流量不均鱼骨状多分支水平井不稳定压力分析

Transient pressure analysis of fishbone multi-lateral horizontal well with non-uniform flux density

为研究分支井和主井筒流量密度分布不均及各生产段表皮分布不均对鱼骨状多分支水平井井底压力(bottom hole pressure,BHP)的影响,通过将分支井段和水平主井筒段考虑成线源,运用格林函数并结合Newman乘积方法,建立了鱼骨状多分支水平井非均匀流量的试井解释模型,利用数值反演算法计算BHP,绘制出典型试井曲线并进行敏感性因素分析.结果表明,该模型出现了新的渗流特征段,其特征段在压力导数曲线上呈现出斜率大于0.5的直线段,将其命名为分支干扰线性流动段.鱼骨状多分支水平井分支井段及主井筒段流量不均时,BHP响应与各分支井段及主井筒段的流量以及表皮分布密切相关,同时也受到分支的长度、角度、地层各向异性、井筒在地层中高度和分支在主井筒上位置等因素的影响.该模型对鱼骨状水平井的产油井段诊断与解释、储层伤害判断以及增产措施制定有指导意义.

By using Green＇s function and the Newman production method,a new well testing interpretation model is established to investigate the effect of non-uniform flux density and skin factor of laterals on transient pressure behavior of fishbone multi-lateral horizontal wells. New semi-analytical solutions of bottom hole pressure and type curves are developed based on the new model by using the Stehfest algorithm for numerical inversion,while sensitivity analysis is conducted accordingly. The proposed model discloses a new flow regime termed as the lateral interference linear flow regime,which can be characterized by appearing a straight line segment with a slope greater than 0. 5 on the bottom-hole pressure derivative curve. The results of sensitivity analysis show that the bottom-hole pressure and pressure derivative are closely related to the distribution of non-uniform flux density,and skin factors of different laterals,meanwhile,are affected by factors such as the section length,orientation,reservoir anisotropy,well height in the formation,and junction locations of well laterals with the primary well sections. The proposed model can assist the interpretation of productive laterals,the estimation of formation damage,and the stimulation measure making in oil industry.