The goal of this project is to develop a next-generation fracture detection and characterization technology for producing natural gas from low permeability formations.
University of Texas at Austin Bureau of Economic Geology
Location:
Austin, Texas 78713
The research proposed here combines a new seismic shear wave (s-wave) imaging concept for 3-1 acquisition geometries with a new microfracture based analysis technique of oriented sidewall cores. This is the next-generation technology for detecting and characterizing subsurface fractures. The seismic component of this research is an approach that abandons the conventional industry practice of using Alford rotation to create fracture-sensitive s-wave images in 3-D geometries. Our investigation of existing industry practice leads us to conclude that data processing techniques, that separate s- waves into fast and slow modes in 3-D geometries, are fundamentally flawed. We propose that a new data- processing model, based on SH and SV mode concepts, be used in 3-D imaging of s-waves. This model is leading us to a new data-processing technology for detecting fractures when s-waves are recorded by 3-1 seismic templates. The seismic calibration portion of the research relies on collecting sidewall cores and then observing and classifying micro-fractures to calibrate fracture-sensitive seismic attributes.
This research used a new seismic shear-wave (s-wave) imaging concept for 3-D acquisition geometries for detecting and characterizing subsurface fractures. An unexpected change in an industry partner resulted in no core being available for microfracture studies. A new data-processing model based on SH and SV mode concepts were used for 3-D imaging of shear waves. Seismic data acquired across a fractured carbonate reservoir system illustrate how 3 component 3-D seismic data can provide useful information about fracture systems. Fast-S and slow-S data are used to illustrate how these effects can be analyzed in the prestack domain to recognize fracture azimuth, and then demonstrate how fast-S and slow-S data volumes can be analyzed in the post-stack domain to estimate fracture intensity.
The key observations from the study were:
and Remaining Tasks:
A final project report detailing activities of the project’s Phase I and II activities is available.. The report is titled, “Combining a New 3-D Seismic S-Wave Propagation Analysis for Remote Fracture Detection with a Robust Subsurface Microfracture-Based Verification Technique,” June 6, 2000–December 31, 2003, Principal Authors: Bob Hardage, M. M. Backus, M. V. DeAngelo, R. J. Graebner, S. E. Laubach, and Paul Murray, Report Issue Date: February 2004.
$599,367
$170,800
NETL – Gary Sames (412-386-5067 or gary.sames@netl.doe.gov)
UTA – Robert Hardage (512-471-1534 or bob.hardage@beg.utexas.edu)
Final Report - [PDF-6050KB]