Relative Permeability Determination of Supercritical CO2 and Equilibrated Carbonated Water in Carbonated Rock of Brazilian Pre Salt Using Experimental and Simulation Methods

Abstract

Abstract The relative permeability curve is the key parameter to determine the CO2 injection strategy in EOR and CCS processes as it can predict the CO2 flow over the reservoir life, and also through hysteresis it is possible to quantify the changes in the reservoir due to CO2 injection. In order to improve simulation fit and increase reliability in storage assurance the research work concerned experimental, analytical and simulation methods to study two-phase relative permeability of scCO2/equilibrate carbonated brine (ECB) system at reservoir conditions (5,000 psi and 70°C). Two techniques were used in order to perform the laboratory experimental tests for unsteady state using reservoir rock composite: X-ray computed tomography and mass balance. The absolute permeability was 106.7 (md) and the composite porosity measured by CT was 18.6%. At the end of drainage, the irreducible saturation (Swi) of ECB results by CT and mass balance were 39.5% and 36.2%, respectevely. The CO2 trapped was 11.09% from the CT data at the end of imbibition test. A simulation model was created using GEM/CMG and eight parameters of the model were optimized using the CMG Bayesian Engine method (CMOST/CMG simulator). The model fitting results are consistent with the experimental results (pressure differential, water production curve and saturation profiles). The history matching results for relative permeability curve provided Corey's exponents values for drainage test: Ng=4.76, Nw=2.30 and critical saturation of gas and water respectively, Sgcrit=0.1268 and Swcrit=0.3696. According to the results obtained from the simulation model, variation in permeability and porosity was observed due to dissolution and precipitation. The average values obtained for these parameters were 119.6 mD and 14.3%, respectively. The experimental work carried out to develop the relative permeability of scCO2/ECB under reservoir conditions and using sample of reservoir rock provided higher reliability due to the both measurements techniques appointed similar results. Also, the analytical approach performed in CMG GEM from experimental data promotes accuracy and confidence. Both experimental and analytical approaches provide reliable results to fill gaps in the literature and practice of science such as the determination relative permeability curve of water-CO2 using equilibrated carbonated brine and the system modeling using GEM/CMG.