沁南煤层气井压裂施工曲线分析

Analysis of hydraulic fracturing operation curves of CBM wells in Southern Qinshui Basin

为研究不同类型煤层气井压裂施工曲线所揭示的储层特征和施工情况,对沁水盆地南部郑庄樊庄区块的230口煤层气井的压裂施工曲线进行对比分析,结合油压、排量、砂比的相互影响关系,对压裂施工阶段进行分类。前置液阶段分为阶梯排量型曲线和稳定排量型曲线,携砂液阶段大体分为压力稳定型、压力波动型、压力上升型、压力下降型等4类曲线,顶替液阶段主要为压力上升型曲线。对不同压裂曲线反映出的工程原因和地质内涵进行分析,结合实际排采资料,对不同类型压裂曲线产气效果进行评价,认为稳定型≈下降型>波动型≈上升型。

In order to study the reservoir characteristics and construction conditions revealed by different kinds of hydraulic fracturing curves, based on the comparative analysis of hydraulic fracturing operation curves of 230 coalbed methane wells in Zhengzhuang and Fanzhuang blocks in Southern Qinshui Basin, combined the interrelation among pressure, displacement and sand-fluid ratio, it was classified the fracturing curves clalsit- ied. The results show that, the fracturing curves can be divided into two classification in the preflush stage, that is ‘‘ladder displacement curve”‘‘stable displacement curve” ; for th e s a n d - lad en fluid s ta g e , the curves can be divided into four classes, including ‘‘pressure stable curve”,“pressure fluctuating”,‘‘pressure rising” and ‘‘pressure declining” model. But in the displacing liquid stage, the pressure curves mainly appear a u ris-ing” tendency. Further, engineering factors and geological connotation reflected by different kinds of fracturing operation curves were analyzed. Evaluation of gas production was done based on the drainage data on the spot,the results show pressure stable and declining model are approximately equal with a higher gas production, while fluctuating and rising model are also approximately equal with a lower gas production relatively.