Area 1: Sustaining Fracturing Operations Within a Deeply Mature Basin

Abstract The heavily mature Area 1 cluster in the Southern Region of the Sultanate of Oman are generally characterized by low to medium permeability, demonstrate significant heterogeneity, suffer extensive depletion and contain medium through extremely heavy crude oil. Extensive hydraulic fracturing operations have managed to sustain and increase production, even in such a complex suite of fields but only through the extensive application of a Continuous Improvement (CI) programme, with line of sight to economics and value cut-off at all stages. The ongoing campaign, performed for almost 15 years now, has demonstrated that while successful multi-year campaigns can be efficiently delivered, that this has only been achieved through incremental technical gains and improvements in the areas of candidate selection, fracturing implementation and technology selection. The foundational consideration is the candidate selection process itself, which is then supported by detailed well intervention preparation and of course the technical selection process for the fracturing placement itself. Many significant challenges have been incrementally overcome, in order to sustain the post-frac success and deliverability, including cement integrity and remediation, perforation quality and enhancement, tortuosity management, deviated wellbore candidate preparation, water-contact assessment and subsequent avoidance, fracture conductivity delivery as well as post fracture flowback management. A Continuous Improvement (CI) program, which was performed year on year, has resulted in the ability to sustain effective hydraulic fracturing delivery even as the candidate pool has dwindled and the opportunity set has incrementally reduced. A very detailed process was established and updated with lessons learned and insights garnered with each new Annual campaign. This approach allowed for the hydraulic fracturing benefits to be delivered with an enduring success rate; and with an increasing capability to accept and develop poorer candidates. In order to enhance the post-frac production delivery, additional surveillance was performed with a particular view to maximising the fracture placement within the reservoir. The detailed fracture design was then adjusted, based on a range of inputs; and subsequently implemented. These new adjustments included solids stages; designed to constrain fracture height growth and this yielded a measurable improvement in the fracture geometries placed. A range of other incremental enhancements were made, which contributed to the ongoing success. The paper follows the progress of the hydraulic fracturing programme across all of the AREA 1 fields, over the last fifteen years, as it has been technically progressed, improved and enhanced throughout the selection, preparation, execution and delivery. The key choices and functional decision demonstrate how success van be sustained with a range of well types, which is a fitting summary as the programme now moves into the fracturing of horizontal wells.