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Tight carbonate reservoirs, although less well understood and believed to require higher development costs and risks than conventional reservoirs, have become an important resource. Historically, tight reservoirs have been unpopular and unfavorable with geologists and reservoir engineers mainly due to difficulty associated with their development with no commercial productive value. Recently, with the increase in demand for oil and continuous development of new technologies, the time is right to carefully examine and develop such reservoirs. This paper discusses the development of one of the tightest carbonate reservoirs offshore Abu Dhabi, UAE. Initially, this reservoir was not planned to be developed based on the appraisal data collected. The average reservoir permeability is around 1 mD with a productivity index of 0.4 bod/psi. However, an intensive work was performed to evaluate the reservoir potential as being commercially attractive. Such process included gathering of additional data during the development of a major reservoir located below and the review of the core and test permeability data across the reservoir. Several model scenarios were created both on static and dynamic sides as well as an evaluation of the uncertainties and associated development risks. Effectiveness of the study took place when drilling horizontal wells across the most permeable intervals resulted in a production five times higher than expected. This resulted in a decision to embark on the field development and additional production data gathering for development optimization. |
