Pore structure of the Cretaceous lacustrine shales and shale-oil potential assessment in the Songliao Basin, Northeast China

2021 ◽  
Vol 9 (1) ◽  
pp. T21-T33
Author(s):  
Weizhu Zeng ◽  
Guoyi Zhou ◽  
Taotao Cao ◽  
Zhiguang Song
Keyword(s):  
Pore Structure ◽  
Saturation Index ◽  
Great Influence ◽  
Micropore Volume ◽  
Songliao Basin ◽  
Hydrocarbon Generation ◽  
Shale Oil ◽  
Oil Saturation ◽  
Positive Correlation ◽  
Layer Mineral

Aiming to study the pore structure and its impact on shale oil enrichment, a total of nine lacustrine shales (including one immature shale and eight mature shales) from the Qingshankou Formation in the Songliao Basin were subjected to low-pressure gas sorption (LPGS) of CO2 and N2 and mercury intrusion capillary pressure (MICP) measurements. The combination of the LPGS and MICP methods demonstrates that the pore volumes of these shales are mainly associated with mesopores, whereas the micropores and macropores are relatively undeveloped. The correlation between the shale compositions and pore volumes of LPGS suggests that the micropores and mesopores are mainly contributed by illite/smectite mixed layer mineral. On the contrary, we have found that the oil/bitumen and carbonates could occupy the micropores and mesopores, respectively, and reduce these pore volumes significantly. The oil saturation index (OSI) was found to display a positive correlation with the maturity Ro value in the range of 0.37%–1.24%, and this may suggest that the shale-oil content is controlled by hydrocarbon generation. However, the pore structure also exerts a great influence on the shale oil enrichment. We suggested that the porosity of MICP could be considered as an index for appraising the shale-oil potential of a given shale player because there is a good positive correlation between the porosity of MICP and the OSI value. Furthermore, a negative correlation between the micropore volume and the OSI value may imply that the shale oil could be adsorbed in micropores, whereas a good positive correlation between the OSI value and the Hg-retained ratio suggests that shale oil is a kind of residual hydrocarbon, which is closely related with the mesopore volume of these shales.

scholarly journals Geological and Geochemical Characteristics of the First Member of the Cretaceous Qingshankou Formation in the Qijia Sag, Northern Songliao Basin, Northeast China: Implication for Its Shale Oil Enrichment

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-20
Author(s):  
Fei Xiao ◽  
Jianguo Yang ◽  
Shichao Li ◽  
Fanhao Gong ◽  
Jian Zhang ◽  
...  
Keyword(s):  
Organic Matter ◽  
Saturated Hydrocarbon ◽  
Saturation Index ◽  
Effective Porosity ◽  
Songliao Basin ◽  
Geochemical Characteristics ◽  
Type I ◽  
Shale Oil ◽  
Oil Saturation ◽  
Extractable Organic Matter

The Qijia Sag, a secondary tectonic unit in the northern Songliao Basin, developed plentiful shale oil resources in the first member of the Cretaceous Qingshankou Formation (K2qn1) as its main target layer. However, the systematic study on the geological and geochemical characteristics of K2qn1 in the sag has not been carried out. Taking the core samples from the SYY1 well covering the whole K2qn1 as the main study object and concerning some relevant intervals from the SYY1HF well and other earlier wells, petrologic features, organic geochemical characteristics, oil-bearing property, and reservoir characteristics of K2qn1 were analyzed in detail. The results show that the lithology of K2qn1 is mainly dark mudstone genera accounting for more than 90% of the formation thickness with few macrostructural fractures, indicating that K2qn1 developing in deep to semideep lacustrine facies of the Qijia Sag belongs to the typical matrix reservoirs for shale oil. According to lithology features and logging curves, K2qn1 can be divided into three submembers consisting of K2qn11, K2qn12, and K2qn13 from above to below. Compared to the K2qn11 submember, the K2qn12 and K2qn13 submembers obviously are more enriched in shale oil, which is supported by the following three aspects: (i) the average TOC (total organic carbon) values of K2qn11, K2qn12, and K2qn13 are 1.96%, 2.42%, and 2.72%, respectively. The organic matter types of K2qn12 and K2qn13 are mainly type I and type II1, while those of K2qn11 are mainly type II1 and type II2. K2qn1 is at the end of the oil window with a R o (vitrinite reflectance) average of 1.26%, and the maturity of K2qn12 and K2qn13 is slightly higher than that of K2qn11. (ii) The average OSI (oil saturation index) values of K2qn11, K2qn12, and K2qn13 are 110.54 mg/g, 171.74 mg/g, and 150.87 mg/g, respectively, which all reach the zone of oil crossover. The saturated hydrocarbon of EOM (extractable organic matter) in K2qn12 and K2qn13 is of higher content than that in K2qn11, while it is the opposite for the aromatic hydrocarbon, nonhydrocarbon, and asphaltene, indicating better oil mobility for K2qn12 and K2qn13. The average oil saturation values of K2qn11, K2qn12, and K2qn13 are 24.77%, 32.86%, and 35.54%, respectively. (iii) The intragranular dissolution pores and organic pores in K2qn12 and K2qn13 are more developed than those in K2qn11. The average effective porosity values of K2qn11, K2qn12, and K2qn13 interpreted from NMR logging are 4.88%, 6.26%, and 5.86%, respectively. Based on the above-mentioned analyses, the lower K2qn12 and the upper K2qn13 are determined as the best intervals of shale oil enrichment for K2qn1 vertically in the Qijia Sag. There is a certain horizontal heterogeneity of TOC, S 1 , and effective porosity in the drilling horizontal section of K2qn1 of the SYY1HF well. Therefore, the lower K2qn12 and the upper K2qn13 in the area with relatively weak horizontal reservoir heterogeneity of the study area should be selected as the preferential targets for shale oil exploration.

scholarly journals Enrichment Factors and Resource Potential Evaluation of Qingshankou Formation Lacustrine Shale Oil in the Southern Songliao Basin, NE China

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-20
Author(s):  
Long Luo ◽  
Dongping Tan ◽  
Xiaojun Zha ◽  
Xianfeng Tan ◽  
Jing Bai ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Well Logging ◽  
Enrichment Factors ◽  
Songliao Basin ◽  
Hydrocarbon Generation ◽  
Shale Oil ◽  
Resource Potential ◽  
Potential Evaluation ◽  
Lacustrine Shale ◽  
Exploration And Development

China shale oil, which is preserved in lacustrine shale with strong heterogeneity and relatively low maturity, has been a research hotspot of unconventional resources. However, controlling factors of shale oil enrichment and resource potential evaluation restricted efficient exploration and development of lacustrine shale oil. On the basis of well logging data, TOC content, Rock-Eval pyrolysis values, thermal maturity, 100 oil saturation data, and pressure coefficient, the core observation, X-ray diffraction analysis, physical property analysis, scanning electron microscopy, CT scan, well logging interpretation, and volumetric genesis method depending on three-dimensional geological modeling were used to determine enrichment factors and evaluate the resource potential of Qingshankou Formation shale oil in the Southern Songliao Basin. Shale oil was mainly enriched in the semideep and deep lake shale of K2qn1, with the high capacity of hydrocarbon generation and favorable petrological and mineralogical characteristics, pore space characteristics, and physical properties in the low structural part of the Southern Songliao Basin. The three-dimensional geological resource model of Qingshankou Formation lacustrine shale oil was determined by the key parameters (Ro, TOC, and S 1 ) of shale oil in the favorable zone of the Southern Songliao Basin, northeast China. The geological resource of shale oil, which was calculated by two grid computing methods ( F 1 and F 2 ), was, respectively, 1.713 × 10 12   kg and 1.654 × 10 12   kg . The great shale oil resource indicates a promising future in the exploration and development of Qingshankou Formation shale oil of the Southern Songliao Basin.

Pore characteristics of lacustrine mudstones from the Cretaceous Qingshankou Formation, Songliao Basin

2017 ◽  
Vol 5 (3) ◽  
pp. T373-T386 ◽  
Author(s):  
Min Wang ◽  
Shuangfang Lu ◽  
Wenbiao Huang ◽  
Wei Liu
Keyword(s):  
Organic Matter ◽  
Source Rock ◽  
Gas Adsorption ◽  
Total Pore Volume ◽  
Songliao Basin ◽  
Hydrocarbon Generation ◽  
Shale Oil ◽  
Pore Characteristics ◽  
Oil Accumulation ◽  
Average Pore

Cretaceous Qingshankou ([Formula: see text]) mudstone of lacustrine origin is the major source rock for conventional hydrocarbon currently being produced in the Daqing and Jilin oilfields of the Songliao Basin, which is one of the largest continental basins in the world. Therefore, elucidating the geochemical and petrological characteristics of the [Formula: see text] mudstone is important to help determine its quality as an economically viable source for shale oil production. In our study, eight dark mudstone core samples from the [Formula: see text] formation were subjected to total organic carbon (TOC), Rock-Eval pyrolysis, X-ray diffraction, scanning electron microscopy (SEM), field emission SEM (FE-SEM), and low-pressure [Formula: see text] gas adsorption (LPGA-[Formula: see text]) experiments. Geochemical and petrological analysis results indicated the presence of a high TOC content, which originated mainly from alginate and some plant-derived organic matter, whereas bitumen was frequently present in mudstones with thermal maturity in the oil-generation stage. The [Formula: see text] mudstones were comprised mainly of clay minerals, followed by quartz, feldspar, and carbonates. The LPGA-[Formula: see text] experiments revealed the presence of nanoscale slit-shaped pores, and the contribution from mesopores to the total pore volume was the highest in most of the samples. The average pore diameters (APDs) of the mudstone samples were all smaller than 20 nm (4.36–17.79 nm). We determined that there was a clear positive correlation between the APD and the free oil content; however, there were no clear correlations between the APDs and the quartz, carbonate, and TOC contents. FEM studies revealed the presence of intergranular pores with widths of approximately 10 μm, micron-level autogenetic organic matter pores within spores, organic matter pores caused by the hydrocarbon generation effect within organic matter or clay-organic complexes, and intraparticle pores within clays or pyrite framboids. The microlevel intergranular pores might play an important role in shale oil accumulation from source rock of lacustrine origin.

The Evaluation of Potential of Shale Oil Resources in K1qn1 Formation of Southern Songliao Basin

2014 ◽  
Vol 1006-1007 ◽  
pp. 107-111
Author(s):  
Yan Wang ◽  
Wen Biao Huang ◽  
Min Wang
Keyword(s):  
Organic Matter ◽  
Source Rock ◽  
Thermal Evolution ◽  
Songliao Basin ◽  
Mature Stage ◽  
Type I ◽  
Hydrocarbon Generation ◽  
Shale Oil ◽  
Oil Resources ◽  
Geochemical Method

Based on the analysis of source rock geochemical index, with K1qn1 Formation of southern Songliao basin as the research objective layer, it’s concluded that the mean TOC value of shale in K1qn1 Formation is higher, generally more than 1%, which belongs to the best source rock. Most of shale organic matter types are type I and type II1. The thermal evolution degree of organic matter is generally in the mature stage: a stage of large hydrocarbon generation. With logging geochemical method applied, the calculated total resources of shale oil in K1qn1 formation are 15.603 billion tons. The II level of resources are 8.765 billion tons, which is more than 50% of the total resources. The I level of resources are 4.808 billion tons while the III level of resources 2.03 billion tons. Overall, the southern Songliao Basin still has a certain degree of prospecting and mining value.

scholarly journals Pore Structure Petrophysical Characterization of the Upper Cretaceous Oil Shale from the Songliao Basin (NE China) Using Low-Field NMR

2020 ◽  
Vol 2020 ◽  
pp. 1-11 ◽  
Author(s):  
Xin Liu ◽  
Jinyou Zhang ◽  
Yunfeng Bai ◽  
Yupeng Zhang ◽  
Ying Zhao ◽  
...  
Keyword(s):  
Pore Structure ◽  
Oil Shale ◽  
Upper Cretaceous ◽  
Distribution Patterns ◽  
Songliao Basin ◽  
Shale Oil ◽  
Low Field ◽  
Wide Range ◽  
Low Field Nmr

Low-field NMR theory was employed to study the pore structure of the upper cretaceous oil shale, on the basis of fourteen core samples collected from Qingshankou (UCQ) and Nenjiang (UCN) formations in the Songliao basin. Results indicated that the T2 spectra from NMR measurements for collected samples contain a dominant peak at T2 = 1∼10 ms and are able to be categorized as three types—unimodal, bimodal, and trimodal distributions. The various morphologies of T2 spectra indicate the different pore type and variable connection relationship among pores in shale. By contrast, UCN shale has more single pore type and adsorption pores than UCQ shale. Besides, NMR-based measurements provide reliable characterization on shale porosity, which is verified by the gravimetric approach. Porosities in both UCN and UCQ shales have a wide range (2.3%∼12.5%) and suggest the strong heterogeneity, which partly makes the challenge in selection of the favorable area for shale oil exploration in the Songliao basin. In addition, the pore size of the collected sample has two distribution types, namely, peaked at ∼10 nm and peaked at ∼100 nm. Similarly, two distribution patterns emerge to the specific surface area of the study shale—peaked at ∼2 nm−1 and peaked at ∼20 nm−1. Here, more investigations are needed to clarify this polarization phenomenon. Basically, this study not only exhibits a preliminary understanding on the pore structure of the upper cretaceous oil shale, but also shows the reliability and pertinency of the low-field NMR technique in the petrophysical characterization of the shale oil reservoir. It is expected that this work is helpful to guide the investigation on the pore structure of oil shale from the Songliao basin in theory.

scholarly journals Pore Characteristics of Lacustrine Shale Oil Reservoir in the Cretaceous Qingshankou Formation of the Songliao Basin, NE China

Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 2027 ◽  
Author(s):  
Xiaomeng Cao ◽  
Yuan Gao ◽  
Jingwei Cui ◽  
Shuangbiao Han ◽  
Lei Kang ◽  
...  
Keyword(s):  
Pore Structure ◽  
Fractal Dimensions ◽  
Nitrogen Adsorption ◽  
Songliao Basin ◽  
Oil Reservoir ◽  
Shale Oil ◽  
Pore Characteristics ◽  
Oil Accumulation ◽  
Average Pore ◽  
Lacustrine Shale

Shale oil is hosted in nanopores of organic-rich shales, so pore characteristics are significant for shale oil accumulation. Here we analyzed pore characteristics of 39 lacustrine shale samples of the Late Cretaceous Qingshankou Formation (K2qn) in the Songliao Basin, which is one of the main shale oil resource basins in China, using field emission-scanning electron microscopy (FE-SEM), and low-pressure nitrogen adsorption. We accomplished fractal analysis, correlation analysis using correlation matrix and multidimensional scaling (MDS), and prediction of fractal dimensions, which is the first time to predict pore fractal dimensions of shales. Interparticle pores are highly developed in K2qn. These shales have mesoporous nature and slit-shaped pores. Compared with the second and third members (K2qn2,3), the first member of the Qingshankou Formation (K2qn1) has a larger average pore diameter, much smaller surface area, fewer micropores, simpler pore structure and surface indicated by smaller fractal dimensions. In terms of pore characteristics, K2qn1 is better than K2qn2,3 as a shale oil reservoir. When compared with marine Bakken Formation shales, lacustrine shales of the Qingshankou Formation have similar complexity of pore structure, but much rougher pore surface. This research can lead to an improved understanding of the pore system of lacustrine shales.

scholarly journals First evidence of the early cretaceous oceanic anoxic events (MBE and OAE1a) in the southern Tethyan margin (NE-Tunisia): biostratigraphy and shale resource system

2021 ◽  
Vol 11 (4) ◽  
pp. 1559-1575
Author(s):  
Rachida Talbi ◽  
Ahlem Amri ◽  
Abdelhamid Boujemaa ◽  
Hakim Gabtni ◽  
Reginal Spiller ◽  
...  
Keyword(s):  
Black Shale ◽  
Saturation Index ◽  
Black Shales ◽  
Source Rocks ◽  
Type I ◽  
Hydrocarbon Generation ◽  
Shale Oil ◽  
Hydrocarbon Generation Potential ◽  
Anoxic Events ◽  
Rock Eval

AbstractThe Jebel Oust region (north-eastern Tunisia) recorded two levels of marine black shale in the Lower Cretaceous marly series. Geodynamic evolution, biostratigraphic and Rock–Eval analysies allow classifying those black shales as unconventional shale oil resource systems that were deposited during two oceanic anoxic events: the Middel Barremian Event "MBE" and the Early Aptian Event "OAE1a". Paleogeographic evolution highlights two transgressive–regressive cycles: the first one is Valanginian-Early Barremian, and the second is Late Barremian–Early Aptian. Each black shale deposit occurs at the end of the transgression that coincides with the highest sea level. During the Barreman–Aptian interval, sedimentation was controlled by extensional faults in a system of tilted fault blocks which were reactivated several times. Kerogen is of type I, II origin in black shales and of type III origin in marls. Tmax values indicate "oil window" stage. Average transformation ratio is around 67% and 82%, respectively, in the Lower Aptian and Middel Barremian source rock related to the relatively high thermal maturity degree due to the deep burial of the later. Estimated initial hydrocarbon generation potential is moderate to high. Oil saturation index records an "oil crossover" indicating expelled and migrated hydrocarbons from the organic-rich to the organic-poor facies. The petroleum system of the two mature source rocks with a high hydrocarbon generation potential enclose all elements characterizing a "shale oil hybrid system with a combination of juxtaposed organic-rich and organic-lean facies associated with open fractures".

scholarly journals The Influence of Reservoir Composition on the Pore Structure of Continental Shale: A Case Study from the Qingshankou Formation in the Sanzhao Sag of Northern Songliao Basin, NE China

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-21
Author(s):  
Jianguo Yang ◽  
Liu Wang ◽  
Shichao Li ◽  
Cheng Zuo ◽  
Fei Xiao ◽  
...  
Keyword(s):  
Organic Matter ◽  
Pore Structure ◽  
Clay Minerals ◽  
Influencing Factors ◽  
Gas Adsorption ◽  
Songliao Basin ◽  
Organic Carbon Content ◽  
Type I ◽  
Shale Oil ◽  
Distribution Diagram

Determining the pore structure characteristics and influencing factors of continental shale reservoir in the oil generation stage is of great significance for evaluating the shale oil reservoir space and analyzing shale oil enrichment mechanism. In this paper, shale from the first member of the Upper Cretaceous Qingshankou Formation (K2qn1) in the Songliao Basin was selected. X-ray diffraction (XRD), Rock-Eval pyrolysis, total organic carbon content (TOC), scanning electron microscopy (SEM), nitrogen gas adsorption (N2GA), and high-pressure mercury injection (HPMI) were used to clarify the composition characteristics of inorganic minerals and organic matter and determine the influencing factors of pore development in the K2qn1 shale. The results show that intergranular pores related to clay minerals and quartz, intragranular dissolution pores related to feldspar, and other mineral intragranular pores are developed. The organic matter pore is less developed, mainly composed of intragranular pores and crack pores of organic matter. Mesopores related to clay minerals are widely developed, rigid quartz particles can protect and support mesopores and macropores, and carbonate cementation can inhibit pore development. Although the TOC contents of shale are commonly less than 2.5%, it has a good positive correlation with porosity; TOC is greater than 2.5%, and the increase of residual oil fills part of the pores, leading to a decrease in porosity with the increase of TOC. Three types (types I, II, and III) of the reservoir space were classified by the combined pore size distribution diagram of N2GA and HPMI. By comparing the characteristics of pore structure parameters, it is found that Type I reservoir space is favorable for shale oil enrichment. It provides scientific guidance for shale oil exploration in the Songliao Basin.

scholarly journals Modeling of Tectonic-Thermal Evolution of Cretaceous Qingshankou Shale in the Changling Sag, Southern Songliao Basin, NE China

2021 ◽  
Vol 9 ◽  
Author(s):  
Yuchen Liu ◽  
Bo Liu ◽  
LiJuan Cheng ◽  
Jilin Xing ◽  
Shansi Tian ◽  
...  
Keyword(s):  
Heat Flow ◽  
Late Cretaceous ◽  
Thermal History ◽  
Thermal Evolution ◽  
Songliao Basin ◽  
Tectonic Activity ◽  
Hydrocarbon Generation ◽  
Shale Oil ◽  
Oil Exploration ◽  
History Of

A series of significant shale oil discoveries have been made recently in the Upper Cretaceous Qingshankou Formation in the Songliao Basin, providing a new resource target for shale oil exploration in Northeast China. In this context, an understanding of the tectonic-thermal evolution and maturation history of the Qingshankou Formation is of great significance for shale oil exploration and evaluation. In this study, the thermal history of the Qingshankou Formation since the Late Cretaceous was reconstructed using the paleothermal indicator method. The results indicate that two stages of thermal evolution exist in the southern part of the Songliao Basin: 1) the gradual heating stage during the Late Cretaceous; the heat flow gradually increases during this period and reaches a maximum heat flow value at the end of the Cretaceous. 2) The decline stage since the Neogene; the tectonic activity is relatively stable and the geothermal heat flow is gradually reduced, and the present-day heat flow ranges from 60.1 to 100.7 mW/m2, with an average of 78.2 mW/m2. In addition, the maturity history of the organic-rich shale was reconstructed based on the new thermal history. The Cretaceous Qingshankou shales underwent deep burial thermal metamorphism at the end of the Cretaceous, whereas thermal has faded since the Neogene. The hydrocarbon generation and migration since the Late Cretaceous period of K2qn1 were modeled based on the maturity model. Two main cooling events took place in the late Nenjiang period and the late Mingshui period in the Changling sag. These two tectonic events controlled the structural style and the formation of shale oil reservoirs in the southern Songliao Basin.

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