Micro pore and throat characteristics and origin of tight sandstone reservoirs: A case study of the Triassic Chang 6 and Chang 8 members in Longdong area, Ordos Basin, NW China

Liu, Hanlin; Yang, Ye; Wang, Fengqin; Deng, Xiuqin; Liu, Ye; Nan, Junxiang; Jin, Wang; Zhang, Hongjie

doi:10.1016/s1876-3804(18)30027-2

Cited by 33 publications

(19 citation statements)

References 6 publications

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“…The Lucaogou Formation in Jimsar Sag mainly develops lacustrine and delta deposits [27,44]. Different sedimentary facies have different rock types and reservoir properties, which are the basis for various diagenetic processes and the evolution of later secondary pores.…”

Section: Sedimentationmentioning

confidence: 99%

“…For example, Liu Li et al used the high-pressure mercury intrusion testing technology to obtain the microscopic pore structure parameters of pore throat size, distribution and connectivity of shale oil reservoirs in the Jiyang Depression and analyzed the contribution degree of different scale pore throats to seepage capacity. The previous researches mainly focused on a single layer and discussed the characterization techniques of the pore throat structure of different lithologies in shale oil reservoirs [22][23][24][25][26][27]. These studies deepen the understanding of the pore throat structure in shale oil reservoirs.…”

Section: Introductionmentioning

confidence: 99%

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Characteristics and Genetic Mechanism of Pore Throat Structure of Shale Oil Reservoir in Saline Lake—A Case Study of Shale Oil of the Lucaogou Formation in Jimsar Sag, Junggar Basin

et al. 2021

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The shale oil reservoir of the Lucaogou Formation in the Jimsar Sag has undergone tectonic movement, regional deposition and complex diagenesis processes. Therefore, various reservoir space types and complex combination patterns of pores have developed, resulting in an intricate pore throat structure. The complex pore throat structure brings great challenges to the classification and evaluation of reservoirs and the efficient development of shale oil. The methods of scanning electron microscopy, high-pressure mercury injection, low-temperature adsorption experiments and thin-slice analysis were used in this study. Mineral, petrology, pore throat structure and evolution process characteristics of the shale oil reservoir were analyzed and discussed qualitatively and quantitatively. Based on these studies, the evolution characteristics and formation mechanisms of different pore throat structures were revealed, and four progressions were made. The reservoir space of the Lucaogou Formation is mainly composed of residual intergranular pores, dissolved pores, intercrystalline pores and fractures. Four types of pore throat structures in the shale oil reservoir of the Lucaogou Formation were quantitatively characterized. Furthermore, the primary pore throat structure was controlled by a sedimentary environment. The pores and throats were reduced and blocked by compaction and cementation, which deteriorates the physical properties of the reservoirs. However, the dissolution of early carbonate, feldspar and tuffaceous minerals and a small amount of carbonate cements by organic acids are the key factors to improve the pore throat structure of the reservoirs. The genetic evolution model of pore throat structures in the shale oil reservoir of the Lucaogou Formation are divided into two types. The large-pore medium-fine throat and medium-pore medium-throat reservoirs are mainly located in the delta front-shallow lake facies and are characterized by the diagenetic assemblage types of weak compaction–weak carbonate cementation–strong dissolution, early medium compaction–medium calcite and dolomite cementation–weak dissolution. The medium-pore fine throats and fine-pore fine throats are mainly developed in shallow lakes and semi-deep lakes. They are characterized by the diagenetic assemblage type of strong compaction–strong calcite cementation–weak dissolution diagenesis. This study provides a comprehensive understanding of the pore throat structure and the genetic mechanism of a complex shale oil reservoir and benefits the exploration and development of shale oil.

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Section: Sedimentationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Characteristics and Genetic Mechanism of Pore Throat Structure of Shale Oil Reservoir in Saline Lake—A Case Study of Shale Oil of the Lucaogou Formation in Jimsar Sag, Junggar Basin

et al. 2021

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“…In recent years, with the deepening of oil and gas exploration in Yanchang Formation of Ordos Basin, new breakthroughs have been made in the exploration of Chang 8 in Wuqi, Zhijing, Ansai, and other areas in northern Shaanxi region of the basin, proving that there are rich oil resources. Previous studies on the sedimentary facies [1][2][3], accumulation mechanism [4][5][6], and other aspects of this area are more, but there are few studies on the characteristics of reservoir micropore structure, compact mechanism, and other aspects, which are limited to a few studies on the whole basin, and relatively few related to the northern Shaanxi area [7]. There are few research results on reservoir characteristics, pore structure characteristics, diagenetic evolution, and tight factors of Chang 8 in Wuqi, Zhijing, and Ansai Yanchang Formation in northern Shaanxi area.…”

Section: Introductionmentioning

confidence: 99%

Characteristics and Genetic Mechanism of Chang Eight Low Permeability and Tight Reservoir of Triassic Yanchang Formation in Central-East Ordos Basin

et al. 2022

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In this article, the characteristics of Chang 8 reservoir of Triassic Yanchang Formation in northern Shaanxi are studied by using polarizing microscope, field emission scanning electron microscope, image particle size, X-ray diffraction analysis of clay, and constant pressure mercury intrusion. The study shows that the target layer is in a relatively stable and uniform sinking burial period after deposition, and the lithology composition in the area is relatively complex, mainly composed of debris–feldspar sandstone and feldspar sandstone, with the characteristics of fine grain and high content of interstitial material. The porosity of the reservoir is generally between 4% and 12%, with an average of 8.05%. The permeability is generally between 0.03 × 10−3 and 0.5 × 10−3 μm2, with an average of 0.16 × 10−3 μm2. Strong compaction and well-developed cementation of calcareous, siliceous, and authigenic illite are important reasons for the formation of extra-low porosity and extra-low permeability reservoirs. But at the same time, because of the protective effect of chlorite film, some residual intergranular pores are preserved, which makes the some reservoirs with relatively good physical property, forming a local relatively high-porosity and high-permeability section of the “highway.”

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“…Recent years, many researches have been carried out on pore segmentation of tight sandstone. From the qualitative evaluation of pores develops into the quantitative evaluation of pore distribution at the micron-nanometer level (Loucks et al, 2009;Andrew et al, 2014;Liu et al, 2018;Zhu et al, 2018;Li et al, 2019;Qu et al, 2020;Shan et al, 2020;, from 2D analysis relying on scanning electron microscopy (SEM) develops into 3D feature analysis using focused ion beam scanning electron microscopy (FIB-SEM) (Curtis et al, 2012;Tartakovsky et al, 2015;Shaina et al, 2016;Alexandra et al, 2020;Chen et al, 2020;Choi et al, 2020;Goral et al, 2020). But most of these researches are focus on imaging technology, the essence of the pore segmentation method is still based on the gray-scale threshold without any significantly improvement (Kang et al, 2019;Shou et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

Dynamic capillary pressure analysis of tight sandstone based on digital rock model

et al. 2020

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In recent studies, dynamic capillary pressure has shown significant impacts on the flow behaviors in porous media under transient flow condition. However, the effect of dynamic capillary pressure effect on tight sandstone is still not very clear. Since lattice Boltzmann method (LBM) is a very promising and widely used method in analyzing flow behaviors, therefore, a two-phase D3Q27 LBM model is adopted in this paper to simulate the flow behaviors and analyze the dynamic capillary pressure effect in tight sandstone. Moreover, a new pore segmentation method for tight sandstone base on U-net deep learning model is implemented in this study to improve the pore boundary qualities of pore space, which is crucial for two-phase LBM simulation of tight sandstone. A total of 3800 3D sub-volume data sets extracted from computed tomography data of 19 tight sandstone samples are selected as ground truth data to train the network and segment the pore space afterward. The simulation results based on the segmented digital rock model, show that nonwetting phase fluid prefer the path with lower dynamic capillary pressure in the seepage process before breaking through the porous model. Furthermore, the increase of injection rate causes the saturation changes more quickly, injection rate also shows apparent positive correlation relationship with capillary pressure, which implies that dynamic capillary pressure effect also exists in tight sandstone, and LBM based two-phase flow simulation could be used to quantitatively analyze such effect in tight sandstone.

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Micro pore and throat characteristics and origin of tight sandstone reservoirs: A case study of the Triassic Chang 6 and Chang 8 members in Longdong area, Ordos Basin, NW China

Cited by 33 publications

References 6 publications

Characteristics and Genetic Mechanism of Pore Throat Structure of Shale Oil Reservoir in Saline Lake—A Case Study of Shale Oil of the Lucaogou Formation in Jimsar Sag, Junggar Basin

Characteristics and Genetic Mechanism of Pore Throat Structure of Shale Oil Reservoir in Saline Lake—A Case Study of Shale Oil of the Lucaogou Formation in Jimsar Sag, Junggar Basin

Characteristics and Genetic Mechanism of Chang Eight Low Permeability and Tight Reservoir of Triassic Yanchang Formation in Central-East Ordos Basin

Dynamic capillary pressure analysis of tight sandstone based on digital rock model

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