Fault-controlled fractured-cave carbonate rocks have great potential for oil and gas resources， but their mechanism of controlling storage， reservoir and enrichment is very complex. Exploration and development in ultra-deep field is more difficult and cost-effective. Cultivating high-yield wells and high-efficiency wells is an important way to promote the conversion of resource advantages into benefit advantages in ultra-deep field. Based on the dynamic and static combination of geophysics， oil and gas geology， reservoir physics and geochemistry， the formation mechanism of multi-source fluid， multi-stage dissolution and superposition complex fault-controlled karst fracture cave body and multi-stage reservoir formation mechanism with strike-slip fracture and unconformity surface as transport guide frame are clarified， a geological model of hydrocarbon accumulation in ultra-deep fault-controlled fracture-cave carbonate rocks in Fuman Oil Field is established， and the distribution law of efficient wells is revealed， with the class I fracture zone as the main line， large fracture-cave body as the main body and normal landform as the background. At the same time， a set of well locations with characteristics of “main fracture + positive geomorphy + long string of beads” have been developed， which greatly improves the output of single well and EUR and guides the further development of exploration and development field. We found and implemented one billion tons oil and gas reserve in Fuman Oil Field and constructed four million tons large oil and gas field.
Fault-cap coupling is the key to controlling hydrocarbon accumulation in deep layers of the Yubei area in the western Tarim Basin. In this paper， the influence of the configuration of hydrocarbon source and fault-gypsum-cap elements on hydrocarbon accumulation in the deep layer was discussed by basin simulation for the first time. The 2D thermal evolution of source rocks shows that the Lower Cambrian source rocks were in the mature stage from the Late Caledonian to the Early Yanshan Period and entered the high mature stage in the Himalayan period， and still have good hydrocarbon generation potential. The dynamic simulation of the fault-gypsum combination shows that the interaction between fault and gypsum is the key factor controlling the hydrocarbon distribution post-salt and pre-salt hydrocarbon system in Yubei area. The structural characteristics of deep faults have more influence on the hydrocarbon migration than the lateral sealing property of fault plane. Different fault-cap assemblages controlled the accumulation of the Ordovician hydrocarbon， and the fault-cap assemblages of non-fault-cap and weak fault-cap assemblages are most conducive to the accumulation of marine oil and gas in this area. The preservation conditions of traps in Himalayan period were of great significance to the formation of late secondary reservoirs. The results of the petroleum system simulation show that the hydrocarbon accumulation of Ordovician carbonate rocks in the Yubei area has the characteristics of long-term oil generation， fault-gypsum controlled charging， fracture-sealing controlled accumulation. The degree of splicing of basement involved fault and reverse strike slip is an important factor to evaluate subsalt oil and gas enrichment. This paper provides a new idea and reference for the study of deep fault-controlled hydrocarbon accumulation law in the Yubei area and Tarim Basin.
As an important reserve growth point and strategic replacement area， the Cambrian subsalt dolomite in Keping area of Tarim Basin has shown great exploration potential and good exploration prospect， but the unclear understanding of the formation mechanism of high-quality reservoir restricts the oil and gas exploration in this area. In this paper， the rock types and characteristics of the Xiaoerbulake Formation are described in detail by means of microscope observation， geochemical analysis and interpretation of well logging data of Well Kepingnan 1. The Xiaoerbulak Formation is divided into four members from downward to upward. The relative high Mn content （87-137.7）×10-6， δ18O （average of －6.37‰） and 87Sr/86Sr （average of 0.710 9） values indicate that the dolomitization of Xiaoerbulake Formation occured in penecontemporaneous-shallow burial period. The dolomite formed in the early period increases the porosity of the reservoir and resists the compaction in deep burial period， which is the basis for the reservoir formation. The δ13C values of the first and second members of Xiaoerbulake Formation show frequent zigzag curves， indicating frequent progression/regression process. The subsequent formed granular beach facies are key factors controlling the reservoir formation of the second member of Xiaoerbulake Formation. While the third member of Xiaoerbulake Formation is mainly controlled by tectonic fractures and perisomorphic karstification. The study analyzes the diagenetic evolution model of the well and studies the restriction mechanism of the diagenetic transformation process to the reservoir. The systematic analysis of downhole data of Well Kepingnan 1 provides basic data for the comparative study of other drilling in this area， and can provide guidance for the next exploration and deployment in the northwest Tarim Basin.
Kuqa Depression has developed two sets of Palaeogene and Neogene paste salt rocks， with trillion cubic meters of natural gas reserves in pre-salt Mesozoic， which is an important natural gas production area in China. The structural oil and gas reservoir of Lower Mesozoic in Kuqa Depression is the focus of oil and gas exploration. The analysis of salt structure style， salt structure deformation mechanism， salt structure balance recovery and deformation period analysis are the difficulties of salt structure research in Kuqa Depression. In this paper， using high-precision three-dimensional seismic splicing profile， drilling and regional geological data， two typical sections of the western and eastern sections of the Kuqa Depression are selected. The structural balance recovery is carried out by 3DMove software， and the structural deformation of the upper salt layer， the lower salt layer and the salt layer are restored respectively. The seismic profile before structural deformation is restored. In view of the specific problems in the recovery process， the salt structure recovery method， salt structure deformation characteristics， salt structure evolution， and salt structure deformation mechanism are discussed. The results show that the recovery of the salt layer needs to meet two basic assumptions： One is to ignore the amount of internal rock shortening caused by extrusion； the other is that the thickness of salt layer in the weakly deformed or undeformed area is approximately constant. Kuqa Depression developed two salt structures： Oligocene-Miocene （tectonic stable period） on the salt layer formation gravity difference induced early salt structure， developed salt dioper， salt mound structure. Oligocene to Miocene （tectonic stable period） overlying strata gravity difference induced the early salt structure， salt diapir， salt dome and other structures， Pliocene to Holocene （tectonic active period） destroyed and reformed the early salt structure， the development of extrusion salt structure. Extrusion action and plastic flow of salt layer are the main reasons for the formation of salt structure. The salt slip and unthrust fault develops in the upper salt layer， and the plastic deformation of the salt layer forms the salt anticline， salt mat and salt wall to develop in the lower salt layer， and the large structural wedge develops near the orogenic belt. Deposition differential load is the main factor inducing the formation of the early salt structure. The early salt structure such as salt mound and salt diopia mainly develops at the front end of the alluvial fan. The boundary of Mesozoic and base ancient uplift. The thickness and distribution range of the paste salt layer control the quantity and scale of the thrust cover structure development under the salt， and the west of Kuqa Depression is still the focus of oil and gas exploration. The overlying sedimentary zone from the Mesozoic boundary is conducive to the development and preservation of the formation of lithological oil and gas deposits， and it is an important field of oil and gas exploration.
Fengcheng Formation has the feature of low exploration degree in Western Well Pen-1 Sag， and a new well has broken the historical record of single well high production in the basin. But the geological characteristics of oil and gas are unclear， and the resource types and exploration potential are unknown， which restrict the next oil and gas exploration and development in this block. The geological characteristics and exploration potential of Fengcheng Formation are discussed by means of structural recovery， sedimentary evolution， well-seismic combination and analogical analysis.P1f1，P1f2 and P1f3 in the Northeast ring of the sag are overlaid on the Carboniferous layer by layer， and P1f3 in the high part is thinned by weathering and denudation， with a large stratigraphic pitch-out background. Fengcheng Formation develops a regressive fan delta–lake sedimentary system， which is positive cyclic deposition. It is predicted that conglomerate， dolomitic sandstone and dolomitic mudstone reservoirs are developed successively from the high part to the sag. The gravel in the high position conglomerate reservoir is mainly medium- acid volcanic rock， the composition of sand is mainly rock debris， and the dissolution pores are developed in large number， which belongs to the reservoir with ultra-low porosity and ultra-low permeability. The oil and gas are condensate oil and gas with high maturity， and the interface between oil， gas and water is not obvious. The whole gas reservoir is quasi-continuous， and it is divided into multiple fault block gas reservoirs by fault blocks. Based on the analysis of accumulation， the oil and gas reservoir forming model of Fengcheng Formation is established. It is predicted that the resources of conventional gas reservoir， tight gas and shale gas in Fengcheng Formation are 1 250×108 m3， 5 020×108 m3 and 6 230×108 m3 respectively， and the natural gas exploration potential is huge.
The Hongche fault zone is adjacent to the Shawan Sag in the Junggar Basin， with favorable reservoir forming conditions and great exploration potential. However， the mixed distribution of oil and gas in different stages and the unclear understanding of reservoir forming controlling factors in different zones restrict the next oil and gas exploration and development in this block. Based on the comparison of biomarker compounds， fluid inclusion analysis and seismic data， the oil and gas sources， accumulation periods， main controlling factors and favorable exploration targets of Hongche fault zone were discussed. The results show that the crude oil in the Hongche fault zone can be divided into four categories， which are mainly derived from the source rocks of the Fengcheng Formation and the Lower Urho Formation. The natural gas can be divided into five categories， which are derived from four sets of source rocks of Carboniferous， Jiamusi， Fengcheng and Lower Urho formations. The oil and gas reservoirs in the Hongche fault zone have the accumulation characteristics of “two stages of crude oil filling and late dry gas intrusion”. The first stage is the Late Triassic-Early Jurassic accumulation period， the second stage is the Early-Middle Cretaceous accumulation period， and the late dry gas intrusion occurs after the Late Cretaceous. Hongche fault zone is controlled by four hydrocarbon accumulation factors： multiple sets of source rocks establish the material foundation for hydrocarbon accumulation； fault and unconformity surfaces provide a transmission system for large-scale lateral migration of oil and gas； the difference of fault sealing and structural evolution control the differences of oil and gas geochemistry characteristics in different zones； poor preservation conditions make it difficult to form large-scale gas reservoirs in the study area. Based on this， the accumulation model of the northern and southern sections of Hongche fault zone is established. Guided by the study， it is pointed out that the slope area， the footwall of fault zone and the deep layer of southern segment are the next favorable exploration targets.
Bozhong Sag is the largest hydrocarbon generation sag in Bohai Bay Basin， and the third member of the Shahejie Formation （E2s3） is the most important source rocks. Previous studies have a certain understanding of source material， sedimentary environment and thermal evolution of the source rocks from the E2s3， but the research on sedimentary events and biological sources is not deep enough. Nine mudstone core samples from the E2s3 in the southwestern Bozhong Sag were analyzed in detail based on organic-inorganic geochemistry and organic petrology. The results show that： （1） The middle and lower sections of the third member of Shahejie Formation are high-quality source rocks， but the quality of the source rocks in the lower section of the third member of Shahejie Formation is better. The increase of water salinity in warm and humid climate and the detection of 24-n-propylcholestane compounds reflected the occurrence of transgression events in the E2s3， and the transgression gradually increased from the lower sections to the middle sections of the E2s3. （2） The abundant presence of 4α-methyl-24-ethylcholestanes， 24-n-propylcholestanes， 2α-methylhopanes， and oleanane in the studied samples， and the presence of abundant algainite and a small amount of vitrinite indicate the diversity of hydrocarbon-forming organisms in the source rocks of the E2s3. （3） The nutrient elements brought about by the moderate marine incursion in the lower part of the E2s3 caused the flourishing of bacteria and algae， which provided abundant material basis for the formation of high-quality source rocks. However， due to the large-scale seawater intrusion in the middle of the E2s3， the water eutrophication is weakened， resulting in a decrease in the quality of source rocks compared with the lower part of the E2s3.
The evolution of reservoir physical properties is very important for the prediction of sweet spots in oil and gas exploration and development. As one of the important factors of physical property evolution， the abnormal high temperature in the formation has a very important influence on the physical property and diagenetic evolution of regional reservoirs， but the relevant influence mechanism has not been fully revealed. In order to specifically discuss the mechanism of the influence of abnormal high temperature on the physical property evolution of deep-water sandstone reservoirs， the coupling effect of different thermal fluids in different regions on the lithology， physical property and diagenetic evolution of reservoirs is analyzed in depth by systematically investigating the literature and data related to the lithology， physical property and diagenetic evolution of reservoirs under the global high temperature background. It is found that the abnormal high temperature mainly reflects on the physical property evolution of the reservoir： The high temperature background accelerates the intensity of compaction， promotes the development of secondary pores or the transformation of primary pores to secondary pores and micropores， accelerates the chemical cementation reaction rate and the diagenetic evolution process， and then has a great impact on the physical properties. By summarizing the previous research progress on reservoir diagenetic evolution under thermal background， this paper discusses the influence mechanism of thermal background on reservoir physical properties and diagenetic evolution， and analyzes the influence of abnormal high temperature background in local areas. This research can provide new ideas and theoretical support for the subsequent prediction of reservoir sweet spots.
Taking the laminated shale oil reservoir in Chang 73 sub-section of Yanchang Formation in Ordos Basin as the research object， the lithofacies type， micro qualitative and quantitative pore structure parameters and the main controlling factors of the pore structure of laminated shale were systematically studied by comprehensive analysis of TOC， rock-eval， X-ray diffraction， polarized light and fluorescence microscope observation， field emission scanning electron microscope observation and low-pressure N2 adsorption analysis. According to the characteristics and differences of sedimentation， geochemistry and mineral composition， the Chang 73 laminated shale can be divided into three lithofacies types：Tuffaceous-organic lamellar shale， clayey-organic lamellar shale and felsic-clayey lamellar shale. The pore network are mainly composed of organic hydrocarbon generation pressurization fractures， clay mineral felsic intergranular composite pores and felsic plasmid intergranular pore fracture systems， respectively. The samples are most developed in mesopores. The pore volume and specific surface area of “tuffaceous-organic matter” “clayey-organic matter” “felsic-clay” increase in turn， while the heterogeneity of the pore network and the roughness of the pore surface are gradually weakened and enhanced， respectively. The overall development of organic matter pores is limited， mainly organic matter-pyrite-clay mineral composite pores， which are the main components of micropores. The primary intergranular pore system related to rigid quartz particles is the main component of mesopores and macropores， and also the mainstay of the entire pore network. The development of feldspar dissolution pores is limited， which makes little contribution to the pore network.
The transitional shale is a promising field for shale gas exploration. Compared with the marine shale， the shale of transitional facies has various rock types， unstable thickness distribution and lower organic matter abundance， which makes it difficult to explore shale gas. With the continuous breakthrough of shale gas exploration of transitional facies in the eastern margin of Ordos Basin， in order to improve the accuracy and efficiency of exploration， it is necessary to carry out fine-grained studies on accumulation process， preservation conditions and spatio-temporal matching of shale gas， so as to clarify accumulation regularity and main controlling factors of transitional facies shale gas in different tectonic zones. Focused on the shale gas potential areas in the north and south of the eastern margin of Ordos Basin， in this paper， the evolution of energy field， the validity of preservation conditions and the matching of accumulation models would be summarized systematically based on the detailed comparison of material basis and hydrocarbon generation potential of shale. Comprehensive analysis shows that， （1） in the northern area， the shale member of Taiyuan Formation has rich material foundation and superior hydrocarbon generation potential， which has the exploration potential of multiple types of unconventional resources； （2） the hydrocarbon generation potential of shales in the southern Shanxi Formation is better than that of shales in Taiyuan Formation， but the study of energy field and shale gas preservation conditions are still very weak； （3） the key parameters of establishing accumulation model of transitional shale gas are lack of correction and need to be discussed carefully. In order to clarify the enrichment mechanism of transitional shale gas， it is necessary to reconstruct the energy field and evaluate the sealing property of cap rock on the basis of fine characterization of lithologic assemblage and fluid units. Only by describing the control of energy field on shale gas occurrence mode can we accurately establish the spatio-temporal matching relationship between shale hydrocarbon generation and expulsion process and preservation conditions. The establishment of fine accumulation model of transitional shale gas would provide important theoretical support for the efficient exploration and development of shale gas in the eastern margin of Ordos Basin.
The northeastern margin of Junggar Basin is located from the northern Lüliang Uplift to Wulungu Depression. The coal seams of Jurassic Xishanyao Formation and Badaowan Formation in this area are thick and widely distributed， buried to a depth of 2 000 m. The deep coalbed methane in Xishanyao Formation of Well Caitan 1H in Baijiahai Uplift， the eastern Juggar Basin， has been tested for industrial gas flow， which broadens the new field of deep coalbed methane exploration in the northeastern margin of Junggar Basin. On the seismic profile， coal seams are characterized by continuous strong reflection， obvious logging response， prominent logging gas logging anomaly， and good gas bearing property. It is proposed that Xishanyao Formation in Zhunbei1， Lu6 and Wushen1 well areas and Badaowan Formation in Lun5 well area are favorable area for deep coalbed methane exploration. It is suggested to carry out coring work of coal seam， analyze the geochemical characteristics of coal seam and the “four properties” relationship of litholofy， physical property， electrical property and gas bearing property， and provide scientific basis for deep coalbed methane exploration in this area.
The Yanxi Formation of Middle Ordovician， as a new exploration layer of Lower Paleozoic in Hunan， has been widely valued by energy geologists. The shale reservoirs of Middle Ordovician Yanxi Formation in central-southern Hunan was comprehensively studied by means of polarizing microscope， high resolution scanning electron microscope， X-ray whole rock diffraction， organic carbon content， low temperature liquid nitrogen and carbon dioxide adsorption desorption. The results show that the Middle Ordovician Yanxi Formation in central-southern Hunan is deposited in slope and basin facies， and shale is developed in deep-water shelf and deep-water basin. Its minerals are mainly quartz and clay minerals， followed by pyrite and feldspar. The brittleness index of the reservoir is high， which is conducive to fracturing and exploitation. There are mainly organic pores， biological structural pores， intergranular pores， interstratified pores， intercrystalline pores， dissolution pores， clay mineral interlayer microcracks and mineral fractures developed in the shale reservoirs in the study area. It has medium porosity and good permeability. There are two types of pore structures developed in the study area. Among the pore structures dominated by mesopores and micropores， the total pore volume and the total pore volume of micropores are relatively large， and the specific surface area is also very large. Its reservoir performance and adsorption capacity are relatively strong， which can be used as the key exploration interval of Yanxi Formation. The pore development of Yanxi Formation shale in Middle Ordovician is mainly affected by thermal evolution， and secondly controlled by mineral composition and organic matter abundance. The Middle Ordovician Yanxi Formation in the study area has a good material basis for hydrocarbon generation. The organic matter in the source rocks are mainly types Ⅰ and Ⅱ2. The TOC content is 0.05%-5.6%. The RO value is 2.72%-3.82%， which has reached the high mature or over mature stage， which is conducive to the massive generation of shale gas. The Middle Ordovician Yanxi Formation in central-southern Hunan has moderate burial depth， good reservoir physical properties and rich organic matter， which has great exploration potential. The favorable exploration area is mainly located in the Dongan-Yongzhou-Qiyang area of Lingling Depression.
The surface of the north slope area in Qaidam Basin is complicated， and the underground is affected by the tectonic compression movement， and the faults are well developed. There are six pieces of 3D seismic data blocks in this area. The seismic acquisition time span is large and the quality of the data varies greatly. The existing single piece processing results show that the signal-to-noise ratio of the data in the 3D jointing area is low， and the difference of frequency， phase and energy is large， the fault imaging is not good， and it is difficult to accurately identify and trace the horizon and fault plane， which restricts the further exploration in this region. To this end， on the basis of detailed analysis of the characteristics and problems of the original data， the key techniques of multi-block 3D static correction， pre-stack purification， data regularization and anisotropic pre-stack time migration are studied for six blocks of 3D seismic data in this area. A high resolution section with good consistency of frequency， phase and energy， prominent reflection characteristics， clear imaging of complex structures， clear breakpoints and clear sections is obtained. The inconsistencies of frequency， phase and energy in post-stack hard splicing section are eliminated. The research results provide a reliable basis for subsequent structural interpretation and reservoir prediction.
In order to predict the rich area of coalbed methane resources in Dahe block of Dahebian syncline and explore the effectiveness of three-dimensional seismic exploration and development in Guizhou Province， based on the 4 km2 three-dimensional seismic exploration data volume in this area， new technologies and methods of seismic （exploration） data processing in the field of coalbed methane are used to carry out prediction. Firstly， based on the idea of progressive reservoir prediction of coalbed methane， the Jason geoscience research platform of CGG company is used to carry out seismic inversion prediction， and the plane distribution maps of four coal-bed methane evaluation parameters， including coal seam thickness， coal seam gas content， coal structure and ground stress， are obtained. Then， based on the “multi-factor weighting step-by-step evaluation method” proposed in this study， each evaluation parameter such as coal seam thickness， gas content， and coal structure is separately weighted， and then the cumulative method is used to form a multi-parameter joint dessert evaluation weight factor parameter. Finally， according to the calculated comprehensive dessert evaluation parameters （the value of dessert evaluation parameters is between 20 and 50）， with 10 as the first grade， the scores between 40 and 50 are divided into one type of dessert， the scores between 30 and 40 are divided into two types of dessert， and the scores between 20 and 30 are divided into non-dessert， and the distribution map of coalbed methane dessert area in the work area is drawn. The prediction results show that the first type dessert area is mainly located in the middle of the work area， which is distributed in the north-south direction as a planning area for CBM well deployment. The research results have certain guiding significance for the next step of coalbed methane exploration and development in the work area.
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