MRC油井稳态产能计算与对比

STABLE PRODUCTIVITY CALCULATION AND COMPARISON OF MRC(MAXIMUM RESERVOIR CONTACT)OIL WELLS

为提高单井产量和油藏采收率,最大储层接触面积井（MRC,Maximum Reservoir Contact）越来越得到重视,但因井眼结构复杂,常规方法难以计算其产能.采用一种离散化半解析方法建立了MRC油井油藏渗流和井筒管流相耦合的稳态产能模型并运用迭代法求解.以某低渗油藏为例对MRC井产能进行了计算和对比,结果表明：MRC井产能受井筒间渗流干扰影响大,主井筒两端泄油能力强,中间弱,在分支侧钻点处最弱;分支井筒从跟端到趾端泄油能力逐渐增强.MRC井单相油流IPR曲线与直井两相流IPR曲线相似,应合理选择生产压差.井筒总长度一定时,三种MRC井产能差值均在10％内,且存在启动压力梯度时均会明显降低.综合考虑钻完井工艺难度,推荐采用鱼骨型多分支水平井实现MRC技术.

In order to increase the production of individual oil well and enhance the oil recovery, Maximum Reser- voir Contact （MRC） wells have attracted more and more attentions, but because of the complex structure of the borehole, their productivity calculation is very difficult for the conventional methods. A stable productivity model coupling the reservoir flow and wellbore conduit flow for the MRC oil wells has been established by a discrete semi- analytical method and solved by an iteration solution-seeking method. Taking a low-permeability reservoir as an example, the productivities of the MRC oil wells are calculated and contrasted. The results show that the productivities are seriously influenced by the seepage interference among the wellbores, the oil drainage ability of the mother borehole is strong at both ends, but weak in the middle and the weakest at the branch sidetracked point; while the drainage ability of the branch borehole enhances gradually from the heel end to its toe end. The IPR curve of the single-phase flow for MRC oil well is similar to that of two-phase flow for the vertical well, so the producing pres- sure difference/differential should be selected rationally. When the total length of the well borehole is constant, the productivity differences for three types of MRC wells are all within 10%, and moreover the productivity will be significantly reduced when the starting pressure gradient exists. Comprehensively considering the difficulty of the drilling and completing technologies, fishbone-type multilateral horizontal well is recommend to realize the MRC technology.