Intraplate small-displacement strike-slip faults cannot be accurately identified and analyzed by conventional techniques. To clarify the tectonic characteristics and deformation process of intraplate small-displacement strike-slip faults, structural physical simulation experiments were designed based on the geological conditions of the study area. Taking the Aman relay zone in the northern Tarim Basin as an example, laser scanning was adopted to elaborately and quantitatively analyze the deformation features and differences at each evolutionary stage. This study indicates that the deformation of the F_I17 fault zone in the Fuman Oilfield evolves in four stages: diffuse deformation, R-fracture, branched fault interconnection, and principal displacement zone (PDZ) connection. During the evolution of the fault zone, en echelon anticlines recorded a diagnostic marker for R-fracture, and their relief amplitude represents a vital parameter to classify evolutionary stages. A formation “Net Deformation Magnitude” method is proposed, which can effectively remove post-tectonic stratigraphic deformations irrelevant to strike-slip-related folds and extract fold geometries and relief amplitudes solely generated by syn-kinematic strike-slip faulting. This method further enables quantitative characterization of along-strike heterogeneities in deformation intensity and connectivity of strike-slip fault zones, thereby realizing integrated seismic-geological interpretation. Case study of the Aman relay zone demonstrates that the F_I17 fault zone is currently in the branched fault interconnection stage, characterized by alternating connected and disconnected segments along its strike. The findings establish a geological model for the refined interpretation of intraplate small-displacement strike-slip faults. Furthermore, the newly recognized fault-karst traps associated with R-fractures are expected to become promising new targets for hydrocarbon exploration.

To address the computational challenges of 3D non-planar fracture propagation near the wellbore during hydraulic fracturing, a hybrid numerical model based on the Displacement Discontinuity/Fictitious Stress Method (DDM/FSM) and Finite Volume/Finite Element Method (FVM/FEM) was developed, incorporating a dynamic mesh tracking technique for the fracture front. This 3D non-planar model, constrained by wellbore boundary conditions, was validated for accuracy and reliability, and subsequently used to analyze fracture morphology under stress shadow effects and its key controlling factors. The results indicate that fracture propagation is jointly governed by far-field stress and wellbore-fracture induced stress. Specifically, wellbore-induced stress dominates initiation and reorientation of fractures within three times the wellbore radius, while far-field stress dictates the direction beyond this range. Furthermore, initial fracture dip and fracture number significantly influence morphology: a larger angle between the fracture and the minimum principal stress increases the reorientation distance, whereas a higher number of initial fractures intensify differential propagation and localized reorientation behavior.

Based on data from cores, well logs, seismic profiles, and carbon isotopic compositions, this study constrains the chronostratigraphic framework using carbon isotopic excursion events and applies cyclostratigraphic methods to establish a high-resolution isochronous stratigraphic framework for the Permian Longtan Formation-Triassic Feixianguan Formation in the Sichuan Basin. Through single-well sedimentary evolution analysis and well-seismic integration, the sedimentary characteristics and the patterns and petroleum geologic significance of carbonate platform evolution during the deposition of the Longtan Formation-Feixianguan Formation are systematically revealed. The results show that the Longtan Formation-Feixianguan Formation exhibits 19 to 22 long eccentricity cycles across the entire basin. The difference in cycle counts is attributed to the significant local absence of the top part of the Permian Changxing Formation. Sedimentation rates gradually increase from the southwest to the northeast of the basin. The sedimentary system is overall controlled by a “high productivity, high supply” background, and jointly influenced by sea-level changes and terrigenous input. The Changxing Formation shows progradational ramp characteristics locally, while the Longtan Formation- Feixianguan Formation presents a carbonate ramp sedimentary model. The “tectonics-climate-astronomy” multi-level synergistic driving mechanism governed carbonate platform development, the regional tectonic setting established the macro-paleogeographic framework and accommodation space configuration for carbonate platform development, while the rhythmic sedimentary infilling and the production intensity of carbonate factories were significantly modulated by paleoclimate and astronomical signals. The three factors exhibited stage-wise synergistic evolution in time and space, collectively driving the formation, development, and demise of carbonate platforms. This study provides a new sedimentary model and basis for an in-depth understanding of sedimentary characteristics and carbonate platform evolution patterns during the Permian-Triassic transition in the Sichuan Basin.

Reservoirs of the 4^th member of the Sinian Dengying Formation (Deng-4 Member) around the Deyang-Anyue intraplatform rift in the Sichuan Basin are highly heterogeneous, alongside with unclear genesis and distribution of high-quality reservoirs. This study investigates the reservoirs of the Deng-4 Member in the Ningqiang area in the northern segment of the rift, and compares them with those in the Penglai area in the central segment and the Central Sichuan paleouplift in the southern segment. Three key insights are obtained. First, the Deng-4 reservoirs are facies-controlled, with stromatolite, framework, and thrombolite dolomites serving as the main carriers of reservoir space. The preservation of pores was mainly controlled by early dolomitization, acid generation from microbial organic matter, a burial history characterized by prolonged shallow burial followed by late-stage accelerated deep burial, and early hydrocarbon charging. Second, the reservoirs show a differential pattern of development. The rimmed platform-margin reservoirs in the southern and northern parts of the rift have better potential than the extensional fault-step platform-margin reservoirs in the central part of the rift. The mode of prolonged shallow burial followed by late-stage accelerated deep burial in the northern part of the rift is more conducive to the preservation of pores compared to the mode of continuous and uniform burial in the central and southern areas. Third, during the deposition of the lower-upper Deng-4 Member, the platform-margin microbial mound-shoal complex prograded from east to west perpendicularly to the facies belt, and migrated from south to north parallelly to the facies belt. The lower Deng-4 reservoirs are mainly distributed in the central and southern parts, the middle Deng-4 reservoirs in the central part, and the upper Deng-4 reservoirs in the Langzhong-Wangcang area the central and northern parts. These insights reveal that the Langzhong-Wangcang area in the northern part of the rift, like the Central Sichuan paleouplift in the southern part and the Penglai area in the central part, has great potential of reservoir development in the Deng-4 Member.

Based on data including seismic interpretation, well logs and core slice, analyses were conducted on seismic reflection patterns, stages and distribution of faults, planar distribution of sedimentary facies, types of reservoir spaces, and genesis of reservoirs. This study identified the types of Ordovician platforms in the Manxi area of the Tarim Basin, analysed the controlling factors for high-quality reservoirs and hydrocarbon accumulation, established an accumulation model, and proposed potential exploration targets. The research indicates that the Ordovician in the Manxi area is characterized by a rimmed platform depositional system, where the platform-margin reef-shoal complexes cover an area of approximately 5 091 km². These complexes, superimposed with multi-stage karstification and reticulated fractures, form high-quality fracture-cavity reservoirs, which exhibit a north-south orientation, large-scale distribution, and excellent storage capacity. The Ordovician platform-margin reef-shoal zone is situated within the hydrocarbon-generation center comprising the source rocks in the Precambrian Yuman rift trough, the Yuertusi Formation, and the Cambrian to Ordovician platform-margin foreslope facies. Large-scale hydrocarbon-enriched zones are densely distributed in a north-south trend within the interval from the Penglaiba Formation to the third member of the Yingshan Formation, while exhibiting a linear distribution pattern from the second member of the Yingshan Formation to the Yijianfang Formation. Guided by these insights, Well Qingyu 2 was drilled, and it achieved a high flow rate of 105.6×10⁴ m³/d gas from the second member of the Yingshan Formation during test, with a stable tubing pressure of 107 MPa. This records a significant breakthrough in the Ordovician platform-margin zones in the Manxi area, and reveals a new domain for reserve growth. The research results provide valuable guidance for exploring ultra-deep carbonate reservoirs in the Tarim Basin.

Based on the core, cast thin section, CT, loggings, test and seismic data, the sedimentary-diagenetic characteristics and controls on favorable reservoirs in semi-restricted carbonate ramp setting were elucidated, through a case study of the Lower Cretaceous Yamama Formation in Oilfield A of the Central Arabian Basin. During the Early Cretaceous, the study area was a carbonate ramp in semi-restricted environment, where low- to medium-energy shallow-water lithofacies were common, and the depositional facies were dominated by large-scale lagoon, locally with grain shoal, point reef, back shoal and tidal flat. Bioclastics were diverse, with algae, benthic foraminifera, bivalve, bacinella, and peloids being the most abundant. The Yamama Formation in the study area underwent intense diagenesis during the penecontemporaneous stage, with cementation and dissolution coupled to control the formation and preservation of secondary pores. The reservoirs in the Yamama Formation are composed of packstone, wackstone and bindstone, indicative of frequently varying lithology with poor lateral correlatability. The reservoirs are porous, dominated by micropores, moldic pores, and skeletal pores, with a low abundance of primary intergranular pores, and the pore throats dominated by medium- and micro-throats. The physical properties generally exhibit low to medium porosity, and low to ultra-low permeability. The medium-high permeability reservoirs are underdeveloped. Favorable reservoirs in the Yamama Formation are controlled by local high-energy sedimentation, soluble bioclastic enrichment, intense dissolution, and abnormal-high pressure. Local high-energy grain shoals contain well-preserved primary intergranular pores with no intense cementation, forming small-scale favorable reservoirs. In contrast, low- to medium-energy facies such as lagoon and back shoal are locally rich in soluble bioclastics such as algae and bacinella. The bioclastics were intensely dissolved, forming a large number of moldic or skeletal pores, which effectively improved the reservoir physical properties, thus facilitating the formation of large-scale favorable reservoirs. The favorable reservoirs of Yamama Formation are mainly discovered in YA and YB sections, and large-scale reservoirs thereof are located in the central-northern part of the study area. These represent key targets for subsequent exploration and development.