Tectonic deformation features and petroleum geological significance in Yinggehai large strike-slip basin, South China Sea

The subtle strike-slip tectonic deformation and its relationship to deposition, overpressure and hydrocarbon migration were studied on the basis of systematic sorting of tectonic data.(1) The local T(tension) fractures derived from sinistral strike-slip process were formed before 10.5 Ma, large in number in the nose structure of the eastern slope, and reactivated episodically under the effect of fluid overpressure in the late stage, they served as dominant vertical hydrocarbon migration paths in the slope area of basin.(2) The dextral strike-slip extension was conducive to the increase of depositional rate and formation of regional under-compacted seal, and induced generation of local T fractures which triggered the development of diapirs; in turn, the development of diapirs made T fractures grow in size further.(3) The sinistral strike-slip process weakened after 10.5 Ma, causing tectonic movement characterized by compression in the north and rotational extension in the south, and the uplift and erosion of strata in Hanoi sag and a surge in clastics supply for south Yinggehai sag. Finally, migrating slope channelized submarine fans and superimposed basin floor fans were developed respectively on the asymmetrical east and west slopes of the Yinggehai sag.

Effects of Intracratonic Strike-slip Fault on the Differentiation of Carbonate Microfacies: A Case Study of a Permian Platform Margin in the Sichuan Basin(SW China)

In intracratnoic basins, the effect of strike-slip faults on sedimentary microfacies is generally underestimated due to their small scale. Based on the integration of core, well logs, and three-dimensional seismic data, this study presents a comprehensive analysis of the Permian carbonate platform and strike-slip faults in the southwestern Kaijiang-Liangping trough of the Sichuan Basin. The relationship between strike-slip faults and Permian carbonate microfacies is investigated. The results reveals the existence of a NW-trending strike-slip fault zone along the platform margin, exhibiting clear segmentation. The western side of the study area exhibits a rimmed platform margin characterized by type I reefs, which corresponds to the presence of a large-scale strike-slip fault zone. In contrast, the eastern side is characterized by a norimmed and weak rimmed platform margin, accompanied by type II reefs, which align with smaller strike-slip fault zones. It was found that the strike-slip fault had some effects on the platform and reef-shoal complex of the Permain Changxing Formation. First, the platform was divided by strike-slip fault into three segments to show rimmed, week rimmed and norimmed platform. Second, reef-shoal complex devolped along the faulted high position in the strike-slip fault zone, and separated by faulted depression. Third, strike-slip faults can offset or migrated the reef-shoal complex and platform margin. Additionally, the thickness of the platform margin varies across strike-slip fault zone, which is related to the activity of strike-slip faults. The strike-slip faults affect the microfacies by controlling the pre-depositional paleotopography. This case suggests that the strike-slip faults play a crucial role in the diversity and distribution of carbonate microfacies in the intracratonic basin.

The Middle and Lower Cambrian salt tectonics in the central Tarim Basin,China:A case study based on strike-slip fault characterization

Due to the considerable depth of the salt layers and the lack of calibration by exploratory drilling,the interpretation of the Middle and Lower Cambrian salt formations in the central Tarim Basin poses a challenge.In this paper,we apply the coupling and decoupling deformation theory in salt tectonics to analyze the No.7 fault mapped in the seismic datasets by the response characteristics of the Middle and Lower Cambrian layers.By quantifying the stratigraphic framework of the Middle and Lower Cambrian strata,we define the position of the salt layer with the seismic data.Structural decoupling is observed in the Middle and Lower Cambrian sequences in the Shuntuoguole Low Uplift,while deformation coupling is observed in these two sequences in the Shaya Uplift.

Characteristics of strike-slip inversion structures of the Karatau fault and their petroleum geological significances in the South Turgay Basin,Kazakhstan

The Karatau fault is one of the important strike-slip faults in central Asia,and the South Turgay Basin is located towards its northern end.Detailed seismic interpretation indicated that the strikeslip tectonism of the Karatau fault weakened gradually from west to east in the South Turgay Basin.Typical flower structures developed on the section,and strike-slip faults showed an echelon pattern on planar view.The Karatau strike-slip fault affected the South Turgay Basin in two periods：（1） The South Turgay strike-slip pull-apart rift basin formed as a result of regional extensive stress in the Early-Middle Jurassic,characterized by the juxtaposition of horsts and grabens.The formation of horsts provided favorable reservoir spaces for later hydrocarbon accumulation,and different filling stages of grabens controlled different reservoir-forming factors in grabens.（2） Two stages of tectonic inversion occurred in the Late Jurassic and Late Cretaceous and played a crucial role in the final shape of the structure in the South Turgay Basin.The oil and gas migrated to form reservoirs and mainly concentrated in the horsts,graben slopes and in both sides of the strike-slip fault zone.In the case of the degree of accumulation of petroleum,the factor explaining why horsts are better than grabens is the strike-slip pull-apart of the South Turgay Basin,and the structure inversion of the South Turgay Basin explains why the west graben is better than the east one.Overall,the Karatau strike-slip fault played a very important role in the formation of the South Turgay Basin and its hydrocarbon accumulations.

Characteristics and evolution of strike-slip tectonics of the Liaohe Western Sag,Bohai Bay Basin

Because of its rich oil and gas resources and the special tectonic location of the Liaohe Western Sag （the Tanlu Fault traverses the sag）, Bohai Bay Basin, a detailed study of its strike-slip tectonics is significant in revealing the sag＇s tectonic evolution, its control on hydrocarbon accumulation, and the activity history of the northern section of the Tanlu Fault in the Cenozoic. Through systematic structure analysis of 3D seismic data of the Liaohe Western Sag, combined with balanced section analysis, a variety of structural features in relation to right-lateral strike-slip faults, such as echelon normal faults, ＂comb＂ structure, ＂flower＂ structure,＂interpretable＂ and ＂buried＂ strike-slip faults have been revealed exist in the Liaohe Western Sag. According to the research in this paper, the complex structural phenomena in the Liaohe Western Sag could be reasonably interpreted as right-lateral strike-slip activity and the strike-slip activities of the Liaohe Western Sag began in the early Oligocene. The activity was weak at the beginning （E3s1-2）, then strengthened gradually and reached its strongest level in the late Oligocene （E3d1）. In the Miocene, the strike-slip activity was low and then strengthened significantly once again from the Pliocene to the present. It is speculated that the entire northern section of the Tanlu Fault has had a similar evolution history since the Oligocene.

Origin and growth mechanisms of strike-slip faults in the central Tarim cratonic basin, NW China

Through fault structure analysis and chronology study, we discuss the origin and growth mechanisms of strike-slip faults in the Tarim Basin.(1) Multiple stages strike-slip faults with inherited growth were developed in the central Tarim cratonic basin. The faults initiation time is constrained at the end of Middle Ordovician of about 460 Ma according to U-Pb dating of the fault cements and seismic interpretation.(2) The formation of the strike-slip faults was controlled by the near N-S direction stress field caused by far-field compression of the closing of the Proto-Tethys Ocean.(3) The faults localization and characteristics were influenced by the pre-existing structures of the NE trending weakening zones in the basement and lithofacies change from south to north.(4) Following the fault initiation under the Andersonian mechanism, the strike-slip fault growth was dominantly fault linkage, associated with fault tip propagation and interaction of non-Andersonian mechanisms.(5) Sequential slip accommodated deformation in the conjugate strike-slip fault interaction zones, strong localization of the main displacement and deformation occurred in the overlap zones in the northern Tarim, while the fault tips, particularly of narrow-deep grabens, and strike-slip segments in thrust zones accumulated more deformation and strain in the Central uplift. In conclusion, non-Andersonian mechanisms, dominantly fault linkage and interaction, resulted in the small displacement but long intraplate strike-slip fault development in the central Tarim Basin. The regional and localized field stress, and pre-existing structures and lithofacies difference had strong impacts on the diversity of the strike-slip faults in the Tarim cratonic basin.

The Dihedral Angle and Intersection Processes of a Conjugate Strike-Slip Fault System in the Tarim Basin, NW China

Recent studies, focused on dihedral angles and intersection processes, have increased understandings of conjugate fault mechanisms. We present new 3-D seismic data and microstructural core analysis in a case study of a large conjugate strike-slip fault system from the intracratonic Tarim Basin, NW China. Within our study area, ＂X＂ type NE and NW trending faults occur within Cambrian- Ordovician carbonates. The dihedral angles of these conjugate faults have narrow ranges, 19~ to 62~ in the Cambrian and 26~ to 51~ in the Ordovician, and their modes are 42~ and 44~ respectively. These data are significantly different from the ~60~ predicted by the Coulomb fracture criterion. It is concluded that： （1） The dihedral angles of the conjugate faults were not controlled by confining pressure, which was low and associated with shallow burial; （2） As dihedral angles were not controlled by pressure they can be used to determine the shortening direction during faulting; （3） Sequential slip may have played an important role in forming conjugate fault intersections; （4） The conjugate fault system of the Tarim basin initiated as rhombic joints; these subsequently developed into sequentially active ＂X＂ type conjugate faults; followed by preferential development of the NW-trending faults; then reactivation of the NE trending faults. This intact rhombic conjugate fault system presents new insights into mechanisms of dihedral angle development, with particular relevance to intracratonic basins.

Vertical Differential Structural Deformation of the Main Strike-slip Fault Zones in the Shunbei Area,Central Tarim Basin:Structural Characteristics,Deformation Mechanisms,and Hydrocarbon Accumulation Significance

Vertical differential structural deformation(VDSD),one of the most significant structural characteristics of strike-slip fault zones(SSFZs)in the Shunbei area,is crucial for understanding deformation in the SSFZ and its hydrocarbon accumulation significance.Based on drilling data and high-precision 3-D seismic data,we analyzed the geometric and kinematic characteristics of the SSFZs in the Shunbei area.Coupled with the stratification of the rock mechanism,the structural deformations of these SSFZs in different formations were differentiated and divided into four deformation layers.According to comprehensive structural interpretations and comparisons,three integrated 3-D structural models could describe the VDSD of these SSFZs.The time-space coupling of the material basis(rock mechanism stratification),changing dynamic conditions(e.g.,changing stress-strain states),and special deformation mechanism of the en echelon normal fault array uniformly controlled the formation of the VDSD in the SSFZs of the Shunbei area.The VDSD of the SSFZs in this area controlled the entire hydrocarbon accumulation process.Multi-stage structural superimposing deformation influenced the hydrocarbon migration,accumulation,distribution,preservation,and secondary adjustments.

Formation and evolution of the strike-slip faults in the central Sichuan Basin, SW China

Based on 3D seismic and drilling data, the timing, evolution and genetic mechanism of deep strike-slip faults in the central Sichuan Basin are thoroughly examined by using the U-Pb dating of fault-filled carbonate cement and seismic-geological analysis. The strike-slip fault system was initially formed in the Late Sinian, basically finalized in the Early Cambrian with dextral transtensional structure, was overlaid with at least one stage of transpressional deformation before the Permian, then was reversed into a sinistral weak transtensional structure in the Late Permian. Only a few of these faults were selectively activated in the Indosinian and later periods. The strike-slip fault system was affected by the preexisting structures such as Nanhuanian rifting normal faults and NW-striking deep basement faults. It is an oblique accommodated intracratonic transfer fault system developed from the Late Sinian to Early Cambrian to adjust the uneven extension of the Anyue trough from north to south and matches the Anyue trough in evolution time and intensity. In the later stage, multiple inversion tectonics and selective activation occurred under different tectonic backgrounds.

Seismic damage zone and width-throw scaling along the strike-slip faults in the Ordovician carbonates in the Tarim Basin

Understanding the scaling relation of damage zone width with displacement of faults is important for predicting subsurface faulting mechanisms and fluid flow processes. The understanding of this scaling relationship is influenced by the accuracy of the methods and types of data utilized to investigate faults. In this study, seismic reflection data are used to investigate the throw and damage zone width of five strike-slip faults a ecting Ordovician carbonates of the Tarim intracraton basin,NW China. The results indicate that fault slips with a throw less than 200 m had formed wide damage zones up to 3000 m in width. Also, damage zone width is found to have both a positive correlation and a power-law relation with throw of two orders of magnitude, with a ratio of these values varying in a range of 2–15. The relationship between throw and damage zone width is not a simple power-law and changes its slope from small to larger size faults. The results indicate that throw scales well with damage zone width for the studied faults, and hence these can be used to predict fault geometries in the Tarim Basin. The study of the wide carbonate damage zones presented here provides new insights into scaling of large-size faults, which involve multiple faulting stages.

A New Growth Model of Fault Attributes in a Strike-Slip Fault System in the Tarim Basin

Fault attributes generally display a consistent power–law-scaling relationship.Based on new 3 D seismic data,however,we found some exceptional fault attribute relationships of lengths(L)–throw(T)(vertical component of displacement),overlap zone length(Lo)–width(Wo)from a strike-slip fault system of the Ordovician carbonates in the Tarim Basin.The L–T relationship shows two linear segments with breakup at^40 km in fault length.This presents an exceptional throw increase in the second stage,which is attributed to a localization of vertical displacement and deformation in overlapping zones other than the different fault scales in a mature fault zone.The Lo–Wo relationship in the overlapping zones shows multiply stepped-shape patterns,suggesting multiple fault differential growth and periodic increase in fault size.Therefore,we propose a new alternative growth model of fault attributes in strike-slip fault zones,in which the overlapping zones accumulated localized displacement and deformation in the intracratonic strike-slip fault zone.

Strike-Slip Faults and Their Control on Differential Hydrocarbon Enrichment in Carbonate Karst Reservoirs: A Case Study of Yingshan Formation on Northern Slope of Tazhong Uplift, Tarim Basin

Objective Oil and gas are abundant in the Ordovician Yingshan Formation carbonate karst reservoirs on the northern slope of Tazhong uplift in the Tarim Basin, and have extremely complicated oil-gas-water distribution, however. The difference in burial depth of the reservoirs between east and west sides is up to 1000 m. Water-bearing formations exist between oil- and gas-bearing formations vertically and water-producing wells are drilled between oil- and gas-producing wells. Macroscopically, oil and gas occur at low positions, while water occurs at high positiona on the northern slope of Tazhong uplift. The mechanism of differential hydrocarbon enrichment in heterogeneous reservoirs is by far not clarified, which has affected the efficient exploration and development of oil and gas fields in this area.

Deformation patterns and hydrocarbon potential related to intracratonic strike-slip fault systems in the east of Central Uplift Belt in the Tarim Basin

Strike-slip faults,proven to be closely linked to hydrocarbon migration and accumulation,are wide-spread in the Tarim Basin Craton.Deformation patterns in the eastern part of the Central Uplift Belt of the Tarim Basin are analyzed in detail to understand the deformation model and genetic mechanism of strike-slip faults,how their patterns impact reservoir formation and influence oil and gas potential.Regional tectonic events are taken into consideration to identify the primary factors that controlled the development of strike-slip faults in the region.The Tazhong Uplift in the eastern part of Central Uplift Belt is believed to be a complex anticlinal uplift formed by compression-and-torsion acting on the Cambrian-Middle Ordovician platform during the middle-late Caledonian period.Multi-stage development of this north-trending fault-fold belt and the NE-trending strike-slip faults make it structurally complex.The NE-trending Paleozoic strike-slip faults were formed jointly by the differential thrusting of the Tazhong Uplift along Fault No.Ⅰand the NE-trending shear sliding of the basal fault blocks during the middle-late Caledonian-early Hercynian.Based on the distribution of effective source rocks,the tectonic setting during the period critical to hydrocarbon accumulation,and the distribution of conductive faults,the northern slope of the Tazhong Upliftd-especially its west-central part where the NE-trending faults are developed is not only located close to the northern hydrocarbon source rock area but also possesses conditions suitable for the development of carbonate reservoirs.In addition,the NE-trending faults provide passage for initial development of the reservoir and the subsequent migration of oil and gas from the Aman area to the uplifted zone,making the Tazhong Uplift an extremely favorable area for oil and gas accumulation with substantial potential for exploration.

Control of strike-slip faults on Sinian carbonate reservoirs in Anyue gas field, Sichuan Basin, SW China

The largest Precambrian gas field (Anyue gas field) in China has been discovered in the central Sichuan Basin. However, the deep ancient Ediacaran (Sinian) dolomite presents a substantial challenge due to their tightness and heterogeneity, rather than assumed large-area stratified reservoirs controlled by mound-shoal microfacies. This complicates the characterization of “sweet spot” reservoirs crucial for efficient gas exploitation. By analyzing compiled geological, geophysical and production data, this study investigates the impact of strike-slip fault on the development and distribution of high-quality “sweet spot” (fractured-vuggy) reservoirs in the Ediacaran dolomite of the Anyue gas field. The dolomite matrix reservoir exhibits low porosity (less than 4%) and low permeability (less than 0.5×10^(-3) μm^(2)). Contrarily, fractures and their dissolution processes along strike-slip fault zone significantly enhance matrix permeability by more than one order of magnitude and matrix porosity by more than one time. Widespread “sweet spot” fracture-vuggy reservoirs are found along the strike-slip fault zone, formed at the end of the Ediacaran. These fractured reservoirs are controlled by the coupling mechanisms of sedimentary microfacies, fracturing and karstification. Karstification prevails at the platform margin, while both fracturing and karstification control high-quality reservoirs in the intraplatform, resulting in reservoir diversity in terms of scale, assemblage and type. The architecture of the strike-slip fault zone governed the differential distribution of fracture zones and the fault-controlled “sweet spot” reservoirs, leading to wide fractured-vuggy reservoirs across the strike-slip fault zone. In conclusion, the intracratonic weak strike-slip fault can play a crucial role in improving tight carbonate reservoir, and the strike-slip fault-related “sweet spot” reservoir emerges as a unique and promising target for the efficient development of deep hydrocarbon resources. Tailored development strategies need to be implemented for these reservoirs, considering the diverse and differential impacts exerted by strike-slip faults on the reservoirs.

Exploration discovery and hydrocarbon accumulation characteristics of the Doseo strike-slip and inverted basin, Chad

Several international oil companies had conducted petroleum exploration, but failed to make any commercially viable discoveries in the Doseo Basin for over 30 years. In this article, an integrated analysis, based on the latest seismic and drilling data combined with exploration practice and tectonic, sedimentary as well as petroleum-geological characteristics of the basin, has been conducted with the aim to disclose the key factors of hydrocarbon accumulation and enrichment and then to find the potential petroleum plays. The Doseo Basin in Chad is a Meso-Cenozoic lacustrine rift basin developed on the Precambrian crystalline basement in the Central African Shear Zone. It is a half graben rift controlled by the strike-slip fault at the northern boundary, and can be divided into two sub-basins, an uplift and a slope. The basin experienced two rifting periods in the Cretaceous and was strongly inverted with the erosion thickness of 800–1000 m during the Eocene, and then entered the depression and extinction period. Structurally, a large number of normal faults and strike-slip faults are identified in the basin, and the boundary faults are inverted faults with normal at first. The main structural styles include inverted anticlines, fault noses, complex fault-blocks and flower structures. The Lower Cretaceous is the main sedimentary strata, which are divided into the Mangara Group, Kedeni, Doba and Koumra Formations from bottom to up. Two transgressive-regressive cycles developed in the Lower Cretaceous indicates with mainly lacustrine, fluvial, delta, braided-delta, fan-delta sandstone and mudstone. The effective source rock in the basin is the deep-lacustrine mudstone of the Lower Cretaceous containing the type Ⅰ and type Ⅱ;organic matters. Furthermore, Inverted anticlines and fault-complicated blocks comprise the main trap types and the Kedeni Uplift is the most favorable play, followed by the Northern Steep Slope and Southern Gentle Slope. Lateral sealing capacity of faults controls the hydrocarbon abundance.

STRUCTURAL ORIGIN OF THE FAULTED BROWN COAL BASIN IN YUNNAN, CHINA──The role of strike-sliping in basin formation and inversion of Xianfeng coal basin

Based on the analysises of regional structural setting, basin formation and deformation, this paper demonstrates that the Xianfeng basin has been formed and inverted under the strike-slip regime. The article is a partial result of the whole research.

SEDIMENTARY-STRUCTURAL EVOLUTION OF A STRIKE-SLIP COAL BASIN IN CENTRAL YUNNAN,CHINA

The Kebao coal basin is located at the middle segment of the Xiaojiang fault zone in the central part of Yunnan Province. The coal-bearing strata of Tertiary age are made up of alluvial fan-lacustrine-swamp genetic sequences. Sinistral strike-slip motion of the N-S trending fault zone has created a locally transtensional or transpres sional tectonic environment, giving rise to the relative movement of fault blocks in the basement, and the development of a strike-slip coal basin at the surface. Based on de tailed sedimentary-structural analyses, the paper proposes geodynamic models for the coal basin formation and its deformation.

Geochemistry and origins of hydrogen-containing natural gases in deep Songliao Basin,China:Insights from continental scientific drilling

The different reservoirs in deep Songliao Basin have non-homogeneous lithologies and include multiple layers with a high content of hydrogen gas.The gas composition and stable isotope characteristics vary significantly,but the origin analysis of different gas types has previously been weak.Based on the geochemical parameters of gas samples from different depths and the analysis of geological settings,this research covers the diverse origins of natural gas in different strata.The gas components are mainly methane with a small amount of C_(2+),and non-hydrocarbon gases,including nitrogen(N_(2)),hydrogen(H_(2)),carbon dioxide(CO_(2)),and helium(He).At greater depth,the carbon isotope of methane becomes heavier,and the hydrogen isotope points to a lacustrine sedimentary environment.With increasing depth,the origins of N_(2)and CO_(2)change gradually from a mixture of organic and inorganic to inorganic.The origins of hydrogen gas are complex and include organic sources,water radiolysis,water-rock(Fe^(2+)-containing minerals)reactions,and mantle-derived.The shales of Denglouku and Shahezi Formations,as source rocks,provide the premise for generation and occurrence of organic gas.Furthermore,the deep faults and fluid activities in Basement Formation control the generation and migration of mantle-derived gas.The discovery of a high content of H_(2)in study area not only reveals the organic and inorganic association of natural-gas generation,but also provides a scientific basis for the exploration of deep hydrogen-rich gas.

Fossil Equidae in the Linxia Basin with Biostratigraphic and Paleozoogeographic Significance

The Linxia Basin is characterized by an abundance of Cenozoic sediments,that contain exceptionally rich fossil resources.Equids are abundant in the Linxia Basin,the fossil record of equids in this region including 16 species that represent 10 genera.In comparison to other classic late Cenozoic areas in China,the Linxia Basin stands out,because the fauna and chronological data accompanying Linxia equids render them remarkably useful for biostratigraphy.The anchitheriines in the region,such as Anchitherium and Sinohippus,represent early equids that appeared in the late stages of the middle and late Miocene,respectively.Among the equines,most species of Chinese hipparions have been identified in the Linxia Basin and some species of the genera Hipparion and Hippotherium have FAD records for China.Furthermore,Equus eisenmannae is one of the earliest known species of Equus in the Old World and is well-represented at the Longdan locality.Some species with precise geohistorical distributions can serve as standards for high-resolution chronological units within this framework.Located at the eastern margin of the Tibetan Plateau and subject to considerable uplift,the Linxia Basin has served as a biogeographic transition area for equids throughout the late Cenozoic.

Geochemical characteristics and exploration significance of ultra-deep Sinian oil and gas from Well Tashen 5,Tarim Basin,NW China

The Well Tashen 5(TS5),drilled and completed at a vertical depth of 9017 m in the Tabei Uplift of the Tarim Basin,NW China,is the deepest well in Asia.It has been producing both oil and gas from the Sinian at a depth of 8780e8840 m,also the deepest in Asia in terms of oil discovery.In this paper,the geochemical characteristics of Sinian oil and gas from the well were investigated and compared with those of Cambrian oil and gas discovered in the same basin.The oil samples,with Pr/Ph ratio of 0.78 and a whole oil carbon isotopic value of31.6‰,have geochemical characteristics similar to those of Ordovician oils from the No.1 fault in the North Shuntuoguole area(also named Shunbei area)and the Middle Cambrian oil from wells Zhongshen 1(ZS1)and Zhongshen 5(ZS5)of Tazhong Uplift.The maturity of light hydrocarbons,diamondoids and aromatic fractions all suggest an approximate maturity of 1.5%e1.7%Ro for the samples.The(4-+3-)methyldiamantane concentration of the samples is 113.5 mg/g,indicating intense cracking with a cracking degree of about 80%,which is consistent with the high bottom hole temperature(179℃).The Sinian gas samples are dry with a dryness coefficient of 0.97.The gas is a mixture of kerogen-cracking gas and oil-cracking gas and has Ro values ranging between 1.5%and 1.7%,and methane carbon isotopic values of41.6‰.Based on the equivalent vitrinite reflectance(R_(eqv)=1.51%e1.61%)and the thermal evolution of source rocks from the Cambrian Yu'ertusi Formation of the same well,it is proposed that the Sinian oil and gas be mainly sourced from the Cambrian Yu'ertusi Formation during the Himalayan period but probably also be joined by hydrocarbon of higher maturity that migrated from other source rocks in deeper formations.The discovery of Sinian oil and gas from Well TS5 suggests that the ancient ultra-deep strata in the northern Tarim Basin have the potential for finding volatile oil or condensate reservoirs.