Schlumberger

Technical Paper: Case Study: Completion Design and Operation in High Dogleg Coiled Tubing Drilling Wells

Society: SPE
Paper Number: 157669
Presentation Date: 2012
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Abstract

Completion operation is one of the most important contributors to successful well deliverables. Without a proper design of the accessories and efficient operation in conveying the completion assembly, the true potential of a well may not be realized. Coiled Tubing Drilling (CTD) was first attempted in Peninsular Malaysia in February 2011 and the wells were designed to be completed as Coiled Tubing (CT) re-entry sidetrack using 2-3/8" pre-drilled liner and swell packers with maximum inclination of 90 degree angle and dogleg ranges between 30-60 degrees per 100 feet.

The liner and swell packer assembly were designed to be conveyed to the target zone via coiled tubing and to go through 3-1/2" tubing with maximum clearance of 2.8" and dual casing exit from the existing completion setup. Apart from the small and rigid clearance, another challenges that the team faced was differential sticking due to mud property that was used to maintain hole stability and to prevent the hole from collapsing before the completion was placed. Since the completion would be conveyed through high dogleg environment, the type of liner and swell packer chosen had to able to withstand the bending stresses applied to it. A small error will result in parted assembly or inability for it to be conveyed all the way to the intended zone.

This paper presents the challenges faced during the design and completion operations and discusses the program devised to overcome the above mentioned issues. Based on the lesson learnt from previous wells in which the operations were not 100% successful, the team made significant improvements in terms of mud property, swell packer design, procedure changes and introduction of friction reducer into the completion program of the final and last well of the campaign that finally enabled the liner to be conveyed to the total depth (TD) successfully.

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