Reservoir quality variations within a conglomeratic fan-delta system in the Mahu sag, northwestern Junggar Basin: Characteristics and controlling factors

Jia, Haibo; Zhang, Liang; Wang, Linsheng; Gao, Yan; Li, Xinwei; Zhou, Hang

doi:10.1016/j.petrol.2017.03.002

Cited by 50 publications

(15 citation statements)

References 27 publications

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“…Lithofacies refers to the rock or rock association formed in a specific sedimentary environment, representing hydrodynamic variation during deposition (Oluwadebi et al, 2018;Sfidari et al, 2019). According to the observed mud content, grain size, support pattern, and sedimentary texture and conclusions of previous studies (Jia et al, 2017;Miall, 1977;Yu et al, 2014), the lithofacies of the Upper Wuerhe Formation is divided into three major types, consisting of 11 subordinate types.…”

Section: Lithofacies Typesmentioning

confidence: 96%

Characteristics and controlling factors of glutenite reservoir rock quality of retrogradational fan Delta: A case study of the Upper Wuerhe Formation of the Mahu Sag, the Junggar Basin

Zhang

Huang

et al. 2021

Energy Exploration & Exploitation

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The glutenite reservoir rock of the fan delta facies is associated with a complex sedimentary environment and high heterogeneity, and by far the characteristics and controlling factors of the reservoir rock quality have not been well understood. By comprehensively investigating the lithofacies, petrology, physical properties and diagenesis of the Upper Wuerhe Formation of the Mahu Sag, the Junggar Basin, it is concluded that the Upper Wuerhe Formation develops three major groups of lithofacies, totally consisting of 11 sub-types, and reservoir rock properties of different lithofacies are greatly varied. This research shows that the lithofacies attributed to the tractive current and density current have well-sorted rock particles, low mud content, well-developed secondary dissolved pores, and thus high overall reservoir rock quality. On the contrary, the lithofacies based on debris flow and sheet flow, are observed with high mud content, suppressed development of intergranular and dissolved pores, and thus poor reservoir rock quality. The system tract controls the macro variation of the reservoir rock quality. The best quality is found in the highstand system tract, followed by those of the lake transgression and at last lowstand system tracts. The micro variation of the reservoir rock quality is determined by the mud content, rock particle size and dissolution. The muddy matrix mainly damages the pore connectivity, and presents the strongest correlation with permeability. The reservoir rock with concentrated particle sizes and well-sorted particles has quality better than those of reservoir rocks composed of excessively large or small particles. Dissolution effectively improves the storage capability of the reservoir rock, resulting in an average porosity increment by 4.2%.

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Section: Lithofacies Typesmentioning

confidence: 96%

Characteristics and controlling factors of glutenite reservoir rock quality of retrogradational fan Delta: A case study of the Upper Wuerhe Formation of the Mahu Sag, the Junggar Basin

Zhang

Huang

et al. 2021

Energy Exploration & Exploitation

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“…Unfortunately, reserves of these sand conglomerate are not abundant enough to gain a worldwide attention. In recent years, the exploration results from Mahu Sag in Junggar Basin, northwest China, show that, high-quality oil is found rich in the uppermost permian Urho Formation and lowermost triassic Baikouquan Formation [5][6][7][8][9]. Rocks are mainly conglomerate in this reservoir with reserves of more than 1 billion tons and a huge development potential.…”

Section: Jw 0000-0003-4435-0291mentioning

confidence: 99%

Numerical simulation study on the crack propagation of conglomerate

Luo

Wang

et al. 2021

R. Soc. open sci.

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The conglomerate reservoir is rich in oil and gas reserves; however, the gravel's mechanical properties and laws are difficult to gain through laboratory experiments, which furthermore constrain the hydraulic fracturing design. To analyse the failure law of conglomerate, we simulated the uniaxial compression test based on discrete element software PFC2D and analysed the effect of different cementation strength, gravel content and gravel geometry on the rock deformation and failure characteristics. Results show that (i) as the cementation strength decreases, the compressive strength and elasticity modulus both reduce clearly, while the crack shapes get more complex and the critical value is 0.3; (ii) as the gravel content increases, the conglomerate strength first decreases then increases under the influences of cracks bypassing gravels; cementation strength and gravel content of the conglomerate both contribute to the increase in local additional stress, which leads to a series of changes in crack shapes and mechanical properties of the conglomerate. Based on the above research, the conglomerate strength and crack shapes after failure are relatively complex due to the common influence of cementation strength and gravel content. The gravel edge crack caused by stress concentration is the micro-mechanism that affects the conglomerate mechanical properties.

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“…This can be evidenced by the fact that the main oil accumulations occurred in the slope sediment failure-originated deposits (Figure 16). However, fair reservoir quality is also shown by hyperpycnal flow deposits (average porosity of 10% and average permeability of 9 mD) (Jia et al, 2017). In terms of reservoir interpretation, the middle part has the highest reservoir quality from the proximal to the distal parts of a retreating fan-delta system, and MSC2 has the highest reservoir quality from bottom to top.…”

Section: Controls Of Depositional Processes On Reservoir Characterimentioning

confidence: 99%

Controls of a Triassic fan‐delta system, Junggar Basin, NW China

Jia

Zhang

Wang³

et al. 2018

Geological Journal

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Both sedimentology and sequence stratigraphy variability in the deltaic area are distinguished in the fan‐delta system of the Northwestern Junggar Basin. Sediment supply plays a significant role in controlling the fan‐delta petrology, evolution, and depositional processes and the delivery of sediment into deeper parts of the basin. The results of this study show that variations in the lithology of the sediment supply control the fan‐delta petrology and spatial and temporal variations in sediment supply influence the location and shifting of depocentres. A fining‐upward fan‐delta succession developed as accommodation rates outpaced the sediment supply rate. Frequent flood events were mostly recorded by sediment gravity flow deposits, which in turn influenced the geometry of the sandstone bodies and their reservoir quality. Hyperpycnal flow was a significant delta front process and an important mechanism for sediment delivery into deeper waters, favoured by the combination of denudation of coastal ranges and the fresh waters of the receiving basin. This study highlights that a detailed understanding of variations in sediment supply is essential to accurately predict sediment partitions in a delta system and the delivery of coarse‐grained sediments into deeper parts of lacustrine basins.

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Reservoir quality variations within a conglomeratic fan-delta system in the Mahu sag, northwestern Junggar Basin: Characteristics and controlling factors

Cited by 50 publications

References 27 publications

Characteristics and controlling factors of glutenite reservoir rock quality of retrogradational fan Delta: A case study of the Upper Wuerhe Formation of the Mahu Sag, the Junggar Basin

Characteristics and controlling factors of glutenite reservoir rock quality of retrogradational fan Delta: A case study of the Upper Wuerhe Formation of the Mahu Sag, the Junggar Basin

Numerical simulation study on the crack propagation of conglomerate

Controls of a Triassic fan‐delta system, Junggar Basin, NW China

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