Oil & Natural Gas Projects
Exploration and Production Technologies
Integrating P-Wave and S-Wave Seismic Data to Improve Characterization of Oil
This project was selected under the Historical Black Colleges and Universities
The research was conducted to produce 3-D vector-wave field images of geologic
systems and then to analyze these 3-D images to determine what new geologic
information can be determined by combining a shear (S)-wave based seismic stratigraphy
interpretation with a compressional (P)-wave-based seismic stratigraphy analysis.
Prairie View A & M University
Prairie View, TX
Bureau of Economic Geology
University of Texas
The internal complexities and heterogeneities within an oil reservoir can be
characterized with seismic stratigraphy. Traditionally, most oil reservoir characterization
studies are done with only compressional P-wave seismic data. This project demonstrated
that the full science of reservoir characterization can be achieved by incorporating
the principles and application of vector-wave field seismic data in which geologic
systems are interpreted using both P-wave and S-wave images of subsurface stratigraphy.
This is because sometimes spatially coincident P and S seismic profiles do not
show the same reflection sequences or the same lateral variations in seismic
The utilization of full-elastic seismic wavefield can be maximized in oil and
gas exploration using knowledge of 9-component (9-C) seismic profiling in order
to optimize the search for hydrocarbons.
The data used in the study were acquired by 9-C vertical seismic profile (VSP)
using three orthogonal vector sources. The 9-C VSP is capable of generating
P-wave mode and the fundamental S-wave mode (SH-SH and SV-SV) directly at the
source station and permits the basic components of elastic wavefield (P, SH-SH,
and SV-SV) to be separated from one another for the purposes of imaging. Analysis
and interpretation of data from the study area show that incident full-elastic
seismic wavefield is capable of reflecting four different wave modes-P, SH,
SV and C-that can be utilized to fully understand the architecture and heterogeneities
of geological sequences. The conventional seismic stratigraphy utilizes only
reflected P-wave modes. The notation SH mode is the same as SH-SH; SV mode means
SV-SV and C mode, which is converted sheer wave is a special SV mode and is
the same as P-SV.
The research program was designed to attempt to answer the following questions:
- How are seismic vector-wave field data to be processed?
- How do these S-wave stratal surfaces differ from P-wave stratal surfaces?
- Do S-wave reflection data provide a different model of sequence relationships?
- How can P-wave and S-wave images be combined to create unified geologic
- How can 9-C VSP data be used to define equivalent sequence boundaries in
P-wave and S-wave images?
The 3-D, 9-C data were recorded using midpoint imaging concepts that are standard
practice in the oil and gas industry. Three orthogonal vibrators were used to
generate a 9-C VSP-vertical, inline horizontal, and crossline horizontal. The
geometry of the three orthogonal vibrators created stacking bins measuring 110
feet x 82.5 feet across the image space, with a stacking fold of 20-24 in the
full-fold area of each data acquisition grid. The recording template that moved
across the image space consisted of six parallel receiver lines, each spanning
96 receiver stations. Three-component geophones were deployed at each receiver
station of this 3-D grid. Each receiver string deployed at a receiver station
contained three 3-C geophones, and all three geophones were positioned in an
area spanning 3-5 feet to form a point array. The geophones were planted carefully
to position one horizontal element in the inline direction (the direction in
which the receiver line was oriented) and the second horizontal element in the
crossline direction. Large (52,000 lb) vibrators were used to generate the 9-C
These four wave modes image unique geologic stratigraphy and facies and at
the same time reflect independent stratal surfaces because of the unique orientation
of their particle-displacement vectors. As a result of the distinct orientation
of an individual mode's particle-displacement vector, one mode may react to
a critical subsurface sequence more than the other. It was also observed that
P-waves and S-waves did not always reflect from the same stratal boundaries.
The P- and C-waves are capable of imaging different stratal surfaces because
P and C modes have different reflectivities at impedance boundaries. It was
observed that it is possible for either P or C mode to have a zero or near-zero
reflectivity at a given stratal geologic surface, while the other mode has a
It was concluded that, in a complex geologic environment, it is necessary that
the sedimentary record be described by one set of P-wave seismic sequences (and
facies), and by a second, distinct set of S-wave sequences (and facies). The
application of both P-and S-wave images to oil reservoir characterization is
the current trend in most oil and gas companies and will sooner or later overtake
the conventional seismic stratigraphy of only P-wave imaging.
Current Status (October 2005)
The project is complete.
Project Start: September 1, 2000
Project End: August 31, 2004
Anticipated DOE Contribution: $183,483
Performer Contribution: $0 (0% of total)
NETL - Purna Halder (email@example.com or 918-699-2084)
Prairie View - Innocent Aluka (firstname.lastname@example.org or 936-857-4510)