Downhole Oil-Water Separation (DOWS) is a water management technology consisting of a hydrocyclone to separate oil from water together with some form of artificial lift to produce an oil enriched stream to surface and to inject the bulk of the produced water into a disposal zone. Field trials have proven DOWS's operational success at reducing the well's water production, but economic success has been sparser. Increased confidence in DOWS technology depends on the development of improved models and methodologies which:

  • Realistically simulate the complete downhole separation process and

  • Evaluate the operational and economical aspects of DOWS

This paper summarises:

  1. The development of a hydrocyclone performance model,

  2. Its integration with a reservoir simulator and

  3. The testing of this integrated model against a real field case leading to a reservoir development strategy for evaluating the optimum time for DOWS installation and DOWS economics.

Our single or dual stage, hydrocyclone performance model allows the oil / water separation efficiency to be calculated for a range of operational conditions. A decision tree identifies the optimum DOWS installation time based on both the economical and the operational aspects of the technology. The impact of operational parameters on DOWS viability are assessed, ranked and compared. These include the importance of casing size, electrical power costs, properties of the water disposal zone, potential use of the reject water and the surface water treating costs. As expected, DOWS mechanical reliability is one of the key parameters controlling economic viability.

Use of our DOWS technical and economic models described here, together with the reported application strategy, will allow confident installation of DOWS technology in the field. DOWS may then be counted as a reliable option in the water management armoury and a tool for improved oil recovery.

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