Modelling the performance of liquefied petroleum gas fracking versus water fracking

Abstract

A novel method and a conventional method for fracking and exploitation of a gas reservoir are compared using numerical models. The novel technique for fracking a reservoir uses viscosified, liquefied petroleum gas (LPG) and the conventional technique uses low-viscosity water instead. Replacing a water-based operation with an LPG-based operation offers a relatively great advantage in the following situation: 1) the risk of formation damage is relatively high; 2) the reservoir is located at a relatively shallow depth; 3) the reservoir pressure is relatively low; 4) the reservoir has a relatively large volume; 5) the potential fracking-induced permeability is relatively low. The basic parameters governing the benefits of LPG fracking relative to water fracking apply to waterless fracking with liquid CO2 or liquid CO2-N2 mixtures as well. This relative advantage decreases with the length of the production period. Nevertheless, LPG/CO2/N2 fracking offers an absolute advantage in that fracking chemicals are left underground, whereas water-based fracking brings them back to the surface.