LMIR - A New Method for Automated Identification of Multi-Rate Pressure Transients

Permanent Downhole Gauges (PDGs) enable continuous well monitoring in industries like oil and gas, geothermal energy, and geological CO2 storage. Pressure measurements with these gauges help in assessing the well and the reservoir parameters using Pressure Transient Analysis (PTA), that identifies and characterizes transient intervals in the pressure time series. However, identifying multi-rate transients – when rate changes step-wise without shut-ins between the steps – may be challenging and often requires manual, time-consuming efforts with continuous adjustments.

This paper presents LMIR (Local Minimum in Rotation), a novel method developed specifically for multi-rate transient identification. LMIR treats the pressure curve as a single unit and applies rotation operator in time-pressure coordinates to identify transient intervals bounded by extrema. Testing on PDG datasets from North Sea water injection wells has demonstrated that application of the LMIR method may be used for automated transient identification, minimizing manual intervention. After transient identification with the LMIR methods, additional steps like pressure-rate synchronization and rate reconstruction also discussed in the paper. Overall, LMIR offers a pioneering solution to automate multi-rate transient identification, streamlining the process and enhancing efficiency in monitoring well and reservoir parameters over time.