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The AAPG/Datapages Combined Publications Database
Houston Geological Society Bulletin
Abstract
Abstract: Case Study:
Highest Possible Resolution (HPR) Stratigraphic
Imaging of a Deep Reef Platform
1N. S. Neidell and Associates (Speaker)
2Starboard Energy
3President, Monoco Petroleum Inc
To illustrate the use and benefits of Highest Possible Resolution (HPR) Stratigraphic Imaging, we present a case study using
a small
3D survey over an onshore reef platform which lies at a depth greater than 15,000 feet. The views offered by the imaging from time
slices and vertical sections offer remarkable direct insights into the development of the reefs on the platform, their hydrocarbon
potential, the cyclic development of the carbonate lithology, shales and anhydrites, and the correlation with the well control. Seismic
images (time slices) in this case look remarkably like modern aerial photographs over reef complexes. The study is significant in that it
readily identifies and explains a high-volume producing gas well and a well that was deemed non-commercial.
Holographic principles applied to seismic imaging produce results having significantly broader band-widths and higher resolution than conventional signal-processing methods. Low-energy boundaries which are sharp and have great lateral continuity allow imaging to extraordinarily high frequencies. Boundaries from high-energy environments showing vertical grading and Fresnel scale lateral variations would have much lower resolution by their nature. Such imaging is termed HPR imaging and actually can estimate depositional energy.
HPR imaging typically produces results having anywhere from 8 to 32 times standard pre-stack imaging outputs in terms of samples. Resolution increases by factors of three or four are typical, although greater factors can be attained as one might expect in low-energy depositional environments.
Inversion displays of velocity
are produced
using
an Extended Visual Dynamic Range Color
format and present five times the information of typical color displays and 25 times more
than black-and-white data presentations. These displays aid significantly in recognizing
lithology, geopressure, porosity, and possible hydrocarbons, particularly in high-
velocity
or
consolidated lithologic conditions.
Figure 1. Great Barrier
Reef Source: ABC News
The seismic displays are readily interpreted on workstations using
standard geological principles and ideas. Lithology identification,
fluids, and other features can be noted with clarity and resolution with a fair degree of confidence based on the known correlations.
These displays are contrasted with conventional views, which, as noted, offer far less insight and information.
Particularly noteworthy is, that by increasing seismic resolution by a factor of three or four, results better approximate the relevant geological
scale, and from 17 to 23 cycles of reef development can be recognized. Dramatic displays are seen where the velocity
range
related to the particular age carbonates are isolated. The resulting “aerial” views via the time slices show tidal channels, atolls, and other
features. Another dramatic series of displays can be developed indicating where gas is most likely
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to be found. This is accomplished
by coloring in black the
velocity
most likely to indicate
porosity with gas presence.
The high-resolution displays of
the reef platform, by its nature
as a high-velocity
carbonate
environment at fairly significant
depth, demonstrate that the
method is robust and can perform
well in a circumstance that
most would agree offers some
challenges. HPR Imaging has
proved itself yet again to be a
most useful interpretive tool
under another set of geologic
conditions.
Figure 2. Time slice –
possible gases.
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