Fields and directions for shale gas exploration in China

Zhang, Jinchuan; Shi, Miao; Wang, Dongsheng; Tong, Zhongzheng; Hou, Xudong; Niu, Jialiang; Li, Xingqi; Li, Zhong‐Ming; Zhang, Peng; Huang, Yuqi

doi:10.1016/j.ngib.2021.08.014

Cited by 51 publications

(47 citation statements)

References 7 publications

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“…China started shale gas exploration and development as early as 2010, and shale gas pilot tests for geological selection evaluation and development in different onshore areas had been conducted, revealing that China had abundant shale gas resources, especially marine shale gas [9,10]. Since commercial exploitation of shale gas in China had been conducted in 2014 [8], the proven reserves and production of shale gas had exceeded 2 × 10 12 m 3 and 200 × 10 8 m 3 in 2020, respectively [11]. At present, China ranks second in the world in terms of shale gas production.…”

Section: Introductionmentioning

confidence: 99%

Lower Cambrian Organic-Rich Shales in Southern China: A Review of Gas-Bearing Property, Pore Structure, and Their Controlling Factors

Gao

Xiao

et al. 2022

Geofluids

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The Lower Cambrian shales are widely developed in southern China, with greater thicknesses and higher TOC contents. Although the shale gas resource potential has been suggested to be huge, the shale gas exploration and development is not satisfactory. At present, the gas-bearing property evaluation of the Lower Cambrian shale is still a hot spot of concern. According to previous works, this paper systematically summarizes the gas-bearing characteristics and controlling factors of the Lower Cambrian shales in southern China. The buried depth of Lower Cambrian shales mainly ranges from 3000 m to 6000 m, and the thickness of organic-rich shale intervals ( TOC > 2 % ) varies from 20 m to 300 m. The TOC content and EqVRo value are generally up to 2%-10% and 2.5%-6.0%, respectively. The gas content of the Lower Cambrian shales in the Weiyuan-Qianwei block of the Sichuan Basin and the western Hubei area generally exceeds 2 m3/t, and gas composition is dominated by CH4. In southeastern Chongqing, northwestern Hunan, and northern Guizhou areas, the gas content of the Lower Cambrian shales is generally <2 m3/t, and the N2 content is generally >60%. In the Lower Yangtze region, the Lower Cambrian shale reservoirs basically contain no gas. Higher maturity, lower porosity, and less-no organic pores are suggested to be responsible for low gas contents and/or the predominate of N2 in shale gas reservoirs. Strong tectonic deformation is an important factor leading to the massive gas loss from shale reservoirs, thus resulting in no gas or only a small amount of N2 in the Lower Cambrian shales. In a word, the Lower Cambrian shale gas plays with low maturity and relatively stable tectonic condition, especially deep-ultradeep zones, may be the favorable targets for shale gas exploration.

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Section: Introductionmentioning

confidence: 99%

Lower Cambrian Organic-Rich Shales in Southern China: A Review of Gas-Bearing Property, Pore Structure, and Their Controlling Factors

Gao

Xiao

et al. 2022

Geofluids

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“…China’s shale gas reserves are abundant, but the geological structure is complex and the reservoirs are deeply buried. In addition, the total organic carbon and gas contents of shale reservoirs change rapidly and have poor predictability, which leads to difficulties in obtaining these parameters by traditional methods 2 . Therefore, it is of great importance to explore new methods for predicting the “sweet spot” parameters of shale reservoirs based on deep learning methods.…”

Section: Introductionmentioning

confidence: 99%

Shale gas geological “sweet spot” parameter prediction method and its application based on convolutional neural network

Qin

2022

Sci Rep

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Parameters such as gas content (GAS), porosity (PHI) and total organic carbon (TOC) are key parameters that reveal the shale gas geological “sweet spot” of reservoirs. However, the lack of a three-dimensional high-precision prediction method is not conducive to large-scale exploration of shale gas. Although the parameter prediction accuracy based on well logging data is relatively high, it is only a single point longitudinal feature. On the basis of prestack inversion of reservoir information such as P-wave velocity and density, high-precision and large-scale “sweet spot” spatial distribution predictions can be realized. Based on the fast growing and widely used deep learning methods, a one-dimensional convolutional neural network (1D-CNN) “sweet spot” parameter prediction method is proposed in this paper. First, intersection analysis is carried out for various well logging information to determine the sensitive parameters of geological “sweet spot”. We propose a new standardized preprocessing method based on the characteristics of the well logging data. Then, a 1D-CNN framework is designed, which can meet the parameter prediction of both depth-domain well logging data and time-domain seismic data. Third, well logging data is used to train a high-precision and robust geological “sweet spot” prediction model. Finally, this method was applied to the WeiRong shale gas field in Sichuan Basin to achieve a high-precision prediction of geological “sweet spots” in the Wufeng–Longmaxi shale reservoir.

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“…As an important unconventional oil and gas resource, shale gas has become the main resource for the increase of natural gas reserves and production capacity in China (Xu et al, 2019). After nearly a decade of development, China's shale gas production has also grown rapidly from 25 billion cubic meters in 2012 (Qiu et al, 2020) to 20 billion cubic meters in 2020 (Zhang et al, 2022). The Sichuan Basin, especially its southern region, has become the main battlefield for shale gas exploration and development in China (Fu et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Evaluation of fracturability of shale reservoirs in the longmaxi formation in southern sichuan basin

et al. 2022

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Major breakthroughs have been made in the exploration and development of shale gas in the Longmaxi Formation in the southern Sichuan Basin, China. The previous have adopted various methods to study the fracturability of shale, but the quantitative characterization of the comprehensive properties of shale during hydraulic fracturing is still difficult. For this reason, in this study, taking the Longmaxi Formation shale in the Changning and Luzhou Blocks in the southern Sichuan Basin as an example, the mineral composition, petrophysical properties, rock mechanical properties and in-situ stress of the shale were systematically studied using X-ray diffraction, pulsed porosity-permeability analysis, rock mechanics and in-situ stress tests. Furthermore, the brittle mineral content, elastic modulus, and in -situ stress parameters were calculated, and the Analytic Hierarchy Process (AHP) method was adopted to establish a comprehensive evaluation index of shale fracturability. The research results show that the shale of the Longmaxi Formation in southern Sichuan is dominated by mixed shale facies, and it has the characteristics of high content of brittle minerals, low porosity, large compressive strength and Young’s modulus, and small value of in-situ stress difference coefficient. Therefore, the Longmaxi Formation shale has good fracturing conditions. TOC and quartz contents have important effects on the fracturability of the Longmaxi shale. The analytic hierarchy process was adopted to determine the weight coefficients of the modulus brittleness index, mechanical brittleness index, in-situ stress difference coefficient, rock compressive strength and TOC content. Furthermore, a comprehensive evaluation index of fracturability was constructed. Calculations show that the comprehensive fracability indices of shale in the Changning and Luzhou Blocks are 0.49 and 0.59, respectively. Moreover, the quality of shale in the Luzhou Block is better than that in the Changning Block, which is related to the organic matter and quartz content and the microscopic pore structures inside the shale.

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Fields and directions for shale gas exploration in China

Cited by 51 publications

References 7 publications

Lower Cambrian Organic-Rich Shales in Southern China: A Review of Gas-Bearing Property, Pore Structure, and Their Controlling Factors

Lower Cambrian Organic-Rich Shales in Southern China: A Review of Gas-Bearing Property, Pore Structure, and Their Controlling Factors

Shale gas geological “sweet spot” parameter prediction method and its application based on convolutional neural network

Evaluation of fracturability of shale reservoirs in the longmaxi formation in southern sichuan basin

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