A New Dual Rov Assisted Well Killing System For Deep Water Blowout Recovery: Development And Testing
Authors: Ferrara Paolo , De Marchi Eliana , Pasquini Matteo 
Published: March 2015

With the Oil and Gas drilling moving to deeper and deeper waters, offshore blow-out control and recovery methods imply bigger challenges. In this scenario of technology complexity and of ever increasing focus on safety and environmental issues, with the aim to minimize operative risks, a new dual ROV assisted well killing system for deepwater blow-out recovery was developed and patented. This system extends the range of actions to be used in case of a deepwater subsea blow-out during drilling operations.

The system stands as a quick-response tool devoted to assist and enhance the probabilities of success of a vertical intervention from a Dynamic Positioning Rig on a deepwater well in blow-out, when the premises for such an intervention exist or could be created. The system is designed to use two ROVs to assist the re-entry of a killing string inside the flowing well to perform the vertical intervention. The system is also equipped with acoustic sensors for a full instrumental localization of the blow-out source in case of impaired visibility. When successful, this intervention minimizes hydrocarbons losses, environmental impact, operational costs and exposure to liability claims.

The system and its sub-systems have been fully designed, developed and tested. System marinization has been addressed to, involving drilling rig operators and a third party certification body to review system interfaces, handling procedures and risk assessment for a safe use on board.

This paper provides a description of the proposed intervention system, along with details on the achievements and lessons learnt in the development and testing phases.

Introduction

It is well recognized that one of the frontiers of the oil and gas industry is today the increasing water depth at which drilling and production take place. The technological challenges posed by ever increasing water depths require a steady improvement of drilling and production equipment and procedures, this being especially true for elements of major concern such as well control and response procedures to critical events. Oil spill disasters have tragically shown the dramatic effects that a sustained deepwater blow-out can have on personnel safety, the environment and company assets. Those accidents have ruled out any doubt on the necessity of evolving our technology to be able to cope with events which, as highly improbable they can be, eventually lead to catastrophic consequences. In this context, the Killing Guidance System (KGS) has been developed and patented, and stands as a quick response tool devoted to assist and enhance the success probabilities of a vertical intervention on a deepwater well in blow-out, when the premises for such an intervention exist (ref.3). To date, the main achievements have been: system manufacturing and integration, main functions dry-testing, main sub-systems performances assessment by shallow water testing, design validation by 1:8 scale model testing in naval basin and system marinization addressed by involving a major drillship operator and an independent certification body. The next project phase foresees to install the system onboard a selected Mobile Offshore Drilling Unit (MODU) to perform a final interface test and a full field qualification.