Abstract:

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 1^st 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 2^nd 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.

Key words: carp rock, surrounding rock, displacement pressure, fractured rock, Hailaer Basin