ConocoPhillips has been on a quest for a high-volume artificial lift system that will operate reliably in a 250°C (482°F) downhole environment. This paper will describe the testing and results of a high-temperature electric submersible pump (ESP) system in a flow loop built to validate downhole equipment for thermal applications, primarily for steam assisted gravity drainage (SAGD) developments. What makes this test program unique from previous tests is the longer duration (4+ weeks), the range of fluid temperatures (90°C to 245°C [194°F to 473°F]), and the type and volume of data collected. One of the key parameters monitored and documented was the internal motor winding temperature, which has been used to validate and calibrate a simulator for predicting motor performance in thermal environments.
The group was tasked to find, select, and further support the development of artificial lift technology with the capability of handling fluid rates up to 1,000 m3/d at 250°C [6,290 B/D at 482oF] downhole conditions. The goal was not to just find and validate a single system, but to qualify several lift systems to provide the production engineers with a toolbox of solutions.
This challenge was approached as two different projects: find, select, and further develop potential lift systems with the needed volumetric capability; and validate these systems through high-temperature testing. The latter was considered to be the bigger challenge. ConocoPhillips did not operate any fields with downhole temperatures close to 250°C [482°F], so validation via field trial was not possible. A more controlled test facility was preferred, so that a comprehensive suite of performance curves could be collected to define the full operating envelope for each lift candidate. A test facility that was not associated with a specific pump vendor was also preferred to avoid the legal and confidentiality issues with testing third-party equipment.
It was decided that an existing high-temperature flow loop located at C-FER Technologies Ltd, in Edmonton, Alberta, Canada, was the best option for the artificial lift validation testing. The loop had been built as part of a joint industry project (JIP)1 in 2004, but needed to be upgraded for testing at 250°C [482°F]. ConocoPhillips contracted C-FER and funded the project entirely. Two lift systems have been tested to date in the flow loop after the high-temperature upgrade was completed in mid-2008. This paper focuses on the results of the second test program, which evaluated a Schlumberger high-temperature ESP system, developed for operation in thermal environments.
In 2008, there were no commercially available ESP systems rated for 250°C [482°F] downhole environments. So, one of the existing systems was selected for testing to fully understand what would happen to the ESP components when the system was operated at or beyond the maximum temperature rating. The results would help determine how close the existing technology really is to reaching operation at the 250°C [482°F] target temperature, and, depending on the outcome, to help direct research funding into the appropriate places.