Abstract

This abstract proposes an optimum plan for offshore Abu Dhabi carbonate reservoir capitalizing on all historic and ongoing lessons learned and defining clear actions, pilots and completion technologies to achieve and sustain desired production target. Different completion designs will be discussed in this paper to define the optimum completion strategy per well and area.

The completion designs were as follows:

  1. Single completion with 10000ft (10k') lateral length

  2. Tri lateral with 10k’ branch (total 30k')

  3. Fishbone with 6×6k’ branches (total 18k')

Long standing strategy to develop this reservoir with line drive depletion. The base plan is to drill a single lateral with 10k’ lateral length and 1 km spacing with a plan to convert the base producer to an injector while the line drive spacing is downsized to 500m. The total footage of reservoir contact in this case is 10K’ in base case followed by 20K’ in the infill timing. The other completion designs are suggested to increase the reservoir contact at initial times to reduce the pressure drawdown in the production wells. Fishbone consists of a cemented motherhole with 6 branches 3K’ laterals at 30° angle (total footage ~18K'). Another completion design is the tri-lateral which consists of three branches parrelel to each other with reservoir contact ~30K'. The conversion strategy is not possible by the application of multilateral production wells due to the wellbore collision concern with infill drilling adjacent to multilateral wells. Note that branches in the fishbone and tri-lateral well designs are left as open hole due to liner access concern. For production performance comparison, due to well management logic of the model it was necessary to normalize the individual well profiles to attain an equivalent online date and equivalent amount of production days. The objective of normalization was to provide a fair and unbiased comparison of the competing completion types.

Calculation of the net present value (NPV) and comparing it for each well while taking into consideration the cumulative oil recovery results in a hybrid development scenario with preferred multilateral and preferred Monobore development wells. The dynamic model results were used to compare well by well the cum recovery and the NPV, which led to create an economical development scenario without jeopardizing the ultimate recovery.

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