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7” Casing Drop Incident

DrillSafe Forum - June 2nd 2011

Nick Muecke

Vermilion Oil & Gas Australia

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Cazaux

Location

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Location

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8 ½” hole drilled to 3497m MD (3275m TV)

Hole stability, torque and drag issues and rig

related problems

Hole logged

Rigged up and ran 7” casing to 2521m where

it held up (20 hours of operations)

Attempted to work through (6 hrs of ops)

POH laying down casing joints in singles

Background to Incident

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The procedure to lay out pipe was as follows:

1. Break out a joint using the TDS system

2. Lift the joint using Side Door Elevator (SDE) / bails attached

to top drive

3. Push the joint over to the V-door and lower pin until its

movement is controlled by a bogey running along the

catwalk

4. Casing joint is allowed to rest at top of V-door while a soft

sling is wrapped around the box end and attached to the jib

crane;

5. Once the soft sling is safely secured to the jib, the SDE lock

pin is removed and the elevators opened;

6. The joint is then lowered down the V-door by jib crane with

pin end controlled by the catwalk bogey.

Picking Up/Laying Down Casing

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CraneLooking from cat walk side with pipe

bins installed– crane in operating pos

Catwalk

location

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The Drillmec HH-220 drilling rig

Looking from cat walk side with

pipe bins removed from carrousel

– crane rotated 180 deg

Jib Crane

“V-door”

Looking

down

“V-door”

from

floor

Crane operator

stands here

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Picking Up/Laying Down Casing

“V-door” & slide

down to catwalk

Looking down

“V-door” from

floor

Crane from

drill-floor

Crane operator

stands here

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85 joints laid out over 8 ½ hrs

10 minutes from shift change @ 18:00 hrs a joint of casing

was lowered down the V-door using Side Door Elevator

(SDE) /bails attached to top drive

As the box end came to rest on the top of the V door, the

safety pin was removed from the SDE and the elevator

was opened before the sling on the casing joint was

secured to the crane

The casing joint fell in an uncontrolled manner down the

V-door, eventually coming to rest with the pin end some

9m past the end of the catwalk.

No one was hurt and no equipment was damaged

What Happened

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Operations were stopped to allow a preliminary

investigation to be carried out

Procedure changed to ensure the sling is installed

and tension taken on the winch prior to removing

safety pin from the SDE

Safety meeting held with both crews to review

incident and highlight the dangers

Elevator was taken out of service and replaced with

backup set

Immediate Actions

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The same procedure, the removal of the elevator safety

pin before the weight of load had been transferred via the

connected sling from the elevators to the jib crane, had

been used for the previous 89 joints without incident.

Personnel involved on the rig floor had all been with the

Contractor for at least 3 yrs and in position for at least 2

yrs and were 11 days into their 2 week hitch.

Crew had run 7” (and other sizes) numerous times, but

had never been involved with pulling casing

Incident occurred 10 minutes prior to the end of the shift.

Floor hand "operating" the elevators at the time possibly

didn't fully understand the critical function of the safety

pin and that it should not be removed prior to completing

installation of sling between casing joint and jib crane.

Investigation Findings

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Personnel carrying out activities at ground level were all

standing in positions that would keep them safe when pipe

moving

No Task Based Risk Assessment (TBRA – the Contractor’s

equivalent to the JSA) was carried out prior to POH with casing

A TBRA was available for use as a guide

A toolbox talk was held, but did not include discussion on the

need for good communication or what should be communicated

No contractor standard operating procedure (SOP) existed for

laying down casing

Once the operation to lay down casing commenced there was

little oversight of activities by either Toolpusher or Drilling

Supervisor

Equipment inspection revealed that safety the pin cannot be

installed if the latch is not fully closed

Investigation Findings

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Varco elevator design - latch cannot open when under load even

if safety pin is removed

Elevator has additional hole for safety pin storage during

transportation

Was the pin installed in the “transport hole”?

Investigation Findings

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Causal Factors

The main causal factor contributing to the incident

was the removal of the elevator safety pin prior to the

weight of load being transferred from the elevators to

the jib crane via the connected sling.

Floor hand "operating" the elevators at the time

possibly didn't fully understand the critical function

of the safety pin.

Causal Factors

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Root Causes

No TBRA conducted for operation despite none of

the crew having prior experience with this operation

No standard operating procedure in place for pulling

and laying out of casing.

Insufficient senior level supervision on the rig floor

for an unfamiliar operation

Root Causes

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Reinforce requirement for TBRA prior to operations

or for any significant change in operation or

personnel and ensure all involved personnel

participate

Reinforce requirement for senior supervisors to

spend time “on the floor”, particularly during non-

routine operations.

Generate SOP for pulling out of hole with casing

Outcomes

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Revise TBRA for pulling / laying down casing and

include:

Communication requirements

Order of steps associated with pulling / laying out

casing

Positions of all personnel involved including lease

hands and forklift driver

Guidance required on steps to cover pulling /

installing safety pin, connecting / disconnecting

elevators and connecting/disconnecting sling to

crane

Associated operational risks

Outcomes

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Questions