Using 3D Integrated Modelling to Manage the Fractured Natih Field (Oman)

A 3D full field dynamic simulation model was constructed for the fractured carbonate Natih field in northern Oman, and was used to update the long-term reserves outlook of the field. The field is presently being produced from a 30-m oil rim in the fractures by gas-oil gravity drainage (GOGD). According to the simulation model, further promoting GOGD by lowering the oil rim in the fractures will increase the cumulative oil production from the field over the next 30 years by about 8 million m3. The basis of the dynamic simulation model is a detailed geological model for both the matrix and the fracture/fault network. These are combined into a fine grid 3D static model for the matrix and the fracture properties. In order to generate a coarse grid 3D dynamic simulation model an efficient upscaling route is constructed, which includes pseudo relative permeability curves, based on an analytically derived saturation profile for the gas-oil gravity drainage process. The resulting dynamic model represents the full 3D geometry of the field and all of the more than hundred wells. After analyzing the different flow processes and understanding their dependency on basic rock and fluid data and their contribution to the recovery, a very good match of overall field performance was obtained over the 30 years of production history. Although the 3D model was constructed to support and optimize field development in general, its first application was to revisit the 30-year ultimate recovery under fracture oil rim lowering.