Mathematical model of land subsidence above fluid-carrying reservoir adjacent to clay layer

It has been known that fluid withdrawal from an underground reservoir adjacent from below to a water saturated clay layer can cause land subsidence running up several meters and extending over a considerable area [1 - 3]. The reservoir's decompression due to fluid withdrawal is accompanied by clay layer's compaction under the influence of rock mass weight and as a result water outflow from it into the reservoir. So, land subsidence in this case is governed mainly by clay layer compaction. In the present paper a mathematica] model of such process is proposed. Analytical expressions for pressure distribution, water outflow from clay layer into the reservoir and land subsidence were obtained. These expressions make it possible to analyze the change of their development rate. The connection between maximum subsidence and rheological parameters of clay layer were found in analytical form.