The crucial geometric distinctions of microfractures as the indispensable transportation channels in hydrocarbon-rich shale reservoir

摘要

This study aimed to investigate the crucial geometric distinctions of microfractures as the indispensable transportation channels in hydrocarbon-rich shale so as to find the new evidence for hydrocarbon exploration and exploitation. This study mainly shows that (1) microfracture length and width would show a good positive linear correlation, but when the length of microfracture reaches a key point, the width of microfracture would gradually deviate from the linear relationship and gradually diverges. (2) compaction or other tectonic stress can promote the formation of shale microfractures and promote the occurrence of pressure solution. (3) Similarly, before a certain key point, the poor orientation degree of microfractures often coexists with the higher convexity of microfractures, which is positively correlated. When this key point is crossed, the two begin to show a negative correlation. This may be due to the fact that the microfractures will open, close, extend or even interlace more frequently when the rock is under complex stress conditions. It proved that when describing the heterogeneity characteristics of microfractures, we should clearly describe them from two aspects of size and geometry so as to ensure the integrity of the conclusion.