晚期注水开发实验研究

An experimental study on late water flooding

目前晚期注水实验研究主要以注水时机评价为主,在注采方式上研究较少,且传统方法开展驱油效率实验过程中,出口端的计量存在气液分离和人为读数产生误差等问题。以国外某油田为研究对象,从晚期注水原油常规相态变化和驱油效率2个方面入手,开展注水时机和不同注采方式对晚期注水效果的影响研究;在常规相态变化研究的基础上,评价注水增压开发对原油相态的影响;在驱油效率实验方法上,利用在线核磁技术实时评价驱替过程中岩心含油饱和度,提高了结果的准确性。研究结果表明:在衰竭开发至饱和压力的34%时,水驱采收率为16.5%;综合考虑采油速度、开发成本等因素,注水时机宜在80%泡点压力附近;对于长期衰竭开发严重脱气的区块,可采取注水增压方式开发,注水增压至80%泡点压力附近水驱效果最好。

Abstract:Earlier experimental study on late water flooding are mainly focused on water flooding timing and seldom on in?jection-production pattern. There was error for gas and liquid separation and human reading on the outlet by traditionalmethods of oil displacement efficiency. An oil field abroad was taken as the research object. The influence of water floodingtiming and injection-production pattern on late water flooding effect was researched on conventional oil phase behavior andoil displacement efficiency during late water flooding. Based on the study of conventional phase behavior,the influence ofwater injection pressurization on the phase behavior was evaluated. In the experiment method of oil displacement efficien?cy,the on-line NMR technique was used to evaluate the oil saturation of core in the displacement process in real time andthen the accuracy of the result was improved. The results show that the water flooding recovery reached to 16.5% when wa?ter flooding was performed at 34% of saturation pressure during the depletion development. Considering the productionrate,development costs and other factors,water injection was superior when the bubble point pressure was around 80%. Forthe long-term depletion development of severe degassing blocks,the development way of water injection pressurization canbe taken. The water flooding effect was the best when the bubble point pressure increased to around 80% by water injectionpressurization.