GEOPHYSICS

Our geophysical research on fractures is led by Sergey Fomel with geological support from Randy Marrett, Peter Eichhubl and the rest of the FRAC team.  Our aim is better seismic methods and better calibration of seismic methods with subsurface geological information.

Starting in 2009, the focus of our effort is a program funded by RPSEA and supported by our industry partners. This program is titled:

Multiazimuth Seismic Diffraction Imaging for Fracture Characterization in Low-Permeability Gas Formations

Natural fractures provide pathways for the flow of gas to hydraulic fractures and to the well bore in many reservoirs. Despite progress in completion technology, prediction and detection of natural fractures prior to drilling or prior to well completion have remained elusive. This project develops novel techniques of predicting fracture occurrence and their attributes by combining seismic tools, fracture modeling, and fracture characterization based on wireline sampling techniques.

The development phase of our project (Phase 1) will create a novel diffraction-based method of detecting and characterizing background fractures and small faults. At the same time we will advance geomechanical simulation of natural fracture patterns and use these realistic fracture patterns, and patterns drawn from outcrop analogs, to calibrate the seismic method according to the realistic heterogeneity that we have shown to exist in low-permeability gas formations.

This aspect of the study will allow us concurrently to advance the unique core (rock sample) based methods we have been developing in order to verify and calibrate seismic methods for fracture characterization in real low-permeability gas formations. The validation/demonstration phase (Phase 2) will follow, in which the Phase 1 strategy will be put to practical test on real data sets and verified in the field. This phase will involve using our new approach to processing seismic data and our enhanced sidewall-core-based verification techniques to collect relatively dense subsurface fracture data throughout the seismic volume.

The techniques of natural fracture prediction and characterization developed in this project are expected to lead to more targeted completion strategies and optimized well spacing, with resultant reduction in water and land use for well development.

The multidisciplinary project team includes research staff and faculty at the Bureau of Economic Geology, the Department of Petroleum and Geosystems Engineering, and the Department of Geological Sciences at The University of Texas at Austin.

For more information on this aspect of the program, see the 2009 FRAC meeting slide set.