重力泄水辅助蒸汽驱开采机理及油藏工程设计

Development mechanism of gravity water⁃drainage assisted steam flooding and reservoir engineering design

针对辽河油田稠油区块蒸汽吞吐后期产量低、转换开发方式难度大的问题,按照“垂向泄水提高热效率、直平采液提高采注比、水平井注汽提干度、注采泄稳定控制扩波及”的技术思路,开展重力泄水辅助蒸汽驱油藏工程研究,进一步明确开采机理并明确了各阶段开发特征,并对油藏工程关键参数进行优化设计。研究表明:采用上下叠置水平井与直井组合的立体井网,实现了平面蒸汽驱替、垂向重力泄水的渗流模式;重力泄水辅助蒸汽驱立体井网可为蒸汽腔的形成创造良好的条件,有效缓解了深层、特-超稠油埋藏深、沿程热损失大造成的井底蒸汽干度低、注采不同平衡等系列矛盾;重力泄水辅助蒸汽驱可划分为直井、水平井井间热连通,重力泄水辅助蒸汽驱驱替阶段和蒸汽驱调整3个阶段;重力泄水辅助蒸汽驱现场试验取得较好的开发效果,预计汽驱结束采收率可达到58.6%,为深层-特深层稠油开发方式转换提供了新途径。研究成果为同类油藏进一步提高采收率提供了借鉴。

In the light of problems of low production and much difficulty in development mode conversion at the late stage of CSS in heavy oil blocks of Liaohe Oilfield,on the basis of technical ideas of“improving thermal efficiency by vertical water drainage,increasing production-injection ratio by producing fluid from vertical wells and horizontal well,increasing injected-steam dryness with horizontal wells,and increasing swept volume by stably controlled in‑jection-production-drainage”,reservoir engineering of gravity water-drainage assisted steam flooding is studied to further determine development mechanism and development characteristics of each stage,and key parameters of res‑ervoir engineering are optimized.The results show that a flow pattern of areal steam flooding and vertical gravity drainage is realized by using 3D well pattern consisting of stacked horizontal wells and vertical wells.3D well pat‑tern of gravity water-drainage assisted steam flooding provides favorable conditions for the formation of steam cham‑ber,effectively mitigating a series of contradictions of low bottom hole steam dryness and injection-production imbal‑ance caused by deep buried ultra-extra heavy oil with much heat loss along wellbore.Gravity drainage assisted steam flooding is divided into 3 stages:thermal connection between vertical wells and horizontal wells,displacement stage of gravity drainage assisted steam flooding stage and steam flooding adjustment stage.Field test of gravity drainage assisted steam flooding achieves good development results,with recovery factor at the end of steam flooding expected to reach 58.6%,providing new way for conversion of deep to ultra-deep heavy oil reservoirs.The research provides reference for further improving recovery in similar reservoirs development..