Monitoring real time well performance is critical to not only maintain safe and reliable operations, but it is also crucial in meeting the yearly production targets. To track the current well rates Tengizchevroil (TCO) utilizes multiphase flowmeters (MPFM) which are installed on a group of wells (meter stations), usually consisting of 8-12 wells. However, there are some minor constraints in the current MPFM well testing process – wells can only be tested one-by-one with minimum 2-hour test durations, meaning that real time rates are only represented for one well only in the time of testing. When wells are not on test, TCO uses the theoretical rate (FTP rates or so called "flowing tubing pressure rates") determination process. This paper describes the application of digitalization tools in daily operations at Tengiz for production tracking and allocation process.
Prosper models are created and maintained for each well in TCO's operating well stock which are stored in Model Catalogue (DOF's model repository). Each month these Prosper models are updated and calibrated based on updated and reviewed well test data – engineers usually set new reservoir pressures or productivity index estimations to match the recent well test results. Revised models are later updated into the GAP integrated network model in Model Catalogue, and an automated workflow in DOF generates updated VLP/IPR tables with well rate trends as a function of varying wellhead pressure. The VLP/IPR tables are later uploaded into SCADA for integration with the real time monitoring tool, where based on current wellhead pressure the FTP rates are computed on a real-time basis for Operations to monitor.
The FTP update process also serves as a foundation for Field Production Allocation – a relationship of the cumulative daily production sourced from Plant intake gauges (actual Field production) to cumulative theoretical (FTP) Field rates. On average, TCO strives to keep the allocation factor in the range of 0.90-1.10 (+/- 10% error). This allocation process is done in Energy Components (EC).
The FTP and Allocation processes are foundational for short-term and long-term forecasting as the Well performance is used for day-to-day operations planning, maintaining, and ensuring enough production is feeding the Plants.
The end-to-end workflow is currently being streamlined to further automate where it makes sense; for example, leveraging DOF's capabilities to automate generating well test records from live real-time data, implementing a management by exception plug-in for the well test QA/QC, and semi-automating the Prosper model calibration process.
