INVESTIGATION INTO THERMAL EFFECTS ON GEOTHERMAL WELL INTEGRITY AFTER CO2 FRACTURING: A CASE STUDY OF WELL X IN INDONESIA

• Main Author: Anwar Sena, M
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/48103
• Institution: Institut Teknologi Bandung

CO2 injection in the geothermal well has a purpose to increase the permeability of geothermal reservoir as geothermal resources consist of the igneous rock formation which has poor permeability. CO2 is considered to have several benefits to be used as fracturing fluid because of high expansivity in high temperature, lower viscosity in supercritical conditions, and in general it can reduce global carbon emission. CO2 injection on geothermal well with high temperature will cause extreme temperature alteration over and over to casing and liner in well X. This will affect to well integrity. This study was conducted to find the impact of repeat extreme temperature alteration to well integrity by considering the effect of corrosion from CO2 in several conditions. CO2 injection in "X" wells with a K-55 casing grade class is carried out at a well surface pressure of 20 bar and an injection temperature of 80o Fahrenheit with a flow rate of 4 MMSCFD for 7 hours. The composition of the injected fracturing fluid has a lean CO2 content of 95%, N2 of 4%, and H2S of 8 ppm. Four conditions are needed to evaluate in the studies at the "X" well. The first condition was at the well drilling and completion, the second condition is at the well being produced before the fracturing process, the third condition was at CO2 injection and the fourth condition was at the well is being reproduced after fracturing. This study presents the parameters of the integrity of the geothermal well after injection of CO2 in the "X" well. To determine the well integrity parameters, commercial software is used as a tool to get results. Important parameters studied in this paper are analysis of the liner and casing stress, the effects of corrosion, and the effects of repeat extreme temperature alteration. The results of studies conducted show the use of K-55 casing can meet the requirements of the casing stress and can withstand the rate of corrosion that occurs in the casing and liner in conditions before and after the process of thermal change but does not meet the safety factor of the thermal effect to be received by the casing and liner during the process of production and injection of CO2, hence modifications are needed to the well configuration or modifications to the CO2 injection activities. The novelty of this study is the analysis of temperature changes effects and CO2 injection on the integrity of the well casing under several conditions.