三类油层分期化学驱开采实验与应用

Experiment and application of staged chemical flooding and production of ClassⅢreservoirs

大庆油田三类油层地质储量大,占大庆长垣喇萨杏油田总地质储量的比例接近一半,具有厚度薄、渗透率低、连通性差、非均质性严重等地质特点。为了使化学驱实现高、低渗透油层同步驱替,达到储层均衡受效的目的,开展了室内平面模型驱替实验,对比了三类油层不同开采模式下提高采收率效果,优选出分期化学驱开采模式并应用于现场,一期优先对有效厚度小于0.5 m、有效渗透率小于0.05 D的薄差油层和表外储层进行聚合物驱,二期补射开其余油层进行笼统弱碱三元复合驱。研究结果表明:在室内实验中,对中、低渗透油层进行分期聚合物驱,最终采收率达65.8%。北二区东部高台子油层分期化学驱现场应用结果表明,试验区整体预计提高采收率12%以上,取得显著效果。

Class Ⅲ reservoirs in Daqing Oilfield account for nearly half of the total reserves in La-Sa-Xing Oilfield of Daqing Placanticline,which have geological characteristics including thin thickness,low permeability,poor connectivity,and serious heterogeneity. For the synchronous displacement of high-and low-permeability oil reservoirs by chemical flooding and balanced reservoir efficiency,the displacement experiment with a laboratory plane model was carried out and the development effects of enhanced oil recovery(EOR)technology were compared at different production modes in Class Ⅲ reservoirs. As a result,the staged chemical flooding production mode was selected and applied in oilfields.In the first stage,polymer flooding was performed in thin and poor oil reservoirs with effective thickness less than 0.5 m and effective permeability less than 0.05 D and untabulated oil reservoirs. In the second stage,commingled weak-alkalinity ASP flooding was carried out in other oil reservoirs by supplement perforation. The results show that in laboratory experiments,staged polymer flooding for medium-and low-permeability oil reservoirs registers ultimate recovery of up to 65.8%. The field application of staged chemical flooding in Gaotaizi reservoir of Beierdong Block indicates that the overall ultimate recovery is expected to increase by more than 12% in the test area,and remarkable results have been achieved.