Triassic Hydrocarbon System of the Middle-Caspian Oil and Gas Basin

2021 ◽  
Author(s):  
Denis Sokolov ◽  
Mikhail Delengov ◽  
Regina Sabirianova ◽  
Konstantin Musikhin ◽  
Oleg Bogdanov
Keyword(s):  
Organic Carbon ◽  
Source Rock ◽  
Oil And Gas ◽  
Source Rocks ◽  
Research Approach ◽  
Basin Modeling ◽  
Petroleum Potential ◽  
Hydrocarbon System ◽  
Geochemical Parameters ◽  
Wide Range

Abstract The objective of this paper is to assess the generation potential of the Triassic hydrocarbon (HC) source rocks for the petroleum potential of the Middle-Caspian Oil and Gas Basin. Tectonically the study area belongs to the Epigercine Scythian-Turanian plate, which includes the following major tectonic elements: the Karpinsk-Mangyshlak ridge and the Prikum-Central Caspian system of troughs and uplifts. Comprehensive research approach to identify the main features of the Triassic hydrocarbon system, such as the interpretation of seismic data, laboratory geochemical analysis and evolution restoration of the hydrocarbon systems elements by 3D basin modeling techniques. The geochemical research includes pyrolytic analysis of potential Triassic source rocks, determination of the vitrinite reflectance values, chromatography-Mass Spectrometry studies of molecular structure. The subsequent basin modeling made it possible to integrate a wide range of geological and geophysical information into a single complex. These basin modeling results provide a better understanding of evolution restoration of the hydrocarbon systems elements and make it possible to foresee hydrocarbon accumulation's localization. The combined set of research helped to identify the boundaries of the Triassic HC source rocks in the Middle-Caspian Basin. It also allowed characterizing in detail their geochemical parameters and evaluating the volume of its generation potential. Triassic deposits are part of the taphrogenic intermediate complex of the Scythian platform and mainly located in graben structures. The increased content of organic matter is associated with the Lower Triassic Neftekum Formation of the Olenek Stage, which is composed of clayey limestones and mudstones. The content of total organic carbon (TOC) in limestones in the Eastern Fore-Caucasus area averages 0.1 % in some layers up to 2.05 %. The average TOC content in mudstones is 0.43 %. This parameter is up to 0.9 % in the direction of the East-Manych trough. Triassic deposits were penetrated by 5 wells, the average content of organic carbon was 1.22% in mudstones. The samples show a migrant presence of bitumen. According to 3D basin modeling results, the Olenek HC source rock has practically exhausted its potential in on most of the except the southern part of the study area, as well as the eastern flank. The Olenek stage's Neftekum HC source rock in the southern part of the model is identified with MK1-3 catagenesis gradations, this grade represents the main zone of oil generation. At the northern part of study area, those strata of source rock are positioned at a great depth. The hydrocarbon source rock in those areas have reached the grades of catagenesis MK5-AK1, which represents the zones of condensate and gas formation. The research results allow to take a new look at the influence of the Triassic hydrocarbon system and its prospects of petroleum potential of the Middle-Caspian Oil and Gas Basin. It also allows evaluating the generation parameters variance of the Olenek stage's Neftekum HC source rock regarding its area and time period.

scholarly journals Hydrocarbon source rock potential of Miocene diatomaceous sequences in Szurdokpüspöki (Hungary) and Parisdorf/Limberg (Austria)

2020 ◽  
Vol 113 (1) ◽  
pp. 24-42
Author(s):  
Emilia Tulan ◽  
Michaela S. Radl ◽  
Reinhard F. Sachsenhofer ◽  
Gabor Tari ◽  
Jakub Witkowski
Keyword(s):  
Source Rock ◽  
Pannonian Basin ◽  
High Energy ◽  
Depositional Environments ◽  
Source Rocks ◽  
Hydrocarbon Source Rock ◽  
Petroleum Potential ◽  
Northern Margin ◽  
Geochemical Parameters ◽  
Study Sites

AbstractDiatomaceous sediments are often prolific hydrocarbon source rocks. In the Paratethys area, diatomaceous rocks are widespread in the Oligo-Miocene strata. Diatomites from three locations, Szurdokpüspöki (Hungary) and Limberg and Parisdorf (Austria), were selected for this study, together with core materials from rocks underlying diatomites in the Limberg area. Bulk geochemical parameters (total organic carbon [TOC], carbonate and sulphur contents and hydrogen index [HI]) were determined for a total of 44 samples in order to study their petroleum potential. Additionally, 24 samples were prepared to investigate diatom assemblages.The middle Miocene diatomite from Szurdokpüspöki (Pannonian Basin) formed in a restricted basin near a volcanic silica source. The diatom-rich succession is separated by a rhyolitic tuff into a lower non-marine and an upper marine layer. An approximately 12-m thick interval in the lower part has been investigated. It contains carbonate-rich diatomaceous rocks with a fair to good oil potential (average TOC: 1.28% wt.; HI: 178 to 723 mg HC/g TOC) in its lower part and carbonate-free sediments without oil potential in its upper part (average TOC: 0.14% wt.). The composition of the well-preserved diatom flora supports a near-shore brackish environment. The studied succession is thermally immature. If mature, the carbonate-rich part of the succession may generate about 0.25 tons of hydrocarbons per square meter. The diatomaceous Limberg Member of the lower Miocene Zellerndorf Formation reflects upwelling along the northern margin of the Alpine-Carpathian Foreland. TOC contents are very low (average TOC: 0.13% wt.) and demonstrate that the Limberg Member is a very poor source rock. The same is true for the underlying and over-lying rocks of the Zellerndorf Formation (average TOC: 0.78% wt.). Diatom preservation was found to differ considerably between the study sites. The Szurdokpüspöki section is characterised by excellent diatom preservation, while the diatom valves from Parisdorf/Limberg are highly broken. One reason for this contrast could be the different depositional environments. Volcanic input is also likely to have contributed to the excellent diatom preservation in Szurdokpüspöki. In contrast, high-energy upwelling currents and wave action may have contributed to the poor diatom preservation in Parisdorf. The hydrocarbon potential of diatomaceous rocks of Oligocene (Chert Member; Western Carpathians) and Miocene ages (Groisenbach Member, Aflenz Basin; Kozakhurian sediments, Kaliakra canyon of the western Black Sea) has been studied previously. The comparison shows that diatomaceous rocks deposited in similar depositional settings may hold largely varying petroleum potential and that the petroleum potential is mainly controlled by local factors. For example, both the Kozakhurian sediments and the Limberg Member accumulated in upwelling environments but differ greatly in source rock potential. Moreover, the petroleum potential of the Szurdokpüspöki diatomite, the Chert Member and the Groisenbach Member differs greatly, although all units are deposited in silled basins.

scholarly journals Effects of igneous intrusions on source rock in the early diagenetic stage: A case study on Beipiao Formation in Jinyang Basin, Northeast China

2020 ◽  
Vol 12 (1) ◽  
pp. 990-1002
Author(s):  
Shouliang Sun ◽  
Tao Zhang ◽  
Yongfei Li ◽  
Shuwang Chen ◽  
Qiushi Sun
Keyword(s):  
Source Rock ◽  
Oil And Gas ◽  
Thermal Evolution ◽  
Vitrinite Reflectance ◽  
Scientific Basis ◽  
Source Rocks ◽  
Temperature History ◽  
Hydrocarbon Generation ◽  
Intrusive Body ◽  
Geochemical Parameters

AbstractMesozoic intrusive bodies play an important role in the temperature history and hydrocarbon maturation of the Jinyang Basin in northeastern China. The Beipiao Formation, which is the main source rock in Jinyang Basin, was intruded by numerous igneous bodies and dykes in many areas. The effects of igneous intrusive bodies on thermal evolution and hydrocarbon generation and migration in the Beipiao Formation were investigated. A series of samples from the outcrop near the intrusive body were analyzed for vitrinite reflectance (R0%) and other organic geochemical parameters to evaluate the lateral extension of the thermal aureole. The R0 values of the samples increase from a background value of ∼0.9% at a distance above 200 m from the intrusive body to more than 2.0% at the vicinity of the contact zone. The width of the altered zone is equal to the thickness of the intrusive body outcropped in the field. Organic geochemical proxies also indicate the intrusive body plays a positive and beneficial role in the formation of regional oil and gas resources. Due to the influence of the anomalous heat from the intrusive body, the hydrocarbon conversion rate of the source rocks of the Beipiao Formation was significantly improved. The accumulation properties and the storage capacity of the shales also greatly improved due to the intrusive body as indicated by the free hydrocarbon migration in the shales. This new understanding not only provides a reliable scientific basis for the accurate assessment of oil and gas genesis and resources in the Jinyang Basin but also provides guidance and reference for oil and gas exploration in the similar type of basin.

Stratigraphic evolution and source rock potential of a Lower Oligocene to Lower–Middle Miocene continental slope system, Hellenic Fold and Thrust Belt, Ionian Sea, northwest Greece

2013 ◽  
Vol 151 (3) ◽  
pp. 394-413 ◽  
Author(s):  
A. MARAVELIS ◽  
G. MAKRODIMITRAS ◽  
N. PASADAKIS ◽  
A. ZELILIDIS
Keyword(s):  
Organic Matter ◽  
Source Rock ◽  
Middle Miocene ◽  
Oil And Gas ◽  
Source Rocks ◽  
Geochemical Data ◽  
Thrust Belt ◽  
Lower Oligocene ◽  
Geochemical Parameters ◽  
Fold And Thrust Belt

AbstractThe Western flanks of the Hellenic Fold and Thrust Belt are similar to the nearby prolific Albanian oil and gas provinces, where commercial volumes of oil have been produced. The Lower Oligocene to Lower–Middle Miocene slope series at this part of the Hellenic Fold and Thrust Belt provides a unique opportunity to evaluate the anatomy and source rock potential of such a system from an outcrop perspective. Slope progradation is manifested as a vertical pattern exhibiting an increasing amount of sediment bypass upwards, which is interpreted as reflecting increasing gradient conditions. The palaeoflow trend exhibits a western direction during the Late Oligocene but since the Early Miocene has shifted to the East. The occurrence of reliable index species allowed us to recognize several nannoplankton biozones (NP23 to NN5). Organic geochemical data indicate that the containing organic matter is present in sufficient abundance and with good enough quality to be regarded as potential source rocks. The present Rock-Eval II pyrolytic yields and calculated values of hydrogen and oxygen indexes imply that the recent organic matter type is of type III kerogen. A terrestrial origin is suggested and is attributed to short transportation distance and accumulation at rather low water depth. The succession is immature with respect to oil generation and has not experienced high temperature during burial. However, its eastern down-slope equivalent deep-sea mudstone facies should be considered as good gas-prone source rocks onshore since they may have experienced higher thermal evolution. In addition, they may have improved organic geochemical parameters because there is no oxidization of the organic matter.

Basin Modeling as a Tool for Research of Regional Oil and Gas Generation Processes and the Possibility of Replacement of Oil and Gas Riches Illustrated through Traygorodsko-Kondakovskoye Oil Field

2021 ◽  
Author(s):  
Vladimir Andreevich Zubkov ◽  
Pavel Vladimirovich Molodykh ◽  
Ivan Vasilievich Goncharov ◽  
Vadim Valerievich Samoilenko ◽  
Svetlana Vasilievna Fadeeva
Keyword(s):  
Organic Matter ◽  
Source Rock ◽  
Oil And Gas ◽  
Oil Field ◽  
Source Rocks ◽  
Material Base ◽  
Basin Modeling ◽  
Hydrocarbon Migration ◽  
Bazhenov Formation ◽  
Gas Source

Abstract The article presents the results of two-year of research aimed at replenishing the resource and raw material base of the northwestern part of the Tomsk region. The practical application possibilities of basin modeling at the prospecting and exploratory stages of geological study of the subsurface are illustrated. The research was divided into two phases. The first of them has sub-regional coverage and includes an area of 25,000 km2 bounded by the Chkalovsky oil and gas condensate field in the southeast and the administrative boundaries of Tomsk Oblast in the northwest. The section is confined to the Alexandrovsky arch, covers part of the Koltogorsko-Nyurolsky chute and the eastern periclinal of the Nizhnevartovsky arch. At the first stage, a three-dimensional model of oil-and-gas bearing basin formation was created, the tasks of which were to replenish the history of generation and formation of ideas about the ways of hydrocarbon migration. The basin submergence has been reconstructed here and the thermal flow history has been restored. The uneven intensity of heat flow at the bottom of the sedimentary cover over the area is explained by tectonic processes and is complicated by a massive granitoid intrusion. In JSC "Tomsk Petroleum institute", the knowledge base of geochemical features of oil-and-gas source rocks and oils of Western Siberia was formed for years, which allowed to use their own kinetic spectra for the surveyed region. To calibrate the paleotemperatures, both the optical characteristics of vitrinite coals and the indicators of the geochemical properties of organic matter of the Bazhenov formation (4/1 MDBT and Tmax) were used. As a result, the conclusion about the presence of two generation centers of different nature was made, the time and volume of oil generation by organic matter of the Bazhenov formation were predicted. Next, the modeling parameters of hydrocarbon migration and accumulation are described. Modeling shows that the primary migration occurs due to the emergence of abnormally high pore pressure during the generation of hydrocarbons and fluid autofracture of the oil and gas source rock. The results of calculations of secondary migration by two different methods are compared. Despite a number of limitations, the results obtained show a fairly high convergence to real data. At the second stage, on the basis of the regional (parent) model a local daughter model of the formation of the Traygorodsko-Kondakovskoye field within the area of 480 km2 covered by 3D seismic exploration was plotted. The rationale for the necessity and description of the results of additional special geochemical studies of fluids and oil source rock, carried out before starting to build a detailed model of the local stage, is given. The article outlines the basic parameters and gives the differences between the local model and the parent model. Conclusions are made about the possibility of assessing the conductive properties of fault in the formation of deposits. The prediction of trap saturation and resource potential assessment is the result, the achievement of which reduced the risks of geological exploration and formed the recommendations for further geological study of the subsurface.

scholarly journals Effective source rock selection and oil–source correlation in the Western Slope of the northern Songliao Basin, China

2021 ◽  
Vol 18 (2) ◽  
pp. 398-415
Author(s):  
He Bi ◽  
Peng Li ◽  
Yun Jiang ◽  
Jing-Jing Fan ◽  
Xiao-Yue Chen
Keyword(s):  
Organic Matter ◽  
Source Rock ◽  
Thermal Evolution ◽  
Songliao Basin ◽  
Source Rocks ◽  
Crude Oils ◽  
Western Slope ◽  
Geochemical Parameters ◽  
Group I ◽  
Oil Source

AbstractThis study considers the Upper Cretaceous Qingshankou Formation, Yaojia Formation, and the first member of the Nenjiang Formation in the Western Slope of the northern Songliao Basin. Dark mudstone with high abundances of organic matter of Gulong and Qijia sags are considered to be significant source rocks in the study area. To evaluate their development characteristics, differences and effectiveness, geochemical parameters are analyzed. One-dimensional basin modeling and hydrocarbon evolution are also applied to discuss the effectiveness of source rocks. Through the biomarker characteristics, the source–source, oil–oil, and oil–source correlations are assessed and the sources of crude oils in different rock units are determined. Based on the results, Gulong and Qijia source rocks have different organic matter primarily detrived from mixed sources and plankton, respectively. Gulong source rock has higher thermal evolution degree than Qijia source rock. The biomarker parameters of the source rocks are compared with 31 crude oil samples. The studied crude oils can be divided into two groups. The oil–source correlations show that group I oils from Qing II–III, Yao I, and Yao II–III members were probably derived from Gulong source rock and that only group II oils from Nen I member were derived from Qijia source rock.

scholarly journals GEOCHEMICAL AND GEOSTATISTICAL ASSESSMENT OF CRETACEOUS COALS AND SHALES IN SOME NIGERAIN SEDIMENTARY BASINS FOR THEIR HYDROCARBON PRONESS AND MATURITY LEVELS

2020 ◽  
Vol 1 (2) ◽  
Keyword(s):  
Source Rock ◽  
Oil And Gas ◽  
Linear Regression Analysis ◽  
Sedimentary Basins ◽  
Source Rocks ◽  
Hydrocarbon Generation ◽  
Good Source ◽  
Type Iii ◽  
Limit Value ◽  
The Impact

The Rock–Eval pyrolysis and LECO analysis for 9 shale and 12 coal samples, as well as, geostatistical analysis have been used to investigate source rock characteristics, correlation between the assessed parameters (QI, BI, S1, S2, S3, HI, S1 + S2, OI, PI, TOC) and the impact of changes in the Tmax on the assessed parameters in the Cretaceous Sokoto, Anambra Basins and Middle Benue Trough of northwestern, southeastern and northcentral Nigeria respectively. The geochemical results point that about 97% of the samples have TOC values greater than the minimum limit value (0.5 wt %) required to induce hydrocarbon generation from source rocks. Meanwhile, the Dukamaje and Taloka shales and Lafia/Obi coal are found to be fair to good source rock for oil generation with slightly higher thermal maturation. The source rocks are generally immature through sub-mature to marginal mature with respect to the oil and gas window, while the potential source rocks from the Anambra Basin are generally sub-mature grading to mature within the oil window. The analyzed data were approached statistically to find some relations such as factors, and clusters concerning the examination of the source rocks. These factors were categorized into type of organic matter and organic richness, thermal maturity and hydrocarbon potency. In addendum, cluster analysis separated the source rocks in the study area into two groups. The source rocks characterized by HI >240 (mg/g), TOC from 58.89 to 66.43 wt %, S1 from 2.01 to 2.54 (mg/g) and S2 from 148.94 to 162.52 (mg/g) indicating good to excellent source rocks with kerogen of type II and type III and are capable of generating oil and gas. Followed by the Source rocks characterized by HI <240 (mg/g), TOC from 0.94 to 36.12 wt%, S1 from 0.14 to 0.72 (mg/g) and S2 from 0.14 to 20.38 (mg/g) indicating poor to good source rocks with kerogen of type III and are capable of generating gas. Howeverr, Pearson’s correlation coefficient and linear regression analysis shows a significant positive correlation between TOC and S1, S2 and HI and no correlation between TOC and Tmax, highly negative correlation between TOC and OI and no correlation between Tmax and HI. Keywords- Cretaceous, Geochemical, Statistical, Cluster; Factor analyses.

Geochemical Inversion - A Modern Approach to Inferring Source-Rock Identity from Characteristics of Accumulated Oil and Gas

1993 ◽  
Vol 11 (3-4) ◽  
pp. 295-328 ◽  
Author(s):  
K.K. Bissada ◽  
L.W. Elrod ◽  
C.R. Robison ◽  
L.M. Darnell ◽  
H.M. Szymczyk ◽  
...  
Keyword(s):  
Source Rock ◽  
Oil And Gas ◽  
Source Rocks ◽  
Specific Information ◽  
Modern Approach ◽  
Age Identity ◽  
Oil And Natural Gas ◽  
Architectural Constraints ◽  
Geologic Setting ◽  
Relative Migration

In recent years, petroleum geochemists have been re-focusing their efforts on developing practical means for inferring, from hydrocarbon chemistry and geologic constraints, the “provenance” of hydrocarbon accumulations, seeps or stains. This capability, referred to here as “Geochemical Inversion”, can be invaluable to the explorationist in deriving clues as to the character, age, identity, maturity and location of an accumulation's source rocks and evaluating a petroleum system's hydrocarbon supply volumetrics. Geochemical inversion is most useful where pertinent source-rock information may be absent because exploratory drilling focused strictly on structural highs and failed to penetrate the deeply buried, effective basinal source facies. Advances in chemical analysis technology over the last decade have facilitated the development of powerful geochemical methods for unravelling of complex chemistries of crude oil and natural gas at the molecular and subatomic levels to extract specific information on the hydrocarbons' source. Inferences on such factors as organic matter make-up, depositional environment, lithology, age and maturity of the source can frequently be drawn. These inferences, together with a sound analysis of the geologic and architectural constraints on the system, can supply clues as to the identity and location of the probable source sequence. This paper describes the principles underlying geochemical “inversion” and provides applications in exploration and exploitation settings. In addition, this paper demonstrates inversion of geochemical characteristics of migrated hydrocarbon fluids to specific attributes of the source. The paper also illustrates the use of systematic variations in fluid chemistry within a geologic setting to infer source location, degree of hydrocarbon mixing and relative migration distance.

The discovery of a new sedimentary basin: offshore Raukumara, East Coast, North Island, New Zealand

2008 ◽  
Vol 48 (1) ◽  
pp. 53 ◽  
Author(s):  
Chris Uruski ◽  
Callum Kennedy ◽  
Rupert Sutherland ◽  
Vaughan Stagpoole ◽  
Stuart Henrys
Keyword(s):  
New Zealand ◽  
Oil And Gas ◽  
East Coast ◽  
Plate Boundary ◽  
Source Rocks ◽  
Fault System ◽  
Northern Coast ◽  
The South ◽  
Petroleum Potential ◽  
The North

The East Coast of North Island, New Zealand, is the site of subduction of the Pacific below the Australian plate, and, consequently, much of the basin is highly deformed. An exception is the Raukumara Sub-basin, which forms the northern end of the East Coast Basin and is relatively undeformed. It occupies a marine plain that extends to the north-northeast from the northern coast of the Raukumara Peninsula, reaching water depths of about 3,000 m, although much of the sub-basin lies within the 2,000 m isobath. The sub-basin is about 100 km across and has a roughly triangular plan, bounded by an east-west fault system in the south. It extends about 300 km to the northeast and is bounded to the east by the East Cape subduction ridge and to the west by the volcanic Kermadec Ridge. The northern seismic lines reveal a thickness of around 8 km increasing to 12–13 km in the south. Its stratigraphy consists of a fairly uniformly bedded basal section and an upper, more variable unit separated by a wedge of chaotically bedded material. In the absence of direct evidence from wells and samples, analogies are drawn with onshore geology, where older marine Cretaceous and Paleogene units are separated from a Neogene succession by an allochthonous series of thrust slices emplaced around the time of initiation of the modern plate boundary. The Raukumara Sub-basin is not easily classified. Its location is apparently that of a fore-arc basin along an ocean-to-ocean collision zone, although its sedimentary fill must have been derived chiefly from erosion of the New Zealand land mass. Its relative lack of deformation introduces questions about basin formation and petroleum potential. Although no commercial discoveries have been made in the East Coast Basin, known source rocks are of marine origin and are commonly oil prone, so there is good potential for oil as well as gas in the basin. New seismic data confirm the extent of the sub-basin and its considerable sedimentary thickness. The presence of potential trapping structures and direct hydrocarbon indicators suggest that the Raukumara Sub-basin may contain large volumes of oil and gas.

scholarly journals Oil chemometrics and geochemical correlation in the Weixinan Sag, Beibuwan Basin, South China Sea

2020 ◽  
Vol 38 (6) ◽  
pp. 2695-2710
Author(s):  
Yao-Ping Wang ◽  
Xin Zhan ◽  
Tao Luo ◽  
Yuan Gao ◽  
Jia Xia ◽  
...  
Keyword(s):  
Source Rock ◽  
Principal Component ◽  
Sedimentary Basins ◽  
Oil Field ◽  
Source Rocks ◽  
Petroleum Exploration ◽  
Crude Oils ◽  
Geochemical Parameters ◽  
Group I ◽  
Oil Source

The oil–oil and oil–source rock correlations, also termed as geochemical correlations, play an essential role in the construction of petroleum systems, guidance of petroleum exploration, and definition of reservoir compartments. In this study, the problems arising from oil–oil and oil–source rock correlations were investigated using chemometric methods on oil and source rock samples from the WZ12 oil field in the Weixinan sag in the Beibuwan Basin. Crude oil from the WZ12 oil field can be classified into two genetic families: group A and B, using multidimensional scaling and principal component analysis. Similarly, source rocks of the Liushagang Formation, including its first, second, and third members, can be classified into group I and II, corresponding to group B and A crude oils, respectively. The principle geochemical parameters in the geochemical correlation for the characterisation and classification of crude oils and source rocks were 4MSI, C27Dia/C27S, and C24 Tet/C26 TT. This study provides insights into the selection of appropriate geochemical parameters for oil–oil and oil–source rock correlations, which can also be applied to other sedimentary basins.

Identification and Distribution of Lower Cretaceous Source Rocks in Ying’er Sag, Jiuquan Basin

2012 ◽  
Vol 616-618 ◽  
pp. 69-72
Author(s):  
Yi Bo Zhou ◽  
Guang Di Liu ◽  
Jia Yi Zhong
Keyword(s):  
Source Rock ◽  
Low Frequency ◽  
Sedimentary Facies ◽  
Organic Content ◽  
Source Rocks ◽  
Potential Source Rock ◽  
Wide Range ◽  
Strong Amplitude ◽  
System Tracts ◽  
High Organic Content

Based on the sequence stratigraphy study, the relation between dark mudstone ratio and sedimentary facies in different system tracts is observed and used to forcast the distribution of dark mudstones in the main formation combining with seismic data and well log. However, not all dark mudstones can generate hydrocarbon, so the source rock quality is quoted to calculate the thickness of the source rock within mudstone. The results show that the favored source rock in lake progressive system tracts and the bottom of highstand system tracts of Xiagou Formation and Chijinpu Formation are related to a group of reflectors with medium-strong amplitude, medium-low frequency and medium to comparatively good lateral continuity. The source rock of Xiagou Formation with high organic content and wide-range distribution is the major hydrocarbon source in Ying’er Sag, while Chijinpu Formation with thick dark mudstones is the potential source rock and the target of the further exploration.

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