沁水盆地南部高阶煤煤层气井压裂效果关键地质因素分析

Analysis of key geologic factors of fracturing effect of CBM wells for high-rank coal in Southern Qinshui Basin

地质条件是影响煤层气井压裂人工裂缝的关键,弄清其对压裂效果的控制对提高改造工艺适应性至关重要。以压裂裂缝扩展试验为基础,分析了压裂施工曲线形态、裂缝监测数据等资料,总结了人工裂缝扩展规律,探讨了人工裂缝与煤体结构、地应力和力学性质的关系及其对产量的影响,提出了压裂工艺优化方向及改进措施。研究表明:煤体结构影响人工主裂缝长度及其复杂程度,地应力控制裂缝的开启及长度、走向,力学参数主要决定了压裂施工的难易程度;上述关键地质因素的差异性导致常规压裂工艺存在局限性。根据不同地质条件优化工艺技术,实施针对性的改造措施,可以改善增产效果。

Geological conditions are key factors which affect the performance of hydraulic fracturing used in CBM （ coalbed methane） straight wells. It is vitally important to figure out the influence of geological conditions on the per- formance of hydraulic fracturing in order to improve the adaptation of formation stimulation techniques. Based on the propagation experiments of hydraulic fractures, this paper analyzes the construction curve shape and the artificial crack monitoring data with equal correlation data, and summarizes the law of fracture propagation and discusses the relation- ship between artificial fracture and coal structure, crustal stress and the mechanical parameters of the CBM straight wells and its effect on gas production. The direction and improvement of fracturing process are put forward. The re- search shows that the coal structural effect of length and complexity of artificial main crack ; the length and direction of the crack opening are controlled by crustal stress;the degree of difficulty in fracturing construction is mainly deter- mined by mechanical parameters. The differences of these geological conditions mentioned above result in the limita- tions of normal hydraulic fracturing techniques. Therefore, the formation stimulation techniques should be optimizedand special formation stimulation measures should be adopted, ac tions, to improve the performance of hydraulic fracturing techniqu improving the hydraulic fracturing techniques of coalbed methane cording to the differences of these geological condi- es. These results will have a guiding significance for wells in Qinshui Basin.