Case Study: Integrated 3D Geomodeling of Minagish Oolite Formation, Umm Gudair Field, Kuwait

Abstract

The Umm Gudair is a large matured carbonate reservoir of Kuwait with a production history of more than 45 years. Umm Gudair has been producing primarily from the Lower Cretaceous Minagish Oolite formation composed of porous limestone consisting primarily skeletal grainstones. In recent past, the main focus of the asset team on this reservoir has been to extend the plateau rate and devise a long term Field development Plan by developing a comprehensive 3D geocellular model which shall be used for running simulation. Three cases of 3D structural modeling scenarios were considered in order to reduce uncertainty attributed to velocity models. Petrophysical data of 223 wells, Core data from 34 wells, 3D Seismic Cube along with Inversion derived porosity and High Pressure Mercury Injection (Capillary Pressure) data from 102 core-plugs were used to generate 3D property model with the help of advanced 3D geomodeling software. A Facies classification model was built utilizing observations from core description, Log data and training a supervised neural network. Porosity was modeled using sequential Gaussian simulation (SGS) honoring core observations and Seismic derived porosity cube. Modeling Permeability was most critical and complex. Analysis of core data suggested a wide variation in Permeability (between 0.2 to 4000mD) with corresponding porosity variation of 0.08 to 0.30. Average capillary pressure data from core observations was converted to Height Vs Initial Water Saturation (J-Function) and water saturation was modeled. Despite the abundance of Log, Core, Seismic and laboratory data, creating a truly representative 3D Geomodel was a big challenge owing to complex relationship and distribution amongst various petrophysical properties. This paper highlights the integration of various data and comprehensive steps of building a consistent representative 3D geocellular model used for flow simulation studies and field development planning.