Well and reservoir characterization using combined temperature and pressure transient analysis: A case study

Significant temperature variations are measured in oil and gas production wells with large pressure drawdown such as high production rate wells and tight formations. The considerable heating or cooling effects in the wellbore sandface invalidates the assumption of isothermal fluid flow in porous media. While this assumption satisfies most of the classic reservoir engineering analyses, the potential of slight thermal effects are attracting extensive interest and numerous thermal models have been proposed recently. The pitfalls and weaknesses of pressure transient analysis have been extensively investigated since 1930's which is still persistence despite developments of more accurate analytical and numerical models. Some of the weaknesses are rooted in the assumption of isothermal fluid flow in well test analysis methods. In this paper, we show the power and added value of combining temperature transient analysis to complement pressure transient analysis. Interestingly, the characteristics of skin effect such as radius and permeability of the damaged zone can be determined from temperature measurements. We study various parameters such as rock and fluid heat capacity, rock thermal conductivity, rock porosity, rock permeability and skin properties to illustrate the effect of each parameter on wellbore temperature data and hence the application of TTA for reservoir characterization. Using an accurate thermal flow mode, a case study has been done to investigate the importance of temperature transient analysis to better characterize an oil field well.