An Offshore Gas Field discovered in early 70’ is a large anticlinal structure located in the shallow marine waters west of Abu Dhabi island. The area is considered by UNESCO as Biosphere reserve and is protected. Several development options have been studied to develop the gas reserves from existing Artificial Island with a minimum impact to the environment.
Geological and reservoir simulation compositional models have been prepared to optimize the development plan, identify the minimum number of wells, target rates in order to maximize the gas recovery and sustain the gas plateau rate as long as possible. Building these models was a challenge due to the lack of 3D seismic data and the limited production data from the appraisal well. Due to the sensitivity of the area, the main challenges of the project implementation are the impact on the environment during drilling phase and the facilities construction and its operation.
The required refurbishment of the existing island and access channel to the island was a concern that was studied. Drilling of 10 to 12 closely clustered directional deviated gas wells from one existing artificial island in the centre of the field into a High Pressure and High Temperature, high H2S (14-24%) and deep reservoirs environment is also a big challenge. To effectively drain the entire reservoir from the island, the rigs should be capable to drill more than 25,000 ft extended reach deviated wells.
Reducing the impact on this sensitive environment was the major concern; hence an HSEA study has been carried out to develop the mitigation plans. The possibility of drilling using more than one rig simultaneously on the island to deliver gas on time has been studied to minimize the duration of the drilling operation and associated risks. Special completion materials for these extreme environments were also studied. Material selection for different well types/conditions has been carried out.