DUSEL
Working Group #9
Preliminary Outline
by
François Heuzé & Jean-Claude Roegiers
Blackburg, Virginia – Nov. 2004
DUSEL national security opportunities
_______________________________________________
Based on the knowledge of DHS, DOD, and DOE programs, there does
not seem to be a need for access to a DUSEL-type facility in order to
conduct national security projects
Note that:
• the national security community already has its own dedicated
underground and surface facilities in rocks at the Nevada Test Site, at
the White Sands Missile Range, and elsewhere
• activities at those facilities often are not compatible with a science
laboratory because of the use of high-explosives, because of
classification, etc…
See-ahead of the bit
• Goal:
Develop technologies required to probe rock formations
conditions ahead of the drilling bit
•Background:
* When encountering unexpected geological conditions, drilling
costs are soaring; can even loose the well
* Safety hazards (overpressured gas)
* Deep Penetrating Radar & Acoustic Tomography have had
limited success
See-ahead of the bit (contd.)
• Proposal:
* Critically review existing technologies (seismic, electrical,
magnetic, …) in view of borehole applications in harsh
environments of pressure and temperature
* Develop miniature downhole warning sensors
• Uniqueness:
A well-characterized underground site will allow the evaluation
of the new-developed sensors. In addition, ‘special conditions’
can be ‘infused’ in limited portions of the rock formation (e.g.
excess pore pressure) to see if it could be detected.
Bottom Hole Assembly Vibration
•
Goal:
To develop tools and techniques to detect lithology changes while
drilling, using the BHA vibration signatures
•
Background:
* Bit wear due to excessive vibrations
* Drilling parameters (weight-on-bit, torque, pressure, …) have to be
adjusted/optimized for each formation characteristics
* Directional bit steering …critical to stay ‘in formation’
* Unnecessary expensive tripping
* Lab results, measuring forces and moments at the bit face on
single PDC crystal, at Montana Tech, have been encouraging
Bottom Hole Assembly Vibration (Contd.)
•
Proposal:
* Develop a diagnostic tool to interpret, in real time, the variation in
cutting forces. Neural networks?
* Develop a dynamic rock/bit interaction model that includes BHA
vibrations
* Test those development in a well-characterized site
•
Uniqueness:
* Access to rock formations being drilled, instead of being
limited to cuttings & logs …rarely core
* Full-scale experiments
* Lithologies under different in-situ conditions
* Only relatively short holes necessary to validate the concepts
Gas Storage & Sequestration
•
Goal:
Develop methodologies to turn abandoned mines in low
permeability rocks into gas storage facilities; including monitoring
•
Background:
* Unpredictable consumption and supply. National security
* Clean energy source
* Present storage in depleted reservoirs and salt solution cavities,
but…pressure limited & cycling limit. Hutchinson, KS explosion
* Abandoned mines have larger storage capacity…unacceptable
leakage rate (Champagne effect?).
Gas Storage & Sequestration (Contd.)
•
Proposal:
* Develop a full inventory control model that includes all physical
phenomena (compositional gas, gas behavior, thermodynamic
effects, phase separation, condensate, heat and mass transfer)
* Understand loss of gas to surroundings
* Rock creep reducing storage capacity
* Cyclic pressurization and fatigue failure studies
•
Uniqueness:
Ability to isolate a chamber, pressurize it and monitor it over time
Hydraulic Fracture Propagation
•
Goal:
Understand mechanism that control fracture propagation in
fractured media
•
Background
* In-situ discontinuities affect propagation (mineback, outcrop)
* Offset magnitude is unpredictable from full containment to nil
* Affects mostly transportation phenomena (proppant placement);
hence, production increase
* Crack arrest lab experiments presently conducted at CSIRO,
Melbourne.
* Material property contrasts? Discontinuity behavior?
Hydraulic Fracture Propagation (Contd.)
•
Proposal:
* Theoretical modeling of a propagating fracture in a bi-material
* When does the pre-existing discontinuity “feel” the approaching
fracture? And inversely?
* Additional controlled laboratory crack arrest experiments need to
be performed, but under polyaxial loading conditions to provide
additional data on size effects when compared to field
•
Uniqueness:
* Access to well-characterized site (discontinuities, intact rock)
* Ability to drill from existing workings in chosen direction(s) with
respect to regional/local in-situ stress tensor condition
* Mineback + large scale underground direct shear tests
Drilling Optimization
•
Goal:
Develop ‘downhole intelligence’ in order to optimize penetration
rate
•
Background:
* More ‘difficult reservoirs’ are being developed
* Present technology of ‘measurement-while-drilling’ limited by
transmission rate through drilling mud
* Trial-and-error is still the approach used in the field
* Reason(s) for reduced penetration rate?
Drilling Optimization (Contd.)
•
Proposal:
* Develop fiber optic components to illuminate borehole bottom
* Use fiber optic recent developments to measure pressure,
temperature, fluid vs. particle motions.
* Develop ‘downhole’ package capable of making decisions, based
on continuous data acquisition
* Take preventive action if ‘unusual’ conditions are encountered
•
Uniqueness:
Capability to drill a number of holes between existing drifts and/or
various horizons in an environment of wellknown geology
Seismic detection & Characterization of Discontinuities
•
Goal:
Test existing and develop new methods for seismic detection and
characterization of rock mass heterogeneities
•
Background:
* Heterogeneities may result from lithology, pore fluid, saturation,
porosity, pore pressure, in-situ stress
* Resolution = f (wavelength/scale of heterogeneity, travel time)
* Interpretation is far from unique
Seismic detection & Characterization of Discontinuities (Contd.)
•
Proposal:
* Develop approach to compute dispersive characteristics of P- and
S-waves as well as their attenuation for various types of media
* Provide numerical modeling of frequency characteristics of body
waves for various media
* Explain surface seismic data and distinguish types of attenuation
•
Uniqueness:
* Provide a highly controlled environment for model verification
* Investigate scaling effects by comparing data with lab tests
* Facility to change fluid composition/pressure in fractures, at least
locally
* Added flexibility to study influence of frequency, compared to
borehole access
Conclusions
•
A number of practical applications would definitely benefit from
access to an existing underground facility
•
Ideally, this facility should be located in a fractured sedimentary
formation, where pore pressure effects could be simulated and
coupled effects are taken into account
•
When fully operational, such a facility will be attractive to industry,
especially to validate new developments and procedures
but… confidentiality issue
NECESSARY TO QUANTIFY POTENTIAL ‘RETURN-ON-INVESTMENT’