应用数值模拟方法判定特高含水期"低效、无效循环"井层的形成条件

针对大庆油田北二东西块地质特征和长期注水开发历程,分析了低效、无效循环在生产过程中所呈现的特征.通过对该区块多年动态开发资料的积累和理论分析,总结出高含水后期油藏极易形成低效、无效循环的3个部位,即垂向高渗透层、厚油层底部和注入水主流线.在此基础上,运用数值模拟方法分别对每种情况进行了研究,并给出了相应的形成条件.结果表明,渗透率级差大于3时,易出现低效、无效循环;油层厚度大于4m时,易出现低效、无效循环;油水井主流线上一定存在低效、无效循环.

Forming Conditions of "Low Efficient and Invalid Circulation Zones" Judged with Numerical Simulation Method at Extra High Water-cut Stage

In consideration of the geologic characteristics and experience of waterflooding in the West Block of Beierdong Area in Daqing Oilfield,through data collection and theoretical analysis of dynamic production for many years in the block,three locations are established,where low efficient and invalid circulation,such as high permeability in vertical position is established,on the bottom of thick pay zone,main streamline of injected water is easily created.On the basis stated above,a numerical simulating method is used respectively for each situation stated,and corresponding forming conditions are pointed out.The result shows that when permeability contrast is higher than 3,low efficient and invalid circulation is easily induced;and as reservoir thickness is more than 4,low efficient and invalid circulation is also easily produced;amd on the main stream line injection there must exist a low efficient and invalid circulation.