Integrated Evaluation of The Clean-Up Performance of Unconventional Gas Plays: Investigating the Impact of Desiccation and Low Permeability Jail

Abstract

Tight and ultra-tight gas formations refer to low permeability gas bearing formations that predominantly produce dry gas. Literature reviewed shows no study has been carried out to investigate the effects of desiccation and low permeability jail on fracture-fluid clean-up. In previous literatures (Tannich, 1975; Cheng, 2012), investigated the effects of inefficient fracture-fluid clean-up on gas production. It was discovered that liquid removal from damaged matrix, capillary pressure and relative permeability are governing characteristics of the flow of water in a fracture.

The aim of this research is to investigate the impact of weak permeability jail and desiccation in fracture-fluid clean-up of unconventional gas plays. Analyzing the effects of these factors will help to mitigate the impact of residual water and maximize the recovery of natural gas.

A numerical model was developed using CMG software, which was then validated by comparing the simulated model to the analytical model. Several geo-mechanical properties and their effects on the reservoir formation, gas and water production and fluid dynamics were also compared.

Some preliminary results gotten from this research are both critical gas saturation and irreducible water saturation have a negative relationship with porosity as well as permeability. Towards the end of production life of the well; there are gas bubbles, which means the gas is not completely dissolved in water due to the average water saturation in the later stages of the well production.

Preliminary conclusions drawn from investigations are presence of water changes the gas percolation. When there is high water saturation within the formation, then gas-water two-phase flow takes place. Gas-water ratio increases with the drawdown pressure, this agrees with the assumption in (Tannich, 1975). Both bottom-hole pressures from analytical and CMG simulation models are overlapping and almost on top of each other, where