涠西南凹陷涠三段构造圈闭断层侧向封闭性定量研究及应用

The Quantitative Research and Application of the Fault Lateral Sealing Ability About the W3 Formation of Weixinan Sag

北部湾盆地涠西南凹陷渐新世末期构造运动强烈,形成了大规模的断块、断鼻构造圈闭,其成藏关键因素为断层封闭性,尤其是断层侧向封闭性。断层侧向封闭性主要依靠断裂带物质与油气目标盘之间排替压力差来衡量。考虑断层两盘对断裂带泥地比的贡献,引用了 R m地质数学模型,通过分析A油田已钻井所在圈闭主控断层涠三段泥地比 R m(Ratio of mud)和泥岩涂抹系数 SSF (Shale smear factor)间关系,建立 R m- SSF 断层侧封定量分析图版。通过油水界面处原油所受合力平行地层分量与断层两侧排替压力差形成平衡的原理,建立油柱高度定量预测模型。将断层侧向封闭性定量分析技术应用于涠西南凹陷A油田,解决了该油田各断块油水界面不一致的问题。

The Weixinan Sag in Beibuwan basin experienced strong fault activity during the late Oligocene, which formed a large-scale fault block, and fault nose structure trap. The fault sealing ability, especially for the fault lateral sealing ability, plays an important role in the process of structural trap accumulation. The fault lateral sealing ability mainly depends on the across fault pressure difference ( AFPD ) between the material in the fault zone and the targeted wall. This study evaluated contribution of two walls of fault to the muddy content of the fault zone by introducing the geological and mathematical model of Rm. After analyzing shale content ( R m) and mudstone smear factor ( SSF ) for the drilled wells of the W3 formation of A oilfield, this study established the quantitative analysis chart of relationship between the Rm-SSF. According to resultant force of parallel to the formation of crude oil component in the oil-water interface (F p) and the balance of AFPD, this study established the oil column height prediction model. This study has applied the quantitative analysis technique of the fault lateral sealing ability to the A oil field in the Weixinan Sag, and solved the problem that the oil-water interface of each fault block is inconsistent.