Stratigraphic and sedimentary responses to compressive tectonism in backbulge regions of foreland basin systems remain poorly understood, compared to those in foredeep regions, particularly under low-intensity tectonic deformation. To improve understanding of such responses, this study integrates sequence stratigraphic and sedimentological analyses of the Triassic succession in the central Tarim Basin, western China, using a comprehensive dataset of local and regional seismic sections, well cores, and wireline logs. The studied succession was deposited within a backbulge depression of a foreland basin system. The results delineate four third-order sequences dominated by braided-river delta systems, comprising four sedimentary facies associations in a shallow lacustrine setting: (1) large-scale distributary channels, (2) small-scale distributary channels, (3) proximal mouth bars, and (4) distal mouth bars. Facies evolution records a progressive shift in sandbody distribution, with increased accumulation of large-scale distributary channel deposits during transgressive systems tracts (TSTs) and reduced deposition during highstand systems tracts (HSTs), a pattern directly correlated with forebulge uplift and backbulge-ward forebulge expansion. The stratigraphic and sedimentary response to tectonic compression is expressed by: (i) regional unconformities bounding the Triassic strata, (ii) migration of the centre of subsidence, (iii) enhanced incised-valley development and associated delta progradation, and (iv) distinctive sandy TSTs formed during active thrusting phases when forebulge uplift increased sediment supply. These results provide a robust framework for identifying compressional tectonics in backbulge settings and contribute to improved reconstruction of foreland basin evolution worldwide.

Deep-water gravity-flow depositional systems are characterized by intricate internal architectural configurations and pronounced heterogeneity. Traditional outcrop studies rely heavily on qualitative observations and often fail to capture the sub-seismic 3D spatial heterogeneity required for precise hydrocarbon exploration. This study leverages an integrated multi-geophysical framework to achieve a high-resolution, quantitative characterization of internal structures within gravity-flow fan units in field outcrops. Focusing on the Upper Ordovician Lashizhong Formation at the Beishan outcrop in Wuhai, northwestern Ordos Basin, the research integrates Terrestrial Laser Scanning (LiDAR) to construct a 3D topographic framework and uses Ground-Penetrating Radar (GPR) to probe subsurface architecture. Furthermore, Full-Waveform Inversion (FWI) is employed for the high-resolution reconstruction of relative permittivity, culminating in the generation of a 3D geological model via Sequential Gaussian Simulation (SGS). Six primary lithofacies were identified: (1) massive-to-graded medium-to-fine-grained sandstone, (2) graded fine- to silty sandstone, (3) parallel-laminated fine sandstone, (4) climbing ripple-laminated siltstone, (5) wave ripple-laminated siltstone, and (6) horizontally bedded mudstone. Geometrically, six channel–levee architectural stages and one sheet-lobe stage within a mid-fan setting. Quantitative analysis shows that channel axes maintain a high net-to-gross (N/G) ratio of 0.82 with 92% connectivity, whereas levee and lobe margins exhibit a significantly reduced N/G of 0.28 and 42% connectivity. The overall cross-validation accuracy of the 3D model reached 86.4%. This research provides an objective, quantitative technical framework for 3D spatial characterization and reservoir modeling of complex gravity-flow systems.

The intricate gas–water distribution patterns in tight sandstone gas reservoirs significantly impede effective exploration and development, particularly challenging sweet spot prediction. In the Upper Paleozoic Shanxi Formation of the Ordos Basin, the complex and variable gas–water distribution characteristics remain poorly understood regarding their spatial patterns and controlling mechanisms. This study employs an integrated analytical approach combining casting thin sections, conventional porosity–permeability measurements, and mercury intrusion porosimetry to systematically investigate the petrological characteristics, pore structure, and physical properties of the Shan 2 member reservoirs in southern Yulin. Through the comprehensive analysis of production data coupled with structural and sand body distribution patterns, we identify three predominant formation water types: edge/bottom water, isolated lens-shaped water bodies, and residual water in tight sandstone gas layers. Our findings reveal that three primary factors govern water distribution in the Shan 2 member reservoirs: sand body architecture controlling fluid migration pathways; reservoir quality determining fluid storage capacity; and structural configuration influencing fluid accumulation patterns. This multi-scale characterization provides critical insights for optimizing development strategies in similar tight sandstone reservoirs.

The central portion of the Red Sea Rift (RSR) experiences passive rifting and represents a major geological structure shaped by the divergence of the Arabian and African plates. Its rifting processes are influenced by mantle upwelling and lithospheric extension. This study integrates seismic tomography and 3D density modeling to develop a comprehensive model of upper mantle density and thermal characteristics in the northeastern Arabian Shield. Gravity anomaly inversion, constrained by seismic tomography, was employed to construct the model. Terrain and crustal gravity effects were removed from the EIGEN-6C4 gravity field to obtain the residual mantle gravity anomaly (RMGA).The results show significant density variations in the upper mantle, with high-density anomalies thickening eastward and westward before diminishing at depths of 300 km in regions such as Afar, related to the tectonics of the Red Sea. However, low-density anomalies are observed in the northern Red Sea and eastern Sudan, particularly along plate boundaries and collision zones, suggesting elevated temperatures and dominant mantle upwelling. In addition, a low-density zone around the Arabian Shield and eastern Sudan dominates the lithosphere beneath the fault belt. A thinner, high-density layer beneath the southwest of the Sea may be related to older oceanic lithospheric fragments.Furthermore, seismic tomography highlights extensive low-velocity zones in the upper mantle, indicating high temperatures and potential partial melting beneath the rift. The RF analysis uses raw data comprised of three-component broadband velocity seismograms from earthquakes with magnitudes greater than Mw 5.8 and epicentral distances ranging from 30° to 90°. Therefore, the thermal structure along the rift axis is not uniform, with hotter mantle material ascending beneath the central and southern portions of the RSR. Additionally, seismic velocities between 1.5 and 4.9 km/s align with sedimentary layers in grabens, reinforcing evidence of lithospheric thinning.These findings enhance our understanding of the region's geodynamic evolution by refining the upper mantle density model. However, the thermal regime remains insufficiently explored, emphasizing the need for further geophysical studies to fully elucidate the Red Sea Rift’s tectonic processes.

The Baihetan Hydropower Station is the world's second-largest hydropower station.Long-term and effective deformation monitoring for this area is of great significance.In this paper,InSAR technology was applied to monitor the temporal deformation of a potential unstable slope of a reservoir bank of the Baihetan Hydropower Station to explore its spatiotemporal deformation discipline under the combined effect of water level and precipitation changes.To address the limitation that the effects of climate and environment are often ignored in traditional InSAR linear deformation models,an improved time-series InSAR method was proposed in this paper.This method is based on a periodic model incorporated with the precipitation parameters in the deformation modeling process,with consideration of the effects of water level and precipitation changes in the reservoir bank area;during the deformation estimation process,parameters of deformation rate,elevation corrections,and precipitation factors were calculated based on the functional systems of temporal phase observations,generating the final temporal deformation results for the potential unstable slopes.The Dawanzi-Qiluogou section of the Baihetan Hydropower Station's reservoir was selected as the study area in the experiment,and a period of 31-month deformation time series was obtained.Findings indicated that the temporal deformation characteristic was dominated by a linear trend with periodical variations following the water levels and a two-month lag effect referencing to the dry-rainy alternate month.In addition,the slope deformation in the near river area of the Dawanzi-Qiluogou section was greater than that in the far river area,with the maximum cumulative deformation of-155 mm from January 2010 to July 2022.The maximum deformation difference for the pixels on the exit and central sections was estimated as 98 mm,which is the main cause of cracks in the tunnel wall of the downstream exit section of the Dawanzi Tunnel.The residual high-pass deformation was utilized to evaluate the modeling accuracy of the proposed model,which was estimated as an accuracy increasement of 12.5％compared to the traditional model.In-situ GNSS monitoring results were used to evaluate the external accuracy of the obtained deformation,which was estimated as±2.9 mm.Research results can provide reference for the long-term deformation monitoring and landslide hazard identification for the unstable slopes on the reservoir bank of the Baihetan Hydropower Station.

The Ingasana Mafic-Ultramafic Complex (IMUC) located in the southwestern Blue Nile region of Sudan, hosts significant chromite deposits of considerable economic importance. Although some preliminary studies have been conducted, however important genetic details, such as integrated geophysical and geological analyses, have not yet been thoroughly investigated. In this study, we conducted a detailed investigation of field features, petrography, and Integrated geophysical surveys in the ore prospect areas of the IMUC for the first time. The aim was to clarify the geological structures and metallogenic characteristics of the region, particularly focusing on the boundaries of rock units associated with chromite deposits. The results from the three-dimensional gravity inversion analysis identify the boundaries between different rock types, including subsurface density variations and major shear zones, revealing that most known mineralization sites are closely associated with structural features and the fault system of the area. Exploratory drill holes (D.H.) of different depths confirm the subsurface occurrence of thin chromite with serpentinite as ven bodies within the ultramafic rocks of Ingasana.On the other hand, Petrological Examinations (P.E.) results identify boundaries between other rocks. These findings further suggest that areas with high-density anomalies are the most favorable for hosting chromium, whereas regions covered with clay rocks exhibit the opposite potential. Furthermore, the study highlights the critical role of fault zones as conduits for magma and mineralizing fluids, emphasizing their significance in controlling the emplacement of mafic-ultramafic rocks and associated mineralization. The integration of geophysical and geological data not only enhances our understanding of the structural framework but also provides a robust basis for future exploration, guiding targeted prospecting efforts for chromite and other related mineral deposits in the IMUC.

Correlation analysis of gravity and magnetic anomaly is a useful method for locating the magmatic rocks, however, it is sensitive to the remanent magnetization effects and results in artifact of opposite correlation of sources. To solve this issue, we propose a method of gravity and magnetic data correlation (GMDC) based on magnetic anomaly modulus (Ta) and gravity anomaly (Vz) or vertical gravity gradient (Vzz). This method eliminates the need for reduction to the pole of magnetic anomaly and is less sensitive to the remanent magnetization. It provides more focus on the location of magmatic sources without artifacts. The GMDC values represent the accurate correlation between density and magnetism properties of geological bodies. We apply this method to interpret the gravity and magnetic data in the Kunlunguan and Mengzhuling areas of Guangxi, China. According to the new discriminant parameters, GMDC, we identify the distribution of magmatic rocks with strong remanence, and give more information of the lithological differences.

Sandy debris flows and high -density turbidity currents are two kinds of gravity flows that have been interpreted to produce massive sandstone deposits, yet no consensus has been reached on the depositional mechanism how the deposits should be subdivided. To show differences in the deposits resulting from these two contrastive types of gravity flows, we designed flume experiments (with sand concentrations ranging from 35 wt% to 55 wt%) to examine how gravity flow states and their associated depositional characteristics vary according to their sand: clay ratio and the gradient of slope across which the flows move. The results show that: (1) gravity flows generally occur with two distinct flow layers, consisting of a lower homogeneous mass flow (debris flow) and an overlying upper turbulent cloud (turbidity current). This indicates that flow transformation from a debris flow to a turbidity current is facilitated by low sand content and high slope gradient; (2) the deposited sand bodies contain lower and upper layers which are characterized by inverse and normal grading, respectively, and these are directly related to the bipartite flow state; (3) laminae dip in the direction of flow within the lower sediment layer and are associated with shear forces within the debris flow. We call this laminated structure "laminar sheared layers" and consider this indicative of the laminar flow state that characterizes debris flows; (4) the process of mixing of the flow with ambient fluid causes the clay matrix to separate from the lower debris flow sediments and be subsequently incorporated into the upper turbidity current sediments. This is the cause of the flow transformation. These observations show clearly that sandy debris flows are capable of depositing clean sand bodies. Most significantly, this study demonstrates that the laminar sheared layers are the key sedimentary feature which allows differentiation between sandy debris flow deposits and high -density turbidites, and reveals the occurrence of clay matrix separation, which is important for predicting high -quality oil and gas reservoirs from submarine fan deposits. (c) 2024 Elsevier B.V. All rights reserved.

Whereas the effects of high-order relative sea level change (3rd-order and higher) on the formation and architecture of submarine fan systems are relatively well established, a lack of large-scale spatial and temporal data has resulted in the impacts of low-order relative sea level change (i.e., 2nd-order) eluding characterization. With the aim of revealing the impacts of 2nd-order relative sea level, this study applied regional-scale seismic geomorphology to examine 142 Miocene-aged (21-8.2 Ma) submarine fans in the Baiyun Sag of the Pearl River Mouth Basin (China), integrating a large 3D seismic volume (6000 km2), well logs and core data. By extracting seismic attributes calibrated to well data, architectural elements were interpreted, statistically correlated, and their evolution through time was assessed. The results were as follows: (1) architectural elements of submarine channels and lobes, as well as associated highstand deltas, shelf-margin deltas and incised valleys, were identified based on their seismic geomorphological features and location, revealing that submarine channels shift paleo-seaward from incised valleys and feed lobes; (2) there is a positive correlation between average width of submarine channels and average area of lobes, as well as between the average width of incised valleys and average width of submarine channels; (3) the size of architectural elements is inversely related to proportion of sand; and most importantly, (4) the size variation of architectural elements coincides with changes in 2nd-order relative sea level. Results also indicate that rapid tectonic subsidence played an important control on the size and sandiness of deep-water architectural elements. The findings of this study may inform reconstruction of submarine fan systems and prediction of their petroleum reservoir potential in other systems globally.

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Objective The Jimsar Sag of the Junggar Basin is representative of successful shale oil exploration in China. However, the sedimentary facies in the Permian Lucaogou Formation hosting shale oil has long been disputed. Previous studies proposed two contradictory environments of shallow lakes and semideep to deep lakes in the interior lacustrine basin and identified sandstone interlays as deltaic distal sandbar deposition and beach and bar deposition. Methods The study combined core observations with analyses of sandstone granularity, logging facies, and reservoir properties to identify the development of sublacustrine fans in a semi-deep to deep lake background. Results Fine-grained turbidity currents played a significant role in the transportation and deposition of sediment in these fans. The lithofacies observed included lenticular-wave bedded muddy siltstone to siltstone (dominant type), parallel bedded siltstone, graded siltstone, and massive-graded bedded siltstone to fine-grained sandstone. The cumulative probability granularity curves exhibited smooth upper arches with a high suspension population, and the cross-spots on the C-M diagram were located in the grade suspension zone. The sublacustrine fans consisted of sedimentary microfacies of sheet-like lobes and gravity flow channel levees, showing fining- and coarsening-upwards successions, respectively. These fans contained numerous interlayers of siltstone and fine-grained sandstone, as well as terrigenous detrital particles that influenced the mineral content and enhanced shale oil reservoir properties by promoting the growth of solution pores. Conclusion The study concluded that sublacustrine fan deposits are thin-bedded and fine-grained, and they occur frequently. It also determined that desert reservoirs formed in the areas where sublacustrine fans were deposited, which has significant implications for shale oil exploration in the study area.

In recent years, new breakthroughs have been made in the field of shale oil and gas exploration in the Lower Jurassic Lianggaoshan Formation in Sichuan Basin. At present, there is a lack of systematic studies on reservoir properties and sedimentary facies of the Lianggaoshan Formation shale. Therefore, in this study, taking the Lianggaoshan Formation in Sichuan Basin as an example, the sedimentary facies types of shale reservoirs and their control over shale oil and gas are systematically studied, based on a large number of outcrops, experimental testing, logging, and seismic interpretation methods. The results show that five sedimentary microfacies are developed in the Lianggaoshan Formation in the study area, namely, semi-deep lake mud, shallow lake mud, wave-influenced shallow lake mud, delta-influenced shallow lake mud, and underwater interbranch bay microfacies. The stratum thickness of the Lianggaoshan Formation is in the range of 26–315 m, and mainly distributed in the eastern region, but rapidly thinned in the northwestern region. The sedimentary sequence framework of the Lianggaoshan Formation has been constructed. Moreover, the lithology of the Lianggaoshan Formation shale has been divided into three types, including shale, massive mudstone and silty mudstone. The brittleness index and total organic carbon (TOC) value of three types of shale show a negative correlation. Silty mudstone has the highest brittleness, while that of black shale is the lowest. For porosity and permeability, massive mudstone is better than silty mudstone, and silty mudstone is better than black shale. There are many kinds of matrix pores in the Lianggaoshan Formation shale, and the development degree of inorganic pores is higher than that of organic pores. Finally, based on the analysis of oil-bearing, pore types, physical properties and productivity, it is considered that black shale facies is the most favorable lithofacies type. The deep–semi-deep lacustrine facies belt obviously controls the shale oil enrichment of the Lianggaoshan Formation.

Polarization-adjusted convolutional (PAC) codes can approach the theoretical bound for block error rate (BLER) performance at short-to-medium codeword length. PAC codes have excellent BLER performance using Monte Carlo (MC) rate-profiles and Weighted Sum (WS) rate-profiles, but the BLER performances of the constructed codes still fall away from the dispersion bound at high signal-to-noise ratios (SNR). This paper proposes a List-Search (LS) construction method for PAC codes, which considers the influence of weight spectrum on BLER performance and the condition that sequence decoding for PAC codes having a finite mean computational complexity. The proposed construction method using LS can reduce the number of minimum weight codewords of PAC codes. The BLER performance of the constructed codes is better than that of the constructed codes using MC rate-profiles or WS rate-profiles, and can approach the dispersion bound at high SNR. Moreover, the BLER performance of successive cancellation list (SCL) decoding PAC codes using LS rate-profiles can approach the theoretical bound, but SCL decoding requires a large number of sorting operations. To reduce the number of sorting operations, a path-splitting critical sets (PSCS) construction method is proposed. The PSCS obtained by this method are the information bits subset that have the greatest influence on the number of minimum weight codewords. The simulation results show that this method can significantly reduce the number of sorting operations during SCL-type decoding.

The Great Artesian Basin (GAB) in eastern Australia is one of the most productive complex aquifers on Earth, covering a large portion of the continent. Yet stratigraphic correlation within and among constituent basins of the GAB remain poorly constrained. This has significant implications for resource estimation and management. In this study and for the first time, palynostratigraphic and zircon geochronologic data are integrated from the Lower Jurassic Precipice Sandstone and Evergreen Formation in the Surat Basin-a component of the GAB. The goal was to better constrain the depositional ages as a starting point for calibrating stratigraphy across the GAB. The results showed that the Precipice Sandstone and Evergreen Formation are highly diachronous, as are their sequence stratigraphic subdivisions. We provisionally revise the stratigraphic framework based on the integration of age information to show that the "lower" Precipice Sandstone (lowstand systems tract) ranges from Hettangian to Pliensbachian, the "upper" Precipice Sandstone (transgressive systems tract) extends from Sinemurian to Pliensbachian, the Evergreen Formation varies from Pliensbachian to Aalenian within which the Boxvale Sandstone varies from Pliensbachian to Toarcian and the Westgrove Ironstone member ranges from Pliensbachian to Aalenian. Additionally, the data allow us to provisionally assign the APJ1 to APJ2 palynozone boundary to similar to 190 Ma, the APJ3.2 to APJ3.3 boundary to similar to 180 Ma, and to constrain the APJ2.2.2 palynozone to span 184.80 +/- 0.20 Ma. This new age-context for the Precipice Sandstone and Evergreen Formation will be useful for future workers correlating strata between constituent basins of the GAB, as well as New Zealand and the broader Gondwana palaeocontinent.

宜昌斜坡残留的白垩系盆地是认识中扬子地块白垩纪构造演化的一个窗口.基于对白垩系露头的构造-沉积特征的观察,并结合二维地震剖面的构造-地层解释,厘定了宜昌斜坡白垩系盆地的构造属性和沉积充填特征,构建了白垩系陆内挤压盆地的挤压断-坳结构.宜昌斜坡白垩系盆地是由天阳坪逆冲断裂带控制的陆内挤压盆地.下白垩统盆地为同造山期的挤压断陷,充填有扇三角洲-湖泊沉积体系;上白垩统盆地为后造山期的挤压坳陷,充填了冲积扇-辫状河-风成-浅水含膏湖泊沉积体系.宜昌斜坡和湘鄂西弧形带的上白垩统盆地属于陆内挤压盆地的挤压坳陷,揭示中扬子地块由挤压向伸展构造体制转换的起始时间是新生代.

异重流和滑塌型重力流是依据沉积物供给条件划分的2种重力流类型,代表了近年来重力流沉积学研究的新进展,但在实际应用中还存在概念混淆和沉积物识别的不确定性问题.基于渤海湾盆地黄骅坳陷歧口凹陷的钻井岩心、测井和砂岩粒度分析资料,对比分析异重流和滑塌型重力流沉积在岩石学、沉积构造和粒度分布特征上的差异和识别标志,研究结果表明,二者在陆相断陷湖盆中的有利发育场所为断控陡坡带扇三角洲前、断阶带辫状河三角洲前和具挠曲坡折的缓坡带三角洲前.异重流沉积突出表现为发育砂基支撑的砂砾岩,砾石磨圆度好,发育粗尾正递变层理或逆递变层理,粒度分布直方图呈双峰式,累积概率曲线呈二级台阶式.相比之下,滑塌型重力流沉积突出表现为分选较好,发育含较多泥岩碎块(撕裂屑)的块状砂岩,具有滑塌构造、液化变形构造和包卷层理,粒度分布直方图呈正态单峰式,累积概率曲线呈上拱式.异重流和滑塌型重力流沉积的差异在于沉积物供给条件和重力流流态的不同.异重流受洪水流物源供给,具有高含水量、低密度和低黏度的特征,主要表现为浊流流态;滑塌型重力流受控于滑塌作用和二次沉积机制,具有低含水量、高密度的特征,主要表现为砂质碎屑流流态.

针对油气勘探中深水扇富砂/富泥特征预测的难题,本文应用三维地震和少量的钻井资料,综合采用地震相分析、地震波形分析和地震反演的方法,对珠江口盆地白云凹陷SQ13.8层序细粒深水扇的内幕结构展开精细解剖,结合该扇体在层序格架中的位置、沉积微相的构成、岩性组成和储层特征的细致分析,建立了深水扇的沉积模式.SQ13.8层序沉积期,白云凹陷发育大型低位体系域斜坡扇,斜坡扇的主体由多条大型下切水道及大型水道之间的天然堤堆积构成,长期的重力流水道向下游方向迁移而形成多条大型下切水道,后续发育的不同期次、不同规模、不同充填物重力流水道完全受限在大型水道内,在大型水道内迁移、摆动、叠置、侵蚀或卸载;该类扇体沉积物粒度细,以泥岩为主,发育少量粉砂岩和细砂岩,较细粒的泥质沉积分异在水道两侧的天然堤上,细砂及更粗粒的砂岩储层主要发育较低部位的下切水道内.这种精细解剖深水扇内幕结构进行储层预测的方法,以及在此基础上建立的具有复杂内幕结构的深水扇沉积模式与有利储层分布预测,对南海深水油气勘探具有良好的借鉴和指导意义.

Review of MS #: os-2020-10, A case study of Kuroshio Extension Front: evolution, structure, diapycnal mixing and instability. This manuscript presents results from a combined analysis of ship-based surveys and satellite observations of a front in the Kuroshio extension system. The data, which include fairly high-resolution in-situ observations from a moving-vessel profiler and multiple shipboard ADCPs, are valuable. However, the synthesis in this particular paper has some major flaws and is not a use-ful addition to the scientific literature in its present form. I suggest that it be rejected or withdrawn. The main problem is that the manuscript reads like a cruise report. The analyses and conclusions are not particularly innovative, except for some results that are so remarkable as to be implausible (but the paper treats as consistent with earlier work). The

High-yielding oil wells were recently found in the first member of Paleogene Shahejie Formation, the Binhai area of Qikou Sag, providing an example of medium- and deep-buried high-quality reservoirs in the central part of a faulted lacustrine basin. By using data of cores, cast thin sections, scanning electron microscope and physical property tests, the sedimentary facies, physical properties and main control factors of the high-quality reservoirs were analyzed. The reservoirs are identified as deposits of slump-type sub-lacustrine fans, which are marked by muddy fragments, slump deformation structure and Bouma sequences in sandstones. They present mostly medium porosity and low permeability, and slightly medium porosity and high permeability. They have primary intergranular pores, intergranular and intragranular dissolution pores in feldspar and detritus grains, and structural microcracks as storage space. The main factors controlling the high quality reservoirs are as follows: (1) Favorable sedimentary microfacies of main and proximal distributary gravity flow channels. The microfacies with coarse sediment were dominated by transportation and deposition of sandy debris flow, and the effect of deposition on reservoir properties decreases with the increase of depth. (2) Medium texture maturity. It is shown by medium-sorted sandstones that were formed by beach bar sediment collapsing and redepositing, and was good for the formation of the primary intergranular pores. (3) High content of intermediate-acid volcanic rock detritus. The reservoir sandstone has high content of detritus of various components, especially intermediate-acid volcanic rock detritus, which is good for the formation of dissolution pores. (4) Organic acid corrosion. It was attributed to hydrocarbon maturity during mesodiagenetic A substage. (5) Early-forming and long lasting overpressure. A large-scale overpressure compartment was caused by under-compaction and hydrocarbon generation pressurization related to thick deep-lacustrine mudstone, and is responsible for the preservation of abundant primary pores. (6) Regional transtensional tectonic action. It resulted in the structural microcracks.