Success Story of using an Integrated Subsurface Model for North Kuwait Jurassic Gas Asset Development

Abstract

The objective of this paper is to show the integrated subsurface reservoir models created for high challengeable HPHT North Kuwait Jurassic (NKJ) Gas Asset. The successful story focuses on the study and modelling achievements that involved applying the appropriate method of upscaling the fine grid static model, calibrating & initializing, history matching with field observation data and finally performing a long-term production forecast. The IPSM (Integrated Production System Modelling) tool has been used to integrate all (six) fields to fill planned facilities and optimize each field forecast to get facilities production target The new history matched models and base forecast scenarios built by an integrated multi-disciplinary subsurface team of Schlumberger, Shell and KOC staff members. KOC is the focal point and the owner of these models and the asset. The new Middle Marrat static model is supported as a tool for dynamic simulation, volumetric calculation and other static model applications. Overall the model presents a number of significant improvements over previous models such as the following list of updates: Updated non-horizontal tilted hydrocarbon contact. Refined zonation and layering to capture vertical heterogeneities observed on porosity / permeability logs Modify the log upscaling method for porosity by removing the bias by facies Update the porosity using the kriging method constrained to IPSOM Correct the log upscaling method for water saturation by using the bulk volume of water Include recent well data Updated fault distribution Discrete fracture network (DFN) model was built for Middle Marrat reservoirs. The ultimate objective of the fracture modelling work is to provide full field heterogeneous fracture properties to be used in the dynamic simulation as input for history matching and forecasting. The full field DFN which has been calibrated by PTA database. The models were upscaled and initialized with different approaches such as up-gridding method (SLB workflow) and Reduce ++ application (Shell workflow) on a field by field bases. After the history match and individual development well number and location optimization by reservoir/field, the models were coupled with IPSM tool to predict the production potential of the assets at the per field and reservoir level This tool is the key enabler for asset development planning in order to achieve KOC's gas production target of 1 Bscf/d. The integrated development planning tool allows KOC to determine the number of wells and drilling rigs required to achieve this target. As there are new coming facilities for NJK fields. The integrated development tool was also used to test the gas production plateau length after start-up of the new production facilities and the gas supply of the underlying fields/reservoirs and wells.