Article
Chemistry, Multidisciplinary
Sotirios Nik. Longinos, Azza Hashim Abbas, Arman Bolatov, Piotr Skrzypacz, Randy Hazlett
Summary: The research focuses on the microstructure and permeability evolution of coal after LN2 treatment, providing insights into the cryogenic fracturing process as an environmentally friendly alternative to hydraulic fracturing. A high-resolution camera was used to examine the 2D microstructure of bituminous coal before and after LN2 treatment, with image processing conducted using functions from the OpenCV Python library. The results reveal an increase in total crack area with longer freezing times and an increased number of freezing-thawing cycles, while crack density remains largely unaffected by freezing time alone but exhibits a significant increase after multiple cycles. The highest crack density value of 300 m(-1) was achieved in FT60, while the lowest value of 31.25 m(-1) was observed in FT90 after LN2 treatment. Additionally, the FTC4 process resulted in a 50% augmentation in the number of cracks, whereas the FTC5 process tripled the number of small cracks.
APPLIED SCIENCES-BASEL
(2023)
Article
Thermodynamics
Chao Min, Guoquan Wen, Liangjie Gou, Xiaogang Li, Zhaozhong Yang
Summary: This study proposes a novel method to discover the latent causality in observed data of CBM wells using causal discovery theory, aiming to interpret machine learning models indirectly. The experiment demonstrates that interpretable machine learning models have better performance in CBM well production prediction compared to traditional methods.
Article
Chemistry, Physical
Tomasz Suponik, Krzysztof Labus, Rafal Morga
Summary: In order to improve the efficiency of methane extraction from coal beds, hydraulic fracturing technology is used. However, there are technical problems associated with stimulation operations in soft rocks, such as coal beds, mainly due to the embedment phenomenon. To address this, a novel coke-based proppant was introduced. The study aimed to identify the source coke material for further processing to obtain a proppant.
Article
Energy & Fuels
Yuan Wang, Liguo Zhong, Lei Zhang, Junpeng Zou
Summary: Based on the theories of mass conservation and CBM adsorption/desorption, this paper establishes a novel reservoir pressure model for CBM production and proposes CBM concentration and production models. The models are solved using the finite element method, and the reservoir pressure, gas concentration, and production characteristics are simulated for the Hunchun CBM field in Jilin province, China. The study shows that hydraulic fractures greatly reduce reservoir pressure and that the permeability sensitivity coefficient, R-pk, decreases logarithmically with distance from the extraction well. The findings provide valuable insights for the design of hydraulic fracturing wells and the evaluation of CBM production.
Article
Energy & Fuels
Hui Wang, Yanbin Yao, Dameng Liu, Yidong Cai, Yanhui Yang, Shengqiang Zhou
Summary: This study proposes a well logging coal structure index (WCSI) to quantify coal deformation and its impact on coalbed methane productivity. The results show that the degree of coal seam deformation affects reservoir permeability and hydraulic fracturing effectiveness, subsequently influencing gas production rate. The WCSI is found to be a useful parameter for preliminary forecasting of gas production in the southern Qinshui Basin.
JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING
(2022)
Article
Energy & Fuels
Xiao Guo, Zihao Yu
Summary: In this article, the expansion law of hydraulic fractures in coal seams was studied through hydraulic fracturing experiments and numerical simulations. The results indicate that (1) high minimum horizontal stress difference in coal seams with undeveloped laminae confined the fractures within the coal reservoir, affecting multilayer fracturing. The high elastic modulus of the spacer facilitated vertical fracture expansion. Critical displacement played a vital role in vertical fracture breakthrough. Fracturing fluid concentration correlated with fracture height and inversely proportional to fracture length. (2) During the development of natural laminae in coal, fracture pressure decreased significantly. Fractures preferred to expand along the direction of laminae with a smaller angle to the maximum horizontal principal stress. When the adhesive strength of the interface was high, fractures passed directly through the interface to form vertical fractures. When interfacial cementation strength was low, cracks extended along the interface, turned to produce new vertical cracks, and eventually formed Z cracks.
PETROLEUM SCIENCE AND TECHNOLOGY
(2023)
Article
Energy & Fuels
Zheng Sun, Bingxiang Huang, Yisheng Liu, Yancong Jiang, Ze Zhang, Mingxiao Hou, Yaohui Li
Summary: This research focuses on the characteristics and flow mechanism of coalbed methane (CBM) reservoirs, and develops a gas-phase productivity equation to accurately evaluate production behavior. The equation considers the coupling influence from coal orthotropic feature, hydraulic fracture, and other factors.
JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING
(2022)
Article
Geosciences, Multidisciplinary
Yixin Lu, Zhaoping Meng, Xuefeng Su, Yina Yu
Summary: This study reveals the evolution of coal sample permeability during fracturing and establishes the relationship between coal sample fracture morphology and permeability. The results provide data support for the reformation of hydraulic fracturing in coalbed methane wells.
NATURAL RESOURCES RESEARCH
(2022)
Article
Geochemistry & Geophysics
Taeyeob Lee, Daein Jeong, Youngseok So, Daejin Park, Munseok Baek, Jonggeun Choe
Summary: An integrated workflow from geomechanics to reservoir simulation is proposed to accurately estimate performances of a shale gas reservoir by updating model parameters. Sensitivity analysis on parameters such as leakoff coefficient and horizontal stress anisotropy influences the propagation of fractures and gas productions. Calibration of the mechanical earth model (MEM) with microseismic measurements helps reduce uncertainties in production estimations.
Article
Engineering, Environmental
Wenrui Shi, Ling Zhu, Meiyu Guo, Zisang Huang, Ganlu Wang, Lijie Lin, Li He, Yong Liao, Haoran He, Junshi Gong
Summary: Shale oil resources in China are abundant, but the traditional hydraulic fracturing technique consumes a large amount of water and causes environmental pollution. This study finds that CO2 fracturing technology can effectively reduce water consumption and store CO2, with CO2 methanol-based fracturing being the most effective.
RESOURCES CONSERVATION AND RECYCLING
(2023)
Article
Thermodynamics
Xiaochu Wang, Youhong Sun, Bing Li, Guobiao Zhang, Wei Guo, Shengli Li, Shuhui Jiang, Saiyu Peng, Hangkai Chen
Summary: Low production rate, limited recovery range, and short period of stabilized production in NGH field trials indicate a large gap to commercial production. Reservoir stimulation methods such as hydraulic fracturing, jet breaking, overlying layer modification, and split grouting have been studied to improve gas recovery efficiency. Split grouting is the most promising method for both reservoir skeleton reinforcement and permeability enhancement. Further evaluations are needed for production enhancement in non-diagenetic hydrate reservoirs considering the evolution of artificial seepage channels. Future developments should focus on obtaining reliable results of NGH reservoir fracability, bridging the gap between concept design and practical application, and ensuring safe and efficient gas production through reservoir stimulation and stability.
Article
Energy & Fuels
Jiaxin Shao, Lijun You, Yili Kang, Mingjun Chen, Jian Tian
Summary: This study investigated the salinity of flowback fracturing fluid from shale gas wells and its damage to reservoirs. The results showed that the salt concentration in shale was 1 mg/g, and the salinity of flowback fluid was about 30,000 mg/L. The analysis also revealed that the content of Na+ and Cl in shale reservoir was the highest.
JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING
(2022)
Article
Geosciences, Multidisciplinary
Jinbin Zhao, Peng Liu, Junjun Li, Zhaoying Chen, Yang Li, Feng Li
Summary: This paper uses microseismic technology to monitor the spatial and temporal characteristics of fracture extension during hydraulic fracturing in the CBM well. The study quantifies the three-dimensional shape of fractures and finds that the development of fractures is intermittent. After fracturing with a large amount of fracturing fluid injection, the fracture area has significantly increased, and gas production has improved.
FRONTIERS IN EARTH SCIENCE
(2023)
Article
Engineering, Chemical
Yanchao Li, Jianguo Shen, Longqing Zou, Yushi Zou, Xinfang Ma, Can Yang, Weiwei Wang
Summary: This study conducted simulation experiments to investigate the temporary plugging and diversion fracturing (TPDF) technique in a horizontal well with multiple clusters. A method of inner-fracture + inner-segment TPDF with multiple clusters of perforation in horizontal wells was proposed, and the influence of the number of clusters and the method of perforating on the effectiveness of TPDF was studied. The results showed that higher peak pressures and increased complexity of hydraulic fractures were observed when the number of perforation clusters was five.
Article
Green & Sustainable Science & Technology
Peibo Li, Jianguo Wang, Wei Liang, Rui Sun
Summary: This study develops an analytical stress model and a seepage-mechanical-damage numerical model to analyze the vertical propagation of I/II mixed fractures in coal-measure superimposed reservoirs. The investigation reveals that hydraulic fracture propagation through the reservoir interface is a process of multi-physical interactions mainly controlled by injection pressure and elastic modulus ratio of adjacent reservoirs.
Article
Energy & Fuels
Yide Guo, Linqi Huang, Xibing Li, Jiangzhan Chen, Jingnan Sun
JOURNAL OF NATURAL GAS SCIENCE AND ENGINEERING
(2020)
Article
Construction & Building Technology
Chunde Ma, Xibing Li, Jiangzhan Chen, Yanan Zhou, Sen Gao
ADVANCES IN CIVIL ENGINEERING
(2020)
Article
Geochemistry & Geophysics
Chunde Ma, Guanshuang Tan, Xibing Li, Jiaqing Xu, Jiangzhan Chen
Summary: This study proposes a technical method for restoring the original spatial attitude of non-oriented geological cores on the ground, and successfully applies it to the deepest shaft in China. Through this method and machine, in situ stress can be accurately identified and used for safe construction design.
