一种基于油通比的油藏优势流场表征新方法

A new characterization method for predominant flow field of reservoirs based on oil-to-flux ratio

优势渗流通道发育是导致中高含水油田平面水驱不均衡和井网波及系数低的根本原因。为了准确定位储层优势渗流通道发育位置,指导油田下一步的稳油控水,基于储层时变数值模拟技术,从水置换油效率角度提出了一个新的流场评价指标“油通比”及流场非均质性评价指标“油通比非均质性系数”。根据油通比特征曲线在不同含水阶段的形态,结合其物理背景,划分4级流场渗流区域,实现了对油藏流场的分级评价。经过验证,流场的优势渗流通道区域与示踪剂测试结果完全符合,证明了油通比流场评价方法的可靠性。利用该方法对渤海BZ油田开展了优势流场评价,制定流场分级调控措施政策,指导部署调剖堵水和水平井控水措施,实施后油通比非均质性系数减小5.6%,流场非均质性明显改善。该方法实现了对高含水油田优势渗流通道的定量表征。

The predominant flow channels are the root cause of the plane waterflooding imbalance and low sweep coefficient of well patterns in medium and high water cut oilfields.To accurately locate the development positions of dominant flow channels in a reservoir and guide the subsequent stabilizing oil production&controlling water cut in the oilfield,by the time-varying numerical simulation technology of reservoirs,this paper proposed a new flow-field evaluation index,i.e.,“the oil-to-flux ratio(OFR)”,and a flow-field heterogeneity evaluation index,i.e.,“the heterogeneity coefficient of OFR”,from the perspective of oil displacement efficiency by water.According to the shapes of OFR characteristic curves in differ⁃ent water cut stages and the physical background,the flow-field flow area is divided into four levels to achieve the hierar⁃chical evaluation of the reservoir flow field.The verification reveals that the predominant flow channel area of the flow field is completely consistent with the test results of tracers,which proves the reliability of the flow-field evaluation method by OFR.This method was used to evaluate the predominant flow field in the offshore BZ Oilfield of Bohai Sea,formulate the flow-field hierarchical control measures and policies,and guide the deployment of measures for profile control and water shut-off,as well as controlling water cut of horizontal wells.Upon application,the heterogeneity coefficient of OFR is re⁃duced by 5.6%,which means the flow-field heterogeneity is significantly improved.This method realizes the quantitative characterization of the predominant flow channels in high water cut oilfields.