摘要
CO_2驱是提高低渗透油藏采收率的一种重要方式,但目前对驱替过程中压力响应动态的认识不足。CO_2的注入使地层流体性质发生改变,形成CO_2区、CO_2-原油过渡区和未波及原油区。基于复合油藏渗流理论,引入幂律型公式和牛顿插值公式来描述CO_2-原油过渡区内流体非均质性的变化特征,建立了低渗透油藏CO_2驱试井模型,并采用数值方法进行求解。对CO_2-原油过渡区内2种流体非均质性变化形式下的试井曲线特征进行了分析。结果表明:当CO_2-原油过渡区内流体黏度与综合压缩系数均呈幂律型变化时,其变化指数均增大,CO_2区与CO_2-原油过渡区流度比和导压系数比均增加,压力导数曲线斜率增大;当CO_2-原油过渡区综合压缩系数呈非连续性变化时,压力导数曲线因CO_2区与CO_2-原油过渡区导压系数比的增加而呈现下凹趋势。最后,通过实例应用提出了CO_2驱试井解释方法。
CO_2 flooding in low permeability reservoirs is considered as one of the most significant EOR methods.However, there is lack of clear recognition on pressure response performance during the flooding process currently.Injection of CO_2 will change the physical property of reservoir fluids, and three zones could be developed, which are CO_2 zone, CO_2-oil transition zone and un-swept oil zone, respectively. Hence, based on the seepage theory of composite reservoir model, the power-law and Newton interpolation equations were introduced to describe the variable characteristics of fluid heterogeneity in CO_2-oil transition zone. The well testing model for CO_2 flooding in low permeability reservoir was presented, and it was solved by numerical differential method. The pressure transient curves at two different fluid heterogeneity variation forms were analyzed. The results demonstrate that for power-law variation of viscosity and compressibility in CO_2-oil transition zone, the mobility and diffusivity ratio between CO_2 zone and CO_2-oil transition zone increased with variation exponents, which leads to the rise of pressure derivative curves slope. As the compressibility in CO_2-oil transition zone varied discontinuously, since the increase of diffusivity ration between CO_2 region and CO_2-oil transition region, the pressure derivative curves would drop. Finally, the well testing explanation method for CO_2 flooding was presented through the application of real case.
出处
《岩性油气藏》
CSCD
北大核心
2016年第4期106-112,共7页
Lithologic Reservoirs
基金
国家重点基础研究发展计划(973)项目"中国东部古近系陆相页岩油富集机理与分布规律"(编号:2014CB239103)
教育部长江学者和创新团队发展计划项目(编号:IRT1294)联合资助
关键词
CO2驱
流体非均质性
复合油藏
试井模型
曲线分析
CO2 flooding
fluid heterogeneity
composite reservoir
pressure transient model
curve analysis
作者简介
李友全（1970-），男，高级工程师，主要从事试井及高压物性实验方面的研究工作。地址：（257015）山东省东营市东营区聊城路2号。电话：（0543）8715470。E-mail：liyouquan．slyt@Sinopec．com。
