Mukhaizna was discovered in Central Oman in 1975. The field contains large volumes of 15° API crude (STOIIP 375 mln m3, in situ viscosity 1700 mPa.s). During the mid 80's it was established that production rates from initial vertical wells were marginally economic, both primary and on steam soak. In recent years the introduction of new technology, especially the drilling of horizontal wells, has significantly advanced the fields potential for commercial development:

A pilot project using five 1000 m long horizontal wells was started in August 1992. The wells were produced with progressive cavity pumps, with production being trucked to a production station at 60 km distance. Productivity improvements of a factor 4 over (cold) vertical wells were obtained. The project demonstrated that owing to the high pore compressibility of the shallow, unconsolidated Gharif reservoir rock, associated with grain crushing, and the field-wide presence of a Middle Gharif shale, satisfactory primary recoveries of 100,000 m3 or more can be obtained from horizontal wells at acceptable (lateral) distances to the oil-water contact.

Theoretical studies and numerical simulations have shown the dry individual well recoveries to increase proportionally with increasing distance to the oil-water contact, Reservoir performance during dry production is characteristic of increasing pore compressibility with increasing rock stress. Significant hysteresis is observed between the increasing and decreasing rock stress cycles. Core plug measurements and pressure recordings in a dedicated observation well have served to validate the results of the modelling study. Based on the results of the pilot, the fields expectation ultimate recovery was increased from 5.3 to 11.0 mln m3.

As a next step towards full field development, a strategic development project has been formulated aimed at narrowing down remaining uncertainties with respect to reservoir performance. Production from ca. 10 horizontal wells will commence in 1996, Dedicated early production (satellite) facilities will be used, to which the oil will be evacuated with admixed water through a 30 km, large diameter pipeline under downhole pump pressure. The current project planning basis includes a number of technology applications aimed at increased cost effectiveness, such as a revised casing scheme, alternative subsurface pumping systems with high output pressure rating, coriolis flow meters and telemetry, Targetting of the additional project wells will be based on a 3D seismic survey acquired during the second half of 1994.

Following a successful project, Ml field development may proceed early in the next century.

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