This paper introduces a formula for predicting the intake temperatures of an ESP during SAGD operations, the "Lagged PVT Ratio Formula". This formula is intended to be used to automate the ESP's operation, with the goal of maintaining select well temperature and subcool targets. Target intake temperatures are determined and are currently monitored manually. If downhole temperatures reach a critical, typically water saturation temperatures, vapors can form at or in the ESP. This can cause the pump to trip or fail, leading to a costly workover being required.
To develop the Lagged PVT Ratio Formula data from eight well pads, approximately 80 SAGD well-pairs, was used. It is based on lagged non-dimensional ratios derived from select well parameters known to effect ESP intake temperatures. Formula inputs are based on the previous five readings of select variables in 10 minute intervals. Frequent readings of appropriate parameters allow for fast and accurate temperature predictions during sensitive well operating periods, and periods of stable production. Accurate temperature predictions are specifically important during the initial start-up period of the well. Verification tests showed that a single equation can be used to predict the ESP's intake temperature for SAGD well-pairs at different stages of the wells life. This formula has proven to be consistently robust and does not change when applied to similar existing well-pairs, well-pairs with different geology, and new well-pairs.
With an increasing number of producing SAGD well-pairs on site, being able to predict ESP temperatures, leading to well-pair automation, will be an economical benefit for operators. It will allow for additional SAGD well-pairs to be drilled without requiring additional production engineers to monitor and operate the wells on a daily basis.