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The Sichuan Basin is rich in shale oil and gas resources, with favorable geological conditions that the other shale reservoirs in China cannot match. Thus, the basin is an ideal option for fully “exploring petroleum inside source kitchen” with respect to onshore shale oil and gas in China. This paper analyzes the characteristics of shale oil and gas resources in the United States and China, and points out that maturity plays an important role in controlling shale oil and gas composition. US shale oil and gas exhibit high proportions of light hydrocarbon and wet gas, whereas Chinese marine and transitional shale gas is mainly dry gas and continental shale oil is generally heavy. A comprehensive geological study of shale oil and gas in the Sichuan Basin reveals findings with respect to the following three aspects. First, there are multiple sets of organic-rich shale reservoirs of three types in the basin, such as the Cambrian Qiongzhusi Formation and Ordovician Wufeng Formation-Silurian Longmaxi Formation marine shale, Permian Longtan Formation transitional shale, Triassic Xujiahe Formation lake-swamp shale, and Jurassic lacustrine shale. Marine shale gas enrichment is mainly controlled by four elements: Deep-water shelf facies, moderate thermal evolution, calcium-rich and silicon-rich rock association, and closed roof/floor. Second, the “sweet section” is generally characterized by high total organic carbon, high gas content, large porosity, high brittle minerals content, high formation pressure, and the presence of lamellation/bedding and natural microfractures. Moreover, the “sweet area” is generally characterized by very thick organic-rich shale, moderate thermal evolution, good preservation conditions, and shallow burial depth, which are exemplified by the shale oil and gas in the Wufeng-Longmaxi Formation, Longtan Formation, and Daanzhai Member of the Ziliujing Formation. Third, the marine, transitional, and continental shale oil and gas resources in the Sichuan Basin account for 50%, 25%, and 30% of the respective types of shale oil and gas geological resources in China, with great potential to become the cradle of the shale oil and gas industrial revolution in China. Following the “Conventional Daqing-Oil” (i.e., the Daqing oilfield in the Songliao Basin) and the “Western Daqing-Oil & Gas” (i.e., the Changqing oilfield in the Ordos Basin), the Southwest oil and gas field in the Sichuan Basin is expected to be built into a “Sichuan-Chongqing Daqing-Gas” in China.

Studying the accumulation rules of organic matter (OM) in paleo-ocean sediments can not only enhance our understanding of how OM becomes enriched in ancient oceans but also provide guidance for the exploration of shale gas in unconventional shale strata. A breakthrough has been made in shale gas exploration in the early Cambrian Qiongzhusi Formation in South China. However, less attention has been paid to the intraplatform basin of the Yangtze Platform, and the factors controlling organic matter enrichment in this special region remain unclear. This study focuses on a continuous drilling core across the full well section of the Qiongzhusi Formation in the intraplatform basin of the Yangtze Platform. Through the comprehensive analysis of total organic carbon (TOC), major and trace elements, and Mo isotopes, this study investigates the controlling factors for OM enrichment with δ98/95Mo ratios utilized to identify the existence of euxinic bottom water. The examined 240 m long core can be divided into four units, where the TOC values of the lower Units 1 and 2 (0.2–5.0 wt.%) average higher than the upper Units 3 and 4 (0.2–2.5 wt.%). Redox indicators (U/Th, Ni/Co, EF(Mo)—EF(U)) indicate an increasing oxidation of bottom waters from the bottom upwards. δ98/95Mo data further confirm the presence of weakly euxinic conditions in Units 1 and 2, addressing the ongoing controversy surrounding bottom water redox environments. Primary productivity indicators (Ni/Al, Cu/Al) suggest a relatively low average productivity level within the intraplatform basin. The upwelling indicators EF(Co) * EF(Mn) of different profiles in the Yangtze Platform suggest that low productivity within the intraplatform basin can be mainly attributed to the absence of upwelling. Consequently, this study proposes an organic matter enrichment mechanism for the Qiongzhusi Formation in the intraplatform basin, which emphasizes the significance of the redox environment in the formation of high-quality hydrocarbon source rocks in restricted environments that lack upwelling, setting it apart from the deep ocean. These findings have the potential to provide valuable insights for the exploration of high-quality hydrocarbon source rocks in other similar regions.

Based on field work, organic geochemical analyses and experimental testing, a six-property assessment method for shale gas is proposed. These six properties include organic matter properies, lithofacies, petrophysical properties, gas content, brittleness and local stress field. Due to the features of continuous distribution over a large area and low resource abundance in shale plays, a sweet spot should have these following properties： （a） TOC〉2%; （b） brittle minerals content （〉40%） and clay minerals （〈30%）; （c） Ro （〉1.1%）; （d） porosity （〉2%） and permeability （〉0.000 1 mD）, and （e） effective thickness （30-50 m）. Applying these criteria in the Sichuan Basin, the Silurian Longmaxi shale consists of four prospecting sweet spots, including blocks of Changning, Weiyuan, Zhaotong and Fushnn-Yongchuan. Although these four blocks have some similarities, different features were usually observed. After comprehensive analyses using the six-property assessment method, the Fushun-Yongan Block ranks the most favorable sweet spot, followed by the Weiyuan Block. For the other two blocks, the Changning Block is better than the Zbaotong Block. By comparing with the Mississippian Barnett shale, characteristics that are crucial for a high-yielding in the Sichuan Basin include a high content of organic matter （TOC〉2.5%）, a moderate thermal maturity （Ro=0.4%-2%）, a high content of brittle minerals （quartz： 30%-45%）, a high gas content （〉2.5 m^3·t^-1）, and types I and II1 kerogen.

Shale gas plays a crucial role in the national energy supply. However, fast pressure drop, production decline, and water resources pollution caused by well interference and fracture hits become more severe in multi‐layer mining shale gas fields. Such as, it is urgent to evaluate the interference of multi‐stage fracturing horizontal wells (MFHWs) between the upper and lower gas layers in Chinese Jiaoshiba shale gas field. Therefore, we put forward a comprehensive method to analyze the MFHW interference in this paper. The method contains bottom‐hole pressure response analysis (BHPRA) during neighboring well fracturing, BHPRA of well interference test, and production dynamic analysis. Our study indicates that longitudinal pressure interference exists between the Jiaoshiba upper and lower gas layers upon the apparent interference pressure response in a multi‐well test. However, MFHW interferences occur in the corresponding fracturing stages with shorter distance, and the interference strength is related to both well distance and fracturing scales. The Jiaoshiba upper gas layers can be developed to increase the gas production performance, but it is necessary to maintain a reasonable well spacing to avoid severe interference during the development. We put forward a comprehensive method to analyze the MFHWs interference in this paper. The method contains bottom‐hole pressure response analysis (BHPRA) during neighboring well fracturing, BHPRA of well interference test, and production dynamic analysis. Our study indicates that longitudinal pressure interference exists between the Jiaoshiba upper and lower gas layers upon the apparent interference pressure response in a multi‐well test.

The Kuche Depression is considered as the most important gas resource potential and gas exploring area with great gas resource potential and prospect in the Tarim Basin. Based on geochemical experimental analyses and comprehensive geological studies, the general geochemical characteristics of molecular and isotope compositions of rare gases as well as hydrocarbon gases and nonhydrocarbon gases are comparatively studied in the Kuche and Southwestern Depressions. Then, their genetic types are separately identified and gas originations are comprehensively discussed. The main results are as follows. (1) Gas fields in the Kuche Depression have a higher methane abundance, accompanied with low N2 and CO2 abundances, but the Akemomu gas field in the Southwestern Depression has a relatively lower average methane abundance, accompanied with high average N2 and CO2 abundances. The helium abundance of natural gases in gas fields from the Kuche Depression general has 1 order of magnitude higher than the air value. Comparatively, it has more than 2 orders of magnitude higher than the atmospheric value in the Akemomu gas field from the Southwestern Depression. The neon, argon, krypton, and xenon abundances in both Kuche and Southwestern Depressions are lower than the corresponding air values. (2) Natural gases from gas fields in the Kuche Depression and the Southwestern Depressions are generally typical coal-formed gases. The rare gases in the Kuche Depression have typical crustal genesis, mainly deriving from the radioactive decay of elements in the crust, while in the Akemomu gas field from the Southwestern Depression, the rare gases have main crustal genesis with a proportion of 92.5%, probably accompanied with a little mantled genetic contribution. (3) Natural gases in the Kuche Depression are generally derived from coal measure source rocks of Jurassic and Triassic, which principally originated from Jurassic in strata period and coals in source rock types. The Jurassic source rocks account for 55%-75% and the Triassic source rocks account for 25%-45% approximately, while coals occupy 68% and mudstones occupy 32% separately. Natural gases from the Akemomu gas field in the Southwestern Depression mainly originated from humic mudstones of marine and continental transitional source rocks of Carboniferous to Permian.

Coal, coal measure gas, coal conversion to oil and gas, and coal-based new materials are reliable guarantees for stable energy supply and economic and social development in China. The coal-dominated resource endowment and the economic and social development stage determine the irreplaceable position of coal resources in the energy system. Coal measure resources, including aggregated or dispersed solids, liquid and gaseous multitype energies, and metal as well as nonmetallic minerals, are the products of multisphere interaction and metallogenetic materials generation, migration, and accumulation. Coal measures record rich deep-time geological information of transitional and terrestrial peat bogs, which is a crucial carrier to reveal ecosystem evolution, significant organic carbon sequestration, atmospheric O 2 /CO 2 variation, and wildfire events. Coal measure evolution is accompanied by the migration and transformation of various materials during diagenesis-metamorphism, forming differentiated coal compositions besides properties and various mineral resources in its adjacent strata. The enrichment condition, occurrence state, and separation potential are the premise for level-by-level use and efficient development of coal measure resources. Coal measure metallogeny is based on the metallogenic system of multiple energy and mineral resources in coal measures and their environmental effects. Fully understanding coal measure metallogeny is beneficial for promoting the coal transition from fuel to raw materials and strengthening its attribute of multiple mineral resources. The metallogeny comprises various aspects, including: (1) the symbiosis mechanism, co-exploration and co-mining conditions of various resources; (2) the source-sink system of ore-forming materials; (3) the differential carbon accumulation and hydrogen enrichment effect; (4) organic (coal and hydrocarbon) and inorganic (mineral) interactions; and (5) combination of minerals naturally enrichment during the metallogenic process and artificial enrichment during the ore processing process. The coal measure metallogeny belongs to the geoscience disciplines, and study the types, formation, distribution, enrichment mechanisms, evaluation methods, and development strategies of resources related to coal measures. The key scientific problems include geological records related to mineral enrichment processes, metallogenic mechanisms, resource distribution, occurrence evaluation, and accurate development. Developing coal measure metallogeny is significant in improving critical mineral metallogenic theory, revealing various deep-time earth system, and realizing national energy transformation and high-quality development.

Mid-high maturity shale oil is the most realistic field for the scale breakthrough of terrestrial shale oil production in China. Generally, three deficiencies hinder shale oil development in China: heavy oil density, small sweet spot areas, and poor distribution continuity. Thus, identifying the “sweet spots” in shale oil reservoirs is critical for the efficient exploration and development of terrestrial shale oil. This study targets the siltstone type (Class-II shale oil) and pure shale type (Class-III shale oil) of the Chang 7 Member in the Ordos Basin, and identifies three stratigraphic units, namely the hydrocarbon accumulation unit, hydrocarbon generation unit, and hydrocarbon retention unit, which together constitute the in-source “shale oil system”. The hydrocarbon accumulation unit is mainly siltstone, where the hydrocarbons are migrated from shales. It has favorable pore-throat network connectivity with a pore connectivity ratio of 32–57%, being the siltstone-type sweet spots. The hydrocarbon generation unit is mainly composed of high-TOC mudstone/shale and is the main contributor to in-source hydrocarbon generation and expulsion. This unit has high three-dimensional connectivity (28–30%), as shown by the pore-throat network model, associated with vertical paths for hydrocarbon expulsion. The hydrocarbon retention unit is mainly composed of low-TOC mudstone/shale retaining self-generated and migrated hydrocarbons. The pore connectivity rate is 17–42%, and the pore-throat network connectivity direction is uneven. Light and low-carbon-number hydrocarbons are preferentially trapped or even sealed in small pores of the retention unit, forming the typical mudstone/shale-type sweet spots. In the process called shale oil intra-source migration, the oil migrates in source rocks causing component fractionation, which allows more shale oil to enrich in the hydrocarbon accumulation and retention units to form sweet spots, compared with the hydrocarbon generation unit. The migration paths include the one from mudstone/shale to siltstone interlayers and that from the high-TOC mudstone/shale intervals to the low-TOC intervals. The in-source accumulation of shale oil shows the differentiated enrichment model featuring “high-TOC mudstone/shale generating hydrocarbons, low-TOC mudstone/shale retaining hydrocarbons, siltstone accumulating hydrocarbons and multiple intra-source migration paths”. In the Ordos Basin, the organic-lean (TOC 1–3%) mudstone/shale intervals appear to be the sweet spots of shale oil, where there are abundant medium-short-chain hydrocarbons retained with high flowability. After fracturing stimulation, their production conditions may be even superior to those of siltstones. This proposed idea changes the previous strategy to look for sweet spots in high-TOC intervals derived from the shale gas industry.

Lean-stratified water injection is one of the most important technologies to increase production and develop potentials for the oilfield with extreme high water content. However, traditional models cannot entirely solve the inner boundary conditions of lean-stratified water injection. Therefore, we established the injection wellbore constraint equations, which were coupled with the oil/water two-phase numerical reservoir models, and then the seven diagonal form sparse coefficient matrix was solved by block precondition of generalized minimal residual algorithm. Considering the specific situation of lean-stratified water injection wells, reservoir geology and production schemes of the middle part of the sixth Oilfield in Xing Shugang, three mechanism models of multi-layer heterogeneous reservoir were constructed to simulate the lean-stratified water injection. The influences of different segments numbers, modes of combination in segment layer and rhythm characteristics of remaining oil reserves and distribution are evaluated.