The Diagnostic 3D Seismic Process (D3DSP): OBJECTS vs. LAYERS
An Alternative (to the Layered-Earth-Model 3D Seismic Process) Method for Imaging, Measuring, and Evaluating
Buried "Common-Impedance Objects" (e.g., Petroleum Reservoirs)
Louis E. Willhoit, Jr.
VTV, LLC, Metairie, LA, USA
Light and matter both have a recognized and useful Wave-Particle duality. It is very difficult to devise any single experiment that will reveal both the wave-nature AND the particle-nature of either particles of matter (fundamental particles, atoms, etc.) or waves of light (electromagnetic radiation). But ample high-tech (commercial) evidence now exists that both Light and Matter share the properties of Matter and Light, respectively. We contend that the earth's seismic subsurface can be characterized by an analogous, Object-Layer duality. Tools and methods used to look for one characteristic of the subsurface ("traps" in faulted, dipping strata or layers) often obscure the evidence for the equally useful effects on the other side of the duality: Three-dimensionally localized Common-Impedance Objects (CIOs), some of which are found to be low-impedance "subtly trapped" reservoirs – or horizontal resource play "sweet spots". In this presentation, we use a Relative D3D (natural logarithm of the) Acoustic Impedance (aka, D3D-impedance) Volume from Blaine County, OK, to outline and compare both the D3D-processing sequence; and the resulting 55' × 55' × 1 ms (~9,' in carbonates; ~5' in clastics) Voxel/samples that comprise the resulting D3D-impedance volume. We will also present some early examples from South Timbalier Blocks 23 and 26, and Eugene Island Blocks 27 and 46, to illustrate this "Diagnostic" 3D Seismic Process that:
Recognizes all the historically useful, layer-assumptions made in acquisition, processing and interpretation; while it
Ignores and re-sequences the (re)processing steps, to accentuate the (3D-volumetric) object nature of the earth's subsurface.
Although conventional (3D, 4D, time and depth, pre- and post-stack, attributes, characterization, etc.) seismic processing flows are performed widely by many Seismic Processing Centers, today, it has always been a time-consuming, expensive, and imprecise way to convert seismic data, recorded over an Object-Filled-Earth, into a relatively smooth, faulted Layered-Earth-Model (using various attributes) data. The D3DSP has proven to be less-expensive, more-repeatable, and quicker-turnaround than the other methods, and the relatively low density and compressional-wave velocity (Acoustic Impedance, or AI) of petroleum-fluid-saturated porous rocks make clastic, carbonate, and igneous rocks (and "shales") all fair game for the use of the D3DSP ... to image, identify and evaluate buried CIOs. We will conclude with three other hard-rock examples:
- a "Basal Permian Carbonate Wash over 45-degree dipping Simpson Sands" Play (Kiowa Co, OK);
- a "Multi-Target Delaware-Sands-thru-Fusselman-Dolomite" Play (Lea Co., NM);
- an "Eagle-Ford-Shale-thru-Smackover-Oolites-thru-Norphlet-Sand-Dunes-on-Louann-Salt" Potential Resource Play (Smith/Cherokee Cos, TX).
This will be both a technical and seismic case history presentation. The technical portion will discuss differences in methodologies for conventional layer/trap/amplitude (and AVO) mapping, and the D3DSP, which works with the 3D shape and volumetric characteristics of CIO's (3D-objects), using volume visualization software (such as VoxelGeo). It also briefly summarizes some of the acquisition- and processing-preference differences between the D3DSP and conventional methods, and presents an outline of a post-stack D3D-processing sequence example, used in the Gulf of Mexico basin. A much fuller description is given in my U.S. Patent write-up, available at www.vtvllc.com.
AAPG Search and Discovery Article #90206 © AAPG Hedberg Conference, Interpretation Visualization in the Petroleum Industry, Houston, Texas, June 1-4, 2014