Seismic physical modeling I: Acquisition of 2D and 3D surveys involving HTI targets

Joe Wong

Scaled-down physical modeling of 2D land and 3D marine seismic surveys has been carried out over two models. Model #1 consists of a Plexiglas layer overlying a smaller rectangular prism of HTI phenolic material. Model # 2 is more complex, consisting of a PVC layer overlying an Plexiglas layer with HTI cylinders of various diameters and directions of HTI symmetry axes, both overlying a second Plexiglas layer with a cut channel. The land surveys were done using different combinations of P-type and S-type piezoelectric transducers. These surveys were done to produce research datasets that are available to CREWES sponsors, staff, and in particular graduate students.

The marine surveys were conducted using piezopin transducers as sources and receivers. Several acquisition techniques employing single sources and single receivers, and arrays of multiple sources and multiple receivers, were tested to explore how different combinations used in different ways affected survey efficiency. Eight sources firing simultaneously into a single or an array of multiple receivers significantly increased acquisition speed. This procedure produced datasets consisting of super gathers that are the equivalent of the sum of eight separate common-source gathers. Standard migration techniques require that each super gather be deblended to yield eight separate common source gathers. Depending on the area covered, 3D surveys using super-gather acquisition were completed in 6 to 22 days. Each 3D deblended dataset contains on the order of half a million to two million individual seismograms.