While there are traditional approaches to the structural interpretation of seismic data for oil exploration and velocity modeling in the industry, these approaches can be enhanced through advancements in technology. Without the ability to integrate and visualize all relevant data in a comprehensive environment, professionals may overlook valuable pays.
Geoscientists can benefit from rapid updates to velocity models to include the latest information. This will enhance the details of the subsurface and improve the accuracy at which depth surfaces are produced. More accurate depth surfaces will enable better volumetrics and reservoir management at the same time reducing risk and depth uncertainty.
Improving Structural Interpretations
Velocity modeling is highly dependent upon input from geological and petrophysical data and interpretations. Often this data can be incorporated in more traditional velocity modeling software. CoViz 4D—data visualization and analysis software created by Dynamic Graphics, Inc. (DGI)—offers a unique addition to the process with its iterative nature of correcting the velocities on a zone by zone basis by incorporating the geologic well picks into the velocity model. At each well location the residual error between the real well pick and the depth converted surface can be assessed and corrected. Any deviations can be easily seen in CoViz 4D and will be adjusted automatically by the process to provide a calibrated velocity model.
As more wells are drilled it is imperative that the velocity model and its constituent parts are kept current. Geoscientists can use this latest information to update interpreted horizons and review well plans and reservoir economics. The added precision and depth uncertainty assessments will greatly aid the process of drilling development wells in a naturally very uncertain environment, reducing risk and costs in the process.
Additionally, CoViz 4D provides an efficient workflow to calculate velocity volumes relative to seismic picks. As a result, users will get an average velocity volume that adjusts to the picks, fostering more accurate time-to-depth conversions, in addition to reservoir volumes and seismic models.
CoViz 4D enhances traditional velocity modeling by allowing users to:
- Rapidly update velocity models. Allowing the latest data to be used in planning new wells
- Provide calibrated velocity volumes to well picks ensuring more accurate structural surfaces are produced.
- Depth uncertainty products provide an estimation on the amount of depth uncertainty to expect in drilling a new well path.
- Well Drop out analysis provides a measure of the accuracy of the model generated.
- Easy to use graphical interface, with a recorded history, does not require an expert to operate.
A prime visualization scheme allows for a more thorough understanding of complicated reservoir conditions with the integration of fault geometries and unit thickness variations. Further, the cross-plotting of quantitative data can be created and connected within the confines of a 3D/4D visualization package such as CoViz 4D. These cross-plotting and data integration benefits can be assessed with the velocity models, giving users greater insight into the integrity of the resulting calibrated velocity mode.
Enhancing Velocity Modeling
When leveraging the velocity modeling module within CoViz 4D, users can create an unfaulted structure model from interpretive time horizons, reviewing results during each stage. The structural models outline the zones in which instantaneous velocity or interval velocities receive inputs, and the zones can have seismic velocity volumes, velocity constants, and velocity trends that can be rendered in a mathematical expression. All zones can also be specified, or the seismic volume can be made to cover a wide array of zones.
Then, users can achieve an average velocity domain within the time domain, derived from instantaneous parameters, giving analysts the ability to depth convert the time horizons contained within the structure model, providing the depth model. After, analysts will get a repeated process that takes into account each depth-converted surface to calculate a scaling view, stemming from the layering residuals. The scaling factors undergo a gridding process and are fed back to the instantaneous velocity model, adjusting the velocity that was used to depth convert the layering.
The new average velocity volume is produced with every iteration, with all layers and zones processed, providing a corrected velocity volume within the well. After the process, the average velocity volume has been adjusted accordingly to reflect the seismic picks, with the workflow outputs reflecting the following:
- a detailed before and after residual
- 3D mapping of the scaling attributes
- the showcasing of assorted velocity volumes
The velocity model function is accessible using a velocity modeling tab in the drop-down menu of CoViz 4D. Users can also create a new velocity project and choose from three types of velocity: average velocity, interval velocity, or Z2D calibration.
Structural Interpretation of Seismic Data for Oil Exploration using CoViz 4D
The cross-correlation and integration of geologic and petrophysical data into the velocity model will aid professionals during structural interpretation of seismic data for oil exploration. The well data provided can be viewed with added clarity in a velocity modeling regimen provided by CoViz 4D, enhancing the overall clarity of the structural interpretation.
CoViz 4D can create depth calibrated velocity volumes coupled with ancillary products such as depth uncertainty and well drop out analysis.
CoViz 4D can create depth calibrated velocity volumes coupled with ancillary products such as depth uncertainty and well drop out analysis. Such products provide integrity to the velocity volumes generated allowing management to plan with confidence new wells and renewed assurance of the reservoir’s reserves. With CoViz 4D, asset teams can integrate all relevant data to obtain a comprehensive view and analysis of a field, lessening the chance for data misinterpretation and missed vital pays that could have contributed to production goals.