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An innovative approach to freeing stuck pipe

Published by , Editor
Oilfield Technology,

During drilling operations the drill string can often become stuck, preventing rotation or retrieval. Such an event is one of the most costly challenges faced by operators and often takes weeks to resolve or, in severe cases, can result in loss of the well.

Conventional methods to recover stuck pipe generally require specialised tools, dedicated personnel and high energy sources such as explosives. The equipment and personnel for these methods need to be mobilised to the well site, resulting in increased non-productive time (NPT) and higher project expenditure.

Coretrax, which provides oil and gas well integrity and production optimisation solutions, has developed the HyPR Holesaver as an effective solution to recover from a stuck pipe event. The tool is the world’s first hydraulic pipe recovery system to quickly and safely recover the drill string while maximising hole recovery.

An operator in the UAE recently utilised the HyPR HoleSaver in conjunction with Coretrax’s DAV MX™ circulation sub to sever stuck pipe in a record time of one hour.

An alternative solution to pipe severing

Traditional methods of stuck pipe recovery introduce hazards and risk in addition to increased NPT, with mobilisation often taking days and in some cases weeks. The use of explosives and chemical cutters are both high-risk operations that require experienced personnel and regulatory permits. Operations on the asset must also be suspended during use, further increasing downtime.

The HyPR Holesaver system consists of strategically positioned subs located in the string, typically above the DAV MX circulation sub. Inclusion of the DAV MX circulation sub provides a reliable method to regain circulation in case of a pack-off, which commonly coincides with a stuck pipe event. A DAV MX circulation sub is an effective tool to establish reliable circulation to aid in the conditioning of the mud, activation of the HyPR Holesaver, and circulation to facilitate the pipe sever. The HyPR Holesaver subs are full strength and do not exhibit any moving parts. They present a landing profile which serves to align the surface deployed HyPR dart to target the connection between the two subs. The HyPR dart is kept on the rig and can be deployed at the operators’ discretion. Once seated in the HyPR Holesaver assembly, the HyPR dart is used to induce a controlled washout of the API connection between the two subs.

Figure 1. The HyPR Holesaver maximises hole recovery and reduces operational time. 

When a stuck pipe event occurs, typically the DAV MX is activated to establish or restore circulation to the well. Once sufficient circulation is confirmed, the HyPR dart is deployed and pumped to seat in the HyPR assembly. The dart is equipped with a proprietary nozzle profile, which converts the axial flow of the mud to a radial jet covering 360°. Upon landing, the dart nozzle will align with the API specified pin stress relief groove between the two HyPR subs. The circulating mud is directed by the nozzle, which ejects the fluid column and solids content within at high velocity to erode the cross section of the HyPR sub.

Typically, within hours of pumping, the HyPR assembly will sever into two parts. The result is a smooth and clean cut, similar to a ‘twist-off pin’ and can facilitate immediate cement spotting in preparation for a side-track. It can also present a common and consistent profile to for fishing operations.

Severing stuck pipe in record time

During a drilling campaign, a UAE-based operator encountered stuck pipe at 12 785 ft. Conventional solutions would have resulted in mobilising a third-party crew with specialised equipment, which would incurr high operational costs. However, the HyPR Holesaver was strategically placed in the bottomhole assembly (BHA) as a contingency, allowing the operator to initiate the severing process immediately.

The Coretrax DAV MX circulation sub was activated to establish reliable circulation.The HyPR dart was then pumped at 200 gpm, with the operator increasing the flow rate to 520 gpm (3980 psi) upon landing to achieve the radial cutting velocity and initiate the cut. After 45 minutes of circulating, the operator applied 25 000 ft-lb of torque to expedite the sever. The application of surface torque and overpull can induce an early fracture of the cut target, once the cross section is sufficiently eroded. By applying the surface torque, the operator severed the string within one hour – a new record for stuck pipe recovery.

Engineered solutions for greater results

Stuck pipe is an expensive and time-consuming issue facing drilling teams, often costing operators millions in NPT and associated equipment and services. As the industry continues to emerge from the challenges of the Covid-19 pandemic, reducing NPT, limiting exposure to third-party crews, and empowering the operator to rapidly and efficiently respond to challenges is more important than ever and the HyPR Holesaver is effectively supporting this industry drive.

Author: John Fraser, Coretrax

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