Wax Thickness and Distribution Monitoring Inside Petroleum Pipes Based on External Temperature Measurements

Abstract

A method to estimate wax thickness inside petroleum pipes from the external pipe temperature measurements is proposed. When wax is deposited inside the pipe, the external pipe surface temperature decreases because the heat resistance of the wax reduces the heat flow from the fluid inside the pipe to the fluid outside the pipe. The decrease in the external pipe temperature can be calculated by solving a heat equation about the heat transfer from the pipe inner fluid to external ambient fluid, and thus the wax thickness can be estimated by measuring the pipe surface temperature. An experiment to validate the method was performed. Crude oil was passed through a pipe with an inner diameter of about 8 mm. Ten thermocouples were installed on the pipe. The pipe was covered by a heat-shrink tube as a substitute for an insulation material. The pipe was cooled by a coolant jacket, and wax about 0.8 mm thick was deposited in the pipe. The wax thickness estimated from the temperature measurements agreed well with the thickness estimated from the pressure rise because of the wax layer and from the final gross weight of the wax. The difference between wax thickness estimated from the temperature measurements and from the final gross weight was less than 0.2 mm.

Analyzing Efficiency of Joint Operation of Gas Separator and Screw Pump on High-viscosity Gas-liquid Mixture

“…In the literature (23) indicates that the single screw pump has a wide range of capabilities when working on gas-liquid mixture, but these studies relate only to model mixtures: "water-air", "water -surfactant -air", i.e. they did not consider the influence of free gas in the composition of high-viscosity gas-liquid mixture on the characteristics of the screw pump.…”

A comprehensive method for determining the dewaxing interval period in gas lift wells

“…To study the wax formation using the proposed model, the heat transfer process is considered in three zones (Fig. 4) and the system is considered to be adiabatic on the outer wall of the cylinder (Creek et al 1999;Hu et al 2019;Ito et al 2021;Phillips et al 2011):…”

“…At a certain temperature, waxy oil will solidify and stop flowing. This temperature is called the pour point of crude oil (Ilyushin et al 2019;Ito et al 2021;Zhao et al 2017;Ulyasheva et al 2020).…”

“…This study investigates the intensity of wax deposition using a cold finger device. According to the literature reviews, many researchers have also studied the kinetics of wax deposition employing the cold finger (Eskin et al 2013;Hu et al 2019;Ito et al 2021;Li et al 2019;Lira-Galeana et al 1996;Phillips et al 2011). The authors stated that four zones were formed in their models.…”