Fracture Properties of Nitrogen–Slick Water Composite Fracturing in Coal Reservoir

IF 2.8 4区工程技术 Q2 ENGINEERING, CHEMICAL

Processes Pub Date : 2024-09-11 DOI:10.3390/pr12091949

Menglong Wang, Lin Tian, Jinghao Wu, Yunxing Cao, Li Wang, Bin Shi, Mingyue Sun, Shimin Liu, Yunbing Hu

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Abstract

Nitrogen–slick water composite fracturing is a novel, recently developed fracturing technology. Due to its impact on increasing permeability, this technology outperforms hydraulic fracturing. This study adopted the horizontal well XJ-1L, Xinjing coal mine, Qinshui Basin, China, as a study area to statistically analyze the fracture properties, stress drop, and b-value distribution characteristics of 1217 effective micro-seismic events generated during nitrogen–water composite fracturing. The results show that: (1) gradually reducing the proportion of gas in fracturing fluid reduced the proportion of tensile fractures at a ratio of between 15.6% and 0.8%, whereas the proportion of strike-slip fractures gradually increased by between 1.6% and 15.2%; (2) the stress drop and b-values in the nitrogen fracturing (NF) stage, representative of stress disturbance, exceeded those in the hydraulic fracturing (HF) stage, consistent with greater numbers of tensile fractures formed in the NF stage; (3) the greater number of tensile fractures and their increasing permeability could be explained based on the influences of gas compressibility and pore pressure on coal fractures. This study provides a theoretical and practical basis for optimizing the exploitation of low-permeability coal reservoirs.

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煤储层氮滑水复合压裂的裂缝特性

氮-粘滑水复合压裂技术是最近开发的一种新型压裂技术。由于其对提高渗透率的作用，该技术优于水力压裂。本研究以中国沁水盆地新井煤矿 XJ-1L 水平井为研究区域，统计分析了氮水复合压裂过程中产生的 1217 次有效微震事件的压裂性质、应力降和 b 值分布特征。结果表明(1）压裂液中气体比例逐渐降低，拉伸裂缝比例降低了 15.6%至 0.8%，而走向滑动裂缝比例逐渐增加了 1.6%至 15.2%；（2）氮压裂阶段代表应力扰动的应力降和 b 值超过了水力压裂阶段，这与氮压裂阶段形成的张拉裂缝数量较多相一致；（3）基于气体可压缩性和孔隙压力对煤裂缝的影响，可以解释张拉裂缝数量较多及其渗透率增加的原因。这项研究为优化低渗透煤储层的开采提供了理论和实践依据。

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来源期刊

Processes Chemical Engineering-Bioengineering

CiteScore

5.10

自引率

11.40%

发文量

2239

审稿时长

14.11 days

期刊介绍： Processes (ISSN 2227-9717) provides an advanced forum for process related research in chemistry, biology and allied engineering fields. The journal publishes regular research papers, communications, letters, short notes and reviews. Our aim is to encourage researchers to publish their experimental, theoretical and computational results in as much detail as necessary. There is no restriction on paper length or number of figures and tables.