Search

Copyright of Acta Petrologica et Mineralogica / Yanshi Kuangwuxue Zazhi is the property of Acta Petrologica et Mineralogica and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Natural Gas Geoscience is the property of Natural Gas Geoscience and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In recent years, multiple exploration breakthroughs have been made in the Third Member of the Leikoupo Formation in the Middle Triassic of Northwest Sichuan Basin. Currently, the overall exploration level is low. The characteristics and formation mechanism of the reservoir are unclear. Techniques such as core observation, pore permeability testing, conventional and cast thin section identification, scanning electron microscopy, mercury intrusion and nuclear magnetic resonance were used to clarify the sedimentary and reservoir characteristics of the 2nd section of the Maokou Formation in the front of the Longmen Mountains in western Sichuan and to explore the main controlling factors of high-quality reservoirs. Research shows that the reservoir rock types are mainly granular dolomite, microbial dolomite and icro-crystalline dolomite. The storage spaces are mainly composed of secondary dissolved pores such as intergranular dissolved pores, microbial “frame” dissolved pores and intercrystalline dissolved pores. The overall physical properties are relatively dense, belonging to medium-low porosity and low permeability reservoirs, with an average porosity of 2. 78% and an average permeability of 0. 76 mD. Sedimentary facies, diagenesis, paleogeomorphology and tectogenesis jointly control the development of the T2 l3 member reservoir in northwestern Sichuan basin. The development of reservoirs is controlled by sedimentary facies, ancient landforms, and diagenesis. The material basis for the development of favorable reservoirs is formed by the deposition of high-energy sand and debris shoals, biogenic debris shoals. The surface dissolution effect of karst slopes in ancient landforms is the best. The quasi contemporaneous dolomitization, recrystallization, and multi-stage karstification are the key factors for reservoir development. Structural fractures and faults are favorable conditions for reservoir improvement. The Zhongba area and the southwestern part of the Shuangyushi area are located at the intersection of high energy beaches and karst slopes with micro ancient landforms. The thickness of the dolomite is large, with developed faults and fractures, strong dissolution, and the development of Class I and II reservoirs. They can be used as key exploration targets for the next step. [ABSTRACT FROM AUTHOR]

Copyright of Acta Sedimentologica Sinica is the property of Acta Sedimentologica Sinica Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Northeast Petroleum University is the property of Journal of Northeast Petroleum University Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Northeast Petroleum University is the property of Journal of Northeast Petroleum University Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The shale oil in the Lower Es3 and Upper Es4 Submembers of Niuzhuang Subsag of Dongying Sag is rich， with high yield， belonging to the typical terrestrial shale oil. Currently， the understanding of material exchanges and reservoir characteristics driven by diagenesis between shale laminae is not clear. The mechanism of the interaction influence of sedimentation and diagenesis on the quality of shale oil generation and storage was analyzed by the petrology， geochemical analysis of trace elements and rare earth elements， and other methods based on the sparry calcite veins and material transfer phenomena， as well as shale hydrocarbon generation and oil-bearing parameters. In addition， material transfer between shale laminae， generation of sparry calcite veins， and shale oil migration were scientifically explained. The geochemical microanalysis of rare earth elements reveals that the Th and U element contents within different material laminae in descending order are as follows： argillaceous layer， sparry calcite vein， recrystallized calcite layer， and contact surface between argillaceous layer and sparry calcite vein. The differentiation of light and heavy rare earth elements in the argillaceous layer and sparry calcite vein is obvious， showing significant enrichment of light rare earth elements and loss of heavy rare earth elements， exhibiting obvious negative anomalies of Dy. The differentiation of light and heavy rare earth elements in the recrystallized calcite layer is not obvious， showing a negative anomaly of Dy. The contents of Th， U， and rare earth elements in the sparry calcite veins are lower than those in the argillaceous layer and higher than those in the recrystallized calcite layer， and it is an essential geochemical indicator to distinguish between the sparry calcite veins and the recrystallized calcite layer. The compaction effect and material component content are the main factors affecting shale porosity. According to the nuclear magnetic resonance experiment， the reduction in pore size greater than 30 nm is the most significant in shale with a burial depth of 3 300-3 600 m， and the reduction amplitude is about 1%/hm. The total content of terrestrial minerals is positively correlated with porosity due to the effect of overpressure fluid pore retention caused by hydrocarbon pressurization. Hydrogenated carbonate minerals have strong resistance to overlying rock pressure， which is beneficial for artificial fracturing. Their intergranular and dissolution pores have large sizes with superior oil storage capacity.

The shale in the 7th member (Chang 7) of Triassic Yanchang Formation on the southeastern margin of the Ordos Basin is characterized by shallow burial depth, light oil quality, large variability in oil well production capacity, and significant resource potential. Identifying the main controlling factors of reservoir enrichment is key to efficient exploration. Based on analysis results of cast thin sections, physical properties, and scanning electron microscope (SEM) tests of the Chang 7 shale member in the Fuxian area, combined with core, well logging, and seismic data, its layer characteristics are described and the main controlling factors are discussed. The results show that the Chang 7 shale in the research area extensively develops gray, dark gray, and gray black source rocks. The lithology is mainly mudstone and mud shale, with organic matter types mainly classified as type Ⅰ-Ⅱ2. The vitrinite reflectance (Ro) values of source rocks range from 0.81% to 1.10%, indicating strong hydrocarbon generation potential. The sandstone reservoirs are mainly fine-grained feldspathic sandstone, with pore types primarily consisting of intragranular pores, residual intergranular pores, dissolution pores, and primary intergranular pores. Porosity ranges from 2.0% to 16.0%, and permeability ranges from 0.01×10-3 to 1.20×10-3 μm2, indicating tight reservoirs. The oil-bearing properties of the reservoir are impacted by the physical properties of the sandstone interlayers and proximity to faults: coarser-grained reservoirs with better physical properties exhibit better oil and gas bearing potential. Reservoir properties are controlled by two factors, sedimentary microfacies and diagenesis. Subaqueous distributary channel microfacies have the best properties, followed by mouth bar microfacies. Strong early diagenetic chlorite cementation and weak calcite cementation contribute to the formation of sweet spots in the physical properties. The development and nature of faults play a crucial role in the Chang 7 shale oil enrichment. Statistical analysis shows that it is difficult to obtain industrial oil flow when the fault displacement exceeds 10 m and the wellbore is within 1 km of the fault. However, when the fault displacement is less than 7 m or when the wellbore is more than 1 km away from a large fault, industrial oil flow is more easily obtained.

Copyright of Petroleum Geology & Recovery Efficiency is the property of Petroleum Geology & Recovery Efficiency and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Natural Gas Geoscience is the property of Natural Gas Geoscience and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Natural Gas Geoscience is the property of Natural Gas Geoscience and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Special Oil & Gas Reservoirs is the property of Special Oil & Gas Reservoirs Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Natural Gas Geoscience is the property of Natural Gas Geoscience and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Petroleum Geology & Experiment is the property of Petroleum Geology & Experiment Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Based on the data of drilling core, casting thin sections, mercury injection capillary pressure, physical property, scanning electron microscope and wireline loggings, the reservoir types of Cenomanian-Early Turonian in Southeastern Iraq were classified based on geological origin and petrophysical characteristics, and reservoirs characteristics and the main controlling factors were clarified. The results show that the reservoirs in Cenomanian-Early Turonian are divided into sedimentary type, diagenetic, sedimentary-diagenetic and composite types. Sedimentary type is developed in high-energy envronments, with abundant primary interparticle pores, and its physical properties are high-porosity and high-permeability, which is the first choice of the target for the development. Diagenetic type is deposited in a low-energy environment, with a large number of secondary pores formed by penecontemporaneous dissolution and physical properties are medium-high porosity and medium-low permeability. It is an important replacement resource for long-term stable production. The depositional energy of sedimentary-diagenetic type is moderate, developing a small amount of primary intergranular pores, and penecontemporaneous dissolution forms secondary pores, with medium-high porosity and medium-permeability, and which is an important support resource to increase the production. The pores of composite types are under the comprehensive control of tectonics, sedimentation and diagenesis, and the physical properties are medium-high porosity and medium-permeability, which is an important perforation target in the early stage of development. During Cenomanian-Early Turonian, Southeastern Iraq is a wide and shallow carbonate ramp, the sedimentary facies is significantly differentiated, and the penecontemporaneous diagenesis is sufficient; during the sequence cycle, the sedimentary fades evolves rapidly, and the climate and exposure span control the type and intensity of diagenesis. Tectonism forms faults locally, and promotes burial dissolution. The results provide a geological basis for the evaluation and development of the thick bioclassic limestone reservoir. [ABSTRACT FROM AUTHOR]

Copyright of Natural Gas & Oil is the property of Editorial Department of Natural Gas & Oil and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

[Objective] Marine red beds are distributed across various stages in geological history, are often interpreted as products of special environments, and have attracted widespread attention. The Sowa Formation in the Jurassic Qiangtang Basin is a set of sedimentary rocks composed of clastic and carbonate mixed sediments. In the Sowa Formation exposed in Bilocuo, Shuanghu county, Tibet, the red beds are mainly composed of carbonate sediments. [Methods] This study explored the causes of th red color and significance in the deposition and diagenesis of the red beds based on sedimentological, mineralogical, and geochemical methods. [Results] Field sedimentology and downhole thin section identification of these red beds revealed that the rocks are composed of grain-supported limestone, with abundant debris from cephalopods, echinoderms, bivalves, bryozoans, gastropods, and other benthic organisms. Biogenic debris and terrestrial quartz debris are the main components of the ooids, which display characteristics of a high-energy beach environment. Spectroscopic studies and scanning electron microscopy indicate that the main cause of the red color is submicron- to micron-sized pseudo-hexagonal and tetragonal hematite crystals. The coloration minerals are concentrated in the ooid cortex structure, and the cementing material is virtually devoid of coloration minerals. This suggests that during early diagenesis, particularly during the formation of ooids and peloids, iron-loving microorganisms played an important role in capturing iron oxides. Furthermore, the geochemical analysis of carbonate minerals shows that the redness is positively correlated with the flux of terrestrial debris input. Additionally, it exhibits a positive Ce/Ce* anomaly (1.1-1.3) and a pattern of enriched-middle rare earth elements "bulge", indicating that the iron oxides underwent reductive dissolution.[Conclusions] Based on these findings, the study reconstructed the red coloration process of these red beds. The input of terrestrial iron-bearing minerals provided the material basis for the red coloration, and then, during early diagenesis, reductive fluids dissolved the iron-bearing minerals, providing free iron ions for iron-loving microorganisms, allowing them to recrystallize and ultimately form hydroxyl iron and cause red coloration through chemical or biological processes. [ABSTRACT FROM AUTHOR]

Copyright of Natural Gas Industry is the property of Natural Gas Industry Journal Agency and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Northeast Petroleum University is the property of Journal of Northeast Petroleum University Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Special Oil & Gas Reservoirs is the property of Special Oil & Gas Reservoirs Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In recent years, natural gas discoveries have been continuously made in the first member of the Permian Maokou Formation in the Sichuan Basin, bringing attention to the genesis mechanism of marlstone reservoir space. Centimeter-scale fracture-cavity type reservoir space is one of the newly discovered types in the first member of the Maokou Formation, and relevant research has not been publicly reported. Taking well A1 in the Sichuan Basin as an example, based on core observation and description, the characteristics and genesis of fracture-cavity fillings were studied through comparative analysis of microscopic petrology, carbon-oxygen isotopes, strontium isotopes, and trace elements. The similar distribution characteristics of carbon-oxygen isotopes and strontium isotopes between calcite cement and mudstone matrix in the fractures of the first member of the Maokou Formation indicated that calcite mainly came from the dissolution and redeposition of surrounding rocks. Compared with marlstone, the fracture calcite cement showed lower contents of valence elements (V, Cr, U, Mo) and rare earth elements (REE), while the content of micronutrient elements (Ni, Cu, Zn) increased, revealing the differential migration pattern of trace elements in this process. The differential variation characteristics of Mn and Sr contents between calcite and marl matrix revealed the marine affinity of diagenetic fluids, further indicating their independence from atmospheric freshwater and deep hydrothermal fluids. Since the Late Jurassic, lateral tectonic thrusting pressure has formed detachment faults and related fold systems in southeastern Sichuan, which potentially caused deformation of the Maokou Formation marlstone and the generation of centimeter-scale fracture spaces. Diagenetic fluids formed during subsequent compaction-dissolution processes (including lateral dissolution) provided material sources for quartz and calcite cement in the fractures.

Objective Defining the distribution of sweet spots in tight reservoirs is the focus of tight oil and gas exploration. Methods Using core observation, thin section identification, X-ray diffraction, homogenization temperature measurements of inclusions, and conventional physical property analysis, the sedimentary characteristics, reservoir characteristics, and diagenesis of Upper Palaeozoic tight sandstones in the Binchang area, southern Ordos Basin were studied in detail.The main controlling factors of reservoir formation were identified and the development model of high-quality reservoirs was established. Results The results show that sedimentary facies are the basis of reservoir formation, and the core beach microfacies of the braided river delta plain have coarse grain sizes, small pore-medium-fine throat pore structures, and relatively good reservoir physical properties. The underwater distributary channel and estuary bar in front of the meandering river delta have fine grain sizes and pore throat structures of micropore-microat throat pore structure, and the reservoir's physical properties are relatively poor. Diagenesis plays an important role in controlling the development and distribution of high-quality reservoirs. Intermittent volcanic tuff is transformed into kaolinite in acidic strata and altered into chlorite sheaths in alkaline strata, which inhibits quartz overgrowth and calcite cementation and protects the reservoir space. The secondary enlargement of quartz is mainly caused by the leaching of SiO2 from mudstone to sandstone.The main reasons for the cementation of calcite roof and floor are the filling of feldspar and the dissolution of cuttings in the middle and late stages of calcite. The microfractures formed by late tectonic transformation have no calcite cementation, which improves the physical properties of the reservoir and plays an adjusting role in the gas reservoir. There are two solution pore development zones near burial depths of 3 750 m and 3 900 m in the Binchang area. The optimal reservoir is the medium-coarse-grained sandstone rich in chlorite mantle formed by the transformation of volcanic tuffaceous matter in the dissolution pore development zone. The sub-optimal reservoir is mainly distributed in the middle and lower parts of the sand body with a greater single-body thickness, cyclicity and no mudstone interval in the dissolution pore development zone.This zone is composed mainly of medium-coarse-grained sandstone lacking chlorite film, calcite cementation and secondary enlargement of quartz are the lowest. Conclusion These research results further increase the understanding of the genesis of the development of high-quality tight sandstone reservoirs in the Upper Palaeozoic, providing important guidance for natural gas exploration and development in this area.

Copyright of Petroleum Geology & Experiment is the property of Petroleum Geology & Experiment Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

[Objective] The restricted environment reservoir of Cretaceous Mishrif Formation in M oilfield in the Middle East is complicated and the understanding of reservoir heterogeneity is insufficient, which restricts the effective development of this type of reservoir. Therefore, reservoir characteristics, distribution and main controlling factors of heterogeneity in restricted environment were studied. [Methods] Based on the data of core, cast thin section, physical properties and mercury intrusion experiment. Through mathematical statistics and well correlation, the petrophysical of different reservoirs are clarified and the spatial distribution is described. The main controlling factors of reservoir characteristics in restricted environment are explained, and the origin models of different reservoirs are established. [Results] Three types of reservoir were found in the restricted environment, designated as reservoir types 1, 2 and 3. Type 1 reservoirs were developed in high-energy depositional environments (tidal channels, intraplatform shoals etc.) and underwent quasi-contemporaneous dissolution. These reservoirs comprise mainly grainstone with medium-to-high porosity and medium-to-high permeability. The reserve space is mainly composed of intergranular pores and dissolution pores. It is the preferred target type for reservoir development, as it is present on a huge scale with stable distribution. Type 2 reservoirs were mainly developed in high-energy depositional environments such as lagoons, and experienced dissolution in the quasi-contemporaneous period. These reservoirs include grain-bearing limestone, wackestone and packstone with mainly medium-to-high porosity and medium-to-low permeability. No primary intergranular pores are developed, and the reserve space consists of matrix-host micropores, mddic pores and intercrystalline pores. This type of diagenetic reservoirs are present on the largest scale, but they are in the form of thin layers with highly frequent interlayers, and development would be difficult. Type 3 reservoirs were formed in intra-platform shoals and experienced quasi-contemporaneous dolomitization. They are mostly dolomite with medium-to-high porosity and medium-to-low permeability. Reservoir type 3 are small in scale and are only locally developed in the upper part of the Mishrif Formation. [Conclusions] The study concluded that the genesis of reservoir type 1 was mainly controlled by sedimentation, which controlled the original structural components of the rock and in turn controlled the type and intensity of diagenesis in the quasi-contemporaneous period. Type 2 reservoirs exhibit weakly sedimentary hydrodynamic conditions and no primary intergranular pores are developed. Their reservoir spaces are mainly the result of constructive diagenesis such as selective dissolution. Type 3 reservoirs have undergone greater diagenetic re-formation and severe damage to the original structural components. The content of local residual biological debris indicates that type 3 reservoirs were formed in a medium-to-high energy sedimentary environment, with mixed dolomitization. [ABSTRACT FROM AUTHOR]

[Significance] The study of the conceptual framework of the "Carbonate Factory" has been hailed by Reijmer as one of the main advances in carbonate sedimentology achieved during the last three decades . It has a unique value in reconstructing deep time carbonate production processes and their controlling factors, as well as in predicting the impact of future climate and environmental changes on the sedimentary system. [Progress] The study of carbonate factories focuses on the major factors influencing the sedimentary system, including producers, production processes and controls, and ecological accommodation. This is different from the traditional facies model that is based on lithofacies and sedimentary environment. As the related conceptual framework has matured, it is worth exploring new directions and research values of the carbonate factories to guide the innovation of theoretical and applied sedimentology. This study reviews the background of the formation of the conceptual framework of the carbonate factories, introduces their compositions and main influencing factors, and recommends the review and research papers in this special issue. [Prospects]The authors hope that through the introduction of these papers, domestic colleagues can be attracted to pay attention and interest to this field, and jointly promote the in-depth research and development of the carbonate factories. [ABSTRACT FROM AUTHOR]

Copyright of Petroleum Geology & Oilfield Development in Daqing is the property of Editorial Department of Petroleum Geology & Oilfield Development in Daqing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Natural Gas Geoscience is the property of Natural Gas Geoscience and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Based on the study of the distribution of intra-platform shoals and the characteristics of dolomite reservoirs in the Middle Permian Qixia Formation in the Gaoshiti–Moxi area of the Sichuan Basin, SW China, the controlling factors of reservoir development were analyzed, and the formation model of “intra-platform shoal thin-layer dolomite reservoir” was established. The Qixia Formation is a regressive cycle from bottom to top, in which the first member (Qi1 Member) develops low-energy open sea microfacies, and the second member (Qi2 Member) evolves into intra-platform shoal and inter-shoal sea with decreases in sea level. The intra-platform shoal is mainly distributed near the top of two secondary shallowing cycles of the Qi2 Member. The most important reservoir rock of the Qixia Formation is thin-layer fractured-vuggy dolomite, followed by vuggy dolomite. The semi-filled saddle dolomite is common in fracture-vug, and intercrystalline pores and residual dissolution pores combined with fractures to form the effective pore-fracture network. Based on the coupling analysis of sedimentary and diagenesis characteristics, the reservoir formation model of “pre-depositional micro-palaeogeomorphology controlling shoal, sedimentary shoal controlling dolomite, penecontemporaneous dolomite benefiting preservation of pores, and late hydrothermal action effectively improving reservoir quality” was systematically established. The “first-order high zone” micro-paleogeomorphology before the deposition of the Qixia Formation controlled the development of large area of intra-platform shoals in Gaoshiti area during the deposition of the Qi2 Member. Shoal facies is the basic condition of early dolomitization, and the distribution range of intra-platform shoal and dolomite reservoir is highly consistent. The grain limestone of shoal facies is transformed by two stages of dolomitization. The penecontemporaneous dolomitization is conducive to the preservation of primary pores and secondary dissolved pores. The burial hydrothermal fluid enters the early dolomite body along the fractures associated with the Emeishan basalt event, makes it recrystallized into medium–coarse crystal dolomite. With the intercrystalline pores and the residual vugs after the hydrothermal dissolution along the fractures, the high-quality intra-platform shoal-type thin-layer dolomite reservoirs are formed. The establishment of this reservoir formation model can provide important theoretical support for the sustainable development of Permian gas reservoirs in the Sichuan Basin.

Shenmu Gas Field in Ordos Basin shows the characteristics of low quality gas reservoir, and its deve-lopment effect is quite different from that of surrounding gas fields, which brings some problems to the exploration deployment and sustainable production of the gas field. In order to reveal the origin of low-quality gas reservoirs, the microscopic characteristics and formation mechanism of Taiyuan Formation reservoirs in Shenmu Gas Field were studied based on microscopic experiments at different scales. The results show that the reservoir of Taiyuan Formation in Shenmu Gas Field is characterized by "rich in quartz, poor in feldspar, and high content of rock detritus". The reservoir of Taiyuan Formation is a low porosity and ultra-low permeability tight sandstone reservoir with small pore-fine throat combination, poor pore throat connectivity, and weak reservoir permeability. The formation of low-quality reservoirs in Taiyuan Formation is affected by the matrix, the content of rock detritus in eruptive rocks and diagenesis. During the late Carboniferous to early Permian, the formation of the reservoir was significantly affected by the volcanic activity of the Inner Mongolia ancient uplift in the north of the Ordos Basin. The content of matrix and rock detritus of the eruptive rock in the sandstone was generally high. The rock detritus of the eruptive rock provided the main material basis for the development of secondary pores. While the matrix blocked the pores, it also produced a certain number of matrix dissolved pores, which had a dual impact on the reservoir. The dissolution during diagenesis is critical to the formation of Taiyuan Formation reservoir, and the increased porosity accounts for 64.3% of the current porosity. At the end of the Late Cretaceous, the late Yanshan movement led to the structural inversion of the Ordos Basin, the readjustment of gas and water, and the escape of natural gas along the fault in the eastern part of the basin. Finally, the low quality gas reservoir of Taiyuan Formation in Shenmu Gas Field is formed. The next exploration focus of Shenmu Gas Field should be based on the clear macro distribution law of diagenesis and favorable lithologic traps, and further search for the development area with high content of eruptive rock detritus and low content of matrix.

Deep-buried tight sandstone reservoirs have strong heterogeneity and complex distribution patterns， which makes it difficult to predict geological sweet spots in those reservoirs. In order to achieve efficient exploration and development， it is urgent to research the accurate identification and prediction of the diagenetic facies of reservoirs among the wells. The identification and distribution prediction of diagenetic facies were carried out using core， well logging， and 3D seismic data based on the diagenesis of Jurassic ultra-deep reservoirs in Yongjin Oilfield， Junggar Basin. It was considered that the diagenesis types of reservoirs mainly include compaction， cementation， dissolution， and metasomatism， which can be divided into five diagenetic facies， such as strong dissolution with chlorite enclave， medium dissolution with authigenic kaolinite， medium calcareous cemented dissolution， strong calcareous cementation， and strongly tight compaction. Based on logging data， petrophysical and physical parameters were used to identify diagenetic facies types of the reservoirs and determine their vertical distribution. The results find that the two dominant diagenetic facies， namely strong dissolution with chlorite enclave and medium dissolution with authigenic kaolinite， are mainly located in the sand body of the main distributary channel of the delta， with suitable reservoir property， and they are the main parts of the oil reservoir development. Based on the analysis of the corresponding relationship between diagenetic facies and seismic P-wave impedance， it is found that the P-wave impedance of the dominant diagenetic facies is relatively low， and the distribution of the dominant diagenetic facies can be predicted by the numerical distribution characteristics of P-wave impedance. Therefore， diagenetic facies distribution is predicted using the inversion results of 3D seismic P-wave impedance， and the development area of the dominant diagenetic facies is determined according to the corresponding relationship between P-wave impedance and different types of diagenetic rocks. The result indicates that the dominant diagenetic facies are mainly located in the Y301-Y302 well area in the northeast of the study area and the Y1 well area in the northwest， showing a locally continuous distribution pattern. Identification of diagenetic facies in reservoirs can provide an essential basis for the distribution prediction of ultra-deep geological sweet spots.

Based on the measurements of petrological, petrophysical and elastic properties of the samples of different sedimentary facies in the fourth member of Sinian Dengying Formation (Deng 4 Member) in the Sichuan Basin, the diagenetic processes of reservoirs of different sedimentary facies and their controls on the petrophysical properties were discussed. The results show that cracks and mineral composition jointly control the petrophysical properties, and both are significantly influenced by sedimentary environment and diagenesis. The microbial dolomite of mound-shoal facies mainly experienced multi-stage dolomitization, penecontemporaneous dissolution, tectonic rupture and hydrothermal/organic acid dissolution processes, giving rise to cracks and dissolved pores. The grannular dolomite of inter-mound-shoal bottomland or dolomitic lagoon facies mainly underwent mechanical compaction, burial dolomitization and tectonic-hydrothermal action, creating cracks and intercrystalline pores. The diagenesis related to crack development increases the pressure- and saturation-dependent effects of samples, leading to significant decrease in the compressional wave impedance and Poisson's ratio. Dolomitization changes the properties of mineral particles, resulting in a Poisson's ratio close to dolomite. The muddy, siliceous and calcareous sediments in the low-energy environment lead to the decrease of impedance and the differential change of Poisson's ratio (significantly increased or decreased). The samples with both cracks and dissolved pores show high P-wave velocity dispersion characteristics, and the P-wave velocity dispersion of samples with only fractures or pores is the lowest.

Objective To clarify the causes of the vertical difference of pore structure in low permeability-tight sandstone reservoirs. Methods Taking the WL area of the Ordos Basin as an example, using physical property tests, casting thin sections, scanning electron microscopy and high-pressure mercury injection, through the division of diagenetic facies and the analysis of vertical distribution differences of different diagenetic facies the characteristics, differences and causes of pore structure in different layers of the Yanchang Formation were discussed. Results The study showed that there were five types of pore structures in the main strata of the Yanchang Formation in the study area, and there were great differences in the pore structures between the same strata and different strata. The Chang 2 and Chang 3 oil layers of the upper combination mainly developed Ⅲa- and Ⅲb-type pore structures, the Chang 4+5 and Chang 6 oil layers of the middle combination mainly developed Ⅳa- and Ⅳb-type pore structures, andthe Chang 7, Chang 8 and Chang 9 oil layers of the lower combination mainly developed Ⅳb- and Ⅴ-type pore structures. With the increasing of burial depth, the pore structure and the porosity and permeability conditions in the reservoir gradually deteriorated overall. There were four types of diagenetic facies types in the reservoir of the Yanchang Formation in the study area. The vertical difference of pore structure was mainly controlled by the difference distribution of diagenetic facies types. The dissolution dominated by atmospheric water leaching in the upper combination was strong. The diagenetic facies types dominated by unstable component dissolution facies and chlorite cementation were developed, and the pore structure formed was dominated by relatively good types. The middle combination had strong cementation, and the diagenetic facies types dominated by chlorite cementation facies and carbonate cementation facies were developed, and the pore structure formed was mainly medium type.The lower combination had strong compaction and cementation, and the diagenetic facies types dominated by carbonate cementation facies and soft-rich compaction filling facies were developed, and the pore structure formed by them was mainly relatively poor. Conclusion The research results can provide favorable guidance for oil and gas exploration and development of the Triassic Yanchang Formation in the Ordos Basin.

Copyright of Acta Sedimentologica Sinica is the property of Acta Sedimentologica Sinica Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Acta Sedimentologica Sinica is the property of Acta Sedimentologica Sinica Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The Upper Paleozoic tight sandstone gas reservoir in Linxing-Shenfu area of Ordos Basin has good exploration prospects. However, the tight and non-homogeneous characteristics of the Upper Paleozoic sandstone reservoirs in the Linxing-Shenfu area are severely limiting the exploration results under the strong diagenetic modifications. A systematic study of the diagenesis of the tight sandstone reservoirs in the study area was carried out based on the cast body thin section and scanning electron microscopy. The microscopic pore structure of the tight sandstone in the study area was characterized by combining the core pore permeability test and high-pressure mercury pressure test. The theoretical lower limit, lower reservoir formation limit, lower effective percolation limit and lower buoyancy equilibrium method of the tight sandstone reservoirs in the study area were determined based on the water film thickness method, filling power method, test gas capacity method and buoyancy equilibrium method in combination with the gas production characteristics of the exploratory wells. The lower theoretical limit, lower reservoir formation limit, lower effective percolation limit and upper tightness limit of the tight sandstone reservoir in the study area were determined based on the water film thickness method, test gas production capacity method and buoyancy balance method. The results show that the tight sandstone reservoir in the study area is now in the middle-formation A-B stage of evolution, and compaction and various types of cementation are the main control factors leading to the decline of reservoir quality. Five diagenetic phases are classified according to the differences between diagenetic transformations of tight reservoirs: chlorite inclusions, dissolution, quartz cementation, mixed cementation and tight phases. According to the reservoir formation boundary, there are conventional reservoir, Ⅰ level tight reservoir, Ⅱ level tight reservoir and Ⅲ level tight reservoir. Between conventional reservoir and Ⅰ level tight reservoir corresponds to the upper limit of tight, conventional reservoir is mainly dominated by chlorite inclusions and soluble phase, Ⅰ level tight reservoir is dominated by soluble phase, followed by mixed cementation phase, between Ⅱ level tight reservoir and Ⅲ level tight reservoir corresponds to the lower limit of effective seepage, Ⅱ level tight reservoir is dominated by soluble phase and mixed cementation phase, Ⅲ level tight reservoir is dominated by mixed cementation phase and tight phase. Among them, conventional reservoirs and class I tight reservoirs are the most promising exploration targets. [ABSTRACT FROM AUTHOR]

Copyright of Petroleum Geology & Recovery Efficiency is the property of Petroleum Geology & Recovery Efficiency and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Natural Gas Geoscience is the property of Natural Gas Geoscience and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The Qingshuihe Formation in the western section of the southern margin of the Junggar Basin has excellent oil and gas exploration prospects. The systematic study of its diagenesis characteristics and pore evolution process will provide guidance for the later fine exploration and evaluation of oil and gas. Therefore, based on the analysis of ordinary thin sections, cast thin sections, whole rock X-ray diffraction, grain size, scanning electron microscopy, carbon and oxygen isotopes of carbonate cements and fluid inclusions, the diagenesis characteristics and pore evolution process of the Qingshuihe Formation in the western section of the southern margin of the Junggar Basin were systematically studied, and the differences of reservoir pore evolution process between different diagenetic facies were further discussed. The study shows that: (1)The reservoir of the Qingshuihe Formation in the studied area is dominated by glutenite. The content of rock debris is high, with an average of 65.97%, mainly tuff rock debris. The cement is mainly calcite. The average porosity of the reservoir is 6.2%, and the average permeability is 7.45×10-3 μm2. It is generally a tight reservoir of low porosity and low permeability, but high-quality reservoirs are still developed locally; (2)The reservoir burial mode of the Qingshuihe Formation in the southern margin of the Junggar Basin is characterized by long-term shallow burial and late rapid deep burial, and can be further divided into four evolutionary stages: long-term shallow burial, tectonic uplift to near surface, normal deep burial, and rapid deep burial. The diagenetic evolution of the reservoir was in early diagenetic stage A in the long-term shallow burial, tectonic uplift to near surface, and normal deep burial stages, while in the rapid deep burial stage, the reservoir was in early diagenetic stage B to middle diagenetic stage A; (3)The reservoir of the Qingshuihe Formation can be divided into four typical diagenetic facies types, namely, strong compaction facies, calcareous/iron argillaceous strong cementation facies, tuffaceous filling weak dissolution facies, and weak compaction pore development facies. The pore evolution model of the clastic rock reservoir of the Qingshuihe Formation in the southern margin of the Junggar Basin was established based on the constraints of diagenetic facies. The weak compaction pore development facies are high-quality reservoir diagenetic facies, followed by tuffaceous filling weak dissolution facies.

The Triassic Baikouquan Formation in the the Junggar Basin has huge oil and gas exploration potential, but the reservoir sand body has poor physical properties and strong heterogeneity. The reason for the formation of high-quality reservoirs is not yet clear, and the understanding of diagenetic characteristics is vague, which limits the exploration and development of oil and gas in this area. Based on the core observation, thin section analysis, scanning electron microscopy and physical property analysis, the diagenesis and pore evolution of the reservoir from the Baikouquan Formation are analyzed in detail. The results indicate that the rock type of the Baikouquan Formation in the study area is mainly sandy conglomerate, and the reservoir can be divided into reservoir supported by sand and gravel and supported only by sand. The overall reservoir space is mainly composed of primary intergranular pores with poor physical property, belonging to the low porosity and low permeability type. The diagenetic stage of the reservoir is the middle diagenetic stage B. Based on quantitative analysis, it was found that compaction and cementation have a significant impact on the physical properties of the reservoir. The pore increasing ability of dissolution is controlled by the type of rock support, and has a significant impact on the pore increasing of reservoir rocks supported by sand and gravel, while it has a relatively poor impact on the pore increasing of reservoir rocks supported by sandy particles. [ABSTRACT FROM AUTHOR]

Copyright of Natural Gas Geoscience is the property of Natural Gas Geoscience and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Acta Sedimentologica Sinica is the property of Acta Sedimentologica Sinica Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Natural Gas Geoscience is the property of Natural Gas Geoscience and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Natural Gas Geoscience is the property of Natural Gas Geoscience and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The tight sandstone of Lower Shihezi Formation of Permian in Northwestern Ordos Basin is taken as the research object, based on the observations of cast thin slice, scanning electron microscopy, nuclear magnetic resonance and nitrogen adsorption porosity permeability test, the characteristics of tight sandstone reservoirs in Lower Permian Shihezi Formation and the factors affecting reservoir quality were analyzed. The findings indicate that the Lower Shihezi Formation reservoir of Permian in the study area predominantly comprises feldspar lithic sandstone and lithic sandstone, representing a typical example of tight sandstone. Rapid burial is the primary cause of reservoir densification, while compaction plays a crucial role in reducing reservoir quality, resuming in a significant loss of 58% in primary porosity. Cementation further compacts the sandstone reservoir, resulting in a secondary reduction of reservoir physical properties and loss of 24% in primary porosity. Other factors diminishing reservoir quality include the occlusion of intergranular pores through diagenetic processes such as calcite and iron calcite formation. The factors influencing the improvement of reservoir quality include extensive intergranular porosity provided by the dissolution of feldspar and the protection of some primary pores by the resistance of rigid quartz particles to compaction. These phenomena can serve as a valuable reference for reservoir research in other fluvial tight sandstone basins. [ABSTRACT FROM AUTHOR]

In order to clarify the distribution characteristics of tight reservoirs in the Upper Triassic Xujiahe Formation in the northern part of the Western Sichuan Depression, we obtained reservoir sedimentary microfacies types and mineral composition characteristics by core description, logging interpretation and X-ray diffraction mineral analysis, combined with the diagenesis obtained from the rock thin section and field emission scanning electron microscopy observation, pore permeability and mercury injection test and the analysis results of the reservoir pore structure, and carried out a study on the factors influencing the tightness of reservoirs in the Member 2 of the Xujiahe Formation. A comprehensive classification evaluation standard was established for the reservoirs Member 2 of the Xujiahe Formation in Northwest Sichuan. The result shows that the main reason for the development of tight reservoirs in the Member 2 of the Xujiahe Formation is that the reservoir porosity is controlled by lithology, and the differences in mineral components make the sandstone in the Member 2 of the Xujiahe Formation characterized by strong cementation, moderate compaction and weak fracture. The study results provide a basis for the screening of favorable sites for the development of tight reservoirs in this area and the favorable target areas for further exploration of tight gas reservoirs. [ABSTRACT FROM AUTHOR]

Understanding the controlling factors of fracture development is of great significance for oilfield well pattern deployment and adjustment. However, there are still some controversial issues in the study of the mechanism of the impact of grain size and porosity on the development of structural fractures. The controversy over the influence of two factors, rock grain size and porosity, on fracture development was summarized. Based on previous experimental analysis data and finite element analysis methods, the influencing mechanism of rock structure on the development of carbonate structural fractures was analyzed, a new interpretation model for the factors affecting fracture development was established, and the impact of diagenesis on the development of carbonate structural fractures based on the new model was discussed. The results show that with the increase of rock grain size, different scholars have completely opposite analysis results on whether rocks are more prone to develop structural fractures. As porosity increases and rock strength decreases, there is still a lack of reasonable explanation for the contradictory phenomenon that rock is more difficult to develop structural fractures. Whether a rock is easy to develop structural fractures depends on the relative changes of two factors, rock strength and rock stiffness, which conform to a power law exponential relationship. The value of the power of the exponential function determines whether a rock is more likely to develop structural fractures. With the increase of particle size, the decrease rate of rock elastic modulus may be greater than the decrease rate of rock strength, making it more difficult for the rock to develop structural fractures, vice verse, the rocks are easier to develop structural fractures. With the increase of porosity, the elastic modulus of rock decreases faster than the strength of rock, making it more difficult for rock to develop structural fractures. The dual-factors-fracture-control theory based on rock strength and rock elastic modulus proposed can not only successfully explain the impact of diagenesis on fracture development, but also have an important guiding significance for further deepening the understanding of fracture formation mechanism. [ABSTRACT FROM AUTHOR]

With the adjustment of China's economic structure and industrial transformation and upgrading, kaolin, included in 15 kinds of minerals, has been suggested to be strategic non-metallic minerals in China. Therefore, it is urgent to study the types and causes of kaolin mineral resources. A new genetic classification scheme of kaolin deposits in China was proposed based on the research results on the genesis of kaolin(rock)deposits and the compound naming principle of parent rock type(or source of ore-forming original material)+ formation + ore type. Kaolin deposits can be divided into 4 genetic types, 8 genetic subtypes and 12 deposit types. On the basis of the existing 6 ore deposit types, 6 new types of ore deposits are proposed, including 3 subtypes of weathered eluvial kaolin ore deposits, which are the weathered eluvial subtype knag soil deposits, rich long sand(rock)weathered eluvial and molding sand quality kaolin ore deposit, and kaolin rocks weathered eluvial subtype aluminum water stone-halloysite-kaolin ore deposit. The origin of hard clay, soft clay and semi-soft clay in refractory clay deposits is attributed to terrigenous clastic and colloidal chemical sedimentary diagenetic subtype kaolin(soil)deposits. For the Carboniferous-Permian coal-bearing rock series in North China, part of coal seam gangue and roof and floor kaolin rocks are formed by descending pyroclastic sedimentary diagenesis. This type of kaolin rocks is unique to China and is classified as descending pyroclastic sedimentary diagenesis subtype. In addition, the variable kaolin subtype deposit is a special type of deposit, and the(thermal)fluid alteration subtype sandstone kaolin deposit is rare, but it is a kaolin deposit with potential economic value. [ABSTRACT FROM AUTHOR]

Copyright of Natural Gas Geoscience is the property of Natural Gas Geoscience and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The tight sandstone reservoir of Jurassic Lianggaoshan Formation in Fuxing area, Sichuan Basin has shown good exploration potential recently. Represented by wells X and Z, the tested industrial oil and gas flows have been obtained. In order to further understand the development characteristics and control factors of tight sandstone reservoirs of Jurassic Lianggaoshan Formation in the Fuxing area, through core observation, ordinary thin section identification, scanning electron microscope observation and multiple test results, the target layer in the study area is analyzed in detail. The results reveal that the tight sandstone reservoir of Lianggaoshan Formation is generally characterized by low porosity and low permeability, and the reservoir space is dominated by inorganic pores with a pore radius of 10-50 μm. Throat width is 2-10 μm。According to the influence of different diagenesis on reservoir physical properties, compaction and partial cementation are classified as destructive diagenesis, while dissolution, tectonism and cementation with chlorite cementation are divided into constructive diagenesis. This study makes clear that the subaqueous distributary channels of the delta front is the most favorable to the development of Lianggaoshan Formation sandstone reservoir. The cementation with dissolution, tectonism and chlorite cementation can improve the physical properties of Lianggaoshan Formation tight sandstone reservoir.

In recent years, some progress has been made in the exploration of Ordovician natural gas in the western Ordos Basin, among which, the Ordovician Kelimoli Formation has the highest degree of natural gas accumulation. However, the controlling factors for effective reservoir development are complicated, leading to unsatisfactory exploration effect. Based on the data of core observation, thin section identification, drilling and logging, the development types and controlling factors of effective reservoir in the Kelimoli Formation were systematically studied, and a development model of effective reservoir was established. The results show that the effective reservoir types of Kelimoli Formation in the western Ordos Basin mainly include dolomite intercrystal (dissolved) pore, limestone karst fracture and structural micro-fracture, and marginal platform granular pore type reservoir is locally developed. The development of effective reservoir was mainly controlled by sedimentary facies, diagenesis, paleokarst weathering and tectonic movement. The tidal flat facies and marginal platform facies provided the material basis for the original reservoir of the Kelimoli Formation, and on this basis, the dolomite intercrystal (dissolved) pore and marginal platform granular pore reservoirs were formed in the early diagenesis. In the stage of burial diagenesis, recrystallization obviously reformed the original dolomite reservoir, and the crystal framework became more stable. New intercrystal (dissolved) pores were formed or underwent secondary recrystallization. At the same time, the original structure of marginal platform granular pores was damaged, filled or improved, and the present marginal platform residual granular pores were formed. Paleo-karst weathering controlled the development of fracture-vuggy reservoirs in the middle and upper parts of the Kelimoli Formation, and high-yield wells were mainly drilled in the upper groove direction of the karst slope groove zone and karst highlands. The multi-stage tectonic movement continuously transformed and controlled the development of micro-fracture system, forming porous media reservoirs distributed around the fault zone. Therefore, it is a favorable direction for further exploration to find favorable facies belts of tidal flat facies and marginal platform facies, updip positions of karst paleo-geomorphology or high positions of fault zone.