Prospective Unlocking of Future Reserves in Offshore Abu Dhabi: Field Life Extension through Hybrid Development Concept
Authors: Nakashima T. , Ouzzane D. , Dudley G. , Al-Marzouqi M. 
Published: September 2016

Field A is a giant field consisting of many sub reservoirs in Abu Dhabi offshore environment, having produced for 50 years mainly through peripheral water injection. The filed considered in this study is planning to build the long-term development plan aiming to extend production plateau by a further 25 years through infill drilling and water flood enhancement. This paper will describe an approach for optimizing the number and type of drilling centres required to enable the development plan to be flexible in design to accommodate a number of infrastructure, facilities, drilling and subsurface constraints.

The proposed reservoir development scheme is to progressively expand from the on the current peripheral water injection to enhanced water injection phase requiring line drive and pattern flooding. The project requires integration of around 180 new wells to be drilled with the associated injection and production facilities into an existing brown field complex with more than 1000 wells, kilometres of pipelines including well head towers and artificial islands. In addition the project requires having flexibility to expand for later field development schemes that could include further infill and EOR phases.

The key challenge for the development plan is to assess the impact of drilling feasibility and the number of drill centres within the constraints of the existing brown field infrastructure and how it impacts on the production profiles, cost, project feasibility and value. Analysis and selection of number and location of drilling centres are essential requirement for finalizing the optimal development.

An integrated subsurface, surface and drilling feasibility assessment analysed several different drilling centre scenarios involving various combinations of artificial islands and well head towers. Different drilling and completion duration were calculated based on drilling complexity and feasibility for the different development plan scenarios. The impact on the production profiles were assessed based on reservoir simulations using the well delivery timing for each scenario. The final screening assessment of the different field development scenario included inputs and constraints from infrastructure, facilities, sea-bed complexity, HSE, flexibility and project economics.

The major findings are followings: (1) field development planning requires integration of different functions and disciplines early in the project phase before entry into Select stage, (2) important to test the feasibility of drilling and its impact on the field development concepts and production profiles, and (3) the results indicated the preferred development plan that best meets the objectives is based on a combination of artificial islands and well head towers.

The preferred development plan will utilizes a novel combination of artificial islands and well-head towers that enables flexibility and expandability to meet the development plan objectives of extending the production profile and provide a foundation for long term asset replacement.