Geomechanical response to seasonal gas storage in depleted reservoirs: A case study in the Po River basin, Italy

摘要: [1] Underground gas storage (UGS) in depleted hydrocarbon reservoirs is a strategic practice to cope with the growing energy demand and occurs many places Europe North America. In response summer injection winter withdrawal reservoir expands contracts essentially elastically as major consequence of fluid (gas water) pore pressure fluctuations. Depending on number factors, including burial depth, difference between largest smallest pressure, geomechanical properties injected formation overburden, porous medium overlying subject three-dimensional deformation related cyclic motion land surface being both vertical horizontal. We present methodology evaluate environmental impact underground sequestration from perspective, particularly relation ground displacements. Long-term records removed volume “Lombardia” field, northern Italy, are available together multiyear detection horizontal west-east displacement above by an advanced permanent scatterer interferometric synthetic aperture radar (PSInSAR) analysis. These data have been used calibrate 3-D fluid-dynamic model develop transversally isotropic model. The latter has successfully implemented reproduce displacements, range 8–10 mm 6–8 mm, respectively, measured 2003 2007 where UGS program underway Stogit-Eni S.p.A. since 1986 following 5 year field production life. Because great economical interest increase working much possible, addresses two scenarios overpressure pushed current 103%pi, pi prior development, 107%pi 120%pi. Results show that there negligible surface, gradients remain well below most restrictive admissible limits for civil structures infrastructures.