Porous rock-fluid systems at elevated temperatures and pressures

This paper is a review and analysis of the effects of elevated temperatures and pressures on the physical properties of porous rock-fluid systems. It is well known that the physical properties of rock vary considerably depending on the magnitude and history of the stresses, pore fluid pressures, and temperatures to which the rocks are subjected as well as the type and amount of fluid saturation. The review shows that the available data are limited and sometimes contradictory. Although general trends have been established, these need to be quantified for use in subsurface performance calculations. It has been concluded that three major problems need to be solved before appropriate values for the properties and behavior of rocks in their subsurface environment may be assigned. The first of these is how to simulate subsurface stress and temperature conditions in laboratory measurements. The second is the need to correlate the physical properties required in reservoir-performance analysis and log interpretation with some simpler properties of the rock-fluid system. All desired properties used in the correlation should be measured concurrently on the same test specimen and under identical test conditions. The third need is to develop models that will make it possible to predict physical properties and behavior of rocks from easily determined characteristics of the rock-fluid system. Examples of successful modeling of the thermal properties and behavior of rocks are presented in the paper.