SR2020 routinely goes beyond the commonly offered modeling services, that are often cartoonlike and merely used as a sales tool. In contrast, our experience has repeatedly shown that, realistic sophisticated modeling is one of the cornerstones of a successful borehole seismic project. We continue to heavily invest in the development of new and more effective modeling algorithms focused on survey design solutions that can be tailored to the given geologic target. In addition, SR2020 is capable of conducting sophisticated R&D modeling activities for clients and we welcome the opportunity to participate in short or long-term cooperative applied technology development activities with our clients. Our team of scientists uses external, as well as, specialized in-house tools and highly accurate modeling algorithms. SR2020’s borehole seismic processing tools, developed over the last 15 years, allow us to solve complex survey design and modeling problems that include:
- Feasibility studies
Proof-of-concept detailed analysis ensures that the 3D borehole seismic technology is fit for purpose and provides risk analysis. In some cases the feasibility study involves evaluating variations in rock physics relationships, which are modeled all the way through the seismic acquisition and pre-stack depth imaging response. We judge the impact of various parameter choices on final images and the impact on every stage in the processing flow. The design of 4D time-lapse monitoring scenarios requires particularly careful and comprehensive modeling to ensure suitability for multi-year seismic programs.
- Survey optimization
Optimal source and receiver configuration are determined to solve the given imaging problem in the most cost-effective manner. The most appropriate grid layout is determined given the target properties of the zone to be imaged and any constraints due to surface accessibility.
- Extent and quality assessment
Two key questions need to be answered in modeling efforts, one is determination of the ultimate extent and shape of the high definition subsurface image; the other is the quality and reliability of the image for high definition interpretation. These questions are answered by constructing realistic complex velocity models and generating characteristic subsurface maps using dynamic 3D ray tracing (Norsar3D) that let us determine fold, angular aperture and other image space quantities. By analyzing these quantities we can reliably determine the quality of the resulting pre-stack migrated depth imagery.
- Tuning effects and resolvability
Detailed stratigraphic targets that exhibit thin layers, pinch-outs or other small scale features require the use of full wave form modeling. Full wave form data are generated from a high-resolution interval velocity model and tuning effects and other sub-wavelengths effects are realistically modeled with full wave form modeling algorithms. Key results typically include the determination of the frequency content/bandwidth needed to resolve particular structural features or amplitude anomalies of the target in the subsurface. Thus the source type, source bandwidth and radiation characteristics used in the acquisition program can be tailored to fall within the optimal range.
- Complex velocity model construction
Detailed structural and stratigraphic targets require the modeling and construction of a highly detailed subsurface model. Instead of analyzing cartoon-like simplified generic models, we construct a full 3D subsurface model from all available data in the survey area, such as well logs, formations tops, horizons, time-depth curves, surface seismic back ground models. The resulting highly realistic model can be used for 3D ray tracing as well as full wave form modeling. In the case of 4D time-lapse feasibility studies, rock physics relations can be incorporated and varied to produce realistic model scenarios. Once such a model is constructed it can be used not only in the survey design, but also as a starting model for field data processing, depth imaging shortening the delivery time for initial processing products.
- Synthetic data generation
Dynamic 3D ray tracing and full wave form modeling allow us to generate seismic data sets that can be processed as if they were collected in the field. Using this data we can efficiently assess the performance of individual processing steps or entire processing/depth imaging flows. Based on such results we can optimally tune processing parameters, even before the actual data are acquired in the field. In many cases, such assessments can lead directly to adjusting some data acquisition parameters in order to optimize the data quality and signal to noise ratio. The synthetic data set is also available during the processing of the field data, where it can be used for interpretive processing, event identification, noise assessment and other tasks. The pre-stack modeled data set and its pre-stack migrated image can be used as a reference when interpreting the actual image, increasing the interpreter’s confidence level in the identification of target formations and features.
- Fit-for-purpose imaging approaches
A comprehensive modeling approach allows us to explore particular survey geometries, acquisition or processing technologies. If 2D or 3D VSP geometries are found to be sub-optimal we can design acquisition programs that utilize novel interferometic imaging algorithms, such as multiple migrations, near-well interferometric imaging, salt-flank interferometric imaging, as well as virtual source techniques for deviated well geometries.