Session: 11-06-01 Integrity of Well Barriers

Submission Number: 157188

Experimental Study of Concept to Ease Pipe Pulling Through Settled Barite 

Drilling and well construction is one of the main cost drivers for offshore field development. Drilling new wells is also needed during the field production life. Drilling offshore wells are normally limited to the availability of free slots in the subsea template. Subsea slot recovery for drilling through an existing well is an option for reducing the overall field development costs. Removing parts of the existing cased sections is needed for drilling such sidetrack wellbores. In addition, removing casing may be needed as a part of the plug and abandonment operations. Casing removal can be complex since pulling a tubular out from an annulus filled with settled particles can be challenging. The solid particles from initial annular drilling and completion fluids are likely to settle over years. This makes it difficult to later pull out the casing sections.

There are several techniques for reducing pulling force of the casing section, but there is a lack of documented knowledge of the key mechanism causing the resistance in these pulling operations. The experimental findings reported here are performed in a down-scaled laboratory setup. The experiments are performed by pulling steel tubulars, scaled down from typical casing sizes, with and without casing collar through an annulus containing settled barite. The required mechanical force to pull out the pipes is measured for different scenarios and then compared. 

The results from pipe pulling tests in the down-scaled setup show significant pulling force reduction with integrated holes located above the casing collar.  

The experimental results provide evaluation of a novel concept for reducing the casing pulling force. Furthermore, the results improve understanding of dominating factors during pipe pulling through the settled barite.

Presenting Author: Ali Taghipour SINTEF

Presenting Author Biography: Ali Taghipour is a senior researcher in the Drilling and Well Group at SINTEF. His area of research mainly covers the hydraulic properties of drilling fluids and the integrity of well barriers.