|
1.0 Executive Summary
Overview: UT GeoFluids will study the state and evolution of pressure, stress, deformation and fluid
migration through experiments, theoretical analysis, and field study. The
Bureau of Economic Geology (BEG) at the Jackson School of Geosciences will
partner with the Department of Civil and Environmental Engineering at MIT: BEG
will lead the consortium.
Experimental: We will analyze
the fabric, acoustic, electrical, and mechanical properties of mudrocks over
effective stresses from 0.1-100 MPa. We will study 1) real geologic materials
(Gulf of Mexico mudrock, Boston Blue Clay) using resedimentation techniques and
2) core from a range of depths in the subsurface. Analysis of resedimented
material allows us to examine material properties of a consistent material at a
range of in-situ stresses. Uniaxial consolidation experiments will measure
vertical and lateral stress, resistivity, permeability, and velocity (Vp &
Vs) during compression. Triaxial experiments will measure strength parameters.
We will describe and quantify mudrock fabric at various effective stresses with
mercury porosimetry, and x-ray goniometry and image mudrock fabric using
electron beam techniques. We will 1) illuminate the origin and evolution
anisotropy in mudrocks, 2) document how composition (e.g. clay/silt fraction
and clay composition) controls geomechanical properties, and 3) develop a
geomechanical model for mudrocks that will better allow us to predict
compaction behavior, pore pressure, and borehole stability at geologic
stresses.
Poro-Mechanical
Modeling: We will develop and apply models that link realistic rheologies, deformation,
stress (shear and normal), and pore pressure. Pressure prediction techniques
and basin modeling generally assume uniaxial deformation. In areas of central
interest to the petroleum industry, deformation is not uniaxial and stress and
pressure are coupled in more complex ways. In thrust belts, the lateral stress
is greater than the vertical stress and sediment that was originally buried in
a basin under uniaxial strain is later deformed in plane strain. In the
sub-salt regime, the interaction of isostatically stressed salt with sediment
that bears differential stresses results in complex stress and deformation near
the salt-sediment interface. To understand and ultimately predict pressures,
stresses, and rock properties in these regimes, a new level of understanding,
modeling, and analysis must be applied.
Field Study: We will
analysize pore pressure in thrust belts and in salt provinces. In the subsalt,
we will analyze pressure and stress in and near the Mad Dog field to understand
how pore pressure couples with salt advancement and to study the present state
of stress and pressure in sub-salt systems. We will study fold thrust systems
through ongoing work in the Nankai Trough. We look forward to working with
industry data sets in deepwater fold-thrust belts.
Importance: Despite
extensive previous work exploring mudrock compressional behavior, there are
still major gaps in our understanding of mudrock evolution. We do not yet have
an understanding of stress and strength behavior over a large range of effective
stresses (0.1-100 MPa) and we do not fully understand the evolution of
anisotropy. Our work will lay the groundwork for a new generation of basin
modeling algorithms and pressure/stress prediction techniques. This new
generation of modeling techniques will go beyond the restrictive assumption
that deformation is uniaxial. Instead, we will couple reasonable assumptions
about far field stress state with rheological models to predict stress and
pressure. The results will allow us to better predict pressure, stress,
borehole stability, and hydrocarbon migration in environments critical to
exploration: thrust belts and sub-salt.
Reporting: The Consortium
will 1) hold Annual Meetings, 2) provide Annual Reports, 3) develop an on-line
database of experimental results, 4) provide Company Visits, and 5) provide
Notice of Papers Submitted for Publication.
Research
Team: The Consortium Team will include Peter Flemings (UT), Ruarri Day-Stirrat (UT), John Germaine (MIT), and Derek Elsworth (Penn State). We envision
supporting 10 graduate students and 3 post-doctoral scientists at 3
universities.
How
Much?
Start
Date: June 1, 2009
Duration: 10 years
Cost: $45,000/year
Project
Director: Peter B. Flemings, Geoscientist and Professor
pflemings@jsg.utexas.edu
512-750-8411
(w) |
