Stuck Pipe Shell PELICAN Plan

SchlumbergerSchlumberger Sedco ForexAuthor : D. Wright

Checked by : G. Donald

Approved by : T. Pittman

VINLANDERNorth Sea Division

RIG SPECIFIC PROCEDURE (RSP’S)

Ref.: VIN-RSP-D042

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Issued : October 1997

Revision: 00.00

SUBJECT : Stuck Pipe Prevention - (Rotating Drill Pipe Through a Closed Annular Preventer).

1.0 Objective

Continued activities on the Shell Pelican development program has identified inherent drilling problems associated with differential stuck-pipe scenarios throughout the reservoir sections. These problems are associated directly to the mud weights required to maintain hole stability and retain suitable overbalance in certain compartments of the structure, yet attempting to optimise mud weights in lesser pressured zones which have been reduced due to commercial reservoir production. It therefore remains a priority that every effort be made to minimise the potential for becoming stuck, and to further highlight the awareness of the Rig Team to the measures that should/can be implemented.

In any stuck-pipe prevention program there are three main areas of focus :

1. Drilling Fluid Planning and Management.2. Drill string configuration and design.3. Best drilling practices and crew awareness.

Drilling fluid management and drill string design with respect to minimising the potential for stuck-pipe has been thoroughly evaluated and the subsequent technical proposals incorporated within the drilling programs for the remaining wells. Therefore these issues will not be included within the content of this document .

2.0 Purpose

The main purpose of this document is to re-inforce the application of good drilling practice. Further, it will aim to give guidance to the rig team on the practicalities of rotating the drill string through a closed Annular Preventer. This practise can be used to minimise the risk of stuck pipe during periods where the well bore requires to be flow checked (i.e. flow / no flow).

The procedure does not endorse rotation of the string in a closed Annular during the execution of well kill operations. In this instance, where an influx has been confirmed, safety and the integrity of the equipment will remain the priority and kill operations will be executed by the fixed ram procedures outlined in the Sedco Forex Well Control Manual.

3.0 References

Sedco Forex Well Control ManualPelican Drilling Programs for wells PU-W17 & PU-P14Recommendations from E.U.A. Technical Department (attached)

4.0 Responsibilities

It will be the responsibility of the Sedco Forex Rig Superintendent to ensure that this procedure is reviewed and fully understood by the Subsea Engineers, Drillers and Assistant Drillers.

5.0 Procedures to be used to avoid differential sticking.






Ref.: VIN-RSP-D042

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Revision: 00.00


The maximum permissible overpull for each and every string configuration in the well will be known and at all times be posted in a visible position in the Drillers Shelter adjacent to the weight indicator

On each string configuration the Rig Superintendent will check and confirm the calculations for maximum allowable overpulls.

Keep the pipe moving as much as possible. Reciprocal raising and lowering is the preferred method, but should the BHA configuration and well trajectory allow, it is acceptable to combine elements of rotation with this process. Localised rotation without vertical movement should be avoided to prevent possible key-seating of the wellbore and/or casing wear. The nominal speed of reciprocation should be continuous.

When circulating off bottom, the string (drilling stand) should be spaced out to allow the maximum amount of vertical travel within the derrick. An optimum value of 90 feet is preferred, but in any case where practical, a minimum of 60 feet should be available.

If a requirement or necessity exists to flow-check the well, the preferred method will be to reciprocate (raise and lower) the string with all BOP components in the “open” position. The mud flow path from the well bore having been diverted to the trip tank for monitoring.

If this method proves impractical due to the fluid displacement volumes induced by the reciprocating process, then again, with all BOP components in the “open” position and flow diverted to the trip tank, the string can be slowly rotated (10-15 RPM) while slowly lowering or raising the assembly.

IF AT ANY TIME there remains any doubt as to the status of the well it will be closed in as per the standard Well Control Procedures WITH THE EXCEPTION THAT, UNTIL AN INFLUX IS CONFIRMED it has been deemed practical and acceptable FOR A SHORT PERIOD OF TIME ONLY to maintain slow rotation through the Annular preventer. In the event that the flow-check proves negative, this process will reduce the potential for becoming differentially stuck during this short period of time.

6.0 Rotating the String through a Closed Annular Preventer

Rotation should be avoided in any instance if the reciprocal process of working the string through a closed Annular can prove to be effective. This will avoid localised wear, heating and damage to both the drill string and the preventer element.

The closing pressure applied to the element while rotating the string shall be maintained to a minimum. Field tests indicate that circa 350 psi should be adequate for this purpose. In any case, it would be preferred to allow a small leakage past the element which would facilitate a lubrication and cooling process of the elastomer.

Rotational speed should be kept to the minimum, 10-20 RPM should be practical. Rotational time should be restricted to periods not to exceed 15-20 minutes.






Ref.: VIN-RSP-D042

of 3


Revision: 00.00


For the purposes of this procedure Only the Upper Annular Preventer will be endorsed for use to meet the purpose of this document.

Upon completion of any rotation, the joint or joints which have been exposed to the closed Annular will be recovered from the well and laid out prior to being shipped ashore for a thorough inspection.

Immediately following the application of the rotating process, steps will be taken to return the string to a safe location in the well and the Annular Preventer tested to a nominal value of 5,000 psi. This operation can be effected by deployment of a BOP test tool, cup type tester, or a retrievable cased hole packer assembly.

A spare Annular Packing Element will be sourced and held on standby should the necessity arise to replace a damaged or worn unit.

A case specific exemption to the standard Well Control Policies will be prepared and submitted to Division Management for approval (Rig Manager).

These Procedures have been prepared solely for the execution of the drilling programme relating to Shell Pelican wells PU-W17 and PU-P14. They will not in any way be deemed valid for any future drilling activities outwith this defined scope of work.

Stuck Pipe Shell PELICAN Plan

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