Shale gas enrichment pattern and exploration significance of Well WuXi-2 in northeast Chongqing, NE Sichuan Basin

Liang, Feng; Bai, Wangfeng; Zou, Caineng; Wang, Hongyan; Wu, Jin; Ma, Chao; Zhang, Qin; Guo, Wei; Sun, Shasha; Zhu, Yanming; Cui, Huiying; Liu, Dexun

doi:10.1016/s1876-3804(16)30045-3

Cited by 52 publications

(23 citation statements)

References 5 publications

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“…WX2 has been recently drilled by Research Institute of Petroleum Exploration and Exploitation-Langfang, CNPC, in the northeastern Chongqing and high gas content (2-8m 3 /t) has been obtained (Liang et al 2016). This breakthrough has made lower Silurian Longmaxi shale in northeastern Sichuan Basin a focus of attention and it is regarded as the next exploration target in addition to the hot spots of shale gas development in southern Sichuan Basin.…”

Section: Introductionmentioning

confidence: 99%

Microstructural investigation of gas shale in Longmaxi Formation, Lower Silurian, NE Sichuan Basin, China

Sun

Liang

Tang

et al. 2017

Energy Exploration & Exploitation

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The purpose of this paper is to probe into the nature and variability in vertical microstructure within Longmaxi gas shales of well WX2, Lower Silurian, located in the NE Sichuan Basin of China. To understand the pore system of these rocks, the total porosity, pore size distribution (PSD), surface area, organic geochemistry, and mineralogy, some image analyses by electron microscopy are performed. The obtained results indicated the following. (1) Gas shales have a complex pore structure. Total porosity from helium pycnometry ranges between 0.75% and 4.62%. Total organic content ranges between 3.4 wt.% and 11 wt.%, and vitrinite reflectance measured between 2.5% and 3.1%. The gas shales are quartz and clay rich. (2) Focused ion beam milling and field emission scanning electron microscopy provide high-resolution images of pores distribution and types. Three primary types of pores, organic matter (OM)-hosted pores, mineral-hosted pores, and micro-fractures, and 11 subgroups have been recognized. (3) The N 2 isotherm curves are grouped into two types, II b as well as IV a, with the hysteresis loop belonging to Type B, reflecting the morphology of slits pores, and Type A, presenting cylinder pores. Combination of N 2 and CO 2 isotherm curve shows bimodal in two diameter sections, 0.3-1 nm and 2-5 nm, revealing meso-pores play important role in pore volume, whereas the micro-pores have great influence on pore specific surface area. (4) Total organic carbon (TOC) is considered to be the dominant contributor to total porosity and pore types, with the proportion of OM-hosted pores following the upward decreasing tendency of TOC. In plane, pore types are controlled by sedimentary facies. The OM-hosted pores are more prevalent in deep shelf facies within lower part of shale other than upper formation, instead of shallow shelf facies.

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Section: Introductionmentioning

confidence: 99%

Microstructural investigation of gas shale in Longmaxi Formation, Lower Silurian, NE Sichuan Basin, China

Sun

Liang

Tang

et al. 2017

Energy Exploration & Exploitation

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“…The organic-rich shale of LSLF in this area is mainly composed of black shale, black mud-shale, carbonaceous mud-shale, and siliceous shale ( Liang et al, 2016). The total organic carbon (TOC) content, low pressure nitrogen adsorption (LPNA) and high-pressure methane adsorption experiments were strictly conducted, and the detailed experimental procedures were presented in our previous study .…”

Section: Methodsmentioning

confidence: 99%

Investigation of methane adsorption mechanism on Longmaxi shale by combining the micropore filling and monolayer coverage theories

Zhou

Yang

Wang

et al. 2018

Adv. Geo-Energy Res.

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Abstract:Understanding the methane adsorption mechanism is critical for studying shale gas storage and transport in shale nanopores. In this work, we conducted low-pressure nitrogen adsorption (LPNA), scanning electron microscopy (SEM), and high-pressure methane adsorption experiments on seven shale samples from the Longmaxi formation in Sichuan basin. LPNA and SEM results show that pores in the shale samples are mainly nanometersized and have a broad size distribution. We have also shown that methane should be not only adsorbed in micropores (< 2 nm) but also in mesopores (2-50 nm) by two hypotheses. Therefore, we established a novel DA-LF model by combining the micropore filling and monolayer coverage theories to describe the methane adsorption process in shale. This new model can fit the high-pressure isotherms quite well, and the fitting error of this new model is slightly smaller than the commonly used D-A and L-F models. The absolute adsorption isotherms and the capacities for micropores and mesopores can be calculated using this new model separately, showing that 77% to 97% of methane molecules are adsorbed in micropores. In addition, we conclude that the methane adsorption mechanism in shale is: the majority of methane molecules are filled in micropores, and the remainder are monolayer-adsorbed in mesopores. It is anticipated that our results provide a more accurate explanation of the shale gas adsorption mechanism in shale formations.

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“…In addition, the thickness of the WFF varies greatly even within the same region. For example, in northeastern Sichuan, the thickness of the WFF shale decreases from 32.3 m in the Chengkou Miaoba section to 7 m in Well WX2 in Wuxi (Liang et al, 2016). Furthermore, the thickness of the WFF shale decreases from 40 m in the Jiuxi Taoyuan section in the Hunan-western Hubei region to 0 m in the nearby Cili Yichongqiao section in Hubei province due to the presence of the Hunan-western Hubei underwater highland.…”

Section: Comparison Of the Interpolation Modelsmentioning

confidence: 99%

A new method for predicting the shale distribution of the Wufeng Formation in the Upper Yangtze Region, China

Sun

Zhang

Wang

et al. 2020

BSGF - Earth Sci. Bull.

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Taking the Late Ordovician Wufeng Formation (WFF) shale in the Upper Yangtze region as an example, we conducted a lithofacies distribution, thickness quantification, and paleo-topographic reconstruction of the Late Ordovician graptolite zones. Specifically, we focused on the Late Katian Dicellograptus complexus and the Early Hirnantian Metabolograptus extraordinarius within a chronostratigraphic framework, using the Geographic Information System (GIS) and 310 stratigraphic sections (incl. drilling) obtained from the Geobiodiversity Database (GBDB). Reconstruction of the geographic distribution indicates that the WFF and the synchronous sediments in the Upper Yangtze region contain 8 litho-stratigraphic units, which are geographically distributed across 7 provinces/municipalities and do not exhibit significant variations in lithofacies. The black graptolite shale extends in a broad swath from east to west within the basin, while the other lithofacies deposited during the same period are present on the periphery of the basin. All these strata were deposited in a normal neritic epicontinental sea environment, except for the flysch sediments in the southern Hunan area. The thickness reconstruction involves a comparison of three spatial interpolation methods, including Inverse Distance Weighting (IDW), Kriging, and the Radial Basis Function (RBF). Based on a general verification, IDW is considered to be the optimal method since it has the minimum standard deviation and variance. Based on the contours obtained from the IDW model, the WFF black shale is estimated to have an overall area of 0.67 Â 10 6 km 2 , an average thickness of 6.2 m, and a total volume of 3902 km 3 . This shale was deposited over a 2.83 Ma period. Therefore, the volume of shale deposited per million years is estimated to be 1379 km 3 /my and the average thickness of shale deposited per million years is 2.37 m/my. The Hirnantian paleo-water-depth values obtained using 275 sections were used to infer the Late Katian paleo-topography. These results suggest that the Yangtze platform was surrounded by ancient highlands to the west, south, and north, exhibiting a paleogeographic framework characterized by one uplift and four depressions. This setting blocked water circulation, causing the water to be contained and forming a closed and restricted marine environment, which was one of the major factors controlling the deposition of the organic-rich WFF shale. With the advent of the big data era of geology, the methodology of GIS-based technology is readily exportable to any resource play having spatial distribution pattern. Results can be provided rapidly and efficiently generated from geological data.

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Shale gas enrichment pattern and exploration significance of Well WuXi-2 in northeast Chongqing, NE Sichuan Basin

Cited by 52 publications

References 5 publications

Microstructural investigation of gas shale in Longmaxi Formation, Lower Silurian, NE Sichuan Basin, China

Microstructural investigation of gas shale in Longmaxi Formation, Lower Silurian, NE Sichuan Basin, China

Investigation of methane adsorption mechanism on Longmaxi shale by combining the micropore filling and monolayer coverage theories

A new method for predicting the shale distribution of the Wufeng Formation in the Upper Yangtze Region, China

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