一种改进后的断裂封堵性研究方法——以龙门山冲断带为例

An improved research method on fault sealing capacity:taking Longmenshan thrust belt as an example

保存条件是前陆冲断带油气成藏的关键因素,其中断层的封堵性能起到至关重要的作用。由于断层两盘岩性对接关系在三维空间上的差异,致使同一断层在不同走向或者不同深度上封堵性存在差异。该文应用改进后的Allan剖面研究断层侧向封堵性,应用断面压力联合断移地层砂地比评价断层垂向封堵性。将同一断层垂向与侧向封堵性相结合,从而实现半定量综合评价。在低勘探程度尤其是无井地区,应用此方法可以初步判断断层封堵性。在勘探程度相对较高地区,可以充分应用勘探资料,将评价结果由半定量向定量化推进。

Preservation condition is a key element of oil and gas accumulation in foreland thrust belt,and fault sealing capacity plays a vital function.Due to the difference of lithologic interface of fault plates in three-dimensional space,the sealing capacity of the identical fault is different along different orientations or at different depths.The improved Allen section was applied in this paper to study the lateral sealing capacity of fault.The vertical sealing capacity of fault was evaluated based on the pressure of fault section and the net-to-gross ratio of displaced layers.Semi-quantitative comprehensive evaluation was made by means of the studies of vertical and lateral sealing capacity of fault.This method might be used to judge the fault sealing capacity initially in the places with low exploration degree,especially in those places without wells.And the places with high exploration degree,we could develop the results of evaluation from semi-quantitation to quantification based on exploration data.