Seismic diffraction imaging on pre-existing seismic data to predict fracturing in unconventional reservoirs

Abstract

The pre-drill knowledge of natural fracture swarms and small offset faults is very important as these geological elements can either help increasing the flow rate or can interfere with the drilling and fracking process and negatively influence the production rate. Seismic resolution from conventional reflection imaging is generally not sufficient to resolve these small scale rock properties. Diffracted waves are events that are produced by the scattering of a wave after it meets a discontinuity such as fracture swarms, small amplitude faults and karsts that cause local sharp changes in the geometrical or lithological characteristics. The MultiFocusing diffraction imaging technology uses the MultiFocusing concept to separate the diffraction component from the overall wave field. The amplitudes of diffracted waves are usually much weaker than those of specular reflections. Diffractions are essentially lost during the conventional processing/migration sequence, or they are masked in conventional seismic stacked sections. Local structural and lithological elements in the subsurface of a size comparable to the wavelength are commonly ignored during processing and identified indirectly during interpretation but not from direct measurements. We are able to show results of diffraction studies over 3 distinctly different study areas, the Levant Basin, Siberian Basin and North America.

AAPG Datapages/Search and Discovery Article #90193 © 2014 Rocky Mountain Section AAPG Annual Meeting, Denver, Colorado, July 20-22, 2014