Operationalizing Upstream Process Safety for Drilling Operations by Adopting an Integrated Risk Assessment Approach
Authors: Todd Bridget , Reese Michael , Brown Shauna 
Published: October 2019

Abstract
Upstream process safety (UPS) events during drilling operations, including kicks and unexpected loss of fluids can occur due to a myriad of reasons viz., unexpected pressure variances, complex geology, or improperly executed procedures. Wellbore influx or kicks occur during drilling when formation pressure is greater than the density of the drilling fluid in the wellbore, resulting in the unexpected influx of fluids or gas into the wellbore due to the pressure variance. Similarly, if density of the drilling fluids exceed the formation pressure, wellbore fluids are unexpectedly forced into the formation or migrate into open fractures. Utilizing historical Health, Safety and Environment (HSE) incident tracking and drilling data for UPS events, specialized models can be constructed to identify the system causes for these occurrences. Too often investigations look at the symptom and relate it to the problem of an event, but do not perform an in-depth investigation to determine the root causes that actually contributed to the event. In some cases there could be a multitude of factors. Once the root cause is determined, a smart strategy can then be developed to mitigate the risks to a safe and cost effective level. By developing an understanding of the actual root causes and analyzing HSE and modeling data for a determined set of events, analysts discovered that approximately 94% of the UPS incidents associated with kicks and fluid loss were preventable using technologies and products readily available. A review of human performance also concluded that safety culture, lack of knowledge and the understanding that preventative planning can lessen UPS incidents and drive efficiency in operations, may not be shared throughout an organization.
Challenges in alleviating UPS events lie with both subsurface complexity, as well as the value that an organization or decision makers place on disciplined and rigorous risk assessments, preventive planning and prescriptive operations to overcome subsurface challenges. The key to developing a smart mitigation strategy to alleviate risks, is through interactive collaboration between multi-discipline subject matter experts from different subsurface disciplines viz. geology, geomechanics, geophysics, as well as drilling fluids, well construction, wireline and drilling services analyzing each individual risk or hazard, leveraging the knowledge developed from the specialized models. Using this risk assessment, a customized approach to drilling risk management can be developed to address the relevant subsurface challenges. Some approaches may require several components to be implemented simultaneously in order to be effective. Proactive mitigation measures can be employed if a high-risk challenge is predicted during the integrated risk assessment approach, including proper preparation at the beginning of the project to reduce potential risks to people, environment, equipment and systems. By conducting a subsurface driven risk assessment and implementing barriers with different tools or services, UPS events can be attenuated or prevented. Additional benefits realized include reduced non-productive time (NPT) and increased efficiency for operations. A review of recent case histories in various regions including North Sea and the Middle East, demonstrate the benefits of a proactive approach to UPS.