Results of studying the acoustic properties of rock samples of natural bitumen deposit

Abstract

The work is devoted to the study of changes in the acoustic properties of rocks of super-viscous oil deposits as a result of heating. The development of the studied field is carried out by the method of steam-gravity drainage, the essence of which lies in the injection of steam leading to the runoff of heated oil to the producing well. The coolant temperature during the development of the object under study is 150 °C. As a result of steam-gravity drainage, the temperature field of the developed formation and nearby rocks changes. There is a need to study the influence of the heating processes of rocks containing high-viscosity hydrocarbons in order to develop a technique for qualitative monitoring of the reservoir and predicting the effect of the coolant on the geological environment. This article presents the results of laboratory researches of the acoustic properties of reservoir rocks and cap rocks under the influence of temperature heating. The collection of core samples is represented by sandy rocks, «linguloid clays» and «spiriferous limestone». In laboratory conditions, the heating of the samples ranged from 20 to 90–100 °C. The measurements of acoustic characteristics were carried out with a heating step of 10 °C. The obtained results illustrate a speed decrease of the longitudinal and transverse waves, the change in Young's modulus and Poisson's ratio under the conditions of a uniformly increasing temperature. The approximation of the results to the coolant temperature was carried out according to the revealed law, based on the points of direct measurements. The results made it possible to establish the patterns of changes in petrophysical parameters, to identify the acoustic characteristics of rocks that are subject to the greatest changes in heating conditions, and to determine the magnitude of the change in the parameters under consideration.