Digital Slickline: Case Studies Setting and Pulling Crown Plugs

Heaney, F. M. (Halliburton) | Smith, C. (Halliburton)



As the scope of deepwater operations increases, the need for cost-effective well servicing is paramount, particularly because of the continued challenges associated with current volatile commodity pricing. One of the first requirements on any subsea deepwater intervention with a horizontal wellhead production tree is pulling the subsea horizontal tree isolation lock mandrel plugs, commonly referred to wellhead or crown plugs. This can be a "show stopper" event if not planned correctly. Because of the critical nature of this action, the majority of operators follow a two-prong approach, with a primary plan of action and a contingency procedure, to help ensure barrier removal proceeds as planned. Although successful removal of the crown plugs is the principal concern, it needs to be completed cost-effectively for the intervention to obtain approval.

The advent of digital slickline (DSL) allows surface readout (SRO) monitoring during the removal and installation of these barriers to provide an increased level of confidence during this important phase of the operation. This paper outlines case studies of the real-time sensors available with the RF communication DSL system that was highlighted previously (Heaney et al. 2018) for pulling and setting these wellhead or crown plugs in deepwater Gulf of Mexico interventions using the traditional jarring approach. Two brands of crown plugs are available on the market, and although both pull the same, there is a difference in the installation procedure and each plug or lock has a unique SRO digital signature.

Additionally, the straight pull battery operated extended-stroke downhole power unit highlighted in McDaniel et al. (2008), Clemens et al. (2014), and Babin et al. (2015) offers a cost-effective contingency that can be deployed on the small-footprint DSL unit. This setup allows starting the operation using the traditional jarring approach, and if required because of high hydrostatic forces, the operation can easily move to a straight pull contingency without rigging down the DSL unit for maximized wellsite efficiency.

New developments as the downhole power generator was ported to DSL are discussed, notably on- command motor controls and SRO, which was traditionally only available in memory. A downhole anchor was added to the toolbox, which can be run in combination with the downhole power generator to expand effectiveness, as new production trees might not allow for a no-go landing shoulder. To address the increased water depths, the 3.59-in. extended-stroke downhole power generator was upgraded to 80,000 lbf pulling force.