Land subsidence due to gas/oil production in inhomogeneous transversally anisotropic half‐space by a boundary element method

In a previous paper1 the authors have developed and implemented a new boundary element (BE) model to simulate and predict land subsidence occurring over three‐dimensional gas/oil fields in a homogeneous and isotropic half‐space. The approach relies on Betti's reciprocal theorem and makes use of the classical fundamental solution of Boussinesq in the framework of the theory of linear poroelasticity. The BE method is here extended to inhomogeneous, transversally anisotropic soils by the aid of a two‐dimensional finite element (FE) model which provides a fundamental numerical solution for the actual multi‐layer setting of the subsurface system. The new FE–BE approach is then used to simulate the subsidence caused by gas production over the deep reservoir of Campo Ravenna Terra, Ravenna (Italy) from 1950 to 1980. The results compare very favourably with the outcome from a full more expensive three‐dimensional FE model of the same occurrence. Copyright © 1990 John Wiley & Sons, Lt