Author : Khair Jan, Sarfraz Ahmed Jokhio, Khalil Rehman Memon and Abdul Haque Tunio

This study involves pressure transient analysis of rich CO2 gas reservoir using pseudo pressure approach. Pressure transient or any other analysis in gas reservoir can be interpreted using pressure, pressure square or pseudo pressure approach. Previously the pressure tests in gas reservoir were interpreted with diffusivity equation solved for liquid (using simple pressure approach). But unfortunately in case of gas reservoir the properties of gas are highly affected with change in pressure. This problem was firstly addressed during 70’s by Al-Hussainy and Ramey, when they conceived the idea of real gas pseudo pressure function, which laid the basis for all gas pressure transient analysis and rate transient analysis equations to be solved in terms of pseudo pressure approach rather than pressure approach, but their work is only limited to the sweet gas. Pressure dependence of gas properties is further complicated when natural gas contains higher amount of contaminant gases such CO2, H2S  and N2 . The main objective of this research is to employ the different approaches of pseudo pressure function in pressure transient analysis of gas reservoir with high concentration of . Furthermore this study involves the comparative analysis of results estimated with different pressure approaches.

Keywords: Pseudo-pressure, CO2 Reservoir, Pressure transient analysis, Pressure buildup analysis, Pressure drawdown analysis, Pressure functions

Article published in International Journal of Current Engineering and Technology, Vol.10, No.1 (Jan/Feb 2020)