Solid Straight Blade Centralizers used in Plug and Abandonment Operations

Mar 23, 2020

Centralizer for 13 3/8" Casing:

Conductor recovery on a North Sea Platform carried out using the contractor's plug and abandonment unit - complete with cutting and pinning equipment.

Ray Oil Tool Solution

As shown above, we manufactured the 13 3/8” x 26” O.D x 12” solid aluminium straight blade centralisers in two halves, making them easier to handle manually. This would allow the centralisers to be installed at the wellsite. Both halves are fitted over the pipe and fastened together by four heavy duty stainless steel nuts/bolts and held in place with 13 3/8” stainless steel stop collars.

By gaining the advantage of allowing the pipe to be rotated from surface, cost savings are made within the BHA design, additionally the centralizers can be in most cases reused many times over again.

At Ray Oil Tool we have the capability to manufacture any custom size required, with quick turn around lead times.

OVERVIEW

Customer Requirement

Solid Aluminium Straight Blade Casing Centralizer for 13 3/8” casing body

Size Requirement

OD of 26.50” to run inside 30” 310ppf conductor. The ID through the Talon connectors is 27.5” with some conductors containing a cementing sleeve restricting the ID to 26.80”.

Functionally Requirements:

Must permit the buttress casing to be rotated from surface at 60 RPM for 30 – 40 minutes to make the cut in the 30” conductor.
Man-portable: - To be installed at the wellsite and held in position with stop collars.
Re-usable (good to have depending on cost)

Background

The Talon connectors are very poor in tension and readily fail when fished in tension.To overcome this, the casing spear is set at the bottom just above where the conductor has been cut. The conductor is bottom supported so if you remove the BHA after making the cut, there is a high probability that the unsupported top section of conductor (400ft long) will drop down the side of the lower section of conductor to the seabed.

The BHA consisted of:

Casing Cutter with 44” Knives.

Mud Motor

Drill Pipe Pup or Pony Collar

30” Conductor Spear

Bumper Sub

Water Bushing

5 x Joints of 13 3/8” Casing

Benefits

At the drill floor pins are bored through the conductor to secure it to the 13 3/8” sacrificial casing. It is then cut and laid out with the pins in place. Centralizers make boring in to the 13 3/8” casing much easier.

A down hole mud motor is employed to cut the casing, expensive, difficult to handle and consumes a lot of power and seawater to operate it.(e.g to spin the casing cutter tool at 60rpm - 400gpm of seawater and around 450 psi operating pressure is needed. By rotating the casing cutter from surface only120 gpm and around 100 psi operating pressure is required for the cut which takes (30 – 40 minutes).

Solutions are at hand;

Contact a Ray Oil Tool Representative for the most advanced casing centralizer technology.

Tel: +44 1224 773313