Abstract
A complex brown-field cluster in South Oman showed decline in production despite aggressive level of development and infill drilling over the last few years. This cluster has more than 18 fields, with 10 of them are producing. Different major reservoirs distributed across several stratigraphic horizons and contains moderate to highly viscous oil (10 to 400 cP). The reservoirs comprise unconsolidated fluvial, fluvial deltaic and glacial sandstones of Palaezoic age. The geologically complex field due to large number of faults and fractures has been on production of more than 15 years and has been developed using vertical and horizontal wells during different phases of development. One water injection well is in operation in one major field for more than 5 years.
Reservoir surveillance and management in this cluster poses a formidable challenge due to:
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Significant well-stock (more than 150 wells) of different types (vertical, deviated, horizontal, multi-lateral)
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Problem associated with data acquisition as all the wells are completed with pumps (beam pump, progressive cavity pump and electrical submersible pump) and most of them are completed with some sand-control devices
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Un-efficient water injection management
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Logistically problems associated with large distance between the Well and Reservoir Surveillance and Production team at company office and the operational team at field location.
The case study presented in this paper describes how a sustained well and reservoir surveillance and management strategy implemented across the entire value chain starting from the planning to operation stage in this cluster could not only arrest but literally reverse the well and field production decline trend using the existing well stock. The paper clearly illustrates that success of reservoir surveillance and management rests not only on the application of right technology but more on close integration among various disciplines in a cohesive work environment.
