Abstract

The Maari Field in the offshore Taranaki Basin, New Zealand was discovered in 1983 by the Moki-1 exploration well (figure 1). Appraisal activities and development studies undertaken by various oil companies over the subsequent two decades failed to identify a viable development concept with an acceptable risk profile. Key factors delaying development were distance from existing infrastructure, field size in association with oil price and critically the high wax / low pour point nature of the oil. The Maari Joint Venture identified a strategy to develop the field and produce the previously stranded oil by means of innovative technology applications.

The self-installing wellhead platform and the FPSO were installed in April and May 2008, respectively but the jack-up rig to drill the five horizontal production and three deviated water injection wells was delayed by three months due to winter weather. First Oil from the field was on 25th February 2009, a milestone achieved some 25 years after its discovery.

A number of new technologies and pioneering applications were put into practice with the Maari field development:

  • The self installing wellhead platform. At the time Maari WHP was the largest self-installing platform of its kind.

  • The production wells have a thermal design with both passive (thermal gel and thermal cement in the annuli) and active (electric down hole heating system) elements.

  • Drilling while casing.

  • The electric submersible pump assemblies were designed to handle free gas conditions down hole in the horizontal section due to the reservoir fluid being close to its bubble point.

  • The injection water is heated to reservoir temperature to avoid wax precipitation in the reservoir and injected above the ‘fracture pressure’.

Two smaller near field satellite oil accumulations were also drilled and completed, including a ~8,000m horizontal ERD production well targeting a deeper reservoir in separate structure to the south of Maari. Numerous challenges, such as scale, hydrogen sulphide, corrosion, completion designs and wax, have been encountered and largely overcome during the production phase.

The paper will detail the innovations, new technologies, major learnings and experiences from the development concepts to production of this originally ‘stranded’ asset.

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