Effect of Cryogenic Liquid Nitrogen on the Morphological and Petrophysical Characteristics of Tight Gas Sandstone Rocks from Kirthar Fold Belt, Indus Basin, Pakistan

Tight gas sandstone production faces enormous challenges from marginal matrix porosity and permeability in rock formations. In this regard, the liquid nitrogen (LN2) treatment remedy has been suggested as an appropriate stimulation approach to resolve this issue. An experimental study was carried out to investigate the cryogenic liquid nitrogen fracturing of tight rock sandstone to enhance gas recovery from such reservoirs. Three core samples from the Kirthar fold belt were subjected to LN2treatment for 30, 60, and 90 min. Petrophysical characterization was performed through scanning electron microscopy, atomic force microscopy, nanoindentation measurements, and quantitative X-ray diffraction technique. The results reveal wide conductive fractures with an optimum size of 30 μm in the 90 minutes treatment case. Moreover, petrophysical measurements show that porosity increases from 8 to 19% at an optimal liquid nitrogen (LN2) treatment duration (90 minutes). Furthermore, the permeability of the samples increased from 31 to 53 md after treatment with liquid nitrogen. Results from nanoindentation studies after LN2treatment revealed a significant decrease in nanoindentation moduli because of the increase in cracked rock compressibility.