Transient temperature behavior and analysis of single-phase liquid-water geothermal reservoirs during drawdown and buildup tests: Part II. Interpretation and analysis methodology with applications

Abstract

In this work, we present new semi-log straight line and temperature-derivative methods for interpreting and analyzing temperature transient data acquired during drawdown and buildup tests in an infinite acting homogeneous, single-phase liquid-water geothermal reservoirs. The methods are based on the analytical solutions derived in our accompanied paper (Part I) accounting for the effects of Joule-Thomson (J-T) heating/cooling, transient adiabatic fluid expansion/compression, convection, and conduction. Drawdown and buildup sand-face temperature data are shown to exhibit three infinite-acting radial flow (IARF) periods; early-time IARF reflecting the adiabatic expansion/compression effects in the skin zone if it exists, intermediate-time IARF reflecting the J-T effects in the skin zone, and late-time IARF reflecting the J-T effect in the non-skin zone. Semi-log straight-line analyses based on the identified proper IARF regimes and their time intervals on a log-log diagnostic plot of the absolute value of temperature-derivative vs. elapsed time, jointly with conventional pressure transient analysis (PTA), provide estimates of porosity, J-T coefficient of fluid, mobility of skin and non-skin zones as well as radius of the skin zone, which are not readily accessible from PTA alone. The applicability of the proposed analysis methods is demonstrated by considering two synthetic test examples and one field test data set.