Transcript Document
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’