Petrophysical Evaluation For Reservoir Implications Of Lower Cretaceous Sands In Sawan Gas Filed,Central Indus Basin,Pakistan

The Sawan Development and Production lease area lies in the Thar Desert,which geologically forms a platform slope area of the Middle Indus Basin.Tectonically,Sawan field lies on the southeastern limb of the Jacobabad paleo high.Sawan field has been divided by two main strike slip faults into three compartments south,center and north.All Sawan wells under study falls in central compartment of Sawan field.Reservoir quality of Sawan field was evaluated using the log facies interpretation from petrophysical logs,which were analyzed to get overall view of subsurface characteristic of reservoir sedimentology around southern side of Jacobabad high.Petrophysical parameters were calculated from volume of shale,density,neutron porosity,and formation water resistivity.Prospective zone of Lower Goru “C sand” of wells Sawan 01,Sawan 02 and Sawan 08 were marked as reservoir zone through incorporating composite logs.Using Gamma ray log,litho-curves of reservoir zone of three wells were correlated to interpret environment of deposition as tidal distributary channel,upper delta plain and distal delta front.(C Sand)member of Lower Goru Formation has shown good reservoir potential in Sawan well-01,well-02 and well-08 on basis of petrophysical analysis of prospective zones.Lower Goru Formation(C Sand)in Sawan 08 has shown greater net pay potential and hydrocarbon saturation compared to Sawan 01 and Sawan 02.Tidal distributary channels deposits of Delta front(Proximal)have shown good reservoir quality and highest hydrocarbon potential among other depositional facies.The net pay thickness of area of interest has find out by applying cut off on the values of volume of shale,effective porosity and saturation of water.There were three cut offs that have been applied on each area of interest.In Sawan 01 two selected area of interest,and Sawan 02,and Sawan 08 one area of interest evaluated for reservoir zone through cut off values where volume of shale has been taken as less than or equal to 30%,effective porosity greater than or equivalent to 8% and saturation of water fewer than or equivalent to 50%.