沁水盆地郑庄区块煤储层水力压裂曲线类型及其地质影响因素

Hydraulic fracturing curve types of coal reservoirs in Zhengzhuang block,Qinshui Basin and their geological influence factors

基于郑庄区块64口直井的压裂曲线分析,对水力压裂裂缝的扩展规律进行了总结,深入探讨了水力压裂曲线类型与煤体结构、天然裂缝发育、埋深和构造应力的关系。研究结果表明:最小水平主应力值较大、裂缝发育情况较差,不利于煤层起裂形成主缝,易形成上升型压裂曲线;最小水平主应力值较低、裂缝发育条件较好时,煤层容易起裂形成主缝,易形成下降型、稳定型和波动A型曲线;当垂向主应力与最小水平主应力相差不大时,易同时发育水平缝和垂直缝,形成波动B型曲线。大样煤岩压裂模拟实验表明该评价结果具有较好适用性。

Based on analysis of fracturing curves of 64 vertical wells in Zhengzhuang block, propagation laws of hydraulic fracturing fissures were summarized, and relationships between hydraulic fracturing curve types and coal texture, natural fissure development, burial depth, tectonic stressed were deeply discussed. Results show that higher minimum horizontal principle stress and poor devel- opment of fissures, are unfavorable for formation of major fissures through coal fracturing, but it is prone to form ascending hydrau- lic fracturing curves lower minimum horizontal principle stress and better fissure development conditions, major fissures are easily formed by coal fracturing, and it is prone to form descending, stable and fluctuating A-type curves; when vertical principal stress is no different than minimum horizontal principal stress, horizontal and vertical fissures are well developed, thus forming fluctuating B- type curve. The bulk-sample coal fracturing simulation experiments proved that these evaluation results have better applicability.