分支数目对鱼骨刺水平井产能的影响研究

Effect of Branch Number on Productivity of Herringbone Well

鱼骨刺水平井具有增大泄油面积、降低钻井数、可利用已有井、节省油田开发成本的特点,尤其是针对边际油田开采具有突出的优势。鱼骨刺水平井的形态结构十分复杂,因此数值模拟研究对指导实际鱼骨刺水平井生产具有重要意义。采用差分法对鱼骨刺水平井的描述与实际条件差距较大,这是目前鱼骨刺水平井数值模拟理论研究存在的难题之一。在二维油水两相模型的基础上,运用有限元方法,对油相压力和水相饱和度的有限元方程进行了推导求解。针对二维平面渗流问题采用混合单元有限元法,利用线单元描述鱼骨刺水平井井筒,用任意形状的三角形单元来描述地层。对不同分支数目的鱼骨刺水平井进行了数值模拟研究。分析了鱼骨刺水平井不同分支数目的渗流规律。通过分析比对含水率、日产油量、累积产油量的动态曲线,得出分支数目的增多对鱼骨刺水平井的见水时间和含水率的影响不大,但对开采前期鱼骨刺水平井的增产却效果明显,随着开采时间的增加,后期累积产油量增加比例相差不大。

The herringbone horizontal well can increase the drainage area, reduce drilling quantity, use the existing mining wells, save the cost of oilfield development, especially has outstanding advantages for the marginal oilfield. The configuration of herringbone well is complex, so it is significant to use numerical simulation to conduct the production of herringbone well. There is a big difference with the reality in using differential method to describe herringbone well. It is one of key problems of herringbone well numerical simulation study. In this paper, the finite element method was used to derive the oil phase pressure and water saturation finite element equation based on the two-dimensional two-phase model. Mixed finite element method was used for the two-dimensional seepage problem. The line element was used to describe the herringbone well and the triangular element of arbitrary shape was used to describe the formationl Herringbone wells with different branch number were studied by numerical simulation. Seepage characteristics of the herringbone well with different branch number were analyzed. Through analysis of the moisture content, the daily oil production and cumulative oil production dynamic curve, it＇s pointed out that effect of branch number on water breakthrough time and moisture content of herringbone well is limited. But its effect on oil production of herringbone well is obvious in the early exploitation. As the exploitation goes, cumulative oil production proportion changes a little during the late stages of development.