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
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.
Final Report - [PDF-6050KB]