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A new method for determining hydraulic properties from slug test well data in a confined aquifer is presented. The new procedure is based on an exact equation which converts measured slug test head data to equivalent head data that would be obtained due to a constant discharge of a well with well bore storage and skin effects. A related procedure yields equivalent head derivative data (time rate of change of head) that would be obtained for the classical constant discharge with well bore storage and skin problem without applying numerical differentiation. After the constant discharge head data and its derivative data are generated by our procedure, these converted data can be analyzed by using existing well bore storage and skin type curves for the appropriate aquifer/well model. Therefore slug test type curves are no longer needed. For cases in which the relative change in the water level is not significant during the slug test, most of the converted data will fall on the unit slope line of the conventional well bore storage and skin type curves and it will be difficult to obtain a unique type curve match of converted head data. For such cases, it is shown that a discharge normalization procedure can be applied to improve the reliability of the analysis. A field case illustrating the reliability of the new method is presented.

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Summary This paper presents new semilog-straight-line and temperature-derivative methods for interpreting and analyzing sandface-temperature transient data from constant-rate drawdown and buildup tests conducted in infinite-acting reservoirs containing slightly compressible fluid of constant compressibility and viscosity. The procedures are dependent on the analytical solutions accounting for Joule-Thomson (J-T) heating/cooling, adiabatic-fluid expansion, and conduction and convection effects. The development of the analytical solutions is dependent on the fact that the effects of temperature changes on pressure-transient data can be neglected so that the pressure-diffusivity and thermal-energy-balance equations can be decoupled. The analytical solutions are verified by and are found in excellent agreement with the solutions of a commercial nonisothermal reservoir simulator. It is shown that drawdown and buildup sandface-temperature data may exhibit three infinite-acting radial-flow (IARF) periods (represented by semilog equations): one at early times reflecting the adiabatic expansion/compression effects, another at intermediate times reflecting the J-T expansion in the skin zone if skin exists, and the third at late times reflecting J-T expansion effects in the nonskin zone. Performing semilog analyses by use of these IARF regimes gives estimates of permeability of skin and nonskin zones as well as the radius of the skin zone, assuming that the J-T coefficient of the fluid and the viscosity are known. Parameters such as skin-zone permeability and radius are not readily accessible from conventional pressure-transient analysis (PTA) from which only the skin factor and nonskin-zone permeability can be obtained. The applicability of the proposed analysis procedure is demonstrated by considering synthetic and field-test data. The results indicate that the analysis procedure provides reliable estimates of skin-zone and nonskin-zone permeability and skin-zone radius from drawdown or buildup temperature data jointly with pressure data.