Is Handling Gas in the Riser a Safe Alternative? Exploring the Limits and Opportunities for Safer Kick Handling During Deepwater Drilling

Abstract

This work complements previous efforts exploring the opportunity for safer return to operations after an influx event in deepwater drilling operations when an MPD system is installed on the floating rig. Additionally, even kicks taken during conventional drilling, with rigs equipped with adequate RGH equipment, can benefit from an alternative way to address the event. An RGH Envelope is proposed, which can be incrementally adopted in a stepwise approach. For MPD operations, influxes greater than IME circulation limits, but within RGH Envelope limits, can be introduced into the riser and then removed using the Fixed Choke, Constant Output (FCCO) method. In non-MPD operations, all influxes need to be initially addressed by shutting the well on the BOP as soon as possible. Then, for influxes within the equivalent MPD IME limits, the surface RGH system can be engaged and routed to the rig choke, and the influx is completely circulated using Driller's method through the riser system. A potential expansion of this method, for influxes exceeding the original IME limits, but within RGH Envelope limits, can be circulated into the riser and then finalized by using FCCO method. For conventional drilling operations without a rotating control device (RCD) seal installed, consideration should be given to installing the seal assembly in the RCD prior to circulating hydrocarbons to surface with an open BOP. The authors explore the RGH Envelope limits and present guidelines for a comprehensive risk assessment on RGH process, limits, and how it impacts multiple aspects of the operations.