Injecting CO2 and Pumping Out Saline Formation Water Simultaneously to Control Pressure Build-Up while Storing CO2 in Deep Saline Aquifers

Abstract

Production of saline formation water from the storage formation in sufficient amounts helps to control the pressure increase during CO2 storage in saline aquifers. In this paper, we present an engineering design to control the pressure build-up during CO2 storage in deep saline aquifers and we propose that the extracted saline formation water can be processed at the industrial level in order to produce commercial salt. We investigated the effects on various aquifer properties of pressure increases. Several design options for the injection operations are investigated: injection of CO2 without saline formation water production, injection of CO2 with one production well and, finally, injection of CO2 with one left side and one right side production wells. We showed that an increase in saline formation water production rate leads to pressure build-up decreases, when the production rate was tripled (from 61.42kg/s to 184.26kg/s); the maximum pressure was decreased by about 15bar. About a half of base case temperature (89°C to 45°C) increased the maximum pressure by about 35bar. The pore compressibility which is a key parameter defining the pressure response to CO2 injection has also been investigated whereby an increase in pore compressibility leads to decreases in pressure build-up. Simulation results showed that the introduction of two wells (left side and right side of the production well) increases more or less the horizontal migration of the CO2.