Date of Award

1990

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

First Advisor

Robert DesBrandes

Abstract

This dissertation presents a formation evaluation method using the formation thermal properties (heat conductivity and volumetric heat capacity). The formation heat conductivity is determined by a modified Horner method, and the volumetric heat capacity is determined by the temperature buildup curve matching method. The comparisons show that the pressure and temperature diffusivity equations and initial and boundary conditions are similar. Therefore, the temperature diffusivity equation can be solved by a method similar to that used in solving the pressure diffusivity equation. The wellbore fluid storage effect is an important boundary condition and is considered in the solution of the temperature diffusivity equation. From the solution of the temperature diffusivity equation, the Horner method used in the formation pressure analysis can be used in determining the formation heat conductivity from the temperature buildup data. However, the conventional Horner method is impractical because the temperature buildup time required exceeds 600 hours. The modified Horner method proposed requires only a little more than 30 hours of temperature buildup time. The theoretical temperature buildup curves can be calculated based on the solution of the temperature diffusivity equation. Curve matching between the calculated and the measured temperature buildup curves can be used to determine the formation heat conductivity. An improved heat conductivity equation for porous rock with multi-phase saturation is developed. The rock porosity and saturations can be determined with the improved heat conductivity equation and the weighted average equation of the volumetric heat capacity. A crossplot technique is developed to achieve this determination. The temperature drawdown and buildup data were recorded at four intervals in a LSU test well. The formation thermal properties were calculated from the temperature buildup data. The formation porosities and saturations were computed with the formation thermal properties. The calculation results agree with the interpretation results of the pulsed neutron log.

Pages

150

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