Electrical Submersible Pumps (ESP) have been used to produce fluids for almost a century in many different industries. Since the 1800s, people have been using hydroelectric dams to produce power, demonstrating the viability of harnessing the potential energy from elevated water sources. However, there is a tremendous opportunity to partially recover that same potential during the yearly reinjection of billions of cubic meters of water in the oil, gas, and geothermal industries by combining the principles from both. The electrical submersible generator (ESG) is a modern interpretation of an old idea. The ESG can generate electricity to meet surface power needs or feed directly into the grid to create a revenue stream under the proper injection conditions. In typical configurations, a standard centrifugal pump is used in combination with an induction motor. Rather than operating the motor in a conventional manner to convert electrical energy to mechanical work, the motor is operated in such a way for the mechanical work of the pump to be converted into electrical energy. Other configurations are optional such as using more conventional turbine pump designs and permanent magnet motors. After the successful completion of a few installations, several changes have been made to optimize the machinery and enhance the equipment operation. Through these efforts, significant knowledge has been gained about how these machines work. For a successful completion, factors including third-party controls, run-away speeds, fluid / reservoir properties, and starting techniques must all be considered. This paper explores the ESG’s design considerations, theoretical underpinnings, and potential future applications. This will involve a review of field operations, installation procedures, and lessons learned. The conclusions of CFD analysis and installations in the actual world will be presented to support the assumptions.
A significant percentage of all ESP failures are electrical failures and this becomes even more noteworthy in harsh, high temperature applications such as Steam Assisted Gravity Drainage (SAGD). For this reason, it is extremely important to continue the enhancement of ESP motor technologies that are specifically designed to address the challenging and unique SAGD environments that include wide bottom hole temperature ranges, abrasives and gas rich fluids. Through experience and testing, it has been learned that for these types of applications it imperative to design not only to a high temperature limit, but also to withstand extreme temperature cycles experienced on steam injection facility shutdown. A combination of historic evidence with controlled laboratory evidence yielded improvement areas for a new high-temperature ESP motor development. The new high ultra-temperature motor breaks paradigms and opens a new generation of motors that looks towards above 300°C downhole temperatures. This paper will review the performance of the motor at Suncor's Firebag SAGD field where 92 units have been installed since January 2015 in bottom hole (BHT) temperatures reaching 240°C. Description of the laboratory qualification, major design characteristics and field results will also be discussed on the paper.
Steam-assisted gravity drainage (SAGD) and other thermal recovery applications require electrical submersible pump (ESP) equipment which can withstand extremely harsh oilfield environments with well conditions typically including high gas, sand, and scale concentrations in addition to the extreme temperatures and temperature cycles generated in the process. Thermal recovery pump construction specifications were developed as part of a new tiered product line covering deployment of equipment in wells with bottom hole temperatures (BHT) as high as 250°C. Special construction considerations were implemented for stage compression, thrust handling, bearing design and materials of construction. The new pump technology combines high temperature and abrasive handling features to extend product life and provide consistent reliability in thermal recovery applications. Enhanced temperature tolerance is achieved through reduced thermal stresses on internal components leading to better reliability and increased run life. This next generation of thermal recovery pumps has been extensively field validated with systems utilizing the new technology currently installed and operating in over 400 wells.
NCG (Non-Condensable Gas) co-injection with steam has been in operation at Surmont SAGD field since 2017. After a significant number of operational attempts to mitigate ESP no flow events (deadheading) suspected to be instigated by increased production of gas (typical SAGD GOR 5-10 m3/m3) a strategy was developed to focus on completion adjustments to the ESP on candidate SAGD producers. These changes were completed in late 2019 to help reduce the loss of production, which could impact viability of NCG co-injection at Surmont. Three separate completion adjustments were made: an inverted shroud installation, a larger OD pump with a gas separator, and lowering of an ESP to the lowest possible TVD. A comparison of the production and operational performance before and after each completion adjustment was completed. In-depth design reviews between CPC and the equipment vendor were done to ensure maximum chance of positive benefit. The inverted shroud installation was expected to improve gas separation efficiency, leading to a reduction in the frequency of No Flow Events (NFEs), which were impacting production rates. The shrouded ESP performance on the first candidate well showed no NFEs with a significant increase in production rates compared to the baseline before the completion adjustment. The larger OD pump with gas separator install was also expected to reduce or completely prevent NFEs. the results were also positive, with an increase in production and no further NFEs recorded. Lowering of a third ESP to a point as close as possible to the liner hanger did not achieve any long-term change in production performance. With the success of the inverted shroud, a second installation was completed on the third well where the ESP was being lowered. A production increase and prevention of NFEs were documented like the first shroud installation, confirming the benefit of the shrouded ESP design. The completion changes confirmed that suitable adjustments to mitigate the effects of NCG injection are possible, with further development on design required to optimize for production capacity and long-term performance. With the results seen so far, further installations will be completed in the future on appropriate candidates to continue to mitigate the effect on ESPs of produced NCG volumes.
One of the major challenges in SAGD Electrical Submersible Pump (ESP) operation is produced water flashing to steam when flowing pressure loss is significant, such as at an ESP intake. "Bottom Feeder" style intakes are a standard SAGD ESP intake which has been applied in the SAGD industry for over a decade. However,it was identified in recent years at ConocoPhillips's (CPC) Surmont Oilsands operations that Bottom Feeder intakes can lead to steam flashing in pump at the right conditions. The flashed steam causes significant cavitation in pump, which in turn causes severe motor load chattering. Further to that, steam locking in the pump can occur, which is called a "no flow event" (NFE) in the SAGD industry. ConocoPhillips and Baker Hughes have been working together to optimize SAGD ESPs by utilizing an integral intake to minimize the pressure loss across the intake ports. This would also streamline the connection between intake and pump housing to minimize pressure loss at these intake flow paths. The improved design has been tested in Surmont successfully, and the integral intake has become an optional intake to be applied in the well cases where steam flashing has been known to cause operation interruptions or ESP damages. This paper will review the process undertaken by CPC and Baker Hughes to study the ESP performance with the bottom feeder intake in comparison to the ESP performance with an integral intake.Design and field data will be presented and reviewed to highlight the performance of each system.
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