Geophysical Data Systems LLC has been examining the potential applications of non-linear phenomena in seismic exploration since 2003, and has completed pilot land surveys (2D and 3D) and VSP surveys to test the proposed method. We completed pilot programs to provide an answer to several fundamental questions, i. e. to evaluate the significance of non-linear wavefield components recorded on the surface and in the wellbore as predictors of the properties of underground features, and first of all of petroleum reservoirs, the effect or non-linearity of vibrator signals and surface waves on recorded non-linear components, and the impact of non-linearity of source and surface waves to non-linear responses from actual geological features.

Many years of GDS research, with pilot exploration programs at several oil and gas fields confirmed that the vibroseis wavefields have noticeable non-linear properties that are primarily related to multi-component porous, fissured, permeable, and fluid-saturated rock and resulted in identification of major indicators of non-linear behavior associated with geological features. These include:

• Generation of harmonics and subharmonics
• Generation of combination frequency waves
• Disproportional changes in received signals in response to increased source signal energy

Applications:

• Prospecting, exploration and production optimization (in combination with conventional seismic surveys)
• Evaluation of reservoir rock properties
• Production monitoring

Employing such non-linear phenomena as generation of multiples and combination frequency waves and the independence of reflected wave amplitude paves the way to the development of new more economical survey, data processing and interpretation techniques.

The results of our work have been published in scientific journals and patented.