Experimental and Theoretical Characterization of Sand-Carrying by Heavy Oil-Flow in a Horizontal Wellbore

Abstract

The world's heavy oil reserves are very large. With the wide application of heavy oil cold recovery technology, the problem of blockage in oil well caused by the deposition of sand in the wellbore is becoming more and more serious. Therefore, it is very important to study the deposition and migration of sand in the wellbore. Based on indoor full-sized experimental apparatus simulating multiphase complex flows, the sand-carrying capacity of heavy oil in pipes is determined using a high-viscosity white oil and water mixture as the fluid medium, and by varying parameters such as the saturation, sand volume concentration, viscosity of heavy oil, and flow. A complete investigation is performed to obtain the basis of the sand flow in pipes and sand-bed development and migration. It is shown that the viscosity of heavy oil, main flow rate, and water content have a significant effect on the sand-carrying capacity of heavy oil, while the effect of the wall inflow on the pressure drop of the wellbore is relatively less. Based on the examination of the experimental flow pattern, an oil–water–sand-bed three-layer pressure drop model with a variable-mass flow is established for the first time. The minimum energy method is used to calculate the model. The model considers the diffusion of solid-phase particles and pressure drop by the fluid of the sand bed in heavy oil and is verified against the pressure drop data obtained from the experiments. The results show that the model is within an average relative error of 12.69%, which is satisfactory for practical engineering. Furthermore, the model provides a theoretical support for reasonable sand production in heavy oil reservoirs.