断裂岩石排替压力预测方法的改进及其应用

An improved method for predicting the displacement pressure of fractured rocks and its application

为了解决目前断裂岩石排替压力预测方法尚存在的问题,以便更准确、科学地反映地下实际情况,根据断裂岩石和围岩排替压力与压实成岩程度之间的正相关关系,利用断裂岩石与相同埋深围岩排替压力之比应等于断裂岩石与相同埋深围岩压实成岩程度之比的关系,推导出了断裂岩石与相同埋深围岩排替压力之间关系,进而改进了目前断裂岩石排替压力的预测方法。利用该方法预测海拉尔盆地贝尔凹陷呼和诺仁背斜带F1断裂在大磨拐河组一段下亚段区域性泥岩盖层内的断裂岩石排替压力,结果表明改进后方法的预测结果明显小于改进前方法的预测结果,更符合F1断裂处南屯组二段油气仅分布在构造高部位的实际情况。改进后的断裂岩石排替压力预测方法适用于碎屑岩含油气盆地张性断裂在脆性地层中的断裂岩石排替压力预测。

This study aims to improve currently used method for predicting the displacement pressure of fractured rocks in order to more accurately and scientifically reflect actual subsurface conditions.Given that fractured and surrounding rocks exhibit a positive correlation between their displacement pressures and their degrees of compaction and diagenesis,the displacement pressure ratio between fractured rocks and surrounding rocks at the same burial depth should equal their ratio of the degree of compaction and diagenesis.Based on this equivalence,we can derive the relationship between the displacement pressures of fractured rocks and surrounding rocks at the same burial depth,thus improving the existing predictive method.The improved method is applied to predict the displacement pressure of fault F1-induced fractured rocks in regional mudstone cap rocks in the lower section of the 1st member of the Damoguaihe Formation(also referred to as the Da 1 Member)in the Huhenuoren anticlinal zone of the Beier Sag,Hailaer Basin.The results indicate that the displacement pressure predicted using the improved method is significantly lower than that derived from the original method,aligning more accurately with the actual observation that the oil and gas in the 2nd member of the Nantun Formation(also referred to as the Nan 2 Member)along fault F1 are merely detected in the structurally higher parts.Therefore,the improved method for predicting the displacement pressure of fractured rocks can be employed effectively to estimate the displacement pressure of extensional fault-induced fractured rocks in brittle strata of sandstone-mudstone petroliferous basins.