基于离散裂缝模型的裂缝井渗流压力场分析  

Pressure field analysis on vertically fractured well with discrete-fracture model

作　　者：单娴[1] 姚军[1] 

机构地区：[1]中国石油大学(华东)石油工程学院,山东东营257062

出　　处：《油气地质与采收率》2011年第3期67-69,73,共4页Petroleum Geology and Recovery Efficiency

基　　金：国家重点基础研究发展计划("973"计划)"碳酸盐岩缝洞型油藏开发基础研究"(2006CB202400)

摘　　要：人工压裂技术是低渗透油藏开采的重要技术手段,为深入了解垂直裂缝井生产过程中地层压力分布规律,基于离散裂缝模型,对人工裂缝进行降维处理,实现对裂缝的合理简化,在保证计算精度的同时有效提高计算效率。以此为基础建立裂缝井渗流压力计算模型,利用有限元方法进行离散求解,得到不同时间地层中压力的剖面图。通过对定压边界下单裂缝井和多裂缝井的计算可以看出,对于定产量生产的油井,在相同的生产时间内,裂缝内压力下降幅度明显高于地层,压力也比周围区域偏低。对于同一地层中的不同裂缝,裂缝导流能力越强,流体在裂缝内流动时消耗压力越少,井底压力等值线越稀疏。井底附近等压线为一组近似椭圆,其长轴长度与裂缝长度有关。Hydraulic fracturing is the main technique for low permeability reservoirs. To get a deeper acknowledge of the pressure law in the reservoir during the producing process of the fractured wells, based on the discrete fracture model, the fractures are described as lower dimensional geometry element. It is a reasonable simplification of fracture description, enhancing the efficiency of computation with precision guarantee. Mathematical model of finite conductivity vertically fractured wells in reservoir is established and solved by finite element method. Then, the pressure evaluation profile is drawn. Compared with constant pressure boundary, it can be seen that, in equal times, pressure in the fracture is lower than that in the reservoir. It also declines faster. For different fractures in the same reservoir, the lager the conductivity of hydraulic fracture, the fewer the pressure consumed in the fracture, corresponding to sparse pressure contours near the wellbore. The contour lines of the bottom hole present as ellipse, whose length of major axis is function of the length of the fracture.

关 键 词：离散裂缝模型 人工裂缝 有限元 裂缝导流能力 裂缝长度 等压线 

分 类 号：TE311[石油与天然气工程—油气田开发工程]