The types and configurations of source-reservoir coupling can be identified based on the shale oil and gas source-reservoir coupling, which provides a basis for the determination of ideas about shale oil and gas exploration and the efficient exploration and development of shale oil and gas. However, until now, shale oil and gas have not introduced by any scholars into a unified evaluation system for the classification of source-reservoir coupling types, which to some extent restricts the exploration and development process of shale oil and gas. In view of this, based on analyzing the source-reservoir configuration characteristics of typical marine and terrestrial shale oil and gas reservoirs in China, the source-reservoir coupling relationship of shale oil and gas is divided into three categories. Moreover, this study makes clear the geological connotations of different source-reservoir coupling types and their mechanisms controlling oil and gas enrichment, and proposes an efficient exploration approach based on the overall evaluation of shale oil and gas in China. The research results suggest that the source-reservoir coupling types of shale oil and gas can be divided into three categories: source-reservoir separation, source-reservoir coexistence, and source-reservoir integration. Specifically, the migration distance of source-reservoir separation hydrocarbons is above meter scale, and the near-source oil and gas forms sweet spots, represented by the Lower Cambrian Qiongzhusi Formation in Sichuan Basin, the first and second submembers of Member 7 of Triassic Yanchang Formation in Ordos Basin, and the Permian Lucaogou Formation in Jimusar sag of Junggar Basin. The source-reservoir coexistence is characterized with the multi-source supply of hydrocarbons and the coexistence of source and reservoir, of which hydrocarbons are migrated into the nearby advantageous reservoirs to make them oil-bearing as a whole, represented by the Member 2 of Permian Wujiaping Formation in Sichuan Basin, the Jurassic Lianggaoshan Formation in Sichuan Basin, and the Member 4 of Paleogene Shahejie Formation in Jiyang depression of Bohai Bay Basin. The source-reservoir integration indicates that the source rock and reservoir are in the same stratum, and hydrocarbons undergo micro migration within the stratum, represented by the Ordovician Wufeng Formation and Silurian Longmaxi Formation in Sichuan Basin and the Cretaceous Qingshankou Formation in Songliao Basin. Sedimentary environment, biogenic silica, thermal maturity, and hydrocarbon generation/expulsion efficiency are the core elements that affect the shale oil and gas source-reservoir configuration and furtherly control the enrichment of shale oil and gas. Taking the typical shale oil and gas reservoirs in China as an example, the paper furtherly clarifies the exploration levels and ideas under the vertical multi-type source-reservoir coupling configuration at different levels of maturity. The research results are beneficial for quickly identifying and optimizing favorable intervals of shale oil and gas, providing an important scientific basis for the efficient exploration and development of shale oil and gas in China.

As the super and most petroliferous basin in China, Songliao Basin has achieved strategic breakthroughs in the exploration and evaluation of Gulong shale oil, of which the potential and scale of resources remain unclear. Based on the extensive geochemical data including total organic carbon (TOC), rock pyrolysis, vitrinite reflectance and pressure-reserved core, in combination with logging and production data, a systematic evaluation was conducted on various types of shale oil, primarily in Qijia-Gulong sag. A classification scheme using organic matter maturity and reservoir type as key indicators was developed for shale oil in Songliao Basin. As a result, grading standards for shale oil were established based on the key parameters such as TOC content, oil content, effective porosity, and oil saturation. A shale oil resource evaluation method was created, involving the key technologies such as precise evaluation of oil content, light hydrocarbon recovery and calibration of recoverable coefficient. Based on dynamic production data, the geological resource potential of shale oil under current technological conditions was assessed, achieving the predictive analysis of resource recoverability. The comprehensive evaluation indicates that Qijia-Gulong sag contains medium- to high-maturity shale oil resources of 107.73×10 ⁸t (including 42.08×10 ⁸t of Class Ⅰ resources and 33.67×10 ⁸t of Class Ⅱ resources), with technically recoverable resources exceeding 8×10 ⁸t. Additionally, the geological resources of dissolved gas are estimated to be 1.75×10 ¹²m ³, and the technically recoverable resources amount to 0.13×10 ¹²m ³. The resource evaluation results suggest that the favorable shale oil resources in Songliao Basin are mainly distributed in Qijia-Gulong sag, as being the essential strategic replacement resource. With future advancements in development technologies, the recoverable potential of shale oil is expected to increase significantly.

The Cambrian Qiongzhusi Formation is one of the earliest series of strata for shale gas exploration and research in China. In the early stage, due to unclear understandings of the overall geological cognition and limited technological conditions, a number of wells were only deployed in the Weiyuan anticline and Changning anticline with a burial depth less than 3 500 m and a relatively gentle structure. The production rate of the wells is low, indicating a failure in the large-scale commercial development. Recently, major exploration breakthroughs have been made in Well Zi201 and Well Weiye1H, marking significant progress in geological cognition of the deep shale gas in Qiongzhusi Formation of the Deyang-Anyue aulacogen. The sedimentary environment of Qiongzhusi Formation is controlled by the aulacogen. The deep-water siliceous argillaceous shelf facies in the trough and deep-water silty argillaceous shelf facies on the slope of the trough edge are the dominant sedimentary facies zones, which are conducive to the enrichment and accumulation of shale gas. Vertically, Qiongzhusi Formation has developed multiple sets of shale reservoirs, mainly consisting of the 1st, 3rd, 5th, and 7th substrata. In particular, the 5th substratum is a key breakthrough layer with the total organic carbon content of 2.7% to 3.1%, porosity of 4.2% to 4.9%, brittle mineral content of 69.5% to 76.5%, gas content of 7.8 m ³/t to 9.5 m ³/t, and moderate maturity of 3.0% to 3.5%. The 3rd substratum is a potential exploration stratum. Qiongzhusi Formation is expected to realize multi-interval three-dimensional development. The bottom margin of the Cambrian System has a simple structure in the middle section of the aulacogen, lacking of obvious major faults. The pressure coefficient of Qiongzhusi Formation is generally above 1.8, and the preservation conditions are favorable. The aulacogen provides sufficient sedimentary space and material basis, as a result of which the shale in Qiongzhusi Formation is rich in hydrocarbon sources and has achieved a high volume of gas production; the existence of Leshan-Longnüsi paleo-uplift prevents the shale in Qiongzhusi Formation from excessive thermal evolution. A "aulacogen-paleouplift" shale gas enrichment model has been established, and it has been determined that the favorable exploration area of Qiongzhusi Formation is 4 400 km ² and the resources amounts to 2×10 ¹²m ³. The exploration breakthrough of shale gas in Qiongzhusi Formation has opened up another new field for achieving a trillion of cubic meters of reserves and a billion of cubic meters of production. Next, the geological-engineering integrated high-yield model of Well Zi201 will be promoted and applied to the exploration and development fields of marine deep and ultra-deep shale gas in the entire Upper Yangtze area of southern China.

Six sets of high-quality source rocks have been identified globally, with three of them in the pre-Mesozoic strata serving as the primary source rocks for ancient oil and gas reservoirs. Ancient oil and gas reservoirs from the pre-Mesozoic strata exhibit five key characteristics. (1) The predominant basin types include foreland, passive continental margin, and cratonic basins. (2) Their primary type of oil and gas resources remains conventional, although shale oil and gas is developing rapidly. (3) Their oil and gas accumulations are primarily concentrated in the Permian, Devonian, Carboniferous, and Ordovician. (4) Their reservoir lithology is primarily composed of limestones, sandstones, shales, and dolomites. (5) Their burial depth is predominantly within the middle to shallow layers, indicating significant potential for deep plays. The substantial discoveries of ancient oil and gas plays demonstrate enrichment in four fields: the periphery of cratons, carbonate reservoirs, shale oil and shale gas reservoirs, and basement reservoirs. After analyzing the major discoveries in key areas, it is revealed that high-quality source-reservoir-seal combinations form readily in the peripheral regions of cratons that were historically located within low-latitude intertropical convergence zones. Global significant events have played a crucial role in shaping the development of source rocks and the enrichment of shale oil and gas. Within the temporal framework of these significant global events, potential plays can be optimized in advance by reconstructing the paleo-positions of accumulation elements. Based on independent evaluations of recoverable oil and gas reserves and yet-to-be-discovered resources, it is evident that conventional oil and gas exploration should focus on the Arabian Basin, Zagros Basin, Tarim Basin, and other basins. Basement rocks and residual strata are also important potential exploration areas. For shale oil and shale gas exploration, the focus should be on the Devonian Domanik shale in the Timan-Pechora and the Volga-Ural basins in Russia, the Silurian hot shale in the Arabian Basin in the Middle East, the Silurian and Devonian plays in the Ghadames Basin in the North Africa, and several sets of shales in the Sichuan and Junggar basins in China.

Based on analyzing the history of shale revolution in the United States and the differences in geological and engineering characteristics of shale oil between continental basins in China and marine basins in the United States, the paper proposes ten noteworthy issues on continental shale oil revolution in China, including the application and evolution of the nomenclatures of shale oil and tight oil in U.S., the development process of shale oil/tight oil in U.S., the proposal and connotation of shale revolution, and the experience in system and mechanism that can be learned from successful shale revolution in U.S., the work pattern of shale oil in U.S., the relationship between the profit model of shale oil and investment channels, the relationship between production declines of shale oil, the concrete time when a breakthrough is made in shale oil exploration in China, the principles and standards for classification of shale oil, and the continental shale oil revolution in China. Research suggests that the concepts of shale oil and tight oil in North America are identical to some extent. The core of "shale revolution" in U.S. is to improve drilling and completion efficiency, reduce well construction costs, and increase single well production; the development stages of its work pattern is divided according to the changes in both well type and horizontal section length of horizontal well, as well as the development of hydraulic fracturing. The number of drilled and completed wells is an important indicator reflecting shale oil exploration and development. The profit models and investment channels of shale oil extraction are closely related. American companies’ pursuit of recovering investment as soon as possible to obtain profits leads to the general adoption of a production model based on pressure release, with a rapid decline in yield and an L-shaped production curve. In terms of system and mechanism, we should draw on the experience from the application of market mechanisms, the project operation model of "oil companies+lean management", as well as the establishment of shared and open databases. From the perspective of resource base, engineering and technological capabilities, and production expectations, China has the basic conditions for the success in the continental shale oil revolution. All efforts should be made to promote the marketization, technological and management transformation of shale oil exploration and development, highlight the "qualitative development and quantitative breakthrough" of shale oil, and effectively transform resources into reserves and then into beneficial production, which can ensure the victory of shale oil revolution.

The Whole Petroleum System theory establishes the unified accumulation mechanism, enrichment regularity and geodynamic control conditions of conventional and unconventional oil and gas. Tight oil and gas are crucial components of the Whole Petroleum System. This paper reviews the development history of tight oil and gas, looks forward to the resource prospect of tight oil and gas, describes the geological characteristics of typical tight oil and gas reservoirs in China, and reveals the accumulation mechanism and enrichment regularity of tight oil and gas from the perspective of the Whole Petroleum System theory. The research results are as follows. (1) China’s tight oil and gas resources have broad prospects and great development potential, and great achievements have been made in the field of exploration and development, but there are still great challenges in the future, including geological theory, engineering technology and enhanced oil recovery technology. (2) Both physical property and accumulation process of tight oil and gas reservoir are between those of conventional oil-gas and shale oil-gas. The complex capillary network composed of pore throats within the tight reservoir is the key to the self-containment of tight oil and gas. (3) Oil and gas resources in different petroliferous basins in China show distinct differential enrichment characteristics. The Ordos Basin is a super tight oil and gas enrichment basin. (4) Based on the source-reservoir coupling relationship, tight oil and gas reservoirs can be classified into far-source type, near-source type, and intra-source type.

Large tight sandstone gas reservoirs in Tianfu gas field of Sichuan Basin were discovered in the Member 2 of Shaximiao Formation in 2019 and the Member 1 of Shaximiao Formation in 2021, respectively. The proven reserves are 1 349×10 ⁸m ³ and the production is 15.7×10 ⁸m ³ in 2022. Based on the core and geochemical analysis data, the paper investigates the sedimentary reservoir characteristics, natural gas geochemical characteristics, gas reservoir types and gas reservoir formation conditions of Shaximiao Formation in Tianfu gas field. In the study area, shallow-water deltaic and lacustrine deposits are found in the Member 1 of Shaximiao Formation, while fluvial deposits are found in the Member 2 of Shaximiao Formation. The lithologies of the reservoir are mainly composed of feldspathic litharenite and lithic arkose, and the reservoir spaces are mainly occupied by residual intergranular pores, followed by feldspar dissolution pores. The natural gas source of reservoir is mainly from the Triassic Xujiahe Formation. The natural gas in the Member 1 of Shaximiao Formation and the 6th, 8th and 9th sand groups of 1st submember of Member 2 of Shaximiao Formation is dominated by coal-type gas with a small amount of mixed gas, while the gas in the 7th sand group of 1st submember of Member 2 of Shaximiao Formation is characterized by the occurrence of both mixed gas and oil-type gas. The gas reservoir in Shaximiao Formation of Tianfu gas field is a large lithologic gas reservoir with accumulation regularity of dual-source and multi-phase charging, fault and sandbody transport, accumulation around the source, and differential enrichment at the channel. A series of key exploration and development technologies have been developed by tackling the key exploitation problems of large tight sandstone gas reservoirs in Shaximiao Formation of Tianfu gas field, i.e., (1) technology of precisely choosing layers under the constraint of high-precision isochronous stratigraphic framework, (2) technology of finely characterizing sand bodies and precisely predicting target based on 3D seismic survey, (3) supporting technology to accelerate exploration and production based on horizontal well and volume fracturing, (4) processing technology of exploitation and transportation on the ground for the purpose of fast construction, investment, optimization and simplification, (5) integrated technical and economic template for scale and cost-effective development. The discovery of Tianfu gas field has improved the exploration and development of tight sandstone gas in China, and enriched the exploration methods of tight sandstone gas, and effectively promoted the exploration and development process of tight sandstone gas in Sichuan Basin.

Deep coalbed methane (CBM) will become an important field for China to increase the large-scale natural gas reserves and production in the future. It is of great significance to review the history and progress of the geological research on deep CBM propose and evaluate the existing problems and exploration directions, which can provide a reference for developing applicable exploration and development technologies. Analyses reveal that China has made three major advances in the geological research of deep CBM in the past 20 years. First, the basic concept and its scientific connotation of deep CBM have been defined. It is found that there is a critical depth for the absorbed gas content of deep coalbeds, which mainly depends on the coupling relationship between geothermal gradient and geo-stress gradient, and other geological factors can adjust the critical depth. A decrease in the adsorbed gas content may lead to an increase in free gas content, resulting in the orderly accumulation of CBM in the depth sequence and the formation of highly to super saturated reservoirs with abundant free gas in the deep coal. Second, remarkable progress has been made in research of the geological properties of deep coal reservoirs, and it has been recognized that the weakening adsorption of deep coal reservoirs and the increase of free gas content are resulted from the dynamic equilibrium between the positive effect of pressure and the negative effect of temperature. Moreover, it has been found that there is a "highly permeability window" of coal reservoirs near the transition zone of geo-stress state on the depth profile, and the formation temperature and pressure indices related to the reconstruction of deep coal reservoirs may have a threshold property, and the temperature compensation and variable pore compressibility effects may significantly lower the decay rate of permeability for deep coal reservoirs. Third, an in-depth research is gradually implemented on the accumulation and geological evaluation of deep CBM reservoirs, and the exploration on accumulation mechanism focuses on CBM gas-bearing property formed by buried depth changes, vertical permeability distribution and its geological control, thus initially revealing the "depth effect" for CBM reservoir formation. Through on-site case analysis, the relevant understandings have been deepened and expanded from basin to favorable zone, then to sweet spot and from reservoir control to production control. The analyses suggest that the organic connection and deep coupling of basic geology (reservoir-forming process), exploration geology (evaluation optimization) and development geology (dynamic process) are key directions for the geological-engineering integration in deep CBM exploration and development. Therefore, it is suggested future research should focus on "depth effect", including the systematic description of deep CBM reservoir and the characterization of gas reservoir engineering responses to geological conditions.

After more than 10 years of theoretical innovation and engineering practice in shale gas fracturing, supporting the scale cost-effective development of marine shale gas, China has established a theoretical and technical system for marine shale gas fracturing in the middle and shallow layers (< 3 500 m). The technically recoverable resources of deep (3 500-4 500 m) and ultra deep (> 4 500 m) shale gas in China account for 56.63% of the total recoverable shale gas reserve. To achieve efficient gas exploitation is essential for the development of the shale gas industry and guarantee of oil and gas security. The recoverable resources of deep (3 500-4 500 m) and ultra deep (> 4 500 m) shale gas in Sichuan Basin and its periphery account for 65.8% of the total reserve, making the most important contribution to the efficient development of shale gas and the construction of "Daqing Gas Base". Based on the preliminary exploration and practical understanding of deep and ultra deep shale gas fracturing in China and according to the 10 characteristics of deep and ultra deep shale gas fracturing, this paper analyzes six basic problems or challenges that are derived from above situation and urgently need to be solved. Further, the paper proposes five key theories and methods that urgently need to be innovated, points out 10 development directions for deep and ultra deep shale gas fracturing, and emphasizes that China's shale gas development should focus on both deep and shallow layers and continue to improve large-scale production and EOR in the middle and shallow layers. There are both opportunities and challenges in advancing into the new fields of exploration in deep and ultra deep layers to achieve efficient development. It is still necessary to continuously enhance the research, and accelerate the establishment of China's fracturing theory and technology system for deep and ultra deep shale gas.

A new wave of technological revolution and industrial transformation is rapidly advancing against the backdrop of global climate change, the consensus on carbon neutrality, and the imperative for energy transition. The emerging industries of new energy has become a key development focus for nations worldwide. Emerging industries symbolize the trajectory of future technological and industrial advancement. The emerging industries is growing under the leadership of established sectors innovately, while nurturing future industries and serving as a crucial direction for the development of new quality productive forces. New energy stands as a pivotal strategic emerging industry, playing a paramount role within China’s energy strategies of "cleaning up coal, stabilizing oil production, enhancing gas utilization, strengthening new energy development, promoting multi-energy complementarity, and advancing intelligent collaboration". Fueled by advancements in manufacturing, infrastructure and intelligentization capabilities, the existing energy system relied on underground resource endowments is shifting to a novel energy system grounded in technological innovation. The advancement of new quality productive forces promotes the high-quality development of emerging industries in the field of new energy. Through the synergy of technological innovation and the dual carbon goals, the "four-wheel drive" of technology innovation and carbon emissions reduction leading the way, and energy economy and security propelling the progress, will successfully resolve the "impossible triangle" contradiction that has been troubling the energy field. This transition steers towards the transformation of the energy landscape from the fossil fuel-dominated "impossible triangle" to the new energy-driven "achievable triangle", enriches and develops the "energy triangle" theory. Through a series of measures such as constructing innovation platforms, driving technological innovation, fostering collaborative innovation, developing talent teams, and constructing industrial supply chains, a group of technology leaders emerge, which will accelerate the formation of new quality productive forces in emerging industries of new energy. This effort holds the promise of transforming fossil fuels such as coal and oil into more chemical material-oriented resources, striving for new energy to achieve "technological independence", and helping China achieve "energy independence".

Archean buried-hill zone in the western section of Bonan low salient of Bohai Bay Basin has good conditions for hydrocarbon accumulation. Bozhong26-6 oilfield is an Archaean integrated oilfield with proven reserves of crude oil exceeding 100 million tons. Based on a large number of core, thin section, well logging and geochemical data, a systematical study was performed on Bozhong26-6 oilfield. The analysis suggests that the Archean buried-hill reservoirs can be vertically divided into weathered conglomerate zone, weathered fracture zone and bedrock zone, among which the weathered fracture zone is the key reservoir development zone. The superimposed fractures formed by the Indosinian, Yanshanian and Himalayan movements provided the foundation for the development of Archaean buried-hill reservoirs. The Indosinian compression and collision and the Yanshanian strike-slip thrust were the main driving forces for the formation of fractures, and the south-north extension of the Himalayan epoch maintained the validity of earlier fractures. Under the communication of fractures, a wide area of high-quality buried-hill reservoirs is formed by the dissolution of atmospheric fresh water, and the high-quality reservoirs are developed in the zone within 420 m away from the unconformity. The mudstone of Dongying Formation with weak overpressure and strong stability overlying buried hill provides good sealing conditions for the preservation of large-scale oil reservoirs. The Archean buried hills are in direct contact with the source rocks of Huanghekou sag in the south, and are connected with the source rocks of Bozhong sag in the north by the unconformity, thus forming a multi-dimensional oil-gas migration and charging mode. In conclusion, the above findings provide a guidance for the efficient exploration of Archean high-abundance oil reservoirs in Bozhong26-6 oilfield, further improve the hydrocarbon accumulation and reservoir mode of deep Archean buried hills in Bohai Bay Basin, and are of important guiding significance for the oil and gas exploration of the Archean buried hill zone around the southwest Bozhong sag.

In 2024, according to the exploration idea of "fracture-cavity gas reservoirs formed after fracture reconstruction of carbonate rock", three exploration wells were deployed in the Ordovician subsalt area of Ordos Basin to test gas and obtain high-yield industrial gas flow, revealing good exploration potential for the subsalt fracture-cavity gas reservoirs. However, the high-yield and enrichment regularity and comprehensive prediction model of fracture-cavity gas reservoirs are still unclear, making it difficult to determine favorable zones and achieve drilling targets. Therefore, based on cores, thin sections, seismic data, logging data, and production performances, this paper investigates the basic geological conditions and high-yield and enrichment mechanism of the Ordovician subsalt fracture-cavity gas reservoir in Ordos Basin. The results show as follows. (1)The subsalt fracture-cavity gas reservoirs have dual source hydrocarbon supply conditions of the Upper Paleozoic coal measures and Lower Paleozoic marine source rocks, of which the latter are the main source rocks, with the maximum hydrocarbon generation intensity of 1.2×10 ⁸m ³/km ² and sufficient hydrocarbon supply capacity. (2)The reservoir spaces of the subsalt fracture-cavity units are mainly composed of fractures and dissolution pores developed along the fracture zone, mixed with a small amount of matrix intergranular pores. The average porosity can reach more than 10 %, and the average permeability can reach up to 10 mD, demonstrating good reservoir performance. (3)The subsalt faults and associated fracture systems can not only improve the physical properties of dolomite reservoirs and form fracture-cavities with good reservoir performance, but also communicate source rocks with reservoirs, thus providing effective channels for oil and gas to accumulate in fracture-cavity reservoirs. (4)The thick layer of gypsum-salt rock developed in the 6th submember of Member 5 of Majiagou Formation serves as the regional cap rock for the fracture-cavity gas reservoir. The gypsum-salt rock developed in the 10th submember of Member 5 of Majiagou Formation, as well as the Member 3 of Majiagou Formation, serves as the cap rock overlying on the gas reservoir. Moreover, the tight carbonate rocks around the fracture-cavities form lateral sealing, and those good preservation conditions are conducive to natural gas enrichment and formation of fracture-cavity gas reservoirs. Through comprehensive evaluation, it has been preliminarily determined that the favorable exploration area for the Ordovician subsalt fracture-cavity gas reservoirs is about 2.5×10 ⁴km ², and the estimated natural gas reserves can reach 5000×10 ⁸m ³, indicating great exploration potential. It is an important direction and real target for exploration of the Ordovician subsalt natural gas.

The upstream petroleum industry in China has achieved remarkable success. The annual crude oil production of 2×10 ⁸ t is successively achieved under difficult resources conditions, and the natural gas production has achieved rapid growth, reaching 2 200×10 ⁸m ³ in 2022. China has become the fourth largest gas producer in the world. Through exploring the exploration and development situation of oil and gas in China, this paper analyzes the theoretical and technical challenges faced by the upstream petroleum industry, and looks forward to the development prospects of domestic petroleum industry. China has realized oil-gas exploration and development in deep strata, deep water, and unconventional fields. It is predicted that China's crude oil output will be stable at 2×10 ⁸t, and natural gas production will be stable at 3 000×10 ⁸m ³ in 2035. The development of the upstream petroleum industry in China faces theoretical and technical challenges from five major fields:deep strata, deep water, unconventional resources, enhanced oil recovery (EOR) of old oil-gas fields, and carbon capture and storage(CCS) or carbon capture, utilization and storage(CCUS) projects. The future development of petroleum industry will rely more on geological theories and technological innovations in exploration of deep strata, deep water, and unconventional fields. A new generation of theories, technologies, equipment, and efficient construction teams that are suitable for deep strata, deep water, and unconventional oil-gas exploration and development are the key to achieving the high-efficiency development with low cost. The advanced technology and equipment, which are applicable for deep layer, deep water, unconventional oil and gas exploration and development, as well as EOR of old oilfields and CCS/CCUS projects, will be essential to the development of petroleum industry in the future.

Oil and gas are generated from organic matters in the rocks of sedimentary basins. Through an intensive and systematic study of global petroliferous basins, it is recognized that the distribution of global oil and gas fields is highly uneven, and most of oil and gas are enriched and accumulated in a few strata of sedimentary rocks. The distribution of oil and gas is significantly controlled by source rock, so that it is necessary to search for the source rocks initially before discovering new petroliferous basins. The nutrients required for biological growth in the sedimentary basins primarily come from rivers, and the nutrients flowing from rivers into the sedimentary basins control the degree of biological reproduction, and then control the abundance of organic matters in the source rocks, which decides the amount of oil and gas generated and the degree of enrichment of oil and gas resources in the sedimentary basins. Oil and gas are mainly distributed in the three systems on the earth, i.e., the river-lake system, river-gulf system and river-delta system. Specifically, the river-lake system is an important oil-bearing area on the earth. Lacustrine oil is mainly produced by sedimentary organic matters from the algae died in lakes. The growth of algae depends mainly on the nutrients that come from the rivers and flow into the lakes, and these nutrients can facilitate the growth of algae in the rift period and provide a guarantee for the formation of high-quality source rocks. The river-gulf system is the main distribution location of global marine oil. Gulfs are the estuary of rivers, which brings abundant minerals for rivers to promote the growth and proliferation of algae and other aquatic organisms; moreover, the gulfs are relatively isolated, which are conducive to the preservation of organic matters. In fact, boasting of the biggest reserves, the coal-type gas generated from coal-measure source rocks is the most widely distributed in the world and is mainly distributed in the river-delta system. The sediments brought by the river provide fertile soil for the growth of higher plants, and the native higher plants on the river-delta plain provide a solid material basis for the formation of coal-measure gas source rocks. The delta stratum reservoir is well developed with good reservoir-caprock configuration, which is beneficial for natural gas enrichment and accumulation.

In 2022, two key shale oil wells (Well HY1HF and Well H2CHF) were explored for Member 2 of Paleogene Funing Formation in Gaoyou sag of Subei Basin, and an industrial oil flow of 29.7 t/d and 50.5 t/d was separately obtained after fracturing in the drainage and production stage, achieving a great breakthrough in the shale oil exploration for Member 2 of Funing Formation in Gaoyou sag. Based on the observations of cores and thin sections from wells such as Well HY1, whole rock mineral composition analysis by X-ray diffraction, nitrogen adsorption analysis, nuclear magnetic resonance analysis, and organic geochemical analysis of frozen cores, in combination with the dynamic production data of Well HY1HF and Well H2CHF, the paper systematically analyzes the geological characteristics of Member 2 of Funing Formation in Gaoyou sag, and further reveals the enrichment regularities and controlling factors of shale oil from Member 2 of Funing Formation in Subei Basin. Semi-deep to deep lacustrine subfacies shale are developed in Member 2 of Funing Formation of Gaoyou sag, characterized by large thickness and wide distribution, laying the foundation for the enrichment of shale oil. Shale lithofacies control the horizontal and longitudinal distribution of "source sweet spots" and "reservoir sweet spots", among which the lithofacies with relatively high content of clay minerals correspond to good hydrocarbon generation potential, and those with high content of felsic minerals and carbonate minerals have good physical properties and pore-throat structure. According to the characteristics of lithologic association, the shale oil reservoir in Member 2 of Funing Formation can be divided into three types, i.e., self-generating and self-preserving shale oil (Type Ⅰ), mud generating and carbonate preserving shale oil (Type Ⅱ), and mud generating and silty laminae preserving shale oil (Type Ⅲ). High-quality pore-fracture system is developed in the source-reservoir combination of Type Ⅱ shale oil, characterized by good oil content and high mobility. Moreover, the existing dynamic production data indicate that Type Ⅱ shale oil reservoir has good productivity. In addition, good preservation conditions and pressurization resulted from secondary hydrocarbon generation are the key to high and stable production of shale oil. The shale oil exploration breakthrough in Member 2 of Funing Formation of Gaoyou sag indicates that the Paleogene shale oil in Subei Basin has good exploration prospects and Gaoyou sag is a key area for increasing reserves and production. These research results have important reference and guiding significance for the exploration and exploitation of shale oil in continental faulted basins in eastern China.

Offshore hydrocarbon exploration and development in China are currently in a booming stage. Extensive experience has been accumulated from oil and gas drilling operations in the shallow waters of Bohai Bay and the deep and ultra-deep waters of the South China Sea. This has led to the development of a series of key technologies suitable for offshore oil and gas drilling operations in China, laying a solid foundation for the advancement of offshore oil and gas engineering technology. Shallow-water drilling primarily focuses on the techniques such as cluster wells, horizontal wells, high-displacement wells, high-temperature and high-pressure wells, and multilateral wells; on the other hand, deepwater drilling mainly applies the deepwater shallow-depth well construction and deepwater deep-depth drilling technology. The development of fast drilling technique in Bohai Sea and the deepwater drilling operations of Well Liwan 22-1-1 in the South China Sea demonstrate the rapid advance of offshore oil and gas drilling technology in China. Shallow-water drilling technology has achieved synchronization with international standards; especially in the fields of offshore drilling riser design and installation, China holds a leading position in the world. However, the deepwater drilling technology, due to its later development, still faces certain challenges in the critical equipment including subsea wellheads, subsea blowout preventers and marine riser. To address these severe challenges and meet the future demands for the development of deep and ultra-deepwater oil and gas drilling technology, it is crucial to put more efforts in technology breakthrough and innovation in the key equipment fields.

China is abundant in heavy oil resources. At present, heavy oil development mainly relies on thermal recovery techniques, including cyclic steam stimulation(CSS), steam flooding, steam assisted gravity drainage (SAGD) and insitu combustion(ISC). Based on summarizing the current situation of four thermal recovery techniques for heavy oil in China, CSS accounts for more than 50% of heavy oil production. And CSS production are generally in the middle and late stages of development, and it is urgent to change the development methods. In recent years, steam flooding, SAGD, ISC techniques have achieved significant advancement, but still need to be improved and upgraded. The results of carbon emissions per ton of heavy oil measured for different development techniques show that under "Carbon Peaking and Carbon Neutrality" targets in China, thermal recovery techniques for heavy oil characterized by "high energy consumption and high carbon emissions" are confronting double challenge from quality and efficiency improvement as well as energy conservation and emission reduction. Through analyzing the key features of heavy oil in main oilfields and assosicated downstream industry chain and value chain, it is deemed that naphthenic-based heavy oil is mainly treated as raw materials for chemical products. The intermediate products play important and irreplaceable part in downstream industry chain in China. Therefore, it is essential to keep stable heavy oil production in China during the "14th Five-Year Plan" period(2021-2025) and in the future. To achieve the "Carbon Peaking and Carbon Neutrality" targets of the state and oil companies and cope with the double challenge, the paper proposes countermeasures and suggestions for future heavy oil development. Specifically, at the policy level, it is recommended to push the upgrading of heavy oil processing industry, enhancing the development of heavy oil products, and adjusting the heavy oil pricing strategy accordingly to make heavy oil more representative of raw materials for chemical products. At the technical level, it is recommended to continuously improve the existing thermal recovery techniques and optimize and adjust the production from various thermal recovery techniques, promopt the study of limited thermal recovery techniques and low carbon steam generation technique; intensify efforts to research and develop efficient cold production techniques for heavy oil, such as heavy oil polymer flooding and emulsion water flooding.

After nearly 40 years of exploration in Kaiping sag of Pearl River Mouth Basin, a medium to large light oil field has been discovered in deep-water Paleogene strata of Kaiping11-4 structure. To further guide oil-gas exploration in Kaiping sag, the paper deeply investigates the petroleum geological conditions such as hydrocarbon sources, reservoirs, traps, preservation and migration conditions in Kaiping11-4 structure, and summarizes the oil and gas accumulation mode. The geological structure of Kaiping sag is a detachment-type compound half-graben with faults in the north and overlaps in the south. In Kaiping sag, Wenchang Formation develops high quality semi-deep to deep lacustrine source rocks with great hydrocarbon generation potential, and the shallow-water braided delta front deposits of Enping Formation develop a favorable reservoir-cap assemblage. The traps formed under the early tectonic activities are various, including faulted block, faulted anticline and plunging anticline, while the weak tectonic activity in the late period is conducive to oil and gas preservation. The inheritance faults that cut through the source rocks provide vertical migration channels so that oil and gas can be transported through the "source-fault-reservoir" system. The reservoirs in Kaiping11-4 structure have undergone multi-phase continuous charging since 17 Ma, presenting a hydrocarbon accumulation mode with the characteristics of "hydrocarbon supplying from high-quality lacustrine sources, strongly charging through near-source faults, and enriching in multiple stages and levels". The discovery of medium to large light oil field in Kaiping11-4 structure is not only a breakthrough of the new area exploration in Kaiping sag, but also a breakthrough of the Paleogene crude oil exploration in the eastern deep-water area of the South China Sea. It shows that the deep-water area of Pearl River Mouth Basin has a broad prospect for oil and gas exploration, and is of great significance to the exploration of petroliferous basins in the northern deep-water area of the South China Sea.

Waterflooding development oilfields have entered a new stage of deep and fine waterflooding exploitation due to complex relationships between injection and production, frequent dynamic changes in the displacement field, and aggravated inter-layer conflicts caused by long-term waterflooding. The waterflooding development program was adjusted based on static and dynamic engineering production data, which can help researchers master the dynamic changes in oil reservoirs and achieve effective tapping of residual oil. To realize the combination of waterflooding development program optimization and advanced separated zone waterflooding process, the paper systematically summarizes the development status of dynamic analysis technology for oil reservoirs, and mainly elaborates the core issues of waterflooding development program adjustment based on the intercombination of AI methods and reservoir engineering. Meanwhile, the cutting-edge intelligent theories and methods are used to explore and prospect the trend of intelligent and fine adjustments to future waterflooding development program, namely to make full use of the refined and intelligent separated zone waterflooding process to monitor a large amount of dynamic production data in real time. In the future, the study of waterflooding development program optimization will focus on the deep integration of "dynamic data, physical constraints, and AI algorithm"; it is also suggested to further promote the implementation of the intelligent optimization application, i.e., real-time acquisition of monitoring data of waterflooding development oilfields, real-time dynamic forecasts of oil reservoirs and real-time optimization of waterflooding program, and finally achieve the integration of reservoir and oil recovery engineering based on synchronously implementing the design and optimization of waterflooding program and the real-time adjustment of downhole separated zone waterflooding.