Petrophysics properties and production simulation on Tight Gas Sandstones (TGS)

Abstract

Unconventional reservoirs are a challenge in the petrophysics discipline, since the core samples have more tiny pores and stress sensitive. Tight Gas Sandstones (TGS) type of reservoir can be classified as conventional or unconventional, because in some layers of the reservoir typically presents permeability ranges from 0.1 mD to 0.001 mD and porosity less than 10%. The aim of this paper is to present the effect of four different water saturation models of a TGS reservoir. Two models by using the Archie model with cementation factor values of m=2 and m=1.8 with wire logs as input data. The next two models based on MICP (Mercury-Injection Capillary Pressure) measurements in stressed and unstressed conditions. Petrophysical characterization was done with Interactive Petrophysics software and reservoir simulation with ECLIPSE 100. Two hydraulic stages were modelled with Local Grid Refinement in a 3D Cartesian grid perpendicular to the wellbore centre. Fracture permeability and half-length were 12.5 D and 100 m, respectively. The results obtained in the simulations runs showed that the Archie models presents a more realistic production than the MICP models. Although, the MICP models presented overestimated gas production, the influence of the stressed and unstressed conditions was observed. However, furthermore analysis is needed to obtain a more accurate model. This can be achieved with a more complex gridding model and use another relative permeability curve method.