Document Type : Original Research Paper
Authors
1 Ph.D. Student, Department of Geophysics, Islamic Azad University, Science and Research Branch, Tehran, Iran
2 Associate Professor, Institute of Geophysics, University of Tehran, Tehran, Iran
3 Professor, Department of Petroleum Engineering, Curtin University, Perth, Australia
4 Assistant Professor, Research Institute of Petroleum Industry, Tehran, Iran
Abstract
Rock physics is the major tool to describe physical property of reservoir rocks; such as porosity, permeability, degree of saturation, property fluid that saturated, shape of pores, compressibility and etc via studying ultrasonic wave transmitting through a rock sample.
Between these parameters, porosity and degree of saturation are more effective on elastic wave velocities which have been studied extensively in recently years. Amplitude of acoustic waves is a function of acoustic impedances (velocity and density) could be used to study lithology, pore fluids and saturation. In this paper we studied how main characters wave (velocity, amplitude, frequency) changes related to two main reservoir characteristics (pore pressure and confining pressure). In our study, we transmitted ultrasonic waves in different frequencies through a sandstone core in reservoir pressure condition. Analysis confirmed that similar to previous studies, amplitude of transmitted signal is a more sensitive attribute to pressure changes rather than velocity of the waves.
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