Land subsidence vs gas reservoir compaction in the Northern Adriatic basin
P. Teatini, D. Bau', G. Gambolati
Dept. Mathematical Methods and Models for Scientific
Applications, University of Padova, Padova, Italy
M. Gonella
Med Ingegneria S.r.l., Ferrara, Italy
ABSTRACT
Land subsidence n above a compacting reservoir is (primarily) related to the gas
pore pressure drawdown, the reservoir thickness and burial depth, the areal extent
of the depleted volume, and the vertical rock compressibility. Other factors that
may influence land subsidence are the stiffness of the overburden and the dynamics
of an active aquifer (waterdrive) hydraulically connected to the gas-bearing
formation. The present communication addresses the transference of the reservoir
compaction c to the land surface for a few typical gas fields of the
Northern Adriatic using a three-dimensional finite element analysis of the
sedimentary basin. It is shown that the ratio nmax/c between the
maximum land subsidence and the corresponding reservoir compaction ranges between
0.9 and 0.2 for the shallowest 1000 m deep Chioggia Mare field and the 3000 m deep
Dosso degli Angeli field, respectively. These results hold during the field
production life and do not account for land settlement induced by the compaction
of the waterdrive surrounding the field.
