The effect of fluid pressure on the pore volume compressibility of carbonate reservoir samples using hydrostatic pressure

Rock compressibility is directly affects the hydrocarbon production process in the reservoir and is controlled by elastic properties so for rocks with porosity values. There are three different methods for measuring the pore volume compressibility. In the CMS (Core Measurement System) method, the pores are filled with helium gas; in the Overburden Rig method are in non-pressure brine saturated condition and in the RCS (Rock Compressibility System) method are in pressure brine saturated condition. In this study, pore volume compressibility was measured for three selected samples in all these methods. As seen in all compressibility, a lower porosity has a higher compressibility ratio and sample with a higher porosity has a lower compressibility value in three instruments. Condensation in CMS and Overburden Rig by states is in a non-fluidized state and less than RCS method. Also the Overburden rig s compressibility is slightly higher than to the CMS method. The main result of this study is due to oil production and reduced of pore pressure, pore volume compressibility of reservoir have fast reduce in the initial productions and against to scale down to production flow.