As a result of shale oil and gas production success in the United States, development of shale resources elsewhere around the world has gained great interest. In the Middle East, where much of the world's conventional reserves are located, huge investments have been deployed to evaluate the potential of shale reservoirs. In this paper, we present an integrated reservoir characterization study of Shilaif shale formation in the United Arab Emirates, which includes an assessment of the primary production from a test well using a multi-phase, dual-porosity model. We also evaluated enhancing production performance via improved well completion.
In characterizing Shilaif's unconventional shale reservoir potential, we developed an integrated plan and workflow that included gathering and assessing the geological, petrophysical, and production data from a horizontal exploration well. The data used in the workflow included well-logs, cores, completion information, and pressure transient and production data from the well. The analysis of pressure build-up data ensuing the rate-transient period provided an estimate of effective formation permeability, which is a unique aspect of this study because such tests are not routinely conducted in shale reservoirs. The hydraulic fracture stimulation had improved the effective permeability nearly two orders of magnitude compared to the matrix permeability from cores and well logs. For the ultimate assessment and future performance, we developed a multi-phase dual-porosity numerical model. The simulation model was used to history-match the production data of hydraulically fractured horizontal well in Shilaif formation and case studies were conducted to evaluate the production potential.
For future development plans, it was determined that decreasing the fracture spacing from 250 feet to 150 feet was not economically feasible because the incremental production was around eight percent during the first year of production. Nonetheless, the simulation model indicated that Shilaif's large shale reservoirs may be viable for future development targets in the Middle East arena.