Accurate reservoir characterization benefits every aspect of development and production activities. However, one of the greatest challenges of reservoir characterization concerns the diversity of data used by the individual disciplines of the reservoir team. Each discipline uses specialized software products. Each provides insight into a specific reservoir attribute such as pressure, fluid saturation, net-to-gross, or velocity. Each has inherent value in depicting reservoir characteristics.
Software that allows the various data sources to be integrated and presented in a shared environment for visualization and analysis maximizes the value of those data and allows reservoir teams to more accurately assess a reservoir’s proven recoverable reserves.
Data Visualization Assists in Determining Proven Recoverable Reserves
Technology and market conditions are also critical factors in determining proven recoverable reserves.
An environment that integrates relevant subsurface data and presents it in a 3D visualization environment for collaborative analysis by a reservoir team facilitates faster, more accurate determination of proven recoverable reserves. It can accomplish this using the following methods:
3D Geologic Models to Depict Subsurface Environment
Interpreted seismic and petrophysical data are combined to calculate a 3D geologic model that is used to generate contour and isochore maps as well as cross sections. With these 3D reservoir models, reservoir teams gain an accurate understanding of complex structural and stratigraphic features such as reverse faults, growth faults, and zone pinchouts. In addition to helping understand geologic conditions that influence (and constrain) reservoir development, these 3D geologic representations provide a foundation for conducting volumetric and hydrocarbon entrapment analysis to determine proven recoverable reserves.
Refined Reservoir Simulations to Estimate Reserves
Combining a reservoir simulation model with other subsurface data in a single geospatial volume gives reservoir engineers the ability to analyze data in context, compare interpretations, and reach a deeper understanding of data interdependencies and modeling assumptions. Reservoir teams can refine simulation variables to more closely approximate reservoir characteristics. Improved models provide better estimates of recoverable reserves and help guide development and operational decisions to maximize recovery.
Reassessed Proven Recoverable Reserves
In the production phase, visualization and analytic software capabilities that bring together the most relevant data regarding changing reservoir conditions can assist reservoir engineers in reassessing proven recoverable reserves in the following ways:
- Compare production volumes to date with estimated ultimate recovery (EUR).
- Evaluate oil-gas-water production metrics for each well across a group of wells or an entire field to help identify candidates for EOR programs.
- Update reservoir models with new interpretations to show how recoverable reserve volumes have changed in response to ongoing well production.
- Explore the underlying reasons (geology, stimulations, wellbore attributes) why production metrics differ from reservoir simulation model predictions.
Based on the outcome of the analysis, reservoir engineers can modify development and production strategies accordingly. That may include adding injection wells to enhance recovery, sidetracking to access newly identified pay zones, use of proppants in fracturing treatments, or any other methods that have been proven successful in nearby wells or reservoirs with similar characteristics.
Time-Step Analysis (4D) for Better Estimates
Time-step analysis (4D) of seismic data and production data also facilitates better estimates of proven recoverable reserves. Time-step analysis can reveal trends that may not otherwise be apparent in 2D charts (decline curves) or 3D images. Time-step seismic data combined and analyzed with production data allow geophysicists and production engineers to:
- Calculate differences between time steps to see how the rate of change in production or oil/gas saturation has varied by well, by field, by recovery method, or other relevant reservoir attributes.
- Update or fine-tune reservoir simulation models per changes observed in recent seismic studies to more accurately forecast production.
- Identify bypassed oil and recalculate the proven recoverable reserve estimate.
- Use data from nearby wells or reservoirs with similar geologic attributes and production history to determine the appropriate secondary or tertiary recovery techniques.
4D seismic analysis enables reservoir engineers to gain a better understanding of a reservoir’s dynamic behavior and adjust their models accordingly to more accurately estimate or update proven recoverable reserves. With a more accurate estimate, reservoir teams can then determine if reserves merit further investments in recovery and if so, which methods maximize recovery while minimizing risk.
CoViz 4D: A Proven Tool for Estimating Recoverable Reserves
Data integration, visualization, and analysis software like CoViz 4D allows reservoir teams to obtain greater value from the wealth of data generated during the life of a reservoir. Detailed geologic models provide an initial characterization of hydrocarbon reserve location and volume. Seismic data combined with reservoir simulations help refine proven recoverable reserve estimates. As wells are produced, time-step analysis shows how development and production decisions have impacted reserves, allowing reservoir teams to modify strategies to optimize recovery.
Data integration, visualization, and analysis software like CoViz 4D allows reservoir teams to obtain greater value from the wealth of data generated during the life of a reservoir.
CoViz 4D facilitates accurate reservoir characterization, modeling, and monitoring to give engineers the ability to understand subsurface changes in greater detail and implement production strategies to maximize recovery of proven recoverable reserves.