安塞油田低渗透砂岩油藏重复压裂技术研究

初次水力压裂后产生的支撑裂缝周围会形成诱导应力场,进而改变原始地应力场,从而导致重复压裂的启裂改向,其延伸方向依然取决于地应力状态。通过改变围压条件进行的水力压裂模拟实验证实了重复压裂造新缝的可能性。安塞油田采用了重复压裂工艺,在老裂缝重张过程中加入暂堵剂进行封堵,形成高压环境,产生新裂缝并沟通部分天然微裂缝,随后加入支撑剂构建新的高导流裂缝体系,使泄油面积大大增加。现场试验的裂缝监测和效果分析资料证实产生了新裂缝。

STUDY OF REPEATED FRACTURING TECHNOLOGY IN LOW-PERMEABLE SAND OIL RESERVOIR IN ANSAI OILFIELD

The propped fracture generated during primary fracturing induces a stress field that changes original stress field and further reorients new fracture during repeated fracturing,the extension direction is still controlled by stress status.By means of altering confining pressure,hydraulic fracturing simulation experiment proves the possibility of new fracture generation during repeated fracturing.Temporarily blocked repeated fracturing is applied in Ansai oilfield,a temporary blocking agent is injected during old fractures' reopening to form a high-pressure environment and newly generated fracture connects the natural fractures which establishes new high-conduction fracture system with later added proppant and the oil-draining area enlarges.Pilot fracture supervision and effect analysis proves the generation of new fractures during repeated fracturing.