Transient Simulation to Analyze Wax Deposition and Flow Pattern Behavior Along Tubing Under Esp Installation and Gassy Well Condition

Abstract

Wax deposition is a typical phenomenon that can cause flow restriction in the tubing, resulting in a decrease in production. To address the production declines, an Electrical Submersible Pump (ESP) is used, but it can affect the thermal condition and flow behavior, especially for gassy well conditions. Therefore, transient simulation is required to determine the production, wax deposition, and flow behavior in the tubing under ESP installation. The well of this study, “X” well is a gassy well that has a solution GOR of 700 scf/bbl, and the reservoir fluid in it is a waxy crude type with a wax content of 38%. In this case, the “X” well use a 400 Series DN610 type pump of ESP with 70 stages. Transient simulation is performed for 7 days using OLGA 2022.1.0 software. The result of the simulation shows that there is already a wax deposition on the first day with a maximum wax thickness of 0.0021 inches, the fluid temperature that is below 153.5°F, and the deposition that occurs at 1677 ft-MD to the tubing head position. In the following days, there is a thickening of the wax at the same depth until day 7 when the wax deposition has reached the depth of 1809 ft-MD with a maximum wax thickness of 0.0114 inches and fluid temperature that is below 153.5°F. Sensitivity analysis is then performed to see the influence of ESP installation on the wax deposition by changing the number of stages and using no ESP during transient simulation. It was found that the more the number of stages that are used, the more wax deposition is formed, and the least amount of wax deposition is when no ESP is used. This is because the installation of ESP can eventually increase the production rate by adding the number of stages. As the amount of oil that flows in the tubing increases, the more wax that is contained in the oil will be able to precipitate and then deposit. The flow pattern that occurs along the tubing under the installation of ESP as the result of the simulation varies. At pump setting depth to KOP (Kick Off Point), the stratified flow is the most dominant flow pattern. At KOP to tubing head position, the slug flow is the most dominant flow pattern although at day 1.4, day 2.8, day 4.2, and day 7 the flow pattern at the tubing head position is annular flow due to the high-moving gas while the liquid being moves slowly as the thin film. The liquid slug body occurs at day 5.6 and has successfully lifted to the tubing head with the rate of 926 STB/d and this will happen frequently.