Overburden 4D seismic analysis: Influence of stress and pore-pressure changes accounting for elastic contrast between a reservoir and its anisotropic surrounding rocks

• DOI: 10.1190/geo2022-0033.1
• Publication Date: 2023-03-28T14:03:02Z
• Authors: Hong Yan; Audun Bakk; Marcin Duda; Rune Martin Holt; Serhii Lozovyi
• Keywords: Poromechanics; Overburden; Overburden pressure; Geomechanics; Effective stress

Time-lapse (4D) seismic data analysis is widely used to monitor producing hydrocarbon or CO 2 storage reservoirs and their surroundings. The influence of potentially significant undrained pore-pressure changes around depleting (or injected) appears be neglected in most previous studies. 4D response the overburden depends on stress strains induced by reservoir. These alterations may challenge stable infill drilling well integrity. We have anisotropic static elastic moduli from laboratory measurements for two different field shales predict surroundings a reservoir through geomechanical modeling. mechanical are quantify using poroelastic theory constrained with Skempton parameters. Finally, an empirical rock-physics model quantifies impact these vertical velocity time strains. This explicitly individual contributions pore pressure, mean stress, shear above (and below) find that stiffer surrounding rock exhibits significantly larger shifts as compared softer rocks because promoted arching. Undrained contribute shifts. Ignoring anisotropy parameters can lead overestimating pressure after depletion. stiffnesses impacts dynamic direction, particularly pronounced vicinity how tailored link geomechanics separate strain, — all essential optimizing production.