姬塬油田长4+5油藏改善水驱开发效果评价研究

Evaluation on Improving the Development Effect by Waterflooding in Triassic Chang 4+5Reservoirs

姬塬油田长4+5油藏位于鄂尔多斯盆地的中部,属于内陆淡水湖泊三角洲相为主的陆源碎屑岩沉积,属于超低渗透油藏,岩心渗透率为0.58mD,孔隙度11.2%。随着开发时间延长,出现局部微裂缝发育油井见水、局部注采对应性差、个别油井堵塞加剧且有效期短等问题,严重制约了油藏的开发效果。因此在精细地层对比的基础上,重新认识该油藏油水井连通关系,评价一次井网条件下的注水政策,开展堵塞机理及措施类型、参数方式优化研究。通过改善水驱方法研究,与2013年相比,姬塬油田长4+5油藏含水率上升减缓,水驱状况稳定变好,地层压力缓慢恢复并趋于稳定,动态可采储量增加19×104t。

The Chang4+5Reservoirs of Jiyuan Oilfield were located in the central part of Ordos Basin.As ultra-low permeability reservoirs,they belonged to a terrigenous clastic sedimentation with the dominant of inland freshwater lake delta facies.The core permeability was 0.58 mD,and the porosity was 11.2%.With the going on of development time,the problems were appeared such as locally-developed micro-fractures,injected water breakthrough in oil wells,locally poor injection-production correspondence,intensified blocking of very few oil wells,and shortening of the effective period.These problems seriously restricted the effect of the reservoir development.The intercommunication between producers and injectors was re-understood on the basis of the fine stratigraphic correlation.The waterflooding policy under the condition of the primary well patterns was evaluated.The mechanism of blockage,types of the stimulation,and modes of parameters wereoptimized and studied.Through researches of improving the waterflooding methods,water-cut rising of Jiyuan Chang4+5Reservoirs is slowed down,compared with those in 2013.The waterflooding condition is stably improved.The formation pressure is recovered slowly and tends to be stable.The dynamically recoverable reserves increase by 19×104t.