Stylolite effect on geochemistry, porosity and permeability : comparison between a limestone and a dolomite sample from khuff-b reservoir in Eastern Saudi Arabia

Abstract EN

Khuff formation constitutes the carbonate reservoirs in the Arabian Peninsula.

In Saudi Arabia, subsurface Khuff is divided into five units (Khuff-A, B, C, D, and E).

Stylolites are abundant in the Khuff-B gas reservoir of the Eastern Saudi Arabia.

Two samples, one of oomodlic grainstone and another of dolomite, were selected from the Khuff-B reservoir for petrophysical and geochemical studies.

SEM, X-ray line scan, X-ray mapping, helium porosimeter, and steady state gas probe permeameter techniques were utilized in this study.

It is a well-known fact that stylolites are vertical permeability barriers.

However, in this study, on a microstructural scale, it has been found that stylolite development completely destroys porosity and kills permeability (Kh and Kv) in the dolomite, while it enhances the horizontal permeability (Kh) in the oomoldic grainstone sample.

This permeability enhancement in the oomoldic grainstone sample is associated with the introduction of new mineral assemblages.