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The shale of the Cambrian Qiongzhusi Formation in the Sichuan Basin is characterized by large burial depth and high maturity, but the shale gas enrichment pattern is still unclear. Based on the detailed characterization of Deyang-Anyue aulacogen, analysis of its depositional environments, together with reconstruction of shale gas generation and enrichment evolution against the background of the Leshan-Longnüsi paleouplift, the aulacogen-uplift enrichment pattern was elucidated. It is revealed that the Deyang-Anyue aulacogen controls the depositional environment of the Qiongzhusi Formation, where high-quality sedimentary facies and thick strata are observed. Meanwhile, the Leshan-Longnüsi paleouplift controls the maturity evolution of the shale in the Qiongzhusi Formation, with the uplift located in a high position and exhibiting a moderate degree of thermal evolution and a high resistivity. The aulacogen-uplift overlap area is conducive to the enrichment of shale gas during the deposition, oil generation, gas generation, and oil-gas adjustment stage, which also has a joint control on the development of reservoirs, resulting in multiple reservoirs of high quality and large thickness. Based on the aulacogen-uplift enrichment pattern and combination, four types of shale gas play are identified, and the sweet spot evaluation criteria for the Qiongzhusi Formation is established. Accordingly, a sweet spot area of 8 200 km2 in the aulacogen is determined, successfully guiding the deployment of Well Zi 201 with a high-yield industrial gas flow of 73.88×104 m3/d. The new geological insights on the aulacogen-uplift enrichment pattern provide a significant theoretical basis for the exploration and breakthrough of deep to ultra-deep Cambrian shale gas, highlighting the promising exploration prospect in this domain.

Considerable debate has arisen regarding studies of the thermal history of Paleozoic source rocks in the Tarim Basin, particularly regarding the thermal evolution of ultra-deep, ancient source rocks. The evaluation method for the thermal evolution stages has long been a key issue in the study of source rocks' thermal history. Research findings revealed that the Cambrian paleo-geothermal gradient in the Tarim Basin varies between 2.95 and 3.6 ℃/hm. Based on the hydrocarbon generation threshold temperature of 65 ℃, the required overlying strata thickness ranges from 2 203 to 1 806 m, with a difference of 397 m, equivalent to 2.58 ℃, showing a relatively small temperature difference. Thus, it is considered that the variation in the Cambrian paleo-geothermal gradient in the Tarim Basin is minimal, allowing the differences in geothermal gradient values for each period to be ignored, and that thickness may be the main determinant of temperature. The sedimentation and residual thickness of the strata can be accurately obtained, with the error mainly depending on the restoration of the denudation thickness. The thermal evolution stages of the Cambrian Yurtus Formation source rocks in the Tarim Basin were evaluated using reliably obtained parameters such as strata thickness, paleo-geothermal gradient, denudation thickness, and hydrocarbon generation charts of source rocks. With this assessment, the effective source rocks and their distribution in the key period of the Manjiaer Depression were delineated. Moreover, the effective source rocks ofthe Yurtus Formation, their large-scale hydrocarbon generation capacity, and the favorable areas for late-stage hydrocarbon accumulation were predicted and classified. The effective source rocks at different stages and their large-scale hydrocarbon generation potential are crucial for hydrocarbon accumulation in each period. This method avoids the issue of unreliable temperature scales in maturity identification, providing an important scientific basis for deep and ultra-deep oil exploration and development in the Tarim Basin and for selecting favorable areas for late-stage hydrocarbon accumulation.

Based on a large number of cranidial specimens of Jiulongshania acalla Walcott, 1905 from the Cambrian Gushan Formation at the Tangwangzhai section in Jinan City, Shandong Province, the traditional morphometric method and geometric morphometrics were used to measure and quantify the morphological features of the cranidium, revealing the cranidial shape variation during ontogeny. The results show that the growth rate of preglabellar field is the fastest, and the rate for the cranidial width is the slowest. The cranidial shape variation during ontogeny is mainly characterized by elongation of cranidium and gradual increase in the length of preglabellar field. It is proposed that the variation of trilobite exoskeletal morphology, particularly the cephalon, might be related to the feeding mode of trilobite. The results may suggest that the feeding habits of J. acalla might have changed during development. [ABSTRACT FROM AUTHOR]

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Copyright of Oil Drilling & Production Technology / Shiyou Zuancai Gongyi is the property of Shiyou Zuancai Gongyi Bianjibu 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.)

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It has not been clearly understood whether the hydrocarbon generated from the argillaceous sourcerocks of the Lower Cambrian Qiongzhusi Formation could upward pass through the regional cap rocks of the Lower-Middle Cambrian gypsum rocks and accumulate in the Middle-Upper Cambrian Xixiangchi Group reservoir, namely the cross-formational hydrocarbon accumulation, in the eastern Sichuan Basin. Therefore, the studies on the reservoir solid bitumen in the Xixiangchi Group and the sealing performance of the regional cap rocks of the Lower-Middle Cambrian gypsum rocks were carried out, and the cross-formational hydrocarbon accumulation of the Cambrian oil and gas and its significance for natural gas exploration were discussed. It was shown by synthetic studies that the reservoir solid bitumen in the Xixiangchi Group mainly originated from the argillaceous source rocks of the Lower Cambrian Qiongzhusi Formation. The sealing integrity of the regional cap rocks of the Lower-Middle Cambrian gypsum rocks was damaged to some extent by the reactivated basement faults and the large nascent faults in the Middle Permian to Middle Triassic though it had good sealing performance in geological times, which could provide convenient vertical pathways for the Cambrian cross-formational hydrocarbon accumulation in the eastern Sichuan Basin. Three evolutionary stages were built up about the Cambrian hydrocarbon migration and accumulation as follows. Stage 1 is the formation of the Cambrian pre-salt early paleo-reservoirs in the period ofthe Late Silurian to the Early Permian (S3-P1), stage 2 is the one of the Cambrian cross-formational hydrocarbon accumulation in the period of the Middle Permian to the Middle Triassic (P2-T2), and stage 3 is the formation of the Cambrian late paleo-gas reservoirs in the period of the Late Triassic to the Early Cretaceous (T3-K1). The cross-formational hydrocarbon accumulation is an important feature of hydrocarbon accumulation in multi-cycle superimposed basins, and the reactivated basement faults and the large nascent faults in the period of the MiddlePermian to the Middle Triassic are important clues to the Xixiangchi Group primary paleo-gas reservoirs. Identification and evaluation of the Xixiangchi Group primary paleo-gas reservoirs will be the key points and the main challenges to natural gas exploration in the study area.

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From the eastern to the western part of Shunbei area in the Tarim Basin, the accumulations of marine oil and gas obviously decrease with the exploration risks significantly increasing. To find out the reason for the differences, the oil and gas accumulations in the eastern Shunbei area on the western margin of Manjiaer Depression and the western Shunbei area on the eastern margin of Awati Depression were analyzed, and the differences of accumulation conditions were discussed. In recent years, the eastern part of Shunbei oil and gas field, which is represented by the northeastern section of Shunbei No.1, 4 and 8 belts, has continuously achieved high yield with multiple stages of oil and gas accumulations and obvious oil and gas enrichment characteristics. While in the western part of Shunbei area, only early-stage accumulations with small scale were discovered. There are differences in the distribution conditions of source beds, hydrocarbon generation evolution history, source resource scale, reservoir-forming period and reservoir-forming mode between the eastern and western parts of Shunbei area, which leads to multi-source and multi-stage accumulation in the east and single-source and single-stage accumulation in the west. Adjacent to the Manjiaer hydrocarbon-generating depression, the eastern part of Shunbei area has favorable accumulation conditions such as pathways for vertical migration, targets for hydrocarbon migration of various sources, qualified cap rocks and lateral sealing, and multiple stages of hydrocarbon generation with strong intensity, resulting in multi-source and multi-stage accumulation. While in the western part of Shunbei area, there is single-source and single-stage accumulation sourced from either local Cambrian Yurtus Formation or Ordovician in the Awati Depression. Breakthroughs in Ordovician in the Yingmaili Oilfield on the eastern margin of Awati Depression and well Yingxi 1 in recent years indicate that the accumulation of marine oil and gas mainly took place in the late Hercynian period, and partially in Himalayan period. Generally speaking, the development of source rocks around the Awati Depression is relatively poorer, and the distribution of marine oil and gas as well as the scale of hydrocarbon resources are limited.

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Based on the latest drilling cores, thin sections, and 3D seismic data, types, features, and evolution processes of Cambrian–Ordovician carbonate platforms in the Gucheng and Xiaotang areas are studied, and favorable exploration zones in this area are also discussed. There are two types of carbonate platforms developed in the Cambrian–Ordovician in the Gucheng–Xiaotang area, namely, carbonate ramp and rimmed platforms, and the evolution process of the platform in the Gucheng area is different from that in Xiaotang area. In the Early Cambrian, the study area was a homoclinal carbonate ramp. During the Middle to Late Cambrian, it evolved into a rimmed platform, with 5 phases of mound shoals developed. In the southern area, mound shoals were in progradational arrangement and the third and fourth stages of mound shoals suffering exposure and further developed abundant karst vugs. In the northern area, the mound shoals appeared in a superposition of aggradation–weak progradation, the third, fourth, and fifth stages of mound shoals suffered exposure and dissolution, and the platform slope developed gravity flow deposits. In the Early to Middle Ordovician, the southern area gradually evolved into a distally steepened carbonate ramp, where retrogradational dolomitic shoal developed; while the northern part experienced an evolution process from a weakly rimmed platform to a distally steepened carbonate ramp, and developed two or three stages of retrogradational mound shoals. The high-frequency oscillation of sea level and local exposure and dissolution were beneficial to the formation of mound or shoal reservoirs in platform margin and ramp, and the configuration of these reservoirs with low energy slope–basin facies source rocks could form good oil-gas enrichment zones. The dolomitic shoal in the Ordovician platform ramp is the practical exploration field for increasing reserve and production in the Gucheng area. The mound shoal at the Cambrian rimmed platform margin is the key exploration object in the Xiaotang area. In addition, the Cambrian slope gravity flow deposits can be taken as the favorable exploration fields in the study area.

Carbon isotope stratigraphy is an important means to subdivide and correlate the Cambrian strata. Based on the carbon isotope analysis of the carbonate strata of Lütuogou Section, northern Henan Province, it is found the δ13C value of carbonate samples collected from the base of the Drumian Stage at Lütuogou Section, northern Henan, ranges from 3.1‰ to -1.7‰, and the δ18O value ranges from -3.9‰ to -9.4‰. No covariance exists between δ13C and δ18O, which implies that the carbon isotope composition is nearly stable. Value of δ13C around the base of the Drumian Stage consists of a negative excursion, the amplitude of the negative excursion is 3.0‰, and the minimum value of δ13C is -1.7‰, which occurs at the place 15 m below the first occurrence of trilobite protasaphiscus. The position and amplitude of the negative excursion are similar to those of the drum carbon isotope excursion (DICE) tested in the Wangcun Section, western Hunan, South China, and the Drum Mountains section in Utah, USA, which suggests that the DICE can be used as a global indicator for the correlation of the Drumian Stage. Furthermore, the cyan shale with thin limestone at the position of minimum δ13C overlies the oolitic limestone; therefore, DICE occurs in the transgressive succession in the early Miaolingian.

The Cambrian Xixiangchi Formation is an important succeeding stratum for gas exploration[JP] in the Lower Paleozoic of the Sichuan Basin, for which, the exploration degree is low, and the main controlling factors of large-scale[JP] reservoirs have not been well understood. Based on core, logging, seismic data and combined with regional tectonic evolution analysis, the original sedimentary structure of the shoal dolograinstone reservoir in the Cambrian[JP] Xixiangchi Formation were restored in this paper, and the characteristics, controlling factors and development patterns were further discussed. Results show that: (1) The rock types of shoal dolograinstone karst reservoirs mainly include dolograinstone, dolopackstone, granulated dolostone, residual granular dolomite and grain dolomite. It appeared to be developed in a variety of sedimentary micro-facies assemblages, such as shoal-shoal superimposition, flat-shoal-flat, lagoon-beach-lagoon and flat-beach-lagoon. The main reservoir space are intergranular (dissolution) holes, intergranular (dissolution) pores and vugs, and a small number[JP] of (dissolution)fractures were also developed. The reservoir porosity ranges from 3% to 6% with a highest value greater than 10%. (2) The dolograinstone shoal facies dolostone of the Xixiangchi Formation was controlled by the sea level changes and synsedimentary paleouplift. A large number of dissolution pores were formed after multiple exposure in the contemporaneous and quasi contemporaneous periods. Among them, the Yunan Movement at the end of the Xixiangchi period has a wide range of distribution and extensive exposure in the whole basin, which may further transform the middle and upper reservoirs of the Xixiangchi Formation. The Duyun and Guangxi movements might transform the central Sichuan paleouplift and its surrounding reservoirs. (3) The favorable reservoir distribution areas of Xixiangchi Formation in the Sichuan Basin were predicted to develop mainly type Ⅱ and Ⅲ reservoirs. Among them, the scale reservoir distribution area of the slope belt around the paleo-uplift is more than 10 000 km2[JP], which is expected to be the most favorable exploration area at present.

The evaluation of post-mature source rocks gradually invalidates by traditional organic geochemical parameters due to the decreasing of organic matter abundance. However, the inorganic elements in source rocks are not easily affected by thermal evolution. In order to explore the application of inorganic geochemical methods in the evaluation of post-mature source rocks, this paper takes the Sinian-Cambrian source rocks in the Sichuan Basin as an example to conduct an evaluation based on the inorganic (major, trace and rare earth elements) geochemistry method with three controlling factors of source rock development (paleoproductivity, sedimentary environment and sedimentary rate). The concentration of Ba and Ni, MoEF and UEF and Ce anomaly, and TiO2/Al2O3 ratio could be correlated with paleoproducitvity, sedimentary environment and sedimentary rate, respectively. The results showed that the enrichment of organic matter was mainly controlled by sedimentary environment and paleoproductivity, but are barely effected by sedimentary rate. Source rocks in the Lower Cambrian Qiongzhusi Formation in the central Sichuan and Weiyuan-Ziyang areas have high paleoproductivity and the most reduced environment and thus are one of the best quality source rocks. Therefore, inorganic geochemistry method is an effective way to evaluate postmature source rocks.

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In order to classify the quantitative characterization method of structural fracture length in low-permeability reservoirs, the Cambrian Longwangmiao Formation of Moxi-Gaoshiti areas in the Sichuan Basin is taken an example in this study. The relationship between structural fracture lengths of low-permeability reservoirs was derived from the perspective of structural stress field by the means of core fracture statistics and rock mechanical experiment. Quantitative relationships between fracture length and fracture volume density, strain energy density and rock mass stress state were established. Results showed a negative exponential power relationship between fracture length and number, a proportional linear relationship between fracture volume density and strain energy density, and a negative exponential power relationship between fracture length and volume density. The derived fracture length formula was applied to the Longwangmiao Formation in Moxi-Gaoshiti areas. Numerical simulation results showed that fracture density generally ranges from 1-5 m2/m3, and the highest value is 9 m2/m3, mainly distributed in fault and its surrounding areas. Fracture length is mainly between 1-20 m. The fractures in fault and surrounding areas are dense and short, usually less than 3 m.

The petroleum geological elements and main controlling factors of the Middle-Upper Cambrian Xixiangchi Group in the eastern Sichuan Basin were systematically analyzed on the basis of geological outcrops and drilling data. Results showed that the reservoir lithology of the Xixiangchi Group was mainly micritic and silt-crystal dolomites, and the reservoir space was dominated by dolomite inter-crystalline pores, inter-crystalline dissolved pores and karst caves, etc., at the meantime, the reservoir quality is generally poor. The Xixiangchi Group was vertically composed by two sets of source rocks strata: the underlying Lower Cambrian Qiongzhusi Formation and the overlying Upper Ordovician Wufeng Formation-Lower Silurian Longmaxi Formation. The Silurian shale and the Lower Ordovician argillaceous rocks acted as regional and local cap rocks of the Xixiangchi Group. High-quality reservoirs are the necessary prerequisite for hydrocarbon accumulation in the Xixiangchi Group, and the source-reservoir spatial configuration and its effectiveness are the key factors to hydrocarbon accumulation. Though the Xixiangchi Group could have been charged by natural gas generated from the underlying and the overlying source rocks, it is difficult for the natural gas generated from the underlying source rocks to migrate up to the Xixiangchi Group due to the barrier of the Cambrian gypsum layers. However, the faulted anticlines developed over the Cambrian gypsum layer were favorable for hydrocarbon accumulation because they could change and construct a series of effective source-reservoir spatial configuration between the Wufeng-Longmaxi source rocks and the Xixiangchi reservoirs, and finally formed reservoirs with "young source in old reservoir" in the Xixiangchi Group.

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Exploration experiences have showed that the main source rocks of the Lower Cambrian have not been developed in the Bachu uplift; however, the well MB1 in this area had a good oil and gas showing in the Lower Cambrian.To clarify the hydrocarbon source of well MB1 and evaluate the exploration potential of the Bachu uplift, the core extracts from the oil and gas display section of the Lower Cambrian Wusongge'er Formation of well MB1 were studied here by using of geochemical analysis, moreover, oil-oil and oil-source correlations have also been carried out.The saturated hydrocarbon fraction of extracts showed a typical signature which is consistent with marine crude oil in the Tarim Basin, of which the n-alkanes have a single-peak pre-peak distribution, the series is preserved intact and there was no apparent "hump" in the basline, the ratio of Pr/Ph was 0.89, the abundance of the tricyclic terpanes was higher than that of the hopanes, the C27-C28-C29ααα20R regular steranes had a typical "V" shape, the carbon isotope value of crude oil is -30.8‰, and the trifluorene compounds were obviously override thiofluorene.It then indicates that they were derived from the saprolite-type sources with a strongly reducing sedimentary environment, moreover, the organic matters are high mature.The Lower Cambrian oil showed in well MB1 have the same origin as the Ordovician crude oil in the Yubei 1 belt, and both of them probably came from the Lower Cambrian source rocks. It was inferred that the Lower Cambrian oil and gas in well MB1 came from the peripheral Lower Cambrian source rocks or paleo-oil reservoirs, which enhanced the exploration potential of Cambrian in the Bachu uplift.

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Based on drilling data of JT1 and CS1, outcrop profiles and seismic data, the sedimentary pattern, space configuration of source-reservoir-cap combinations and paleouplift evolution characteristics of the Cambrian Lower Canglangpu Member in the central Sichuan paleouplift have been investigated to determine the favorable exploration zones. Controlled by Deyang-Anyue rift, the Lower Canglangpu Member features differential characteristics from east to west in sedimentary framework. In the west side of the Deyang-Anyue rift, this member is composed of clastic sediments, while in the east side of the Deyang-Anyue rift, it is fresh water shelf sediments, with grain beaches occurring along edges of the depressions, shelf and lagoon. Among the beaches, the dolomitic ones are mainly distributed around the depression edge and in the north of the lagoon. The beach sediments could become high quality reservoirs under the effect of karstification. Underlying the Lower Canglangpu Member is the widespread source rock of the Qiongzhusi Formation, so oil and gas generated by the Qiongzhusi Formation source rock can directly charge into the beach reservoirs. The sandy mudstone of the Upper Canglangpu Member can serve as the caprock of the Lower Canglangpu Member reservoir. The dolomitic beaches are located at the higher part of the paleo-uplift during the main accumulation period, with good hydrocarbon accumulation elements. Blocks PT1-CS1, HT1-GT2 and east GT2 are favorable exploration zones.

The Cambrian gypsum-salt rocks in the Tarim Basin are key geological elements to the pre-salt play typical marine evaporites, yet little attention has been paid to this set of evaporites. Based on a field survey, the latest 2D seismic interpretation and comprehensive analysis of sixteen exploratory wells, a study on the sedimentary characteristics of gypsum-salt rock was carried out in a progression of "point to line, and to plane", and a contour map of the Lower to Middle Cambrian cap rocks, gypsum-salt rocks and the sedimentary facies maps of the Awatag Formation were compiled. A development model of "dry and hot paleoclimate, continuous regression process, reef barrier background" of the Lower to Middle Cambrian gypsum-salt rocks was established. There are four sets of gypsum-salt rocks with four lithofacies combinations developed longitudinally and stably in the Wusongger and Awatag formations. The gypsum-salt rocks in the regression stage are featured by "inner salt, middle gypsum, outer red-layer", while those in the transgression stage are interbedded with gypsum, mudstone and dolomite. The average thickness of the Lower to Middle Cambrian cap rocks in the Tarim Basin is 245 m, and the average thickness of the gypsum-salt rocks is 167 m (340 m maximum), showing good sealing capacity. The arid-hot paleoclimate, continuous regression and reef and reef barrier provided favorable conditions for the development of thick gypsum-salt rocks in the Early to Middle Cambrian of the Tarim Basin. The paleoclimate and sea level change restricted the facies boundary between limited platform and evaporation platform, and made the Bachu Uplift and Awati Sag (the stable thickness of gypsum-salt rocks is over 300 m) become the salt accumulation center at that time.

Based on the observation of outcrops and cores, thin section identification, restoration of paleogeomorphology by residual thickness method, fine description of seismic facies, etc., the coupling relationships between the development patterns of various types of Cambrian platform margin mound-shoal complexes and paleogeomorphology in the Gucheng area of Tarim Basin have been examined. The Cambrian platform margin mound-shoal complex is divided into mound base, mound core, mound front, mound back and mound flat microfacies, which are composed of dolomites of seven textures with facies indication. The different paleogeomorphology before the deposition of mound-shoal complex in each period was reconstructed, and three types of mound-shoal complex sedimentary models corresponding to the paleogeomorphologies of four stages were established: namely, the first stage of gentle slope symmetric accretion type, the second stage of steep slope asymmetric accretion type and the third and fourth stages of steep slope asymmetric progradation type. Their microfacies are respectively characterized by “mound base - mound back + (small) mound core + mound front - mound flat” symmetric vertical accretion structure, “mound base - (large) mound core + mound front - mound flat” asymmetric vertical accretion structure, “mound base - (small) mound core + mound front - mound flat” asymmetric lateral progradation structure. With most developed favorable reservoir facies belt, the steep slope asymmetric accretion type mound-shoal complex with the characteristics of “large mound and large shoal” is the exploration target for oil and gas reservoir.

The Cambslan strata of Zhucaoying Section in Qinhuangdao, Hebsi are intact and continuous, and stromatolltes are developed in the top of Zhangxla Formation of Mlaoling Series. Based on field data and microscopic observation, the characteristics and sedimentary envtronment of columnar(domal) stromatolltes are studied. The results show that stromatollte bioherms and high energy oolltic shoal limestones are developed in the forced regressive system at the top of the Cambslan Zhangxla Formation in Qinhuangdao, Hebsi, which are produced in an interactive manner, representing the carbonate deposition during the slow sea ievel delline in the North Chma Platform during the Cambrian. The well-pre-served filamentous calcified cyanobacteria sheath fossils and window-like fabrics can be found in the dense micrite of the stromatolites from the Zhangxia Formafion, suggesfing that the stromatolites were formed by the complex calcification of photosynthesis microbial mats or microbial membranes. A small amount of pyrite residue associated with precipitation induced by sulfate reducing bacteria was observed. The results provide an important case for studying the sedimentary environment of Cambrian stromatolites. [ABSTRACT FROM AUTHOR]

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In recent years, great achievements have been made in the exploration of ultra-deep marine oil and gas in the Tarim Basin. New oil and gas discoveries have been achieved in the Shunbei Ordovician, Tazhong Cambrian and Tahe deep strata, which provide abundant basic data for studying the marine oil and gas accumulation in the Tarim Basin. The marine oil and gas in the Tarim Basin are mainly distributed in the platform-basin area. There are various types of reservoirs, and the physical properties of crude oil vary greatly, showing the complexity of hydrocarbon accumulation. Through the analysis of a large number of samples, simulation experiments and extensive geology and geochemistry analysis, combined with the research results of tectonic evolution, sequence stratigraphy, sedimentary facies and sedimentary environments, some significant progress has been achieved such as the distribution and evolution of source rocks, oil and gas geochemistry characteristics, and the distribution characteristics of marine oil and gas reservoirs. The following achievements have been made: 1) clarification that the marine oil and gas in the Tarim platform-basin area mainly come from the Lower Cambrian-Middle/Lower Ordovician source rocks formed under strongly reducing environments, especially the Lower Cambrian Yuertusi Formation in the platform-basin. Two alterations types of ultra-deep marine reservoirs, namely, TSR and thermal cracking are defined, and the corresponding identification indicators are proposed. 2) by establishing the sedimentary development mode of the gentle slope-type high-quality Yuertusi source rocks, through well-seismic calibration, forward modeling, regional survey line interpretation of seismic facies, 3D area attribute analysis and seismic inversion, the distribution of source rocks in the Yuertusi Formation may be predicted, and their evolution characteristics clarified: the "high-pressure hydrocarbon generation evolution inhibition mode" under the long-term low geothermal background since the Yanshan period has delayed the thermal evolution of Shuntuoguole low uplift Cambrian source rocks, and the Shuntuoguole area still has the formation conditions of late high-maturity liquid hydrocarbon. 3) by comparing the hydrocarbon accumulation characteristics of the platform-basin area, the Ordovician oil and gas distribution characteristics have been clarified, further delineating the Cambrian Yuertusi in situ source rocks there, and identification of the light oil-gas reservoirs matching with the active strike-slip faults in the late Yanshan period and charged by the late hydrocarbon supply, which provide an key direction for oil and gas exploration in the ultra-deep carbonate rocks of the Tarim platform-basin area.

An evaluation of carbonate oil and gas was carried out based on the petroleum accumulation system theory of a superimposed basin. Considering the evaluation parameters of previous achievements, the hydrocarbon resource, plays, pathway systems and the preservation of the petroleum system were analyzed for carbonate beds in the Tarim Basin. A new evaluation standard was prepared. In this standard, the plays which go through the same tectonic evolution process, and the hydrocarbon resource and pathway system, which provide hydrocarbon for the play, comprise one petroleum accumulation system. In the evaluation of pathways, three parameters, type of migration pathway, hydrocarbon supply mode, and migration distance are chosen. The statistics of migration distance and reservoir numbers showed that migration distance can be divided into four sections, < 10 km, 10-50 km, 50-100 km, > 100 km. Oil and gas accumulation units and basin structural units were both used to divide the oil and gas area, and the uncertainty of geological parameters was also taken into account. The evaluation of the carbonate oil and gas in the Tarim Basin was carried out. The east of the Tabei uplift and the north of the Tazhong uplift belong to class 1, while the Shuntuoguole low uplift, Southwest Depression, south of Tazhong uplift, north of Bachu uplift, west of Tabei uplift belong to class 2.

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.)

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 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 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 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 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.)

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 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 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 Cambrian dolomite reservoir in Tarim Basin is characterized by old age, deep burial and strong diagenesis, whose primary porosity is almost completely destroyed，and the development of effective fracture is the key to the quality of reservoir. Research on the effectiveness and filling characteristics of the fractures of Cambrian dolomite reservoir in the northern Tarim Basin is based on the core and thin-sections, formation microscanner image (FMI) logging, scanning electron microscope (SEM), cathode luminescence microscope (CLM), electron microprobe and fluid inclusion methods. The results indicate that the fracture is growing in the northern Tarim Basin, in which the fractures in the southern Tianshan area and Tahe area are different in occurrence, linear density, shapes and the filling characteristics. In the southern Tianshan area, the linear density and effectiveness of fractures are lower than those in Tahe area, and the filling minerals are dominated by idiomorphic dolomite and quartz, followed by calcite, gypsum and pyrite. Dolomite-filling is divided into three stages and the corresponding temperature ranges are 70 ℃-90 ℃, 90 ℃-110 ℃ and more than 110 ℃, which are caused by diagenetic fluid in strata; the quartz-filling is divided into two phases, the first is caused by the clay minerals alteration, and the second may be the hydrothermal genesis. Tahe area, in which the linear density and effectiveness of fractures are well and the dissolution develops, is a favorable exploration zone; the filling minerals are made of hydrothermal minerals, which are dominated by calcite and followed by gypsum, saddle dolomite, clay mineral, asphalt, etc., and the barite occurs in the form of metasomatic dolomite. Calcite-filling is four times in Tahe area and the corresponding temperature ranges are 70 ℃-100 ℃, 100 ℃-130 ℃, 130 ℃-180 ℃ and more than 180 ℃, among the first three periods are the genesis of diagenetic fluid in different buried depth, and the last one is caused by high temperature hydrothermal fluid from the lower migration. [ABSTRACT FROM AUTHOR]

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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.)

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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.)