The Effect of Ultrasonic Alternating Loads on Restoration of Permeability of Sedimentary Rocks during Crude Paraffinic Oil Flow

Abstract

This paper presents the results of experimental studies on the filtration of reservoir fluid through the rocks under the influence of nonlinear loads. A laboratory rig is assembled that allows for modeling the flow of fluid from the reservoir into the well during the propagation of elastic waves from the well. It is shown that depending on the permeability of the rock matrix as well as on the concentration of paraffins and asphaltenes in crude oil, the effect of the nonlinear load is different. Three types of sandstone are studied: low, medium, and high permeability. The greatest influence of nonlinear loads is observed in high-permeability sandstone. The effect manifests itself in fully unblocking the pore space from paraffins and asphaltenes accumulated in pore throats and restoring the oil permeability to its original value. In the case of medium-permeability sandstone subjected to nonlinear loads, blocking of the pore space is slow. In the case of low-permeability sandstone, the impact of nonlinear loads does not have a significant effect. When studying water filtration in the presence of residual oil saturation, the effect of nonlinear loads is observed as a mobilization of additional oil not previously involved in the filtration process, which also leads to an increase in the water permeability of the rock.