Optimized use of 3D VSP data in anisotropic model building for depth imaging

Improved imaging at Thunder Horse South with joint surface and borehole seismic tomography

“…We decided to use all VSPs in the initial model validation stage at the beginning of the project. As discussed by Zdraveva et al (2017), model validation is the quality control and assurance step carried out after any modification of model parameters, either in the initial model building phase or during the iterative tomography or full-waveform inversion (FWI) loop of the EMB process. In cases with no well control, the main criteria used are the model's ability to produce: (1) well-focused seismic images with minimum residual curvature on gathers, (2) geologically plausible images, and (3) model property fields that are free of artifacts and consistent with rock physics and geomechanics.…”

“…In preparation for production EMB with the new OBN data, we conducted another proof-of-concept study to demonstrate the effectiveness of joint tomography of borehole and surface seismic data with simultaneous parameter updates (Zdraveva et al, 2017) in a global sence. We used one ZO, two WA and one 3D VSP at Well 822-3.…”

“…We first present the necessary quality control and data preparation steps required to ensure that the different data sets to be used in joint tomographic inversion carry the same information in regard to the earth model properties. Secondly, we discuss using joint tomography of surface seismic and borehole seismic data with a simultaneous parameter update (Zdraveva et al, 2017) in this project and how it complements the overall earth model building (EMB) strategy. Finally, we show that the new earth model yields improved borehole and surface seismic images over THS that better-resolve the structural and stratigraphic details and, therefore, represent a better starting point for future interpretation, and fine-tuning THS field-development plans.…”

Joint Inversion And Cross-Validation Of Bore-Hole And Surface Seismic Data For Reducing The Uncertainty Of Anisotropic Models

“…Bakulin et al (2010) used these types of updates for anisotropic parameter derivation in a local sense. The same approach for simultaneous update of multiple anisotropic parameters can be used in a global joint tomography scheme to fine-tune a model that is already reasonably accurate (Zdraveva et al 2017). To illustrate that, Figure 2a shows a 3D vertical seismic profile (VSP) transit-times misfit graph for a model that was built without the use of 3D VSP information.…”

“…Achieving all these objectives requires fairly accurate Earth model to be used in imaging of the 3D VSP data but, unfortunately, very often such data is processed and imaged separately and in complex media that may affect adversely the quality of the final images. Borehole seismic is often used in Earth model validation and for inversion of transit times to obtain anisotropic parameters (Li et al, 2015) but joint inversion with surface seismic data (Zdraveva et al, 2017) is not yet a common practice. We will illustrate the benefits of such joint inversion with an example from the Green Canyon area of the Gulf of Mexico.…”