Simulation studies concerning the mechanisms of gas storage in an aquifer

In this work, we present a parametric simulation study to investigate the effects of important reservoir and well parameters on the efficiency of gas storage in an aquifer. We have also conducted a history match of an actual gas storage aquifer. We used results from the parametric study to improve the history match.; Our parametric simulation study shows that formation permeability is the most important parameter affecting the cumulative gas recovery. The formation dip angle and porosity are of second-order importance in affecting the cumulative gas recovery. Using the same perforation scheme and gas injection/withdrawal scheme, homogeneous formations have much higher cumulative gas recovery than heterogeneous formations, especially in the earlier gas injection/withdrawal cycles. Cumulative gas recovery is mainly determined by permeability, porosity and formation dip.; We found that cumulative gas injection/withdrawal increases almost linearly as permeability or formation thickness increases. Porosity and formation dip angle have both positive and negative effects on gas storage performance. At a given gas injection/withdrawal strength and formation thickness, there is an optimal well perforation interval generating maximum cumulative gas injection/withdrawal. The curves of the logarithm of the cumulative gas injection/withdrawal versus the gas injection/withdrawal cycle for different permeabilities or formation thicknesses are parallel to each other.; To investigate the effects of reservoir heterogeneity, we evaluated different permeabilities in the various layers of the reservoir, using wide ranges for the values of the investigated parameters to ensure a comprehensive parametric study. We found that reservoir heterogeneity was an important factor that affected the efficiency of gas storage in an aquifer.; Published correlations were used to calculate the variations of the noninvestigated parameters from the variations of the investigated parameters. The correlations between primary reservoir parameters and gas storage performance parameters under a given well perforation and gas injection/withdrawal scheme were developed using multiple-regression software. In the correlation analysis, we found that the dominant influential parameters of the cumulative gas injection are permeability and formation thickness. However, the four primary parameters (permeability, formation dip angle, porosity, and formation thickness) present almost the same importance in affecting the cumulative gas recovery.