基于模糊数学方法的涠西南凹陷D洼断圈成藏条件评价

Evaluation of Hydrocarbon Accumulation Conditions of Fault-related Traps in D Sub-sag of Weixinan Sag Based on Fuzzy Mathematics

涠西南凹陷D洼经历多期构造运动,断裂发育,断块圈闭是最重要的圈闭类型,同一构造不同断圈或者同一断圈不同层圈闭含油气性复杂,优选勘探部署圈闭风险较大。通过储层发育特征、油气充注特征、断裂侧向封堵特征以及断-盖耦合垂向封盖特征四个断圈成藏评价地质因素的确定,基于模糊数学方法,对断圈成藏条件进行了定量化评价。研究表明,当成藏的综合评价值D≤0.618时为超高风险断圈,当0.618<D≤0.691时为高风险圈闭,当0.691<D<0.807时为中等风险圈闭,当D≥0.807时为低风险圈闭。研究结果使断圈评价优选更加客观全面,为该区勘探部署提供定量参考。

D Sub-sag of Weixinan Sag has experienced several intense tectonic movements. Multistage faults are developed. The fault-related trap is the most important type of hydrocarbon-bearing traps. Hydrocarbon accumulation conditions are complex in different traps and horizons. Exploration target optimization has high risks. Based on the fuzzy mathematics evaluation, this paper recognized reservoir characteristics, charge modes of oil and gas, lateral sealing ability of faults and spatial matching types between faults and caprocks as the key geological factors controlling the hydrocarbon accumulation, and quantified the evaluation of the four factors. The results show that when the comprehensive evaluation value D≤0.618, it is a super-high risk trap. When 0.618<D≤0.691, it is a high risk trap. When 0.691<D<0.807, it is a medium risk trap. And when D≥0.807, it is a low risk trap. The new evaluation process is more objective and comprehensive, and provides a quantitative reference for the exploration in this area.