A Novel Approach to Estimate the Variations in Stresses and Fault State Due to Depletion of Reservoirs ; Case Study

A Novel Approach to Estimate the Variations in Stresses and Fault State Due to Depletion of Reservoirs ; Case Study

Estimation the changes in rock can have different technical and economic aspects. A good study on this field can enhance drilling and production operations. Lack of information and management about these matters can cause events with high cost happen during drilling, completion and production. In fact, Geomechanics focuses on evaluation, modelling and controlling of changes in rocks during drilling and production[1]. Addressing problems associated with the changes of stress within depleting reservoirs is important for many reasons. Most well-known are the problems associated with casing collapse and surface subsidence that create substantial difficulties in some oil and gas reservoirs due to compaction in weak formations. Make drilling a new well to deeper targets quite problematic. Depletion also has the potential to change the state of faults or induce faulting[2]. The activation or generation regional faults may have effect on both the production and further drilling operations. In fact, the opening or slip of fault contact surfaces affects the flow of the pore fluids and the surrounding porous medium deformation. Hence, permeability may be increased to a significant amount [3, 4]. The activation of faults can weak the rock structure and change the distribution of stresses and displacements. As a major result, large local displacements may arise with possible damages, or even breaks, in the well casings or lead to lost circulation in drilling [5]. Fault activation is studied using different approaches [3, 6]. The important and common part of these studies is determination of stresses. Amount of in-situ stresses is the key to determine the state of faults