This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 202636, “Fishbone Stimulation: A Game Changer for Tight Carbonate Productivity Enhancement—Case Study of First Successful Implementation at ADNOC Onshore Fields,” by R.V. Rachapudi, SPE, S.S. Al-Jaberi, SPE, and M. Al Hashemi, SPE, ADNOC, et al., prepared for the 2020 Abu Dhabi International Petroleum Exhibition and Conference, Abu Dhabi, held virtually 9–12 November. The paper has not been peer reviewed.
The operator’s first successful installation of fishbone stimulation technology was aimed at establishing vertical communication between layers in a tight carbonate reservoir and maximizing the reservoir contact. Furthermore, the advanced stimulation technology connects natural fractures within the reservoir, bypasses near-wellbore damage, and allows the thin sublayers to produce. This technology requires running standard lower-completion tubing with fishbone subs preloaded with 40-ft needles and stimulation with the rig on site.
Introduction
The operator plans to develop tight carbonate reservoirs as part of its production growth strategy. Field Q is a 35×15-km field under development with a phased approach. Phase 1 was planned and production began in 2014. Phase 2 is being developed by drilling wells using the pad concept.
Reservoir A, a tight carbonate formation with low permeability ranging from 1 to 3 md and porosity from 15 to 25%, is part of Phase 2 development. The aver-age thickness of Reservoir A is approximately 90 ft across the field, with seven sublayers. The major challenge of Reservoir A development is poor vertical communication and low permeability. Based on appraisal-well data, the average production rate per well is approximately 200 to 400 BOPD with a wellhead pressure of 200 psi. Therefore, appraisal-well testing confirmed the poor productivity of the wells. In addition, the wells are required to produce to the central facilities located in a Phase 1 area 18 km away from Phase 2. In summary, each Phase 2 well is required to be produced against a back-pressure of 500 to 600 psi.
Fishbone Stimulation Technology
Fishbone stimulation technology is an uncemented-liner rig-deployed completion stimulation system. The liner includes fishbone subs at fixed intervals, and each sub consists of four needles that will connect the sublayers by penetrating into the formation. The typical fishbone completion after installation and jetting the needles in formation is shown in Fig. 1.
Well testing of multiple high H2S reservoirs in an environmentally sensitive area offshore Abu Dhabi