影响煤层气井产量的关键因素分析——以沁水盆地南部樊庄区块为例

Influencing factors on coal-bed methane production of single well:A case of Fanzhuang Block in the south part of Qinshui Basin

研究了沁水盆地南部樊庄区块煤层气投产井地质特征、压裂增产工艺、生产状况及排采技术等,分析了影响煤层气单井产量的关键因素,并讨论了提高煤层气井单井产量需要关注的问题。研究结果表明,煤层气高产井通常临界解吸压力与地层压力的比值较高,压裂施工时加砂量、用液量高;采用变排量施工工艺,控制裂缝形态,可提高压裂效果;特别是煤层气产出表现出"气、水差异流向"规律:构造高部位利于产气,构造低部位利于产水。在煤层气开发中,必须保证科学的排采制度,坚持"缓慢、长期、持续、稳定"的原则,排采早期保证液面稳定缓慢下降。在产气阶段,要保持合理套压,排采制度切忌变化频繁,避免由于煤层压力激动造成煤层坍塌和堵塞。

Based on the geologic characteristics, fracturing and production technologies and accompanying performance for producing in Fanzhuang Block in the south part of Qingshui Basin, the influencing factors on coal-bed methane production of single well were analyzed. It is proved that the high capacity well of coal bed methane has a high ratio of critical desorption pressure to formation pressure. Great amounts of sand and fluid are required in the coal-bed methane fracturing production. Especially, there are differential flow directions of gas and water. The variable displacement fracturing technology can effectively control the fracture morphology and enhance the fracturing effect. In the process of coal-bed methane development, the appropriate producing method should be adopted with the principles of unhurried, long term, continuous and steady. It is necessary for slowly dropping liquid level in the early production period and taking advisable casing pressure in gas production. The frequent alternation of producing measures, which would cause coal seam collapsing and blocking, should be avoided.