断层侧向封闭性定量评价方法

Quantitative evaluation method of fault lateral sealing

基于断层封闭性机理及其影响因素研究,在考虑断层承压时间的情况下对断层封闭性定量评价的断-储排替压力差法进行改进,建立了考虑时间因素的断层封闭性定量评价地质与数学模型。采用给定步长、逐渐逼近的算法,确定围岩地层岩石具有与靶点断层岩相同泥质含量和成岩程度的埋深,再根据研究区所建立的岩石泥质含量和埋藏深度乘积与排替压力的关系,定量计算出靶点断层岩的排替压力,用目的盘储集层排替压力与之比较,定量评价断层的封闭与否及封闭能力的大小。通过歧口凹陷板桥断层圈闭油气藏的实际资料的验证,以及与断层岩的泥质含量(SGR)法和未考虑承压时间的断-储排替压力差评价断层封闭性方法的比较,证实该方法具有更好的可行性和更高的可信度。

The fault-reservoir displacement pressure differential method, as a quantitative evaluation method of fault sealing which considering diagenetic time of fault rock, was improved based on the study of fault sealing mechanism and its influencing factors. A geology and mathematical model of quantitative evaluation of fault sealing considering diagenetic time was established. First, the depth of surrounding rock which has the same shale content and diagenetic degree as the fault rocks at the target was determined using the method of successive approximation at the given step length. Second, the displacement pressure of target fault rocks was calculated based on the relationship between the displacement pressure and the product of shale content and burial depth that was established for the study area. And third, the sealing states and capacity of the faults were quantitatively evaluated by comparing the calculated displacement pressure with that of the target reservoir. By the actual data of reservoirs at Banqiao fault in Qikou sag and the result comparison between fault rock shale content method （SGR） and fault-reservoir displacement pressure differential method without considering the bearing time, it is verified that this method is more feasible and credible.