Simulation of Elastic Waves Transmission and Attenuation Considering Fluids Properties Change and Radiator of Branches Well

Abstract

ABSTRACT: Crude oil production is promoted by means of physical vibration, such as the use of high-power acoustic waves, ultrasonic waves, electro-hydraulic pulse waves, and high-pressure shock waves of explosive gases to stimulate the reservoir. And the propagation speed, distance, and attenuation of the elastic waves generated by physical vibration are the main factors affecting the effect of production enhanced by physical vibration. In this paper, the Biot model is improved. Firstly, the influence of elastic wave on reservoir physical properties is considered, and the change of viscosity and permeability field under the elastic wave is obtained by numerical superposition method. Then, the branch of horizontal wellbore is equivalent to a finite linear radiator, the wave field constructed as a superposition of fields generated by branches in all. And we simulated for different branches cases, the propagation and attenuation of pressure wave in oil reservoirs are obtained. When the lateral level is used as the vibration source, the fast attenuation area and the slow attenuation area of the pressure fluctuation can be formed in the reservoir. The size and range of slowly decreasing pressure wave can be controlled by optimizing the structure of branch horizontal well pattern. 1. INTRODUTION Improving the recovery rate of oil and gas resources is a crucial subject in the petroleum industry. Stimulating reservoirs through pulse injection is one of the important methods. The elastic waves generated during the pulse injection process can facilitate the flow of oil and gas, thus increasing the production yield of oil and gas. Heavy oil is an important fossil energy source(Zheng, Li, Sun, & Yang, 2016; Zhou, Yuan, Peng, Zeng, & Zhang, 2018). Due to its high viscosity and poor flowability, the cost of extracting heavy oil is higher than conventional oil and gas resources. Heavy oil extraction typically requires methods such as steam injection or chemical viscosity reduction. Supplementing existing techniques with physical vibrations can further reduce crude oil viscosity and increase production yields. During pulse injection, elastic waves primarily propagate in the form of pressure waves (longitudinal waves). This study simulates the propagation velocity and attenuation of waves in heavy oil reservoirs, considering the coupled effects of fluid and solid phases in the reservoir, particularly the influence of liquid phase viscosity. The wave field is simulated using staggered-grid finite difference method. Ultimately, the transmission characteristics of elastic waves are obtained.