Paper Details

In the evaluation of a petroleum reserve, it is necessary to determine accurately certain petrophysicalproperties such as porosity and permeability of the reservoir rocks under different compaction conditions. Theseproperties are affected by the relevant physical properties and such physical properties and mechanical properties affectthe drilling programs and the development plans for a reservoir. It is more convenient to use homogenous rock sampleswith nearly constant initial permeability, obtaining such cores is very difficult. In this paper a simulated natural andhomogeneous compacted sandstone rock with known physical and petrophysical properties were used. The physicalproperties include grain size, cementing material concentration, and compaction (confining) pressure. The effect of theseproperties on the petrophysical properties of Rock such as permeability and porosity were also known. For the samesimulated natural sandstone rocks, Sound wave velocity was measured using an ultra sound tool. Good relationshipshave been developed between sound wave velocity and other rock properties; porosity, permeability, cementing conditionand grain size distribution at different confining pressures. The sandstone cores have been grouped according grain sizeto five groups ranged between 45 and 300 μm mixed with different concentrations of cementing material. The mixturewas compacted at three different compaction pressure ranges from 11000 to 23000 psi. These varying lithificationfactors gave these sandstone rocks a wide range of petrophysical and physical properties. The results of this study werepresented as graphs of simulated lithification factors, porosity, and permeability versus sound wave velocity.Sonic logging data; compressional wave travel time (∆tp) and shear travel time (∆ts) are tested to investigate the type ofreservoir fluids. Ratio (∆tp/∆ts) or VP/VS has shown higher sensitivity than relying only on shear wave or compressionalwave data to study change of reservoir fluids from water to oil and to gas. Reliable reservoir fluids identificationdepending on the ratio (∆tp/∆ts) has been mainly attributed to the different physical response of compressional wave andshear wave to change of fluids from oil to gas in the presence of water in the reservoir. Field examples from sandstonereservoirs showed that sonic ratio (∆tp/∆ts) helped to identify the type of reservoir fluids gas, oil and water. Results ofwell testing data for studied wells confirmed the capability of VP/VS cross plot technique in identifying types of reservoirfluids.

Ghareb M. HAMADA, Veronique JOSEPH, “Determination of Mechanical and Petrophysical Properties of Sandstone Reservoirs Using Compressional and Shear Waves”, International Journal of Advance Engineering and Research Development (IJAERD), Vol. 5, Issue 2, pp. 349-358, February 2018.