Abstract
The Yibal Khuff field is located in the North of Sultanate of Oman and is renowned to be part of the second largest and most technically complex project in Petroleum Development Oman's history. The target oil and gas wells are Highly Sour with High Pressures and Temperatures. This paper describes successful Tubing-Conveyed Perforation (TCP) in horizontal wells using Coiled Tubing, where over 100 m of additional reservoir was perforated boosting the production of wells existing perforations.
The coiled tubing attended the horizontal live well at highly sour and HPHT downhole conditions with a suspended height above 25 m. The approach was to manage the downhole environment prior to proceeding with the Tubing-Conveyed Perforation by controlling the bottomhole pressure. Once the downhole environment was addressed and controlled, the depth correlation took place using Memory CCL-GR to locate the required target zones. The main operation consisted of 10 repeated perforation runs at a gun length of 12m per run to accumulate a total of120m of perforation interval.
The well provided a combined challenge of highly sour environment, existing open perforations, high surface and high bottomhole pressures. Following a thorough analysis and selection criteria where multiple conveyance methods were considered and evaluated such as Eline Tractors, Tubing Conveyance with Rig/Hoist, E-Coil and Conventional Coil Tubing via Sand Jetting and deployment means, the selected method of intervention was Tubing Conveyed Perforation via Coiled Tubing. A combined approach of utilizing controlled intervention techniques enabled the increased production access to the hydrocarbon reserves. In addition to the inherent safety precautions, the project maintained quality assurance as another main driver resulting in flawless delivery of the project.
This solution provides an effective method of tackling perforating challenges in highly sour environments, where coiled tubing conveyed perforation was executed for the first time at a suspended height in a live horizontal well with open perforations. The bottomhole pressure was 4,600 psi and H2S above 3%. TCP via Coiled Tubing has proved to be a high production gain concept, where replication will be beneficial not only to Petroleum Development Oman but to the industry as a whole.
