The cratonic strike-slip fault zone is an important hydrocarbon accumulation zone in the ultra-deep carbonate rock field of Tarim Basin. At present, the natural energy of the oil reservoirs in the strike-slip fault zone is insufficient, and the decline rate of the oil reserves is fast. It is urgent to deepen the understanding of the geological characteristics of such oil reservoirs, explore new development methods, and investigate countermeasures for enhancing recovery rate. Based on the detailed study of the 12th and 17th fault zones in Fuman Oilfield through comprehensive analysis of outcrops, drilling, seismic surveys, core thin sections, production dynamics, well tests and other data, the types of reservoir space, internal structural characteristics and hydrocarbon accumulation features of the fractured breccia reservoirs are precisely characterized. Appropriate countermeasures for enhancing recovery rate are proposed. The research results indicate: (1) The fractured breccia reservoirs belong to vertical plate-shaped oil reservoirs. The reservoirs develop in the fault core and fracture zone, their reservoir space types are breccia interstitial pores, cavities and structural fractures formed by cataclasis. (2) The ultra-deep fractured breccia reservoirs are initially deposited as tight lithofacies, with very low pre-existing formation porosity and permeability, preserving a low amount of original formation water. There was no significant dissolution of atmospheric water in the later stage, which led to the fractured reservoir bodies having the characteristics of high oil column (up to one thousand meters) and being water-free or having little water content. (3) In terms of geological understanding, detailed description of reservoirs and development methods, three aspects of understanding transformation have been formed: from fault-controlled karst reservoir to fractured breccia reservoir, from description of fault-karst oil reservoir to the internal structure description of fractured breccia oil reservoir, from water injection development to gas injection development.

Taking the Cambrian Xiaoerblak section in the Keping outcrop area as an example, this study aim to clarify the differences in the characteristics and distribution patterns of dolomite reservoirs of the Upper Cambrian Xiaqiulitage Formation in the western Tarim Basin. Based on a systematic analysis of rock thin section, carbon and oxygen isotope compositions, and U-Pb dating, the conclusions are drawn as follows: (1) The Xiaqiulitage Formation, with a total thickness of 350 m, is divided into six members, and is composed of grain dolomite, thrombolite dolomite, stromatolite dolomite, and laminated microbialite dolomite. Seven lithofacies association and two third-order sequences are identified in the Xiaqiulitage Formation, reflecting the overall transition of tidal flat subfacies to inner platform shoal subfacies from bottom to top. (2) The reservoir spaces are dominated by matrix dissolution pores, vugs (dissolution cavities), and intergranular fractures within breccias. The columnar stromatolitic dolomite and thrombolitic dolomite exhibit the best physical properties, followed by grain dolomite, with the overall characteristics of moderate-to-high porosity and moderate-to-low permeability. A comprehensive evaluation indicates that the reservoir properties are optimal in Member 1, Member 2, and Member 6, while Member 5 ranks slightly lower. (3) The dolomite was formed during the early diagenetic stage, and reservoir development is primarily controlled by the combined effects of sedimentary microfacies, unconformity surfaces, and high-frequency sequences. The reservoirs can be classified into two types: unconformity-karst dolomite reservoirs and inner mound-shoal dolomite reservoirs. This research provides critical support for evaluating favorable exploration zones in the Cambrian dolomite plays of the western Tabei area, and offers reliable evidence for hydrocarbon reservoir assessment, particularly in the Xiongying region.

The Ledong gas field group is located near the slope break zone of the Yinggehai Basin, and the gas field has entered the middle and late stages of development, and it is of great significance to clarify the distribution of residual gas for tapping the remaining potential of the gas field. It is important to conduct research on sedimentary facies types, sedimentary models, sand body stacking relationships, and configurations based on rock facies characterization, grain size analysis, logging facies identification, and seismic facies characterization of the 1st member of Yinggehai Formation.Two types of sedimentary facies are identified in the research area, including littoral-shallow marine, and submarine fan. Among them, the littoral-shallow marine subfacies can be further subdivided into three types of sedimentary microfacies: shoreface bar, shoreface beach, and shelf mud.Three types of sedimentary models have been established: progradational shallow marine beach-bar composite model on the gentle shelf slope; slump-reworked bar-filling depositional model at the slope margin; shallow marine gravity-flow slump fan model below the slope break.Three types of sand body stacking relationships have been identified: progradational stacked sand bodies developed above the slope break zone exhibit good connectivity; laterally contacted stacked sand bodies (formed by slump-reworked bar sands) near the slope break show moderate connectivity;vertically isolated submarine fan sands deposited below the slope break display poor connectivity. The slump-reworked bar sand bodies near the slope break zone and the submarine fan-derived sand bodies below the slope break are identified as the most promising potential targets for future gas field development.

The interaction between deep-water gravity flow and bottom flow is a currently hot topic in deep-water sedimentary research in the world. This study focuses on the Upper Eocene of the Rovuma Basin in East Africa, utilizing a comprehensive approach integrating drilling and 3D seismic data to investigate this geological topic. The sedimentary architectural elements and evolution characteristics under a high-frequency sequence stratigraphic framework is studied to reconstruct the depositional and evolutionary patterns of the submarine fan under the interaction of gravity and bottom currents in the Upper Eocene. The results show that: (1) The Upper Eocene submarine fan in the study area develops three types of sedimentary architectural elements: deep-water channels, overbanks and lobes. The channels can be further divided into two types: confined deep-water channels and semi-confined unidirectionally migrating channels. (2) The Upper Eocene third-order sequence can be divided into three fourth-order sequences: Ps1, Ps2 and Ps3. Among them, the Ps1 sequence develops a confined deep-water channel-lobe complex, the Ps2 sequence develops a semi-confined unidirectionally migrating channel-lobe complex, and the Ps3 sequence develops a lobe complex. The evolution of these sequences represents a cyclic evolution process within the third-order sequence under the background of continuous rise in sea level, changes in seafloor landform filling, attenuation of gravity flow energy, and relative enhancement of bottom currents. (3) Bottom currents could strip fine-grained materials in gravity flows accumulate on the northern side (downstream side of the bottom current) of the deepwater depositional system, forming asymmetric overbank / drift deposits with positive topography. This, thereby, restricts channels and lobes to southward erosion and deposition, resulting in the Eocene deepwater depositional system and depositional architectural elements that exhibit a unidirectional migration and stacking pattern on the upcurrent side. It is inferred that bottom currents may enhance the reservoir quality of gravity flow deposits.

For the Carboniferous Huanglong Formation, an important natural gas production layer in Sichuan Basin, in low-relief structural zone on the west side of Huayingshan Fault, there are still problems of unclear accumulation conditions and undetermined favorable exploration zones due to low exploration degree. Based on exploration wells, 2D and 3D seismic data, a new round of evaluation is conducted on the distribution of strata, lithofacies paleogeography, and natural gas accumulation conditions of Huanglong Formation on the west side of Huayingshan Fault. The results show that: (1) The residual strata of Huanglong Formation with thickness mainly between 10-40 m are widely distributed (about 13 100 km2), and about 4 000 km2 according to the new seismic interpretation is added in the northern Sichuan Basin. (2) The intertidal shoal dolomites are widely developed (about 8 200 km2), mainly in the Huanglong Member 2, followed by the Huanglong Member 3. The newly discovered Pingchang-Bazhong shoal belt covers an area of about 2 000 km2. The thickness of dolomite reservoir of the shoal facies in HuangLong Member 2 is mainly 2-20 m. The reservoir has good physical properties, with an average porosity of 3.90%. (3) The source rocks of Wufeng Formation-Longmaxi Formation in the northern Sichuan Basin are widely developed covering an area of about 25 000 km2, and the total thickness is 50-150 m in which the high-quality is 10-60 m. The source rocks of Wufeng Formation-Longmaxi Formation and the reservoirs of Huanglong Formation form favorable reservoir combination of lower generation and upper storage. (4) Controlled by the paleo-uplift slope zone, strata denudation zone, and large fault zone, the Huanglong Formation has developed two large trap groups, i. e., Pingchang-Bazhong, and Guang'an-Quxian, with diverse trap types dominated by lithological-stratigraphic traps and good preservation conditions. Four favorable exploration areas are predicted, indicating a promising prospect for natural gas exploration.

The recent exploration discoveries in Luzhou area indicate that the reef-shoal body of the Silurian Shiniulan Formation has certain potential for reservoir formation. A systematic study based on drilling, outcrop, and 3D seismic data is conducted to explore the development characteristics and exploration significance of the reef-shoal body of Shiniulan Formation. The results indicate that: (1) Reef/bioclastic limestone mainly develops at the top of the first member of Shiniulan Formation, with a thickness ranging from 6 to 40 meters, characterized by moderate-strong amplitude and medium-high frequency seismic reflection character. (2) Affected by the ancient uplift in central Sichuan, the first member of the Shiniulan Formation is developed at mixed tidal flats and intra-platform depressions, forming contiguous tidal edge reefs and shoals on the high terrain of the mixed tidal flats. At some high belts of the intra-platform depressions, intra-platform reefs/bioclastic shoals are developed. (3) The reservoir formation model of Shiniulan Formation is characterized by "near-source hydrocarbon generation, fault-mediated migration, lower-generation and upper-reservoir storage, and composite accumulation". The high-quality hydrocarbon source rocks of the Longmaxi Formation, the reef-shoal reservoir of the first member of Shiniulan Formation, the mudstone of the second member of Shiniulan Formation and the overlying strata form a good source rock-reservoir-caprock combination. The complex network fault system provides conditions for oil and gas migration, and the oil and gas filling period matches the trap formation period (P-K), laying the foundation for large-scale oil and gas accumulation. The Shiniulan Formation reefshoal body is an important oil and gas exploration field worthy of attention.

In recent years, many large-scale biogenic gas reservoirs have been discovered in the world, which has be⁃ come one of the hotspots of natural gas exploration. Biogenic gas reservoirs are mainly distributed in passive continental margin basin, foreland basin, craton basin, fore-arc basin, and accretionary wedge, etc. The conditions of biogenic gas accumulation in accretionary wedge are complicated due to the intense tectonic activity, and there is a lack of systematic understanding of biogenic gas enrichment rules and main controlling factors in accretionary wedge. Based on 2D seismic, well data, we discuss the biogenic gas accumulation conditions in Barbados accretionary wedge, north of South America and define the hydrocarbon migration and accumulation model, and furtherly reveal the law of oil and gas enrichment and point out the favorable exploration direction. The results show that: (1) From west to east, the inner (western) depres⁃ sion, the central uplift, and the outer (eastern) thrust zone develop successively, and the inner zone develops the large sag. (2) The thick mudstone in the large sag provides sufficient biogenic gas source. Large channel complexes, channel-le⁃ vee complexes, channel-lobe complexes, and lobes are mainly developed in western depression, which has a good rela⁃ tionship with traps. Early high relief thrust-faulted anticline is located in the convergence area of oil and gas, which is con⁃ ducive to efficient biogenic gas accumulation. (3) Since the Pliocene, under the compression of the Caribbean Plate, the central uplift belt has widely developed mud diapirs, forming numerous mud diapir-related structural traps. The continu⁃ ous activity of these mud diapirs persists to the present day. The activity of late-stage mud diapirs has led to the destruc⁃ tion of biogenic gas reservoirs, resulting in the failure of all drilling attempts on the flanks of the mud diapirs. So late pres⁃ ervation conditions are the key factors for biogenic gas accumulation. (4) The model of Biogenic gas self-generation and self-storage or lower-generation and upper-storage is established. The western depression has favorable conditions for the formation of biogenic gas reservoirs and is a favorable exploration direction.

Fault interpretation is one of the core tasks in oil and gas exploration and development. However, with the increase of exploration scale, traditional artificial fault interpretation and conventional fault detection methods are unable to meet practical needs. Deep learning methods provide an important approach for intelligent seismic fault recognition, among which deep network models represented by Unet have achieved many successful cases in this type of task. However, due to the particularity of convolution operations, this method loses some information in the feature extraction process, resulting in the need for further improvement in the accuracy and robustness of fault recognition. In this paper, we design a CNN-Transformer hybrid module and embed it into the Unet network framework, proposing a hybrid network model based on U-CNNformer. The hybrid network model improves the mining ability of both global features and local details in the sample set, overcomes the limitations of the conventional Unet network in weak information correlation in fault recognition, and improves the robustness of the model while ensuring the accuracy of fault recognition. Testing on the publicly available North Sea F3 data and applying with actual data in a certain area of Sichuan Basin in China demonstrate that the proposed hybrid network model not only accurately detects fault features but also provides a more detailed characterization of fault distribution, achieving high-precision intelligent fault recognition with excellent application effectiveness.