Capital Expenditures and Investments.”

Exploration and Production

We engage in crude oil and natural gas exploration, development and production. Substantially all of our total estimated proved crude oil and natural gas reserves are located in China, principally in northeastern, northern, southwesternNortheastern, Northern, Southwestern and northwesternNorthwestern China. Meanwhile, we have enhanced our overseas cooperation and expanded our strategic presence in five major overseas oil and gas cooperation regions by conducting new project development. In the year ended December 31, 2016,2019, the crude oil and natural gas produced by us at overseas regions accounted for 17.0%18.7% and 8.1%7.0% of our total production of crude oil and natural gas, expressed in BOE, respectively.

We currently hold exploration and exploitation licenses for oil and gas (including coal seam gas) covering a total area of approximately 340.2288.0 million acres, including the exploration licenses covering a total area of approximately 311.3256.9 million acres and the exploitation licenses covering a total area of approximately 28.931.1 million acres.

The following table sets forth the financial and operating data of our exploration and production segment for each of the years ended December 31, 2014, 20152017, 2018 and 2016:2019:

Reserves

Our estimated proved reserves as of December 31, 2016 totaled approximately 7,437.8 million barrels of crude oil and approximately 78,711.8 Bcf of natural gas. As of December 31, 2016,2019, our total estimated proved reserves of crude oil was approximately 7,253.3 million barrels and our total estimated proved reserves of natural gas was approximately 76,236.0 Bcf. As of December 31, 2019, proved developed reserves for crude oil and natural gas accounted for 69.6%75.5% and 51.7%52.3% of our total proved crude oil and natural gas reserves, respectively. Total proved hydrocarbon reserves, including our overseas crude oil reserves of 1,096.7753.5 million BOEbarrels and overseas natural gas reserves of 2,467.41,702.9 Bcf, totaling 1,507.9 million BOE, decreased by 4.1%2.1% from approximately 21,441.920,385.3 million BOE as of December 31, 20152018 to approximately 20,556.419,959.3 million BOE as of December 31, 2016.2019. Natural gas as a percentage of total proved hydrocarbon reserves increased from 60.3%62.5% as of December 31, 20152018 to 63.8%63.7% as of December 31, 2016.2019.

We preparedApproximately 54% and 33% of our estimated proved reserves estimates as of December 31, 2014, 20152019 and 20162018, respectively, were assessed by our internal assessment team and audited by our independent engineering consultants. The other part of our estimated proved reserves as of December 31, 2018 and 2019 and all of the estimated proved reserves as of 2017 were based on the basis of reports preparedassessment performed by our independent engineering consultants namelyaccording to the reserves assessment methodology generally adopted in the U.S. Our independent engineering consultants for 2017, 2018 and 2019 were DeGolyer and MacNaughton, Ryder Scott Company L.P., GLJ Petroleum Consultants and McDaniel & Associates Consultants Ltd. Our reserves estimates include only crude oil and natural gas which we believe can be reasonably produced within the current terms of our production licenses or within the terms of the licenses which we are reasonably certain can be renewed. See “Regulatory Matters — Exploration Licenses and Production Licenses” for a discussion of our production licenses. Also see “Item 3 — Key Information — Risk Factors — Risks Related to Oil and Gas Reserves” for a discussion of the uncertainty inherent in the estimation of proved reserves.

Our reserves data in 2014, 20152017, 2018 and 20162019 were prepared in accordance with the SEC’s final rules on “Modernization of Oiloil and Gas Reporting”.

McDaniel & Associates Consultants Ltd., a petroleum consulting firm with its headquarters in Canada, carried out an independent assessment of our reserves held through PetroKazakhstan Inc. as of December 31, 20152017, 2018 and 2016.2019. Mr. Paul Taylor, the seniorCam T. Boulton, an executive vice president of McDaniel &Associates& Associates Consultants Ltd., was responsible for supervising the preparation of our reserves report. Mr. Paul TaylorBoulton is a member of the SocietyAssociation of Petroleum EvaluationProfessional Engineers and theGeoscientists of Alberta and a member of Society of Petroleum Engineers. He has over 3010 years’ experience in oil and gas reservoir evaluation.

None of the above consulting firms or their partners, senior officers or employees has any direct or indirect financial interest in our company and the remunerations to the firms are not in any way contingent upon reported reserves estimates.

For detailed information about our net proved reserves estimates, please refer to the summary reports of reserves filed heretoherewith as exhibits to this annual report on Form20-F.

The following table sets forth our estimated proved reserves (including proved developed reserves and proved undeveloped reserves), proved developed reserves and proved undeveloped reserves of crude oil and natural gas as of December 31, 2014, 20152017, 2018 and 2016.2019.

As of December 31, 2019, our total proved developed and undeveloped reserves on consolidated basis and on equity method, were 20,312 million BOE, including 7,540 million barrels of crude oil and condense, and 76,629.6 bcf of natural gas.

Our proved undeveloped reserves were 8,602.97,840.6 million BOE in 2016.as of December 31, 2019. The main changes in our proved undeveloped reserves in 20162019 included (i) an increase of 1,286.81,221.0 million BOE through extensions and

discoveries; (ii) an increase of 93.090.9 million BOE through improved recovery; (iii) a decrease of 146.891.3 million BOE through revisions due to our optimization adjustment in explorationthe investment plans in responsewith respect to the decline of crude oil price;certain existing proved undeveloped reserves considering certain new discoveries; and (iv) the conversion of 1,141.81,234.2 million BOE of proved undeveloped reserves into proved developed reserves. In 2016,2019, we spent RMB82,485RMB 166,115 million on developing proved undeveloped reserves. The overwhelming majority of our proved undeveloped reserves were situated around the oil fields that are currently producing. The majority of our proved undeveloped reserves are already scheduled for development within five years after initial booking.

Some of our natural gas proved undeveloped reserves of natural gas are being developed more than five years after their initial disclosure primarily due to the effect oflong-term natural gas supply contracts. The sale of natural gas produced from our reserves located in China is subject to ourlong-term contractual obligations to provide a stable supply of natural gas to customers. We sell all of the natural gas through our pipelines and underlong-term supply arrangements with customers.

There are mainly two types oflong-term supply arrangements. The first ismulti-year supply contracts with terms ranging from 20 to 30 years that can be extended upon mutual agreement. The second type is renewable annual contracts. The majority of the natural gas produced from our gas fields in China is put into our nationwide,long-range pipeline system andto be sold to customers who have entered intomulti-year supply contracts with us in the areas where thelong-range pipeline system covers. A small portion of the natural gas produced by our company is put into local or internal pipeline systems andto be sold to customers in the areas adjacent to our gas fields. These customers typically have formedde-factolong-term relationships with our company over the years and enter into supply contracts with us before the year end to determine the amount of gas to be purchased for the next year, with such contracts being renewed every year. In general, our supply relationships with customers under the annual contracts have existed for more than ten years.

Mainly as a result of our contractual obligations to ensure along-term, stable supply of natural gas to customers, we must maintain a relatively large amount of proved undeveloped natural gas reserves and develop them over an extended period of time (in some cases, longer than five years).

The following tables set forth our crude oil and natural gas proved reserves and proved developed reserves by region as of December 31, 2014, 20152017, 2018 and 2016.2019.