Estimating reservoir parameters and gas storage volume available in the DU6 gas field, Northeast China

Abstract

This study comprehensively evaluated the feasibility of the DU6 gas reservoir for gas storage in terms of storage performance, safety, and effectiveness. First, based on the fine division of small layers in the target area, the existing sedimentary facies markers, and paleoenvironment were identified and the fan delta front subfacies sedimentary model was established. The microfacies included an underwater distributary channel, mouth bar, sand sheet, and interdistributary bay, and the horizontal and vertical distributions of the effective reservoir sandstone were determined. Then, using petrophysical experimental data, the macroscopic and microstructural characteristics of the reservoir rock were examined, and the type and composition characteristics of the sandstone, pores, and the connectivity between pores were evaluated. By employing mechanical experiments, it was found that the sandstone permeability change rate with pressure is very large, reaching as high as 50%. In addition, the relationship between the pressure and rock micropore structure change was established. Finally, based on the fine reservoir characterization, the potential of transforming DU6 reservoir into gas storage was evaluated, and the sealing properties of its faults, top caprocks, and surrounding water were identified. The effective pore volume for underground gas storage was determined quantitatively, and the utilization rates of pores were calculated according to different sedimentary microfacies. Overall, the available gas sand body volume of the DU6 gas reservoir was found to be 9048 × 104 m3, with a gas storage capacity reaching 99.27 × 108 m3. These results will provide reliable technical support for the successful reconstruction of underground gas storage areas.