低渗透油藏启动压力梯度的应力敏感性实验研究  

Laboratory study on stress sensitivity of threshold pressure gradient in low permeability reservoir

作　　者：刘丽[1] 

机构地区：[1]中国石化股份胜利油田分公司地质科学研究院,山东东营257015

出　　处：《油气地质与采收率》2012年第2期81-83,116-117,共3页Petroleum Geology and Recovery Efficiency

基　　金：国家重大专项“低渗油气田高效开发钻井优化设计技术”(2008ZX05022-001)

摘　　要：低渗透油藏由于天然能量不足、岩性致密和压力传导能力差,导致开发过程中地层压力下降幅度较大。地层压力的下降会造成岩石变形而影响其物性和渗流能力,岩石表现出应力敏感性特征。借助室内岩心流动实验,模拟再现地层压力的下降过程,研究了低渗透油藏有效上覆压力对岩石启动压力梯度的影响。结果表明,当地层压力下降时,启动压力梯度随着岩石骨架承受的有效上覆压力的增加而增加,即启动压力梯度具有应力敏感性;且岩石的渗透率越低,当地层压力下降幅度相同时,启动压力梯度的增幅越大,即启动压力梯度的应力敏感程度越强。因此,在根据启动压力梯度计算低渗透油藏合理井距时,要充分考虑地层压力保持水平对启动压力梯度的影响。Inadequate natural energy and poor transmission of pressure will give rise to deep pressure decline after putting into development in low permeable reservoir.Pressure decline will induce damages to rock physical properties and flowing character,i.e.reservoir rock presents stress sensitivity.Simulating changing process of reservoir pressure by flowing test,threshold pressure gradients at different effective overburden pressures are tested,and relationship between threshold pressure gradients and effective overburden pressures is studied.With mercury-injection test,nuclear magnetic resonance spectrometry analysis and rock mechanics test,changing mechanism for threshold pressure gradients in changing process of reservoir pressure is thoroughly analyzed.It was understood that,the threshold pressure gradients increases with reservoir pressure declines,i.e.threshold pressure gradients is sensitive to stress.It is also indicated that the lower the rock permeability,the bigger the increasing amplitude of threshold pressure gradients,which means that the stress sensitivity is stronger.It is suggested that,when calculating rational spacing between wells,it is necessary to consider the effect of reservoir pressure maintenance level on threshold pressure gradients.

关 键 词：低渗透 启动压力梯度 应力敏感性 有效上覆压力 孔喉 

分 类 号：TE311[石油与天然气工程—油气田开发工程]