Proposing, Drilling, Completing and Producing the World's First Offshore Horizontal Multi-Stage Proppant Fractured Well that Targeted Tight Carbonate Source Rock – Dubai's Unconventional Shilaif Formation Case Study
Authors: Chemin Frederic , Freile Juan Pablo , Moreira Luis , Mehrotra Nagendra , Alabi Ibraheem , Thompson Hamish , Arcano Nelson Suarez , Bukovac Tomislav 
Published: October 2016

The development of offshore unconventional reservoirs through hydraulic fracture stimulation has been debated for more than a decade. Attempted in isolated cases in small scale, such operations have been considered too complex, expensive, risky, and finally not economically attractive compared to other development opportunities. Technological breakthroughs in hydraulic fracturing in the past decade have enabled the renaissance of the oil and gas industry with the development of tight and source rock reservoirs mainly in onshore applicationsland in North America.

New and dramatically improved operational efficiency standards have been set for fracturing in the last years. However, the same efficient operational set up, successful in onshore North America, cannot be directly emulated in an offshore environment due to limited space, more complex logistics, cost and environmental constraints. DPE, oil operator headquartered in Dubai-UAE, was able to overcome these challenges successfully and in 2016 drilled, completed and produced the world's first offshore horizontal multi-stage proppant fractured well that targeted a tight carbonate source rock, the Shilaif Formation at 8,400ft true vertical depth, source rock for most of the oil produced in Dubai. The successful concecusion of this project has allowed DPE to unlock a very significant volume of reserves in the Dubai acreage and possibly in the whole region.

Albeit being one of the most complex and largest offshore stimulation jobs ever attempted, it was executed with minimum environmental impact; no freshwater was used, the post-frac flow-back was performed in a closed loop system where clean-up and production testing packages were specially designed conveying the flow-back fluids directly to the offshore production facility. The use of a modular type frac-package with continuous seawater mixing capability minimized environmental impact and avoided any freshwater consumption. The stimulation was executed from a lift boat, less sensitive to maritime conditions, which accommodated equipment and crews for continuous wellsite operation. Eight proppant fracturing treatments were performed in 48hr. Wellbore conditions and petrophysical data acquired while drilling allowed for a robust multi-stage open-hole completion design. The eight stage proppant fracturing treatment was engineered using channel fracturing techniques with 560,000 lb of proppant. This specific technique was applied to optimize proppant volumes and operational footprint while limiting screen-out risk in this complex reservoir stress setting and maximizing frac conductivity. This paper describes wellbore, completion, stimulation, clean-up and production testing design and planning that lead to this important technical success. It also highlights the potential of Dubai's offshore Shilaif resources.

DPE's reservoir appraisal strategy followed during phase-one (2012-2016), potentially has opened the door to a new oil producing era in Dubai. This remarkable operation performed in the UAE with cutting edge technology and innovative operative integration was able to set a new efficiency benchmark, not only for well completion and fracturing operations within Middle East but also for offshore in general.