COSI 2007 03 Mining Subterranean Fragmentation and Dense

COSI 2007 -03 Mining Subterranean Fragmentation and Dense Slurrying of Oilsand Project Investigators M. G. Lipsett D. S. Nobes Project Team M. Evans A. Lam A. Kotchon K. Draganiuk

Subterranean Fragmentation and Dense Slurrying Project • Objectives • Recent Progress • 1) to study the feasibility of an underground method for accessing a deposit of intermediate depth, fragmenting the oilsand in a zone, and producing a dense slurry or lean froth, including a review of the previous work in underground mining of oilsands and depositing paste backfill; and • • Fragmentation study: Cutting tests completed in pressed oilsand blocks Rheological study: testing completed on effects of dynamic pressure on non. Newtonian fluids, bitumen, and bitumen and sand (as an alternative to cutting or jetting) Two theses, two publications, and final report in preparation 2) to conduct preliminary tests of candidate fragmentation techniques on engineered and actual oilsands. MG Lipsett DS Nobes COSI Deep Frag & Dense Slurry

System Concept • • Horizontal drilling used to gain initial access to the ore region Articulated tool creates cavity by milling at progressively larger radius and outward spiral path Semi-cylindrical cavity is fluid filled and pressurized to reduce the risk of rockfalls Milled ore enters the tool with the working fluid or falls to floor Baffles and internal volutes direct slurry to an internal pump Slurry in sump must be fluidized Progressive cavity pump pushes slurry to the surface

System Concept (2) Closed Tool Partially Extended Tool

Fragmentation Study • Investigating methods for fragmenting material using a soil-engaging tool • Experimental apparatus developed & calibrated • Samples prepared by pressing co-milled oilsand • Dry, wet, and frozen samples with one tool geometry

Experimental Apparatus Development • Cutting models – Parameters from dynamic soil cutting model for shear strength estimation – Milling models to provide necessary parameters to estimate machinability

Experimental Apparatus Development (2) • Controlled variables – Depth, rotational speed, linear tool speed, tool geometry, oil sand type, temperature, wet/dry • Measured variables – Force, torque • Calculated variables – Material removal rate, cutting energy, horsepower at cutter/spindle, power, feed per tooth

Oilsand Milling Apparatus Tachometer Torque Cell (wireless) Cutting tool in holder (currently a commercial 2 -flute end mill) Sample Holder (on rails to constrain some motions) with axial load cell

Test Matrix

Oil Sand Samples • Athabasca oil sand compressed into 25 cm x 15 cm x 8. 9 cm blocks – Bitumen content – Solids content – Water 11. 4 % 84. 5 % 4. 1% • Blocks sealed in impermeable pouches and placed in a freezer for storage • Sample thawed and then mounted in support frame for cutting experiments

Oil Sand Sample Preparation cont’d • Scanning electron microscopy images – To visualize internal microstructural features of the oil sand blocks – Compaction appears similar to that of unfragmented oil sand

Cutting Tests – Still Images

Cutting Tests – Video Clip

Dry & Wet Cutting Tests 1 Dry Force vs Feed Wet

Dry & Wet Cutting Tests 2 Dry Torque vs Feed Wet

Frozen & Thawed Cutting Tests 1 Frozen Force vs Feed Thawed

Frozen & Thawed Cutting Tests 2 Frozen Torque vs Feed Thawed

Cutting Tests – Summary 1

Cutting Tests – Summary 2

Cutting Tests – Findings Controlled parameter Force Torque When increasing feed rate Increases Constant When increasing rotational speed Increases Cutting condition Force Torque Dry Increases Constant Wet Decreases Constant Frozen Increases Constant

Analytical Modeling • Steady-state cutting force model • Feed rates are within a fairly narrow range (mm/s) • Higher feed rates (m/s) should be tested for more representative data to validate model – Redesign of torque transducer would be required – Faster mill bed driving mechanism

Model Compared to Data

Sources of Error • Equipment – Fluctuations in rotational speed – Only a modest range of linear speeds possible • Milling process – Electrical interference – Cutter runout – Heat transfer from cutter • Sample preparation – Difficult to ensure uniform properties

Industrial Scale-Up • Cutting forces in milling operations can only be scaled up with confidence with wider range of testing conditions (faster speeds, additional cutter types, realistic ore types and interburden)

Rheological Study • Identify quantitative/qualitative effects of acoustic stimulation on the viscosity of bitumen and oil sand • Specifically effects of stimulation: – Amplitude – Frequency – Duration

Test Matrix Fluid Name Fluid Behavior Temperature [°C] Static Pressure [psi] Acoustic Amplitude [±psi] Acoustic Frequency [Hz] N 2500 Newtonian 20, 40, 60, 80 0, 200, 400, 600, 800, 1000 100, 200, 400 5, 10, 15, 20 Bentonite & Water Non-Newtonian (pseudoplastic) 20, 40, 60, 80 0, 200, 400, 600, 800, 1000 100, 200, 400 5, 10, 15, 20 Cornstarch & Water Non-Newtonian (dilatant) 20, 40, 60, 80 0, 200, 400, 600, 800, 1000 100, 200, 400 5, 10, 15, 20 Bitumen Non-Newtonian (pseudoplastic) 80 0, 200, 400, 600, 800, 1000 100, 200, 400 5, 10, 15, 20 Oil Sand Suspected Non. Newtonian (pseudoplastic) 80 0, 200, 400, 600, 800, 1000 100, 200, 400 5, 10, 15, 20

Final Experimental Apparatus • Controls – Temperature – Pressure • Amplitude • Frequency • Duration • Measures – Temperature • Radial Profile • Axial Profile – Pressure – Viscosity • Other • Fully automated control and logging

Experimental Apparatus (2) Mounting Bracket Water Jacket (Temperature Control) Pressure Measurements Sample Containment Viscosity Measurement Temperature Measurements (RTD) Hydraulic Piston (Static & Acoustic Pressure Stimulation)

Experimental Apparatus (3) Actual Apparatus Installation Hydraulic Piston Motion (Video) Computer Control & Logging

Static Experiments • Commissioning and calibration of viscosity measurement over a range of static temperatures and pressures (N 2500 Calibration Fluid) 2 -D Representation 3 -D Representation (with interpolation)

Small Section of a Typical Acoustic Experiment Stage 1: Wait for temperature to stabilize at setpoint Start Acoustic Stimulation Stage 2: Begin acoustic stimulation at setpoint amplitude/frequency for a controlled duration Stop Acoustic Stimulation Stage 3: Cease acoustic stimulation. Allow viscosity to recover (observe thixotropic or rheopectic effects) Stage 2 Stage 3 Stage 1 Repeat cycle at next setpoint amplitude and frequency

Acoustic Experiments (1) N 2500 Calibration Fluid Values below this threshold line indicate a viscosity reduction due to acoustic stimulation Conclusion: No appreciable effect of acoustic stimulation on viscosity of N 2500

Acoustic Experiments (2) Bentonite & Water (20°C) Threshold line is there but barely distinguishable ± 400 psi caused physical degradation of the fluid (and permanent viscosity reduction) Conclusion: Significant viscosity reduction seen at greater acoustic stimulation amplitudes

Acoustic Experiments (3) Bitumen (80°C) No viscosity readings beyond the threshold line 60 C was attempted, but outside range of viscometer Conclusion: No appreciable effect of acoustic stimulation on viscosity of bitumen at 80 C

Acoustic Experiments (4) Oilsand • At temperatures and pressures tested to date, oil sand samples have been too viscous for accurate measurement • Testing will be attempted with more bitumenrich samples

Summary - Acoustic Experiments Test Fluid Change in Viscosity due to Acoustic Stimulation? (Y/N) Details N 2500 No Viscosity Reduction Effect of Amplitude Effect of Frequency Effect of Stimulation Duration - - - Negligible Asymptotic viscosity decline over time Reduction ∝ Amplitude Bentonite & Water Yes Bitumen (80 C) No Only Tested at 80°C - - - Oil Sand TBD TBD TBD Permanent reduction at large amplitudes

Conclusions 1. Acoustic Stimulation can have an effect on the viscosity of fluids. When present, response to acoustic stimulation: • In our experiments, does not seem to be affected by: – Newtonian or Non-Newtonian fluid classification – Stimulation frequency • Does seem to be affected by: – Stimulation Amplitude – Stimulation Duration 2. Data thus far shows no appreciable effect of acoustic stimulation on the viscosity of bitumen therefore: • At temperatures around 80 C, acoustic stimulation can be discarded as a viscosity reduction technology for the production of shallow depth oil sand reserves

Recommendations for Future Work • Three options for cutting head: additional experiments should be done to characterize cutting forces and validate cutting model for prototype cutter design • Combined water jet & cutter should be tested • Consumable casing requires development & tests • Ground support to prevent roof collapse will have to be developed, modeled, and tested – brine freezing could be considered • Dense slurry pumping from depth requires design & tests • Paste backfill geotechnical stability requires development and tests • System basic design should be done, economics revisited