各向异性油藏水平井多角度人工裂缝线性单元计算方法

考虑各向异性油藏渗透率张量的表征,利用Green函数和拉普拉斯变换建立裂缝流动的一维单元,裂缝的流量分布采用节点线性插值,裂缝内的流动处理为线性积分,耦合地层与人工裂缝的流动,建立有限导流裂缝井底压力的求解方法.结果表明:多裂缝压裂水平井存在压裂裂缝线性流、地层线性流、系统径向流3种流动形态,压裂裂缝条数越多,相同的生产时间,无因次井底压降越小;裂缝条数对流动影响明显.随着裂缝条数的增加,压降变化减小;裂缝长度和导流能力有相似的变化.人工裂缝与井筒角度越大,产能越大,当裂缝垂直于井筒时,产量最大;地层最大渗透率方向垂直于人工裂缝时产量最大,平行裂缝时产量最小.当人工裂缝垂直于井筒,并同时垂直于地层最大渗透率方向时,达到最大产量值.

Linear Element Method for Multi-angle Fractured Horizontal Well in Anisotropic Reservoir

With Green function and Laplace transformation, one-dimensional element is established considering effect of permeability tensor of anisotropic reservoir. Inflow of fracture is obtained by linear interpolation of endpoints and flow in fracture is treated with linear integral of flow rate. Coupling flow in formation and fractures, calculating method for bottom-hole pressure is formed semi-analytically. It shows that there are three flow regimes including fracturing linear flow, formation linear flow and system radial flow. The more the fractures, the less the dimensionless pressure and number of factures has significant impact on flow rate. With increase of fractures increasing rate is dropping in the same time. Fracture length and conductivity have similar characteristics. Flow rate is improving as angle between fracture and wellbore is increasing. Flow rate reaches maximum as fracture is perpendicular to wellbore, and vice versa. Angle between maximum permeability and fracture has similar impact on production. In summary, production rate reach maximum as fracture is perpendicular to wellbore and direction of maximum permeability.