Reliability Gaps in ESP Technology for Deepwater Applications

Abstract

Abstract The plans for many of the upcoming deepwater projects involve the use of highpower Electrical Submersible Pump (ESP) Systems for Artificial Lift. However, the perception in the industry is that the average run-life currentlyachievable with such high power ESP Systems is much shorter than what would bedictated by robust project economics, given that intervention costs in theseapplications can be very high, in the US$50MM - 75MM range. Therefore, theconsensus among operators is that there is a need to try and improve thereliability of these systems. In response to this industry need, DeepStar® recently commissioned a gap studytowards identifying the barriers that may be preventing ESP Systems fromachieving the desired reliability as well as the additional R&D effort thatmay be required for the industry to close the existing gap. DeeepStar® providesa forum for deepwater technology development, while leveraging the financialand technical resources of the industry (http://www.deepstar.org/). This paper presents a summary of the results of this study, including:the Mean Time To Failure (MTTF) that people believe is currently achievable (i.e.with current technology);the biggest differences about these applications, which introduce additional uncertainty to the ability of the system to performreliably;the main sources of uncertainty regarding each of the major ESPSystem component's reliability; andthe tentative plan that was outlined aspart of the project, to address the gaps that were identified. The Gap Analysis was based on phone interviews conducted with recognizedindustry experts, on discussions that took place with members of a TechnicalCommittee (TC) that was put in place for the project, and on a broader industrysurvey conducted through the internet. The proposed go-forward plan consists oftwo follow-up projects: one focused on improved system design and operationalpractices, including system monitoring (or surveillance) and control; and onefocused on validating the design of key components of concern, for thespecifics of these applications, through laboratory testing. The proposednear-future R&D effort has the support of major operators, but still needsto be fine-tuned, with input from the industry, before the actual work canproceed with buy-in and financial support from all of the partiesinvolved. Introduction The Oil and Gas industry continues to move towards more challengingexploitation environments offshore: deeper water (over 10,000 ft), longertie-backs, deeper reservoirs (up to 20,000 ft below the mud line), and/or withhigher viscosity oil. The plans for many of the major projects currentlyunderway in such offshore environments involve the use of relatively high powerElectrical Submersible Pump (ESP) Systems for Artificial Lift. These include, for instance: Shell's " Parque das Conchas" and Petrobras' " Parque das Baleias" in Brazil's Campos Basin, as well as Shell's Perdido, Petrobras' Cascade andChinook, and a few other projects in deep waters in the US' Gulf of Mexico(GOM) such as Chevron's Big Foot. Operating in these extreme environments will likely require deploying newproduction systems (e.g. with subsea boosting) and/or new generations of ESPequipment. While individual well production rates can exceed 20,000 bpd of oil, understanding of well performance is usually only marginal at the time ofsystem design and installation. Intervention costs in these scenarios can bevery high, sometimes in the US$50MM - 75MM range (per intervention). Productionlosses following an equipment failure can also be quite significant, especiallyfor wells with higher production rates. Therefore, the economic success ofthese projects is closely linked to the ability to minimize the number ofinterventions for equipment repair and maximize production uptime. Thisrequires not only using highly inherently reliable equipment but also havingthe best possible design and operational practices in place, in order to beable to actually realize the whole reliability potential of the equipment. Astated goal by some operators is to have 95% confidence that a 5 year run-lifecan be obtained from the ESP System, despite this very challenging operatingenvironment.