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Enhancing Oil Production from a Matured Reservoir by Drilling NCWs with Intelligent Well Completions in the Lower Burgan Reservoir of North Kuwait- A Case Study

Abstract

The Lower Burgan reservoir is one of the major sources of Kuwait oil's production. It is a good quality consolidated sandstone reservoir. It can be divided into lower massive sand and upper sand shale intercalations (layered Lower Burgan). The Lower Burgan reservoir is under production for more than fifty years. More than one thousand vertical wells have been drilled through the reservoir. The lower massive sandstone, underlain by a strong aquifer, has been the layer under extensive exploitation since early days of field development. As a result, a significant portion of reserves have been produced from massive sandstone. Increasing the production level from the Lower Burgan requires targeting the relatively thin (10 – 25ft) intercalated sand layers in the upper part of the reservoir. A feasibility study concluded that the most effective strategy to increase production and ultimate recovery of oil from the Lower Burgan Layered Reservoir was to drill horizontal/high angle wells in the thin pays zones for maximum reservoir contact. The NCW drilling campaign in the Layered Lower Burgan reservoir started in 2010 with more than 25 wells being successfully drilled and completed to date. The major challenge in the development of this mature reservoir is water breakthrough and the consequent decrease in hydrocarbon production rates and well profitability. Most of the Horizontal wells were completed with Inflow-Control Devices (ICDs) to control/defer water production thereby maintaining optimum oil production. Subsequent production testing showed that more than 80% of the wells drilled produced at oil rates more than double that of vertical wells. Nevertheless, approximately 30% of the Horizontals experienced ineffective water control. This case study highlights how the NCW locations were selected, and successfully drilled and completed with ICD's within the thin sandstone pays underlain by a strong aquifer. In addition to ICDs, alternate methods to control water production were also employed successfully.