This paper describes the planning, execution, improvements, and results from a multi-well fishing campaign using a snubbing unit on pressurized H2S wells for a national oil company (NOC) in the Middle East. A suitable blow out preventer (BOP) stack is shown for fishing coiled tubing, wireline tools, and milling along with the contingencies considered and how these were incorporated into the design of the stack. The challenges encountered during the execution phase are explained along with the solutions implemented. The key performance indicators used and how these improved the operational efficiency during the campaign are discussed. The well problems, desired results, and actual results of the interventions on the wells completed to date are shown.
Approximately 3,762 m of coiled tubing (CT) became stuck downhole in a live, offshore high-pressure well. The CT parted after fatigue limitations were exceeded.
This paper discusses a snubbing operation that was conducted to fish the parted CT. To ensure flawless execution the following was employed:
Successful job design, operational planning, and execution. A complex engineered solution to improve the fishing operation and clean up debris. Introduction of well control applications (hot tapping) to help minimize risk of pressure becoming trapped in the CT. Multiple successful trials.
Successful job design, operational planning, and execution.
A complex engineered solution to improve the fishing operation and clean up debris.
Introduction of well control applications (hot tapping) to help minimize risk of pressure becoming trapped in the CT.
Multiple successful trials.
A unique job design was introduced and executed according to plan. Careful engineering, study, and yard trials supported the actual operation. The crew's technical expertise helped improve safety and enhanced efficiency.
Significant underbalance skill and fishing proficiency helped make the fishing operation successful. The operator and service company improved their understanding and operational competence by fully communicating with all parties involved.
The operator was able to remove parted CT and perform plug and abandonment (P&A) operations in this live, high-pressure offshore well with no incidents or spills. The successful engineering and testing during this campaign are discussed.
Plug-and-perf multizone fracturing remains a dominate completion method in the Haynesville shale. Removing the composite frac plugs (CFP) utilizing coiled tubing (CT) remains a challenging operation with increased risks due to extreme well environments. Operations completed using older, conventional methodologies increase the likelihood of stuck CT events. These stuck pipe events add considerable cost to the completion through fishing, lost production time, or worse, loss of the entire well.
In one such instance while milling CFPs, the downhole tools seized resulting in loss of circulation, subsequently leading to a stuck in hole event. Wireline severing tools cut the pipe in the vertical section, leaving over 4,500 ft of 2 in. CT in the lateral. Removing the CT fish without damaging the formation was paramount to the long-term profitability of the well. Conventional fishing methods were considered, but unfavorable economics in addition to the risk of formation damage lead to the selection of a hybrid approach combining wireline, snubbing, slickline and CT.
The fish was successfully latched using a snubbing unit, providing a conduit for 1-¼ in. CT to convey a severing tool to free the larger coil in the lateral section. This enabled the continuous removal of the 2 in. CT under live well conditions, saving over 4 million dollars and 55 days compared to conventional techniques. Following the stuck pipe event, a complete change in the drillout procedure was implemented, increasing efficiency while minimizing the risk of a repeat event.
This paper examines techniques necessary to fish coiled tubing (CT) with internal weld seams in a live well environment without back pressure valves (BPVs) using a hydraulic workover unit (HWO). The challenges of placing barriers in internal seamed CT verses using the slip and shear method is addressed.
The discussed onshore operation was completed August 2013 in North America. Using the techniques described, a 14,000-ft (4267 m) 2-in. (50.8-mm) CT fish was successfully removed from a well with an average surface pressure of 5,500 psi. This was achieved by first opening the blind rams, snubbing in, and dressing off the CT fish. Next, the CT fish was latched with an overshot and a pull test was performed, pressure was equalized, and the slip and pipe rams were opened. Following, the CT fish was picked up and moved to a desired location in the blowout preventer (BOP) stack (approximately 51 ft 4 in.). The slip rams were then closed and a weight check was performed. The pipe rams and inverted rams were then closed. The CT fish was shear/cut, the pipe was picked up and the blind rams were closed. This was concluded by laying down the fish and the process was repeated 276 times with an average cut of 50 ft. The HWO fishing procedures consisted of 541 hours without any health, safety, or environment (HSE) incidents, accidents, injuries, or job failures.