This paper will outline the snubbing operations conducted to carry out a complex reabandonment in a remote jungle location.

The abandonment called for the fullbore removal of the existing cement plugs with suspected poor integrity and with uncertain pressures below. The challenge was compounded by a restricted ID in the surface equipment which was installed due to unforeseen bubbles in the 13-3/8″ casing after wellhead removal during the original abandonment. The pressures observed required the use of live well intervention techniques and equipment

Several vendors for the supply of the snubbing unit were considered with focus on their stand alone capability and the availability of suitable interlock safety systems.

Due to the nature/condition of the well a number of concepts were considered to initially mill a pilot hole through the surface plug to establish communication with any pressure below the plug. As the intervention was considered urgent the primary plan was to utilise coiled tubing for this (available in country), however due to the cement plugs being inside the 13-3/8″ casing it was decided to hang off a 3-1/2″ conduit string from a slip ram assembly down to the surface plug to contain any CT “walk”.

Following the milling of a pilot hole, a new cement plug was to be set to act as a barrier to allow surface equipment reconfiguration to a 13-5/8″ snubbing stack.

Prior to the CT being mobilised to location and whilst the snubbing unit was in transit from The Netherlands the pressure trend changed from a building trend to a stabilised pressure. As such a judgement call based on the safest and greatest chance of success was made to use the snubbing unit for all operations upon its arrival. The snubbing unit was mobilised and rigged up on to the tree to perform the initial phase of the operation of re-establishing communication to the well through a pilot hole thus allowing reconfiguration of the surface equipment. Following the reconfiguration of the surface equipment the snubbing unit was re-rigged in fullbore 13-5/8″ snubbing stack mode, whereupon the reabandonment operations were conducted based on an assured programme which was amended through management of change during operations due to the wells behaviour.

The remoteness of the location required that all downhole scenarios had to be planned and equipment for all had to be prepared, tested and shipped to location. Meticulous planning was essential for this.

Post job it is evident that utilising the latest interlock systems and modular tower paid dividends in providing a safe conclusion to an uncomfortable situation.

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