Effect of Temperature on Petrophysical Properties of Reservoir Rocks
Authors: Sanyal S.K. , Marsden S.S. , Ramey H.J. 
Published: December 2007

This paper was prepared for the 49th Annual Fall Meeting of the Society of Petroleum Engineers of AIME, to be held in Houston, Texas, Oct. 6–9, 1974. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL OF presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal provided agreement to give proper credit is made. provided agreement to give proper credit is made. Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines.

Abstract
This paper briefly reviews the current status of knowledge on the effect of elevated temperature on pore volume, permeability, electrical resistivity and capillary pressure behavior of reservoir rocks. Various authors have suggested that these effects may be caused by changes in the properties of the rock matrix or the properties of the rock matrix or the fluids or by a change in the wettability of the rock-fluid system. These suggested causes are examined in the light of the similarities and the contradictions in the published results, consider the basic petrophysical relationships and idealized pore geometries. It is concluded that the temperature sensitivity of rock-fluid wettability in explaining the observed temperature effects on petrophysical properties may have been overemphasized in the literature, and in this regard due consideration should be given to the change in fluid viscosity and rock matrix with temperature.
Although the explanation of some of the observed effects on rock properties or the extent to which the properties or the extent to which the reported results apply to real reservoirs may be questioned, these effects are important, particularly when dealing with production from deep, hot reservoirs or thermal oil recovery projects. The possible errors in projects. The possible errors in well log analysis and formation evaluation due to the common practice of neglecting temperature effects on some rock properties are pointed out. No results are available on the effects of temperature on the relative permeability to oil in gas-oil and permeability to oil in gas-oil and gas-oil-water systems. Calculations were made to predict these effects. Through hypothetical examples it is shown that the error due to neglecting temperature effects on petrophysical properties may be significant when properties may be significant when predicting performance of primary predicting performance of primary (oil expansion, solution gas) and secondary (water-flood) recovery projects.

Introduction
The thermal oil recovery techniques have become well accepted in the oil industry during the last two decades.