Study of development alternatives for remote offshore, low energy reservoirs: the Wisting field case
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This work summarizes a series of analysis conducted to determine an optimized field development plan for Wisting oil field. The field presents several unique challenges, such as low reservoir pressure, very shallow reservoir depth and remoteness from the available infrastructure.The study used a homogeneous reservoir simulation model built during the Specialization Project. Some of the crucial data, such as porosity, permeability and horizontal-to-vertical permeability ratio had a huge uncertainty involved in it. In order to account for this, 27 reservoir models with a combination of those uncertain properties were constructed and integrated with the 3 production network models. As a result, 81 integrated models were run and the oil production data was then used to evaluate the NPV (Net Present Value) of each of the considered cases.3 production network models have been used for the analysis wells with no artificial lift, wells with gas lift and subsea multiphase boosting. Gas lift rate optimization study was conducted to maximize the production and the economics of this development option. Multiphase booster pump power requirements, which would meet the field operational conditions were also determined.NPV was set as an objective to decide on the most preferable development alternative. The capital expenditures for each of the development options were estimated with a commercial software, which was available for a limited period. The CAPEX values were then used in NPV calculations.A simplified EXCEL tool was also developed for estimation of capital expenditures. The motivation for this was to have a robust tool for CAPEX calculations after the student license of the commercial software was set to expire. The output of the developed simplified tool was then compared to and tuned with the output from the commercial software.Several sensitivity studies involving CAPEX and oil prices variation were performed for the previously obtained NPV values for the coupled simulations. As a result, a normal NPV probability distribution was obtained and presented in the report.