海上低幅底水稠油油藏特征及水平井开发初探

Initial study on Characteristics and Development with Horizontal Wells of Heavy Oil Reservoirs with Small Bottom Water in Offshore

秦皇岛32-6油田属海上低幅底水稠油油藏,经多年定向井开采目前进入高含水开发期,受储层非均质性、隔夹层等多种因素的影响,油层水淹规律和剩余油分布规律极为复杂。为解决以上问题,在建立油藏数值模拟模型基础上,研究了油层水淹规律和剩余油分布规律,进行了水平井参数的优化设计,并实施了水平井先导试验研究。研究结果表明,纵向上油层底部水淹严重、剩余油较少;油层中上部水淹较轻,是剩余油富集区。平面上定向井能够动用的区域只是井筒附近油层,即井间和油层中上部无水淹,为剩余油富集区。实际生产证明,利用水平井开发海上低幅底水稠油油藏可提高采油速度和最终采收率。

QHD32-6 Oilfield belongs to heavy oil reservoirs with small bottom water.The development of the oilfield has accessed to the stage with high water cut after development for many years.Water breakthrough regularity and residual oil distribution regularity are complex due to reservoir heterogeneity and many interbeds,etc.In view the problems above,the paper presents the study on water breakthrough regularity and residual oil distribution regularity;optimization horizontal well parameters and pilot test with horizontal wells based on reservoir numerical simulation.The results of the study show that,vertically,water breakthrough is more serious in the bottom of oil-bearing formation and therefore residual oil is relatively small and water breakthrough is light in mid to upper formation and therefore the mid to upper formation is the oil-rich region;and laterally,the oil that can be recovered is only from the region adjacent to well bore,namely,no water breakthrough between wells and in mid to upper formation and therefore oil is rich in those regions.It is proved in practice that recovery percentage and recovery factor can be increased with horizontal wells for heavy oil reservoirs with small bottom water in offshore.