中国东部几个主要油田高含水期提高水驱采收率的方向

中国东部大庆、胜利等６个注水开发油区综合含水已达８５．５％，处于高含水期开发阶段，主河道砂体油层绝大部分水淹，但其年产油量、剩余可采储量在全国仍占举足轻重的地位。分析了影响高含水期水驱采收率的３个要素（驱油效率，平面波及系数，厚度波及系数）的现状。预计在高含水期阶段要实现预期目标相当艰巨，６个油区标定的平均采收率为３７．８％，目前实际采出程度为２７％，剩余油分布总体高度分散，但局部相对富集。在水驱开发方式下，钻加密调整井和采用再完井技术是剩余油挖潜的基本措施。目前井网已较密，井网控制不住的边角部位未淹砂层的剩余油（约占可采储量的１５％）相对富集，平面调整主要是在这些位置打些调整井，通过提高平面波及系数挖潜；目前厚度波及系数约为５６．７％，纵向挖潜的目标主要是吸水差、渗透率低的河道间及三角洲前缘薄砂层的剩余油（其可采储量约占总剩余油储量的８０％），到含水９８％时，厚度波及系数可能达到７０％～７５％。根据剩余油分布的不同规律，提出８项挖潜措施，指出为达到高效调整的目的，可采用定向侧钻井、多底井及侧钻水平井技术，既能有效挖掘剩余油，又可节约钻井费用。参１（郭海莉摘）

Direction in enhancing waterflooding recovery of oil fields with high water cut in eastern China.

Overall water cut in main oil fields in eastern China, such as Daqing and Shengli oil fields etc., has reached 85.5%. These oil fields are producing at a high water cut stage currently. Most of channel sandbodies have been flooded out almost completely. However, their annual productions and remaining oil reserves still plays an important role in petroleum industry in our country. Based on an analysis of present state of 3 factors (oil displacement efficiency, areal sweep efficiency and thickness conformance) affecting water flooding efficiency, ultimate water flooding recovery in 6 oil regions have been estimated to be 37% on an average, and the actual current recovery is 27% currently. The distribution of remaining oils is rather highly dispersive on a whole, but are relatively concentrated in some areas. Infill drilling and recompletion of production wells will be main measures taken under further water flooding. Infill drilling wells will locate on the sides or corners of sandbodies not controlled by present well networks; and the remaining oil in these parts is estimated to be about 15% of the total, so that the areal sweep efficiency is improved. Vertical sweep efficiency can be improved by producing the remaining oils in interchannel and delta front thin sandbodies with low permeability and low water intake (the reserves in these parts accounts about for 80% of the total remaining oil reserves). Such a measure can increase the vertical sweep efficiency from 56.7% to an estimated figure of 70% 75% at 98% water cut. Eight technical measures are suggested to tap this production potential. Directional side tracking and multi lateral horizontal drilling are suggested to lower the drilling cost. Subject