Reservoir Pressure Anomalies: Investigating Causes with CoViz 4D

In a California onshore field, with hundreds of closely-spaced production and injection wells, a horizontal production well was experiencing occasional dangerously high pressure and temperature spikes—leading to a serious health and safety issue. The suspicion was that a nearby injector well was leaking, and hence causing these temperature and pressure anomalies. However, all well data for the field resided in a sizeable static database; and with no spatiotemporal reference between the wells, it was nearly impossible for the team to assess which injection well or wells might be responsible for the hazard.
The team turned to CoViz 4D to better understand the well relationships. The expansive onshore wellpath data set was easily and quickly read from the database directly into the CoViz 4D visualization environment. This allowed the team, for the first time, to see the spatial and temporal relationships between the hundreds of wells in the field.

Figure 1. The well geometry of the California field, showing producing wells in green and actively injecting wells in red.

Figure 2. 2D time-series plot of temperature and pressure for the horizontal producer. Two spike events are clearly visible.

Preliminary analysis of the dataset indicated that injection wells greater than 100m from the horizontal well could be eliminated as the potential source of the spikes; this left a much smaller set of injection wells to investigate. 4D analysis of the remaining injection wells showed that several wells were injecting during both of the high pressure and temperature anomalies; this determination was easily made through the use of visual alert flags to identify when the temperature increased by 10% over a user-defined moving time window.

Figure 3: Animation of wells within 100m of the horizontal producer. The pressure and temperature data, represented as yellow and red towers, includes an alert setting (flag) to indicate a dangerous temperature spike occurrence. Several wells are injecting at the time of the spike.

Through a customized analysis, the dates of the temperature and pressure spikes were compared with the injection well status to identify which wells were actively injecting at the time of both events; this easily confirmed that only one well was injecting and was the culprit. Moreover, the script also confirmed that there were no reservoir temperature/pressure anomalies when the suspect injector well was not injecting—an equally critical part of the analysis and conclusions.
This example shows the combined power of the CoViz 4D visualization environment; the ease of data access from custom databases, the ability to integrate multiple datasets, a time aware visual environment, and user-customizable tools and workflows. By finally identifying and then fixing the leaking injection well, the team solved a critical H&S issue that could have resulted in a permanent shutdown of the field.

Contact DGI to find out more about how CoViz 4D can help your team determine the causes of reservoir pressure anomalies.

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