Managing Blowout Risk Using a Dynamic Barrier Approach

Abstract

Abstract The oil and gas industry is moving into some of the most challenging and hostile exploration environments on the planet ranging from the Arctic to Ultra-Deepwater. Hydrocarbon resources are becoming more difficult to extract physically, economically and, in some cases, politically. While there is enormous pressure to tackle these challenges, we must not lose sight of operational, environmental and safety risks and how to best manage them. One such risk that can lead to catastrophic consequences is well blowouts as illustrated by "Macondo" and "Montara" incidents. Such incidents imply lack of risk management to blowouts and well barriers in current approaches. This is, in part, due to the complex physical mechanism of blowouts, complexity of the decisions needed to respond to well control incidents, unique configurations of each well, geological and operational uncertainties, and barrier effectiveness over time. A new practical method of dynamically managing barriers that can reduce blowout risk during the operational phase is described in this paper. This method is based on a dynamic blowout simulation tool that is applicable for onshore/offshore oil and gas well blowouts. This tool integrates fluid dynamics and heat transfer modeling in wellbore and reservoir pressure changes due to depletion during blowout. It provides a dynamic estimation of site specific blowout rates, and then incorporates with other uncertainties to demonstrate the total risk picture using a barrier based approach. To demonstrate this method, a sample case study is presented. First step is to establish the initial risk picture. The case of drilling an exploration well is modeled and risk picture established without incorporating any well barriers. Second step is to frequently update this risk picture to current activity. As the drilling activity progresses, well barriers are introduced into the wellbore. Inclusion of any such well barriers minimizes the flow paths for a blowout to surface reducing such risk; conversely effectiveness of these well barriers is assessed by demonstrating how the risk is reduced when effective barriers are put in place. This risk picture is hence updated each time a barrier is added or removed and hence is dynamic. Finally, the cost-benefit relationship of each barrier is ranked according to their performance in reducing risk versus their associated costs. This provides opportunities to assess the effectiveness of well barriers during the well lifecycle phases. The method described in this paper enables faster decision-making, improved visibility of risk management in operations, enhanced organizational communication, better testing of barrier solutions and enables a step change in site safety. Utilizing dynamic barrier analysis reduces risk uncertainty in more challenging drilling sites by enabling the operator to assess the current risk status rather than rely on out of date information.