气顶底水油藏水平井最优垂向位置研究

Study on optimum vertical location of horizontal wells in reservoir
with bottomwater and gas cap

王德龙 凌建军 郑双进 谭习群 黄凯 朱文娟

长江大学石油工程学院，湖北 荆州 434023 中国石油大学石油工程教育部重点实验室,　北京 102249

在带气顶的底水油藏开发中，气水锥进是目前面临的重要问题，水平井开发能够有效地避免油井过早见气和过早见水，而确定水平井最优垂向位置是获得最佳开发效果的关键。水平井垂向位置与临界产量、产纯油时间、油水密度差和油气密度差比值，以及临界产量与产纯油时间的乘积等关系的研究结果表明,水平井垂向位置越靠近气顶或底水,临界产量越高,但产纯油时间越短；越靠近最佳位置（气水同时锥进到油井中），临界产量越低，产纯油时间越长。通过分析，确定了气顶底水油藏水平井最优垂直位置的范围，其结果对气顶底水油藏水平井开发具有重要意义。

During the exploitation of reservoirs with gas cap and bottom water, a serious problem we confronted is the gas breakthrough and water coning. Using horizontal wells is an effective way to avoid early gas breakthrough and water coning of reservoirs. Determining the optimal vertical location of horizontal wells is the key factor to obtain the best development effect. The paper has discussed the effect of vertical locations of horizontal wells on the critical output and producing pure oil time, analyzed the ratio of density differences between oil-water and oil-gas, and determined arithmetic product of critical output and producing pure oil time. Curves have been obtained, showing the relationship between the vertical locations of horizontal wells and the considerated factors. The research shows that as the horizontal well gets closer to the bottom and cap of reservoir, the critical output will be increasing but time of producing pure oil will become shorter；as the horizontal well gets closer to the optimal vertical location （water and gas entering into wellbore simultaneously）the critical output will be decreasing and the time of producing pure oil will become longer. Through the study, a range is obtained for the optimal vertical location of horizontal wells drilled to reservoirs with bottom water and
gas cap. The results will be of real significance in exploitating reservoirs with bottom water and gas cap