Electrical submersible pumps (ESPs) are employed in a growing number of oil and gas developments. A high level of availability of the ESPs is essential to production assurance. The purpose of this research was to develop a basic ESP fuzzy expert system and to demonstrate its application. An ESP Fuzzy Expert system can provide a consistent means to analyze ESP operational data. The analysis can be used to either predict developing failure modes or to retroactively determine the causes of a prior failures. The main steps involved in the development of the ESP fuzzy expert system are as follows: identify input variables, develop membership functions, develop rule sets and develop output functions. Input variables representing slopes were mapped to membership functions denoted by linguistic terms such as "increasing", "constant", and "decreasing". The input variables are also assigned a member value to indicate the Degree of Fulfilment (DOF) of the individual premise. The Degrees of Fulfilment (DOF) of all the premises are then combined to determine the overall DOF of the rules (Adesanwo et al. 2016), with each rule representing a distinct failure mode. To validate the system, operational data from an offshore oil and gas field located in the Gulf of Thailand was collected and analyzed using the prototype ESP Fuzzy Expert System. This dataset consisted of nine ESP systems selected from a pool of more than 100 ESPs installed in the field. The nine ESP systems were composed of four ESP pumps which were running smoothly and five ESP systems that eventually failed. For the failed ESPs the operational data leading up to the failure was analyzed. Trends were analyzed for periods of 7 days, 30 days and 60 days for each ESP system.
The concept of energy return on investment (EROI) is applied to a set of electrical submersible pumps (ESPs) installed on a small offshore platform by conducting a detailed energy accounting of each ESP. This information is used to quantify the energy losses and efficiencies of each ESP system as well as the EROI of the lifting process (EROILifting), which is derived by dividing the energy out of each well, which is the chemical energy of the crude oil produced, by the energy consumed by each ESP system and by the surface equipment used to dispose of the well’s produced water. The resulting EROILifting values range from 93 to 565, with a corresponding energy intensity range of 18.3 to 3.0 kWh/barrel of crude. The energy consumed by each well is also is used to calculate the lifting costs, which is the incremental cost of producing an additional barrel of crude oil, which range from 0.64 to 3.90 USD/barrel of crude. The lifting costs are entirely comprised of procured diesel fuel, since there is no natural gas available on the platform to be used as fuel. Electrical efficiencies range from 0.60 to 0.80, while Hydraulic efficiencies range from 0.12 to 0.56. The overall ESP efficiencies range from 0.09 to 0.39, with the largest losses occurring in the hydraulic system, particularly within the ESP pump itself. Improvement of pump efficiencies is the only practical option to improve the overall ESP system efficiencies. Other losses within the electrical and hydraulic systems present few opportunities for improvement.
Net Energy Analysis (NEA) has traditionally been utilized by non-industry actors, such as academics, economists and regulators. It has not been widely accepted as a beneficial method within the oil and gas industry with regards to oil extraction systems. This research suggest several practical benefits to oil and gas owner/operators of conducting NEA. The benefits are primarily realized by integrating NEA into economic analysis at the field level, facility level and well level. The impact of energy on both capital and operational (OPEX and CAPEX) expenditures is explored. The case is made that NEA can be used to illuminate the drivers behind energy intensive oil and gas extraction processes, and thus can be used to reveal important economic risks and opportunities.
The main objective of this study was to develop a simple and effective methodology for capturing, analyzing and improving energy intensive processes in an upstream oil and gas field. The improvement of an upstream field's energy intensive processes can be challenging due to the dynamic, time variant, nature of the operations involved. It is nonetheless essential to minimize energy consumption in marginal fields in order to realize lower operating costs and remain profitable in a low-oil price environment. Therefore, Mubadala Petroleum researchers in Operational Excellence developed an effective energy efficiency improvement methodology. This study describes the methodology developed. The methodology involved consists of the following steps: identificationand decomposition of system boundaries, selection of suitable energy metrics for the facility, collection of operational data, calculation of energy balances and metrics, assessment of performance against design expectations and best practices for systems, subsystems and equipment, and finally the application of a structured approach to identify and screen potential opportunities for improvement.
Aging facilities are a common issue within the oil and gas industry. This research demonstrates a practical approach to aging life extension, taking into account risks and constraints, such as budgets, resources and offshore field-level logistics. The case study reviewed is Mubadala Petroleum's (MPs) small, but aging, upstream offshore oil facility located in the Gulf of Thailand, known as the Jasmine/BanYen field. The field includes six offshore platforms, subsea pipelines and a Floating Production, Storage and Offloading asset (FPSO). The field, which commenced production in 2005, was initially expected to have a relatively short field life, and as a result, the facilities were genially specified for only a 10-year lifespan. As the field exceeded expectations in term of volumes and longevity, it became clear to MP management that a practical and cost effective life extension plan was necessary. As such, this research describes the approach to taken by MP to extend the life of the Jasmine/BanYen facilities. The approach taken by MP was closely aligned with the recommendations and best practices proposed by several regulatory authorities with extensive experience in managing aging offshore oil and gas facilities, such as the United Kingdom's (UK) Health and Safety Executive (HSE) and the Norwegian Petroleum Safety Authority (PSA). As such, the facilities were first functionally decomposed into a number of subsystems, such as Wells, Structures, Pipelines, Topsides, Risers and Floating Assets. A target life extension period was specified, which was followed by a series of focused risk assessments to determine the levels of risk expected during the life extension period, with the critical gaps identified. Each risk assessment involved specialist resources related to the subsystem under review, such as structural engineers, process engineers, marine engineers, instrument engineers, as well as technical safety and environmental engineers. For any risks that were deemed unacceptable, a mitigation plan was suggested and associated costs developed. Finally, a phased master plan was developed that took into account constraints while prioritizing actions based on the determined risk levels. The implementation of the plan was challenged by the intricacies of offshore logistics, including constraints on supply boats, Persons On Board (POB) etc., and budgetary constraints, which were considerable given the relatively high operational expenses of the field and the low oil price environment. As per the risk assessment, high priority activities were determined to be with respect to FPSO, well integrity and the integrity of subsea pipelines. The platform structures and topsides were considered to be lower priority, as they had already been verified for the life extension period by the company's Asset Integrity (AI) program. Additionally, MP also has a robust Safety Critical Element (SCE) system in place which is an integral part of the AI program, and as such there were no unexpected revelations with regards to the condition of the SCEs. Obsolescence was determined to be a low priority since the equipment on the platforms are relatively new, and most of the Original Equipment Manufacturers (OEMs) provided assurance on the availability of spare parts for the main equipment items. Highlights of the life extension plan are as follows: Production flexible riser connecting the steel pipeline network to the FPSO has been replacedPipelines inspections are ongoing, and repairs are being prioritizedThe design life of platform subsea structures has been extended based on fatigue analysisSubsidence analysis has been carried out on all platforms and indicated no major anomaliesPlatform power generation facilities are progressively being upgradedA comprehensive well integrity systems have been implemented and critical activities such as barrier testing and well repairs are being carried out regularlyRepairs to the hull of the FPSO have been carried out
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