Diagenetic characteristics, evolution, controlling factors of diagenetic system and their impacts on reservoir quality in tight deltaic sandstones: Typical example from the Xujiahe Formation in Western Sichuan Foreland Basin, SW China

Luo, Long; Meng, Wei; Gluyas, Jon; Tan, Xianfeng; Gao, Xili; Feng, Ming; Kong, Xianjing; Shao, Hengbo

doi:10.1016/j.marpetgeo.2019.02.012

Cited by 43 publications

(36 citation statements)

References 36 publications

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“…The XRD method used a Bruker D2 Phaser Diffractometer (230 V, 45 KVA from 4 to 60 2θ, step size of 2 per minute). Combined with the burial history curve of the target formation (L. Luo et al, 2019), the diagenetic evolution sequence was determined.…”

Section: Research Methods Of Diagenesismentioning

confidence: 99%

Effects of diagenesis on natural fractures in tight oil reservoirs: A case study of the Permian Lucaogou Formation in Jimusar Sag, Junggar Basin, NW China

et al. 2020

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Compared with conventional reservoirs, tight reservoirs experience more intense diagenesis; thus, their properties are extremely poor. Nevertheless, natural fractures with high‐strength can appear in these reservoirs and could play an essential role in the accumulation and production of tight oil. In this study, we focused on the effects of different diagenetic processes in the formation and transformation of natural fractures to determine the effects of natural fractures on tight reservoirs. Various observation techniques and analysis methods were applied (i.e., observations of cores, cast thin sections, scanning electron microscopy; field emission scanning electron microscopy; and X‐ray diffraction analysis). We clarified characteristics of the fractures and distribution patterns based on core descriptions and microscopic observations and explained the diagenetic stage and evolution sequence of reservoirs. Past studies regarding carbon and oxygen isotope analysis and basin simulation were considered. This study also reviewed the fracture formation time, source of fracture fillings, and oil charging time. We obtained insight into the coupling relationship of fracture states, diagenetic sequences, hydrocarbon charging, and, in particular, the controlling effect of diagenesis on natural fractures. The results revealed that formation, preservation, and destruction of natural fractures in tight reservoirs were closely related to diagenesis. Compaction and cementation in the reservoirs decreased the porosity and altered the petrophysical properties of the reservoir. They also provided favorable conditions for the development of tectonic fractures, while dissolution did not. The influences of dissolution and cementation on natural fractures depended on the duration for which these processes were active. Compaction and cementation formed related types of diagenetic fractures, while dissolution increased the effectiveness of natural fractures. The purpose of this study was to evaluate the influence of diagenesis on the formation, controlling effects, and effectiveness of natural fractures, as well as the effects of natural fractures on tight reservoirs through geological history. This study is expected to provide guidance for future exploration and development of tight oil and gas with similar geological origins.

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Section: Research Methods Of Diagenesismentioning

confidence: 99%

Effects of diagenesis on natural fractures in tight oil reservoirs: A case study of the Permian Lucaogou Formation in Jimusar Sag, Junggar Basin, NW China

et al. 2020

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“…Since the theory of diagenesis was put forward, 27 a lot of studies have been carried out on sandstone and marine shale, and generally accepted results have been obtained 28‐30 . Li et al 31 indicated that the linkage of diagenesis to diagenetic structure mainly includes: impacts of mechanical compaction during burial history,effects of depositional facies and stratigraphy,chemical process of mineralogical conversions,fluid chemistry, temperature, and stress experienced during evolution 32‐35 .…”

Section: Introductionmentioning

confidence: 99%

Study on pore evolution and diagenesis division of a Permian Longtan transitional shale in Southwest Guizhou, China

Guo

2020

Energy Science & Engineering

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Organic‐rich shales, deposited in marine‐continental transitional environments, are widely distributed in southern China. The pore evolution of the Late Permian Longtan Formation shale (Guizhou Province) during its diagenesis and organic matter (OM) evolution was quantitatively and qualitatively investigated through thermal simulation, mercury intrusion capillary pressure, gas adsorption, fractal dimension, and field emission‐scanning electron microscopy observation. Diagenesis and OM evolution stage were subdivided on the basis of X‐ray diffraction, rock pyrolysis, and vitrinite reflectance test; moreover, the main controlling factors of pore structure during evolution were also discussed. Shales were heated to different temperatures with their vitrinite reflectance ranged between 1.23% and 3.12%, indicating that organic matter had evolved from a low‐ to a post‐mature stage. According to the changes in clay mineral composition, hydrocarbon generation, and Tmax, we subdivided diagenesis into four parts, each of which has a good correspondence with OM evolution. Pore volume (PV) varied between 0.012162 and 0.033482 cm3/g, while the specific surface area (SSA) varied between 13.3693 and 23.0094 m2/g. Mesopores were the main contributors to the total pore volume, while mesopores and micropores were the main contributors to the total specific surface area. In this study, the evolution of pore structure was not monotonous, but intermittent: The PV and SSA of shale samples first decreased and then increased. Maturity was the most important factor affecting the evolution of pore structure. The abundance of pores in OM, associated with hydrocarbon generation, resulted in large micro‐PV and micro‐SSA; moreover, the composition of clay minerals also influenced the pore structure evolution. The transformation of kaolinite into illite increased the content of illite and illite/smectite mixed layer, hence affecting the overall meso‐PV and meso‐SSA.

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“…The Upper Triassic Xujiahe Formation has become an essential tight gas unit over the last five decades of tight gas exploration and exploitation of the Western Sichuan Basin (Wang, Huang, Gong, Wu, & Yu, 2013). Numerous studies have been conducted on the diagenetic facies, porosity evolution, tectonic evolution, natural fractures, and sedimentary environment of the Xujiahe Formation Liu et al, 2018;Luo et al, 2019;Qin, Zhang, Zhao, & Zhou, 2018;Wu et al, 2020;Yu et al, 2017;Yu et al, 2019;Yue et al, 2018). However, the previous understanding of the Xujiahe Formation is mainly limited to the Xu4 member rather than the Xu2 sandstones.…”

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confidence: 99%

“…The location of the Sichuan Basin. (b) The tectonic feature of the Sichuan Basin (modified from Luo et al, 2019). (c) The location map of structural in the western Sichuan Basin.…”

mentioning

confidence: 99%

“…Locations of wells from which core was selected for samples are shown on the map [Colour figure can be viewed at wileyonlinelibrary.com] valuable reservoirs in the Western Sichuan Depression. However, the Xu2 member is deeper and is significantly controlled by diagenesis (Luo et al, 2019;Wu et al, 2020). Therefore, the diagenetic aspects are important in predicting the reservoir quality of the Xu2 sandstones in the Upper Triassic Xujiahe Formation.…”

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Diagenesis and reservoir quality of the second member of the Upper Triassic Xujiahe Formation tight gas sandstones in the Western Sichuan Depression, southwest China

et al. 2021

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The tight sandstones reservoir of the second member of the Xujiahe Formation (Xu2 member) is gradually becoming the main reservoir for natural gas exploration and exploitation in the Western Sichuan Basin. The tight sandstone is normally deeply buried, where it is controlled by complex diagenetic processes. To gain insights into reservoir exploration of the Xu2 member, the diagenetic history and the impacts of diagenesis on reservoir quality were established using several experimental methods.The sandstones were found to be mainly litharenite, sublitharenite, and feldspathic litharenite. The reservoir quality was characterized by low porosity (3.4% on average), low permeability (0.17 mD on average), low pore throat radius, and high displacement pressure. The tight sandstones experienced a series of significant diagenetic processes, including mechanical compaction, early dissolution, and precipitation of carbonate and siliceous cements during eodiagenesis. They also underwent chemical compaction, late dissolution, and transformation of clay minerals during mesodiagenesis. The silica cementation mainly resulted from chemical compaction, feldspar dissolution, and the transformation of clay minerals. A higher degree of compaction has a vital role in destroying most of the primary pores. Cementation had a significant impact on reducing the porosity and permeability, although chlorite preserved primary pores by slowing the compaction. This study aimed to provide a comprehensive insight into diagenesis and its impact on the reservoir quality of deeply buried sandstone, and provide insights into reservoir exploration and development in deeply buried tight sandstones.

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Diagenetic characteristics, evolution, controlling factors of diagenetic system and their impacts on reservoir quality in tight deltaic sandstones: Typical example from the Xujiahe Formation in Western Sichuan Foreland Basin, SW China

Cited by 43 publications

References 36 publications

Effects of diagenesis on natural fractures in tight oil reservoirs: A case study of the Permian Lucaogou Formation in Jimusar Sag, Junggar Basin, NW China

Effects of diagenesis on natural fractures in tight oil reservoirs: A case study of the Permian Lucaogou Formation in Jimusar Sag, Junggar Basin, NW China

Study on pore evolution and diagenesis division of a Permian Longtan transitional shale in Southwest Guizhou, China

Diagenesis and reservoir quality of the second member of the Upper Triassic Xujiahe Formation tight gas sandstones in the Western Sichuan Depression, southwest China

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