Well-to-well communication—often found as frac hits during hydraulic fracturing—is common in unconventional oil and gas development. When the fracture network of a newly drilled well connects to an older well’s fracture network, the older well may fill with sand and fluids, requiring an expensive cleanout to restore production. If not properly mitigated, these frac hits can cost operators billions of dollars in lost production. The key to developing sound frac hit mitigation strategies is data visualization.
This article will discuss a solution that is helpful during both pre-drill planning and frac monitoring.
Visualizing Potential Frac Hits During Pre-Drill Planning
While it’s not likely that frac hits can be eliminated completely—the rapid growth in the number of infill wells and tighter well spacing makes it nearly impossible—engineers can develop mitigation strategies during pre-drill planning to reduce their impact on production. These strategies can be improved with technology such as CoViz 4D, a data visualization and analysis software package created by Dynamic Graphics, Inc.
CoViz 4D is an ideal pre-drill tool to analyze both drilling and frac plans because it has the ability to highlight wellbores that are closer than predetermined limits, providing the means to visualize where well plans need to be adjusted before wells are drilled. For example, engineers can input the frac model data for each well into the drilling plan via CoViz 4D to determine if the projected frac length may intersect another adjacent wellbore’s fracture network. If there is the risk of a frac hit, either the drill plan or frac size can be adjusted to help lower the risk.
Monitoring Frac Data: From Visualization to Analysis
CoViz 4D allows engineers to visualize large volumes of strain and microseismic data for analysis. Strain data, or other DAS (distributed acoustic sensing), is usually collected in an adjacent well in continuous ten-second intervals during a frac job. This continuous collection results in a large dataset that shows how the adjacent well is being affected by each frac stage. In CoViz 4D, frac hits can show up as significant changes in strain. If the strain continues to gradually increase, this could indicate a breakthrough is close to happening.
If microseismic data are accessible, it can be used to visualize frac hits in CoViz 4D. With respect to microseismic data analysis, CoViz 4D can achieve the following:
- microseismic viewing in 2D, 3D, or 4D, with the addition of fracking data combined with subsurface datasets (i.e., FMI logs, fault geometries, or earth models) to gain better insight into complex reservoir systems
- the viewing of fracturing data in an animated sequence via 3D, with the inclusion of relevant data such as petrophysical or geologic data to know what exactly is happening during microseismic events
Microseismic data show where microfractures occur during the frac job, which in turn show how close the strain and pressure get to other wells. Each microseismic event represents where the rock actually cracks, but around each event is where the rock may deform due to the stresses. By leveraging CoViz 4D to place a radius around each event or to calculate distances away from each event, geoscientists can estimate if they may have had a frac hit.
By leveraging CoViz 4D to place a radius around each event or to calculate distances away from each event, geoscientists can estimate if they may have had a frac hit.
Improving Frac Hit Mitigation Strategies with CoViz 4D
CoViz 4D provides a comprehensive visualization scope that allows engineers to know the expected nature of subsurface conditions. The use of 3D and 4D is a vital tool during the monitoring process, especially for unconventional fields that yield mass volumes of data. Similarly, during the pre-drilling stages, the added data can help engineers minimize the risk of collisions with existing wells and enhance the decision-making process. Using CoViz 4D’s monitoring capabilities, engineers can also follow the performance of adjacent wells as new wells are drilled, ensuring field stabilization as fracking commences. CoViz 4D provides the best of both worlds—comprehensive data visualization and large volume data analysis—allowing asset teams to mitigate risks and maximize hydrocarbon extraction.