Hydrothermal alteration and hydrocarbon accumulations in ultra-deep carbonate reservoirs along a strike-slip fault system, Tarim Basin, NW China

Large-scale weathering crust karsted carbonate reservoir beds were developed in the Lower Ordovician Yingshan Formation on the northern slope of the Tazhong area in the Tarim Basin, NW China. The research on weathering crust karsted reservoir beds and faulting showed strongly heterogeneous karsted reservoir beds characterized by horizontal contiguous distribution and vertical superimposition, with fracture-hole as the main reservoir space. High quality reservoir beds were developed in the vertical seepage zone and horizontal phreatic zone, 0–200 meters below the unconformity. Reservoir bed quality of karsted carbonate rock was greatly improved by faulting, which increased the depth and size of karstification. A strike-slip fault developed over a long period in the NE direction and a thrust fault in the NW direction crossed each other, and caused distinct segmentation of the Tazhong No.1 Fault and dissection of the Yingshan Formation into multiple structural units. The strike-slip fault was the significant hydrocarbon migration pathway. Multiple hydrocarbon charging points were formed by the thrust fault and strike-slip fault, as the important fill-in of late-stage gas accumulation. Under the dual control of faulting and karstification, accumulation of hydrocarbons in the Lower Ordovician Yingshan Formation showed distinct segment-wise and block-wise features. Oil distribution is “high in the west and interior, low in the east and exterior”, while gas distribution is the opposite. The hydrocarbon play extends within 0.8–4.5 kilometers from the strike-slip fault and appeared layered vertically at 10–220 meters below the unconformity.

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Controls of a strike-slip fault system on the tectonic inversion of the Mahu depression at the northwestern margin of the Junggar Basin, NW China

Journal of Asian Earth Sciences ◽

10.1016/j.jseaes.2020.104229 ◽

2020 ◽

Vol 198 ◽

pp. 104229 ◽

Cited By ~ 1

Author(s):

Yuanyuan Liang ◽

Yuanyuan Zhang ◽

Shi Chen ◽

Zhaojie Guo ◽

Wenbin Tang

Keyword(s):

Junggar Basin ◽

Strike Slip ◽

Strike Slip Fault ◽

Fault System ◽

Nw China ◽

Tectonic Inversion ◽

Northwestern Margin

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Integration Applications of Image and Sonic Data in the Fault-Dominated Carbonate Reservoir in Tarim Basin

10.2118/207427-ms ◽

2021 ◽

Author(s):

Yu Zhang ◽

Honglin Xiao ◽

XiaoMing Zhang ◽

Haidong Liu ◽

Bo Liu ◽

...

Keyword(s):

Tarim Basin ◽

Image Interpretation ◽

Three Dimensional ◽

Research Area ◽

Strike Slip ◽

Carbonate Reservoir ◽

Strike Slip Fault ◽

Fault System ◽

High Definition ◽

Borehole Image

Abstract Carbonate reservoir is one of the most complex and important reservoirs in the world. It was confirmed that the slip-strike fault played a crucial role in the fault-dominated carbonate reservoir in Tarim basin. It is challenging to evaluate this kind of reservoir using the open-hole log or seismic data. Identifying and characterizing the fault-dominated carbonate reservoir were the objectives of this case study. High-definition borehole resistivity image and dipole sonic logs were run in several wells in the research area. It was revealed the detail features of the fault-dominated carbonate reservoir, such as natural fractures, faults or breccias. Compared with the typical geological model of strike-slip faults and outcrop features, the characteristics of the breccia zone and the fracture zone in the strike-slip fault system were summarized from the borehole image interpretation. A unique workflow was innovated with the integration of image and sonic data. Breccias and fractures were observed in the borehole image; and reflections or attenuations in Stoneley waveforms can provide indicating flag for permeable zones. Integrated with the other related geological data like mud logging or cores, the best pay zones in the fault-dominated carbonate reservoir were located. The characteristics of the strike-slip fault was revealed with the integration of the full-bore formation microimager and dipole shear sonic imager data. The fault core was a typical breccia zone with strong dissolution, which showed good potential in permeability, but it was found that some fault cores were filled with siliceous rock or intrusive rock. The features of the fillings in the fault zone were described based on the image and sonic data. The side cores or geochemical spectroscopy logs data helped to determine the mineralogy of the fillings. The fracture zones had clear responses in the image and sonic data too. The un-filled or half-filled breccia zone were the best zones in the fault-dominated carbonated reservoir. The details of the fault-dominated carbonate reservoir could be used in the future three-dimensional geological modelling.

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Characteristics and evolution process of strike-slip fault in Halahatang area, North Tarim Basin, NW China

10.5194/egusphere-egu2020-20861 ◽

2020 ◽

Author(s):

Debo Ma

Keyword(s):

Tarim Basin ◽

Seismic Data ◽

Strike Slip ◽

Strike Slip Fault ◽

Evolution Process ◽

3D Seismic ◽

Flower Structure ◽

Nw China ◽

Area North ◽

3D Seismic Data

Characteristics and evolution process of strike-slip fault is a key issue restricting further exploration in Halahatang area, North Tarim Basin, NW China. This paper uses the new-acquired 3D seismic data and applies fault structural analysis method to study the characteristics of Halahatang area, and discusses evolution process of the faults. The data used in this paper include 1960 km2 3D seismic data in prestack time migration in Halahatang area, and 4 wells logging data used to calibrate seismic horizon. The bin size of 3D seismic is 25 m&#215;25 m with sampling rate of 4ms, and data length of 7000 ms. Firstly, the Eigen-structure coherency and SO semblance are used to identify the distribution of the strike-slip fault. Secondly, the segmentation of Ordovician strike-slip fault in the study area is studied and the control effect of segmentation on reservoir development and oil and gas enrichment is discussed. The slip distance of strike-slip fault is very small, the maximum is no more than 2 km. They are typical cratonic strike-slip faults which are developed inside the craton. There are four kinds of structural styles on the profile, which are vertical and steep, positive flower structure, negative flower structure and semi-flower structure. Five structural styles of linear extension, X type, braided structure, horsetail structure, and en-echelon structure are developed on the plane. There are obvious segmentation along the fault trend. According to the strata subjected to strike-slip deformation and the structural styles in different strata, it is determined that the strike-slip faults have three stages of activity in Halahatang area.&#160; In the Late Ordovician, NNE, NNW, NE, and NEE strike-slip faults are mainly developed in the study area. The faults on the seismic profile are steep and upright, with small displacements. Faults generally only break into the Ordovician, and later activities will cause faults to go up to the Silurian and even the upper Palaeozoic, which have different tectonic styles with that of the Ordovician faults. The NNE and NNW strike-slip faults form an &#8220;X&#8221;-type conjugate strike-slip fault, reflecting the conjugate strike-slip fault is generated by near north-south compression. In the Late Permian, 4 NNW transtensional strike-slip faults are generated by the activation of some Ordovician strike-slip faults. In the Late Cretaceous-Palaeocene, the study area mainly develop several groups of NNE, near SN transtensional strike-slip faults. These transtensional strike-slip faults appear as graben and horst or stepped faults on the section. These transtensional strike-slip faults are R-shear faults in the Mesozoic and Cenozoic strata formed by the Ordovician NNE faults slip dextrally under the tectonic stress.

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