Experimental study of implementing nano thermal insulation coating on the steam injection tubes in enhanced oil recovery operation for reducing heat loss

Abstract

Thermal recovery in oil fields is an effective conventional method for extracting heavy oil. Steam injection is one of the main techniques in thermal recovery. Temperature reduction of the injected steam due to heat transfer from tubes to the reservoir environment is one of the essential problems in this method. Increasing the steam temperature or injection rate to overcome this energy loss and to provide the required temperature at the tube outlet considerably enhances the steam generation costs. Furthermore, increasing the injection temperature enhances the thermal stress to injection tubes that in turn brings irreparable damages to production units like casing breakage. In this study, an experimental setup used to simulate steam injection operation in order to decrease the heat transfer coefficient and reduce heat loss to conserve the injected steam temperature. This aim ascertained by using nano coatings as thermal insulator. Two types of thermal insulators including nano silica-based and nano ceramic-based insulators used in this study. Temperature, pressure, and injection rate of steam, and type and thickness of nano thermal insulators were the operating variables. Results show that increasing the injection temperature from 119 °C to 145 °C improves the heat transfer coefficient about twofold that in turn, causes rapid reduction of temperature in injection process. It was also shown that increasing the injection rate from 2.1 g/l to 6.3 g/l inside the bare tube improves the heat transfer coefficient up to 2.5-folds. Therefore, increasing the temperature or injection rate of steam could not be the suitable solution for compensating steam heat loss. The experimental results showed that using ceramic-based and silica-based nano insulation with 5 mm thickness reduces the heat loss up to 45% and 33% for injected steam at 145 °C, respectively.