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以大港油田埕北断阶带控烃断层上、下盘储集层内油气存在与否作为判别断层启闭性的指标,综合考虑多种因素的影响,提出了一种定量评价断层启闭特征的新方法——断层连通概率法。此法将影响断层启闭性的主要因素归结为泥岩流体压力、断面正应力和泥岩涂抹3个代表性参数,依据其影响断层启闭性的机理构建出一个无量纲的断层启闭系数。在此基础上,选取横切断层的典型油气藏剖面,计算断面不同位置处的启闭系数,根据其上、下两盘储层内是否含油来确定其“开启”或“封闭”性质。通过概率统计分析所建立的断层启闭系数与断层连通概率间的相关关系表明,当断层启闭系数小于1.0时,断层连通概率为0;启闭系数为1.0~3.5时,二者关系可表达为一个二次多项式;当启闭系数大于3.5时,断层连通概率为100%。由此在拓扑展开的断层面上勾绘出连通概率等值线,展现出断层面不同位置处的启闭性特征。
Taking the presence of oil and gas in the upper and lower reservoir reservoirs in the Tiebei fault zone of the Dabang oilfield as an index to judge the opening and closing of the fault, considering the influence of various factors, a quantitative evaluation method of fault opening and closing features New method of fault connectivity probability method. In this method, the main factors that affect the opening and closing of faults are attributed to three representative parameters of mudstone fluid pressure, normal stress in cross section and smear of mudstone, and a dimensionless fault opening and closing coefficient is constructed according to the mechanism that affects the opening and closing of faults. On this basis, the cross section of the typical reservoir of the fault is selected and the opening and closing coefficient at different positions of the section are calculated. According to whether the upper and lower reservoirs contain oil to determine its “open” or “closed” "nature. The correlation between fault opening and closing coefficient and fault connectivity probability established by probability statistical analysis shows that when the fault opening and closing coefficient is less than 1.0, the fault communication probability is 0; when the opening and closing coefficient is 1.0 ~ 3.5, the relationship between the two can be expressed Is a quadratic polynomial; when the opening-closing coefficient is greater than 3.5, the probability of fault connectivity is 100%. Thus, the contour of connected probabilities is plotted on the fault surface expanded in the topography, showing the characteristics of opening and closing at different positions of the fault surface.