SPE 125552 Maintaining an 'Evergreen' Model to Optimise a Waterflood Development in a Carbonate Transition Zone Field

摘要

Over the last three years the first stages of a waterflooding project comprising 200 horizontal producers and injectors were implemented in a thin oil column (10-15m) transition zone carbonate field (Shuaiba formation) in the Sultanate of Oman. The reservoir is composed of high porosity, low permeability matrix. Porosity and rock quality vary across the field to such a degree that wells in some areas of the field are not economic. Therefore prediction of reservoir quality is critical to a successful field development. The field development plan (FDP) that underpins this project utilised sequence stratigraphy, acoustic impedance and production behaviour of existing wells to create static and dynamic models which formed the basis for the development well patterns. This paper focuses on the updates made to the static model since the FDP model in 2005, integrating drilling results from the first 50 wells of the project and continued reservoir characterisation and modelling work, to ensure that the planned wells remain economic and the well sequencing and placement optimised. Automated workflows were established to incorporate drilling data on a day to day basis for improved reservoir performance predications and well design. Information from appraisal wells and production behaviour from the production wells was used for improved well sequencing and property model rebuilding. Updated methodologies for rock typing, permeability and saturation height functions were established. Keeping an 'evergreen model' has proven a good practice to ensure continuously optimised drilling and recovery from the field.