断块油藏气顶-边水双向驱油藏筛选标准

Screening Criteria of Gas Cap-Edge Water Drive Fault Block Oil Reservoir

为提高断块油藏采收率,提出气顶-边水双向驱的开发方式,即利用注入N2挖潜阁楼油,利用边缘注水挖潜低部位剩余油的双向驱替方式,以此提高波及体积和采油速度。新方法提高采收率的主控因素有待明确,相应的油藏筛选标准尚未建立。运用数值模拟方法,建立了断块油藏双向驱的理论模型,研究了不同因素对双向驱开发效果的敏感性及相应的油藏筛选标准。研究表明:对于含油条带较窄(低于100 m),气顶宽度低于50 m的油藏不推荐进行双向驱;低渗透油藏采用双向驱时应降低注气速度,保持注采平衡;在油层厚度不大于10 m,地层原油黏度小于75 m Pa·s,没有较厚夹层的条件下,双向驱开发能取得较好的效果。采用该筛选标准选取实际区块,预测双向驱比水驱提高采收率14.21个百分点。研究成果对断块油藏高含水期剩余油有效动用和高效波及有重要意义。

For the sake of improving the recovery factor of fault block oil reservoir,gas cap- edge water drive development mode has been presented,i. e.,tapping the attic oil potential by injecting N2 and tapping the structural low remaining oil potential by edge water flood,and hence improving the swept volume and oil recovery rate. However,the main control factors of this IOR method awaits to be ascertained,and the corresponding oil reservoir screening criteria have not been established. In view of the above,this paper used the numerical simulation method to have built the gas cap- edge water drive theoretical model of fault block oil reservoir,and studied the sensitivity of different factors to the development effect of this development mode and the corresponding oil reservoir screening criteria. The study results showed that as to the oil reservoir with narrower oil- bearing belt( less than 100 m) and smaller gas cap width( less than 50 m),it was not recommended to implement gas cap- edge water drive; as to the low permeability reservoir,while implementing gas cap- edge water drive,it should reduce the gas injection rate and keep voidage balance;while under such circumstances as oil layer thickness thinner than 10 m,formation crude oil viscosity less than 75 mP a·s and free of thicker interbed,the gas cap- edge water drive could achieve good development effect. The screening criteria were used to have selected an actual block,and it was predicted that the gas cap- edge water drive could improve 14. 21% more oil recovery than waterflood. The study results are of great significance to the effective producing and efficient sweeping of remaining oil at high water cut stage of fault block oil reservoirs.