水力压裂条件下“三软”煤层压裂渗透模型及应用  

The research on permeable model of hydraulic fracture and its application in the “three soft” coal seam

作　　者：王志荣[1] 贺平[1] 郭志伟[1] 陈玲霞[1] 徐培远[2,3] 

机构地区：[1]郑州大学水利与环境学院,河南郑州450001 [2]河南省煤田地质局,河南郑州450053 [3]河南省能源钻进工程技术研究中心,河南郑州450053

出　　处：《天然气地球科学》2017年第3期349-355,共7页Natural Gas Geoscience

基　　金：国家自然科学基金项目(编号:41272339)资助

摘　　要：为了探索水力压裂条件下由软煤、软顶和软底构成的特殊地质体(简称"三软"煤层)裂缝的扩展规律,以及压裂后储层的裂隙分布特征,结合河南焦作煤层气田的注水压裂试验,基于PKN模型的裂缝宽度假设与裂缝流动的摩阻压降规律,着重考虑软煤裂隙中压裂液的滤失因素,构建了水力压裂条件下"三软"矿区碎裂煤的裂缝扩展模型与渗透率计算模型,并运用地震实测法和渗透率反演计算法分别进行了验证。研究结果表明,实际施工条件下试验区二_1煤层压裂后的裂缝几何特征大致相同,长度分布区间为81.85~139.23m,平均为100.41m;最大裂缝宽度区间为24.83~32.78mm,平均为27.32mm,裂缝长度与地震实测结果基本一致。应用裂缝渗透模型,进一步计算得到压裂后煤储层的渗透率一般在(9.21~86.61)×10^(-3)μm^2之间,平均为31.63×10^(-3)μm^2。与后期排采结果所得到的储层渗透率反演值相对比,二者基本吻合。由此可见,压裂改造后的煤储层的渗透率得到显著提高,裂缝扩展与裂缝渗透模型皆可应用于指导"三软"矿区的压裂抽采实践与产能预测。In order to find out the crack propagation law in hydraulic fracturing conditions and crack distribution features for＂Three Soft＂coal seam,this paper combines the hydraulic fracturing test of coal seam gas field in Jiaozuo Henan based on the assumption of crack width in PKN model and frictional pressure drop law of fracture flowing.This paper focuses on fluid loss factors of fracturing fluid,finally the crack propagation and permeability calculation model of cataclastic coal under hydraulic fracturing was established,and it verified the result by earthquake measure method and retrieval algorithm.The results show that each crack of Ⅱ_1 coal seam has roughly similar geometric feature.Its length is 81.85-139.23 m with an average of 100.41 m.The maximum width is 24.83-32.78 mm with an average of 27.32 mm,and the length results accord with the earthquake measurement.Based on the fracture permeation model,the permeability of coal reservoir is about（9.21-86.61）×10^-3μm^2with an average of 31.63×10^-3μm^2It＇s easy to find the results are consistent with the later inversion reservoir permeability.Thus,after fracturing treatment,coal reservoir permeability is significantly improved.Crack propagation and fracture permeability model can be used for guiding fracturing gas extraction and predicating the productivity of the＂Three Soft＂coal seam.

关 键 词：“三软”煤层 水力压裂 裂缝扩展模型 裂缝渗透模型 渗透率反演 

分 类 号：TE122[石油与天然气工程—油气勘探]