چكيده به لاتين
Abstract
According to the world`s energy problems these days, trends toward use of alternative energy has increased. Geothermal energy is one of the renewable energys that uses layers heat energy of earth's pays to energy production. Geothermal energy is one of the most environmental friendly energy sources, although not free from environmental damages. One of the most important environmental impacts is surface settlement at the exploitation of site. Since the simplified method to calculate, the subsidence on geothermal sites is retrieved from the method of calculating the settlement site drilling and operation of oil wells, Presented methods of computational methods will be included. In this research we present two improved method to calculate land subsidence in geothermal areas and then base on these methods a relyable way will be given to predict subsidences coused by geothermal activites. These new methods are presented a way for calculating subsidence in “Meshkin Shahr” or other geothermal sites which is a combination of two methods , Cylindrical method and subsidence-reservior which approach that using two modeling software TOUGH2 and ABAQUS deal to modeling of subsidence. Among the advantages of the new method presented fully three-dimensional reservoir simulation, allowing simulation of groundwater flow, multi-phase, multi-component and thermal and mechanical changes in geothermal reservoirs. The accuracy of the subsidence-reservoirs model compared with the results of the cylindrical method and has been proven. Finally, a sensitivity analysis has been performed and the characteristic parameters and changes in pressure and temperature on subsidence in this site has been evaluated. From the results we can see in this geothermal site, temperature changes controls subsidence amount as well , a big range of changes in subsidence is created by changing the ground thermal and mechanical properties (such as compressibility factor, thermal expansion coefficient, and Poisson's ratio). One the other hand due to the small thermal changes in 30 years the subsidence is more coused from pressure. In addition, results showes that subsidence after 30 years operation going to be less than 30 cm. This amount of subcidence does not cause serious damage on the buildings and structures of the site.
