A Review of Geophysical and Geomechanical Methods in Oil Reservoirs Production

This study aims to investigate several phenomena, including reservoir pressure drop, compaction, reduction in formation volume, changes in the strain field and the imposed displacement in neighbor rocks, fracture incidence, changes in porosity and permeability, free level subsidence, deformation of the reservoir-related environment that occur sequentially, and finally reservoir dynamics. Since study of these phenomena is of utmost importance in reservoir management and risk analysis related to the safety of wells, pipelines and platforms, complementary methods are used which can be referred to ۴D seismic, ۴D gravitational and geomechanical modeling methods. Our purpose is to introduce the gravitational method as the main subject, its association with other methods, to study how to model the mentioned phenomena and review the developments and advances in the use of geophysical methods, especially gravity in the oil industry. For instance, simultaneous use of ۴Dseismic data, ۴D gravity and geo-mechanical data can be used to show the distribution of strain after compaction in rocks on the reservoir. In view of the gravity perspective, displacement or deformation of the subsurface layers containing hydrocarbons causes changes in density and eventually changes in the gravitational effects observed on the earth's surface, which is measured in gravitational operations and at frequent intervals. The use of these methods has been considered with two analytical and numerical approaches. Nowadays, these methods are used as advanced method in the manage and control of reservoirs. The validity of these methods and the importance of their simultaneous study has been proven in North Sea reservoirs and many other places. In Iran, some publications raise in this point have been done, as well; however, their number is small and in some parts is limited

Keywords:

Pressure drop , Reservoir compaction , Subsidence , Displacement , Geomechanical methods , ۴D seismic , Gravity methods