Challenging Offshore Dynamic Kill Operations Made Possible With the Relief Well Injection Spool | Schlumberger
Tech Paper
Location
Offshore
Byline
Ray T. Oskarsen and Ole B. Rygg, Add Energy; Mike Cargol and Brett Morry, Trendsetter Engineering
Society
SPE
Paper Number
180279
Presentation Date
2016
Products Used
Premium

Challenging Offshore Dynamic Kill Operations Made Possible With the Relief Well Injection Spool

Abstract

Before a well is drilled in deep to ultradeep waters or environmentally sensitive areas, operators’ internal rules and regulatory agencies usually call for a contingency relief-well plan that includes dynamic-kill evaluation. Simulations for a worst-credible-blowout scenario often show that the pumping requirements exceed the capability of a relief-well rig, particularly when in deeper waters and/or where the reservoir is shallow. Installing a Relief Well Injection Spool (RWIS) between the wellhead and the blowout preventer (BOP) on a relief well provides additional inlets for pumping kill mud into the well at the seabed and ensures sufficient flow capacity to perform a high-rate dynamic kill. During the pumping operation, one or more additional high-pressure pumping vessels from remote locations are connected to the RWIS inlets using flex lines.

The RWIS system has been validated by hydraulic modeling using the OLGA-WELL-KILL simulator. Two hypothetical case studies, for shallow and deepwater wells, are presented here to show applications of the RWIS and the potential benefits. In both cases, a kill rate of 200 bpm is required at the relief well intersect to stop the uncontrolled flow from a blowout well. For both case studies, the benefit of the RWIS is pronounced and could prevent the need for two relief wells. Relief wells designed to control a deepwater blowout will require long choke and kill (C&K) lines, which could result in significant frictional loss during a dynamic kill with high pump rate. This flow restriction is mitigated by introducing additional inlets at the wellhead.

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