海上复杂断块油田综合调整对策——以南海西部A油田为例

Research on comprehensive adjustment countermeasures of offshore complex fault-block oilfields——Taking oilfield A in western South China Sea as an example

由于海上断块油藏地质构造、油水系统等的复杂性,综合调整对策研究成为重点。南海西部A油田属于断块砂岩油藏,具有初期产能高、产量递减快、注水效果差异明显、各断块采出程度差异大等开发特点。对该油田进行开发指标效果评价,从“注好水”“注够水”“精细注水”“有效注水”的角度,筛选确定了水质达标率、能量保持水平、水驱储量控制程度、水驱储量动用程度、水驱状况、含水上升率、剩余可采储量采油速度等7项评价指标,表征注水工作在油藏、工艺、生产的系统性特点,客观反映海上水驱砂岩油藏的开发水平。然后对海上断块油田提出了增产措施和建议:建立定量地质知识库,采用针对性的工艺技术,加深对断块破碎程度的认识;及时补充地层能量,抑制地层脱气,注水时地层压力不能低于饱和压力;采用低部位注水、高部位采油的三角形井网,并考虑进行气水交替注入的注水方式;合理的井网密度等。这些措施可以更加有效地对海上复杂断块油田进行开发调整。该研究对同类型的海上断块油藏综合调整具有重要的借鉴意义。

Due to the complexity of geological structure and oil-water system of offshore fault-block reservoirs,the study of comprehensive adjustment countermeasures has become the focus.Oilfield A in western South China Seabelongs to fault-block sandstone reservoir,which has the characteristics of high initial production capacity,rapiddecline in output,obvious difference in water injection effect,and great difference in the recovery degree of each fault-block.The development index effect of the oilfield was evaluated.From the perspectives of sufficient water injection,good water injection,fine water injection,and effective water injection,seven evaluation indexes were selected and determined,including water quality compliance rate,energy retention level,water flooding reserve utilization degree,water flooding reserve control degree,water flooding status,water-cut rising rate,and oil recovery rate of remaining recoverable reserves.It characterizes the systematic characteristics of water flooding in reservoir,process and production,and objectively reflects the development level of offshore water drive sandstone reservoirs.Then the stimulation measures were proposed for offshore fault-block oilfields,including deepening the understanding of the degree of fragmentation of fault blocks,no lower of formation pressure than the saturation pressure during water injection,the combinedproduction with long and short pipes,the triangular well pattern with low water injection and high oil production,and the strengthening oilfield testing.The measures can be used more effectively for the development and adjustment of complex fault-block oilfields and have important reference significance for the comprehensive adjustment of the same type of offshore fault-block reservoirs.