Wellbore Stability Analysis of CO2 Sequestration in Saline Aquifer

Abstract

The reduction of greenhouse gases is helpful to mitigate the effects of global warming Geological sequestration of CO2 is a promising solution to reduce net emissions of greenhouse gases into the atmosphere Deep saline water-saturated reservoir rocks (saline aquifer) has the best storage potential in the options of CO2 geological sequestration While injecting the CO2 spontaneous fracturing might take place with injection temperature below reservoir temperature The purpose of this study was to analyze wellbore stability by using Mohr-Coulomb failure criterion while injecting CO2 into a saline aquifer The stresses used in Mohr-Coulomb failure analysis were calculate from the model we derived The safe wellbore pressure buildup was analyzed from the failure criteria The effects of low temperature CO2 flowing into the high temperature saline aquifer were discussed In the wellbore stability analysis the following four stress fields around the wellbore are concerned (1) nonhydrostatic regional stresses after well drilled (2) stress induced due to pressure difference (3) stress induced due to pore pressure changing and (4) stress induced due to temperature changing A case of CO2 saline aquifer storage located in Tienchanshan field west-central Taiwan was studied The estimated allowing wellbore pressure buildup was 600 psi for a 5200 ft deep saline formation based on the calculated stress field with the Mohr-Coulomb failure criteria The temperature difference between the injected CO2 at the reservoir was critical on the stress fields When the low temperature fluid was injected to a high temperature reservoir the tensile stresses will be developed in wellbore wall of 90 degrees direction which increases the risk of a tensile failure The model derived in this study can be applied to CO2 sequestration and gas storage

Date of Award	2015 Aug 28
Original language	English
Supervisor	Bieng-Zih Hsieh (Supervisor)