Perforation sealing and improved foam properties for controlled foam injection (CFI) fragmentation of rock and concrete

Abstract

Rock and concrete fracturing based on Controlled Foam Injection or Penetrating Cone Fracture (PCF) uses high pressure fluid to pressurize pre-drilled holes. A high pressure seal (18) is formed between the injection barrel (2) and the wall of the pre-drilled hole in the material to be fractured. A leak-tight poppet valve holds the fluid in the pressure vessel before rapid discharge. A variable charge of foam / water is generated and delivered to the fracturer. The injection barrel (2) is pre-filled with a low viscosity fluid. An annular reverse action poppet valve allows for the simultaneous injection of chemical additives and / or microparticles to change the foam viscosity during the release of high pressure into the material to be fractured. The high pressure foam generator (55) is compact and reliable. Removal of the seal and cleaning releases the injection barrel.

Description

Summary of the Invention

[0001] The present invention provides an improved method and apparatus for fracturing rock and concrete based on the Controlled-Foam Injection (PCF) or Penetrating Cone Fracture (PCF) method, in which pre-drilled holes of appropriate geometry are pressurized using high-pressure fluid. The present invention provides automated methods, apparatus, and techniques for forming a high-pressure seal between an injection barrel and the wall of a pre-drilled hole in the material to be fractured, and for removing and cleaning the seal to release the injection barrel from its location. An improved leak-free poppet valve retains the fluid within the pressure vessel and rapidly discharges it. Generating and delivering variable-volume foam and water charges to the fracturing machine involves pre-filling the injection barrel with a low-viscosity fluid. An annular reverse-action poppet valve allows for the simultaneous injection of chemical additives and / or microparticles to vary the foam viscosity during high-pressure release into the material to be fractured. The improved high-pressure foam generator configuration is compact, reliable, and allows for PLC control.

[0002] The present invention provides an improved continuous excavation / demolition system based on the controlled fracture of hard, tough rock and concrete via Controlled Foam Injection (CFI) and Penetrating Cone Fracture (PCF) techniques. Both the CFI and PCF techniques, outlined in commonly owned U.S. Patent Nos. 6,375,271 and 5,098,163, deliver pressurized fluid to the bottom of a pre-drilled hole in the material to be fractured. U.S. Patent Nos. 6,375,271 and 5,098,163 are incorporated herein by reference in their entireties as if fully set forth herein.

[0003] The efficiency of the CFI and PCF methods in terms of energy use is largely dependent on the effectiveness of the seal between the injection barrel and the perforation. In terms of operational efficiency, both methodologies rely on the ability to automate the operations of drilling the hole, installing the barrel and seal, and removing the barrel to achieve minimum cycle times.

[0004] To this end, the assignee developed a novel, fully automated sealing system. This new PLC (Programmable Logic Controller)-based pneumatic system automatically delivers sufficient sand directly into the sealing cavity. It also activates a hydraulic system to effectively crush the sand within the sand-filled cavity, forming a highly effective high-pressure seal.

[0005] Field testing has revealed the need to occasionally free the injection barrel from the host rock. It has been found that CFI fracturing occasionally leaves the injection barrel locked in a portion of the host rock that contains intact sand seal within the borehole. The present invention provides a means through the direct delivery of compressed air and pressurized water to flush out the remnants of the sand seal, thereby allowing the injection barrel to be removed from the borehole at will.

[0006] In this invention, an improved poppet is described that has a novel self-aligning conical valve seat that reduces leakage and improves operational durability and resilience to surface imperfections. By preventing premature leakage of pressurized fluid into the material being fractured, the possibility of accidental premature fracture is greatly reduced or eliminated.

[0007] The parent material being fractured varies physically in terms of porosity, parting plane structure, discontinuities, and composition. These differences can negatively impact fracture size, sometimes creating gaps large enough to cause incomplete fracturing of the host rock. To avoid this outcome, it is desirable to dramatically increase the viscosity of the foam as it moves through the fracture so that high foam injection pressures can be maintained. The present invention describes a unique annular poppet device capable of simultaneously injecting a pressurized stream of reactive liquid into the mainstream foam discharge, which then increases the foam viscosity.

[0008] The present invention provides both a method and apparatus for automating the formation and optional removal of high pressure sand seals without the negative penalties of manual operation and the resulting delays.

[0009] The present invention includes a programmable logic controlled (PLC) pneumatic sand delivery system capable of metering, transporting, and placing a sufficient amount of desired sand from a pressurized sand hopper into a sealing annulus or cavity. Both the sealing cavity and the sand are sized so that the cavity captures the sand and holds it firmly in place. Following sand placement, the PLC or operator can activate a hydraulic valve, which activates the crushing and compaction of the captured sand, forming it into a fine-grained, dense annular layer seal. This crushed sand layer creates a high-pressure seal that tightly secures the injection barrel within the borehole and prevents leakage between the bottom of the hole and the outside. By holding the barrel in place against the material to be fractured, recoil forces are minimized or eliminated, thereby reducing cyclic stresses on the conveyor and equipment.

[0010] The seal is effective even when the drilled holes are not round or uniform and are of varying diameters, all of which are realities in rotary impact drilling, and the new seal is effective in all such applications.

[0011] The sand is kept dry in a 100% humidity underground environment, and the dry sand is kept in a hopper.

[0012] The fixation of the injection barrel position provided by the sand seal has proven effective, occasionally necessitating techniques to free the injection barrel from the material being crushed. A preferred embodiment of the present invention provides a method and means for freeing the injection barrel by flushing out the crushed sand seal. The present invention incorporates port connections and valves within the apparatus to allow a combined flow of compressed air and pressurized water to be selectively delivered along the injection barrel toward the crushed sand seal ring. The turbulence and agitation of the combined flow, combined with the vibratory motion of the crushing tube, erodes and flushes out the exposed finely crushed sand, thereby achieving seal removal and barrel opening.

[0013] Leakage of pressurized fluid through a poppet valve into a sealed borehole can result in premature, unexpected, and sudden fracture of the parent material. To mitigate the possibility of such premature fracture, the present invention incorporates an improved poppet valve with a hard, conically-sectioned piston that automatically aligns against a softer mating conical seat. Under pressure, the harder poppet piston can mechanically deform imperfections in the seat surface to form an airtight seal against its mating surface, thereby eliminating subsequent leakage. The large surface area provided by the conical seat allows the poppet piston to conform to axial misalignment between them and be held in a stable position by fluid backpressure.

[0014] The footprint of the high-pressure foam generator is minimized by internally housing the viscosity enhancer injection device. In previous embodiments, this device was externally housed as an additional, slim piston / cylinder extension to the body. This shorter internal configuration eliminates this potential for failure and, in addition, limits concentric misalignment between the cylinder wall and the piston. [Brief explanation of the drawings]

[0015] [Figure 1]FIG. 10 is a detailed cutaway side view, in foreshortening fashion, of the injection barrel and grinding tube subassembly in a retracted position for automated sand delivery to the sand sealing cavity. [Figure 2] FIG. 10 is a detailed cutaway side view, drawn in foreshortening fashion, of the injection barrel and crush tube subassembly in the extended position, showing the device inserted into the pre-drilled hole after sand seal installation has secured the barrel in the host rock. [Figure 3] 1A-1C show side cross-sectional, perspective cross-sectional, and perspective views, and cross-sectional views, of the present PLC-controlled pneumatic sand delivery device. [Figure 4] FIG. 10 is a detailed cross-sectional view of the barrel and annular poppet valve for injecting a modifier into the main bubble discharge stream. [Figure 5a] 5A and 5B are close-up views of the annular poppet valve depicted in FIG. 4 with the piston seal in a closed and open position, respectively. [Figure 5b] 5A and 5B are close-up views of the annular poppet valve depicted in FIG. 4 with the piston seal in a closed and open position, respectively. [Figure 6] 1A-1C are three detailed cross-sectional views of a simplified poppet valve having a conical seat. [Figure 7] 7 is a perspective cross-sectional view of the same poppet valve depicted in FIG. 6 in a shortened manner, with a reduced number of parts. [Figure 8] FIG. 1 is a diagram of a dual action foam generating system having a pressure regulator capable of supplying foam to a breaker with variable gas quality and viscosity enhancer. [Figure 9] FIG. 1 is a cross-sectional view of a compact foam generating device with a piston core assembly at the center. [Figure 10] This is a schematic representation of the control. DETAILED DESCRIPTION OF THE INVENTION

[0016] The automated seal placement system includes the following elements: an air-pressurized sand hopper and metering device controlled by a PLC (Programmable Logic Controller), pressure-resistant hoses and conduits connecting the sand hopper to the crusher barrel shown in Figure 1, and seal cavities in the host rock formed in the gaps between the barrel, the expanded end of the barrel, and the perforations and the end of the crusher tube. Also required is suitable sand and a low-pressure compressor capable of delivering a steady, sufficient flow of compressed air to the system.

[0017] In one embodiment of the present invention, automated seal installation is accomplished by first pre-drilling the host rock and inserting the retracted crusher barrel 2 assembly, FIG. 1, into the borehole 19, as shown in FIG. 2. As depicted in FIG. 1, the crusher tube 3 and crusher piston assembly 13 are initially in the retracted position, thereby connecting the sand channel 4 to the sand port 9 in the nose cone 5 through the crusher tube opening 6. The seal installation operation is initiated at will by the continuous miner operator simply by pressing a button on the appropriate control panel, which sends a command to the PLC. The PLC is appropriately programmed to open the solenoid air valve, which opens the flow of compressed air to the sand hopper 22 with lid 21, FIG. 3. This pressurizes the entire hopper 22 through inlet ports 20 and 28, which are sealed except for the sand delivery port 26. A steady flow of air is established through this port 26 and its connected hose to the crusher nose assembly, FIG. 1. Air enters the nose cone through inlet port 9, travels the open path provided by holes 8, traverses elliptical openings 6 in the grinding tube 3, and is routed through a groove between the semicircular channel 4 in the barrel 2 and the outer surface of the grinding tube 3. The air eventually reaches the sealed cavity 18, where it expands outward and exits through perforations 19 to the exterior, eventually reaching atmospheric pressure. This initial airflow is required to a) adequately pressurize the sand hopper 22 and metering equipment 24, b) clear all lines and conduits, and c) remove any residual water and cuttings from the drilling hole.

[0018] After an appropriate time, the PLC then activates a relay which turns on roller motor 27 of sand hopper 22 while still keeping it pressurized and with continuous air flow. Rollers 24 are intermeshed 29 and begin to counter-rotate relative to each other, thereby metering a constant sand flow longitudinally into and out of through-funnel 23 and through-funnel 25. The gap between the rollers is calibrated to meter the optimum flow rate of sand entering the airflow stream and avoid line stoppages or blockages due to excessive sand volume.

[0019] The sand thus delivered enters the stream of compressed air 26 and travels with the air to the sealing cavity 18. The sand grains are of a diameter such that most of the sand is trapped in the sealing cavity 18 because they are too large to escape outward through the gap between the wall of the borehole 19 and the grinding tube 3, or to the bottom of the hole through the gap between the borehole 19 and the conical upset end 1, which forces the sand outward. Once enough sand has been delivered to the sand sealing cavity 18, the PLC automatically deactivates the roller motor relay to stop any further sand from being delivered down the funnel 25 and through the outlet port 26 into the sand supply line. For and during a short, predetermined period of time, the PLC maintains a steady flow of air through the sand line and into the sand sealing cavity 18. This ensures that any remaining sand is cleared from the lines and conduits and also prevents the sand from building up into a buildup that could cause blockages or plugging.

[0020] The PLC then closes the solenoid air valve, which stops the flow of compressed air to the sand hopper 22. All air pressure in the hopper 22 is vented to the outside through the sand line 26. The PLC or an operator now sequences the crushing of the sand accumulated in the sand sealing cavity 18 by actuating the electrohydraulic valve that routes hydraulic fluid pressure to the grinding tube cylinder 14. During grinding tube extension, the PLC monitors two appropriate sensors: one measuring the distance the grinding tube has traveled, and the other measuring the hydraulic pressure acting on the grinding tube piston 13. Alternatively, the PLC software can numerically calculate an estimate of grinding tube travel using only one pressure sensor. To calculate the estimate, the PLC software first measures the time interval between the actuation of the grinding tube and the resulting pressure peak at the end of travel, then multiplies that time by a preset constant grinding tube extension rate. At the end of travel, the PLC compares the distance the grinding tube 3 has traveled with a predetermined maximum value. If the distance traveled by the crushing tube is below this threshold, the PLC determines the seal placement and crushing operation to be successful. The operator is notified appropriately by the appropriate pilot light on the control console. However, if the distance exceeds the threshold, the PLC sets an error pilot light to alert the operator of a failed seal placement operation. In this way, the operator is notified of the success or failure of the automatic seal placement and can proceed with either the subsequent crushing operation or further seal placement work as appropriate.

[0021] During subsequent bottom-hole pressurization, the crush tube 3 remains under significant force, being forced against the annular sand seal 18 by the action of hydraulic pressure on the piston 13, which remains trapped within the cylinder 14. The enlarged end 1 is in contact with the sand seal through its unique conical outer surface. By compressing the seal between this surface and the end of the crush tube 3, a significant portion of the compressive load is transferred radially and equally to both the wall of the seal cavity borehole and the corresponding outer surface of the barrel / crush tube. The trapped sand is thereby crushed into a fine silica powder, which forms an extremely impermeable seal. Additionally, the seal tightly bonds the barrel 2 to the host rock 17 through the resulting seal's excellent coefficient of friction.

[0022] The conicity of the expanded end 1 is determined by the angle between the barrel axis and its surface. In the preferred embodiment, a nominal angle of 20 degrees is used and shown. However, this angle can be varied and optimized for the particular rock type, fracture pattern, and ease of barrel extraction.

[0023] In FIG. 2, the grinding tube 3 is elongated to isolate the sand groove 4 from the seal cavity 18, thereby preventing blockage of the sand barrel groove 4 due to accumulation of crushed sand at its end. At the same time, the grinding access tube hole 6 is aligned with the washout port 7 in the nosecone 5, thereby allowing the barrel groove 4 to act as a conduit for seal washout fluid. Once the seal 18 is installed, the barrel assembly is most easily extracted from the borehole 19 with effective removal of the crushed sand seal. This operation begins when the operator activates a set of motorized valves that direct a flow of combined water and pressurized air through appropriate hoses to the nosecone washout port 7. This jet is directed through the grinding tube access hole 6 into the barrel groove 4, which opens directly into the annular seal cavity 19. The agitation caused by the turbulence of the combined flow erodes the crushed sand material, carrying fine particles out of the borehole. To aid in the erosion of the seal, the operator hydraulically vibrates the grinding tube, further agitating and dislodging the crushed sand seal particles, suspending them in the surrounding bubbling water flow. The repeated grinding of the sand by the grinding tube 3 reduces the particles to a fine dust that, once suspended in the scrubbing fluid, easily escapes through the gaps in the surrounding perforations 19. The combined water and air flow is prevented from flowing back into the sand conduit hole 8 in the nose cone by the portion of the grinding tube that now covers the opening.

[0024] Radial alignment of the nosecone access ports 8 and 7 with the grinding tube access hole 6 is maintained by a pair of semicircular mating grooves 10, 11 that accept ball bearings of appropriate diameter. The ball bearings are free to slide along these grooves, preventing axial rotation of the grinding tube as it is extended or retracted. Similarly, the sand groove 4 in the barrel 2 is fixed in alignment with the grinding tube access hole 6 during assembly. The significant compressive force exerted by the hydraulic cylinder 14 on the barrel flange 15 when the nosecone 5 is bolted to the center plate 16 prevents accidental rotation during operation.

[0025] Sand particle size, mineral composition, and geometry aid in the installation and effectiveness of the seal. Sand containing a majority of particles that are not sufficiently rounded or too wet, or containing excessively large particles, is prone to blockage and plugging within the conduit during seal installation. Sand with an insufficient diameter will not be trapped in the seal cavity 18 and will therefore escape either to the exterior or to the bottom of the hole. Sand whose mineral composition does not contain enough quartz may not provide a sufficient coefficient of friction to prevent the barrel from leaking when the bottom of the hole is fully pressurized. Field testing has shown that the ideal sand grain size, between 8 and 12 sieve sizes, is well rounded and crushed to a fine powder. "Frac sand," a sand primarily used as a proppant in the petroleum industry, has performed well in this method and provides ideal specifications. Synthetic proppants, such as sintered bauxite, have not yet been tested but may meet the desired specifications.

[0026] The quartz sand placement and sealing system can also be used in conjunction with conventional propellant-based rock fragmentation (PCF) methods to reduce the energy, and therefore the charge size, required to adequately fragment rock or concrete. The reduced charge size in turn minimizes the negative effects of high wind blast, flying stones, toxic gases, and noise associated with standard PCF fragmentation.

[0027] A cross-section of the improved CFI crusher is shown in Figure 4. A specialized annular poppet valve allows for the simultaneous injection of chemical fluids into the foam stream during foam release. The addition of chemicals serves to increase foam viscosity or change its composition to improve its rock-breaking properties.

[0028] Injection of the crosslinking agent or other liquid foam modifier is achieved by differential motion of a small injection tube 81, which acts as a piston, within an injection cavity 82 in an injection cylinder 83. The injection cylinder 83 is threaded to a foam piston 84 and displaces with the foam piston as the foam is expelled along the barrel. A suitable high-pressure seal 86 isolates the injection chamber from the high-pressure foam 39 and high-pressure air pad 78 compartments. A rapid change in volume of the chemical chamber 82 occurs simultaneously and proportionately with the expulsion of foam through barrel 2, thereby forcing the modifier out of the tube 81 and into the throat 92 of the poppet core, shown in Figures 5a and 5b. The foam thereby mixes with the injected chemical as it travels through the barrel, achieving the desired change in viscosity or fracturing characteristics during the fracturing process.

[0029] The chemical liquid is replenished into the injection cavity 82 from the foam generator 55 shown in Figure 8 through a fixed tube 87, which occurs simultaneously with the delivery of the foam charge to the crusher 59, Figure 8. The tube 87 also provides a sliding seal between the movement of the injection cylinder 83 and the crusher air pad compartment 78. It threads directly into the rear crusher plug 88.

[0030] A close-up view of the annular poppet is shown in Figures 5a and 5b within the main foam cylinder 40, which consists of an inner poppet cylinder 75, an annular poppet piston 76, and a poppet core 77. The through-hole poppet valve allows access to the interior of the barrel 4 for injecting selected additives into the high-pressure foam stream as the foam passes through the barrel and is expelled to the bottom of the perforated hole. As shown in Figure 5a, the poppet piston 76 is held tightly closed using high-pressure air from the air pad 78 (shown in Figure 4), which is ported to the air cavity 80 through access port 89 (shown in Figure 5b). To open the poppet valve, as shown in Figure 5b, the high-pressure air in cavity 80 is released to the outside through port 89 and appropriate external valve operation. This allows stored foam within the crusher to push the annular poppet piston 76 to the left, thereby exposing four angled access ports 90 in the poppet core 77. The poppet core has four equally diametrically spaced access ports 90 that allow bubbles to escape through its throat 92 into the barrel 4 .

[0031] This unique annular poppet allows access to the bottom of the borehole for specific operations at the bottom of the borehole independent of the injection of high-pressure foam for fracturing. For example, a small-charge propellant system can be used to provide a short-duration high-pressure pulse that initiates a bottom-hole fracture that aids in the complete fragmentation of the material.

[0032] Such a propellant charge augmentation system incorporates a rotating ball check valve within the poppet core throat 92, which can be used to deliver a small propellant charge to the barrel prior to injection of the low-pressure foam or gel. The propellant charge may include a pressure-sensitive switch to ignite the propellant. Most, if not all, of the energy for fracturing would come from the propellant. The propellant system can be rapidly deployed to break and fracture dense materials with unique hardnesses when such materials are encountered during normal CFI operations. A foam modifier may be delivered directly to the bore of the barrel 4 through the poppet valve throat via opening 91. The foam modifier can be a chemical such as a crosslinking agent or small particles such as proppants used in oil and gas wells. Small particles include micro- and nano-sized particles.

[0033] If the CFI function does not require access to the barrel bore or bottom, a simpler plug-type poppet may be used, as shown in FIG. 6 and described below.

[0034] The unique poppet valve shown in Figures 6a, 6b, 6c, and 7 mitigates potential leakage of pressurized fluid 39 held within the crusher 40 from escaping down the barrel through the poppet outlet 36. This compact configuration is backward compatible with the major structural features of the crusher assembly depicted in Figures 4 and 5. The crusher center plate 16 and main cylinder 40 are identical in both figures. The poppet valve itself consists of three main components: an annular stationary core 32, a free piston 33, and an adapter cylinder 34. The core 32 provides both a valve seat 41 and a guide cylinder for the piston 33. In one embodiment, the piston 33 is made from a hard maraging steel alloy, while the core 32 is made from a softer stainless steel. This provides a valve seat 41 that can deform surface imperfections with the closing action of the piston 33. A solid plug 35 threads into the rear of the core 30, allowing for manual insertion and removal of the piston 33. It also forms a detent for the cylindrical chamber 43 that houses the piston 33. The geometry of the core 32 includes four large, angled holes 31 arranged perpendicular to one another, terminating at the junction of the valve seat 41. To close the poppet, pressurized air consistent with the fluid in the crusher 39 is ported into the cylindrical poppet core chamber 43 through four mutually perpendicular access ports 37 and 38. As depicted in Figures 6b and 6c, gas pressure acting on the circular end 42 displaces the piston 33 to the left, holding it firmly against the valve seat 41 and thereby preventing the escape of pressurized fluid in the crusher 39. To open the valve, the gas trapped behind the poppet piston 43 is released to ambient pressure. Without an opposing force, pressurized fluid in the crusher acting on the front of the piston through port 31 displaces the piston to the right, as shown in Figure 6a, thereby allowing fluid to escape through port 30 and throat 36, as shown in Figure 6c.

[0035] An alternative embodiment of this poppet configuration with reduced parts count is shown in FIG. 7. The annular adapter flange 34 is combined with the core 32 into one piece 45, as shown in FIGS. 6a, 6b, and 6c, thereby simplifying the overall configuration and eliminating the need for an intermediate O-ring seal. Upon sudden release of pressurized fluid 39, the floating piston 44 achieves a large momentum that, if unrestrained, could result in damage to itself and / or the poppet assembly. The annular adapter flange 34 acts as a forward stop for the floating piston assembly 44 and provides sufficient area to dissipate the impact without damage.

[0036] Figure 8 shows the piping diagram of a PLC-controlled automated foam generation and delivery system. Foam generator 55 is attached to breaker 59 via a high-pressure gas line and associated valves 51-58. The foam generator mixes two main components: a liquid phase that is greater than 95% water, and a gas phase that is normal atmospheric air compressed to the desired foam pressure. The liquid phase may contain gels and thickeners to increase viscosity, as well as surfactants that make up less than 2 percent of the liquid phase. By hydraulically displacing a piston core, the foam generator mixes both components through a static in-line mixer 61. A standard check valve 56 controls the flow direction. High-pressure gas inlet ports 46 and 49 may be provided by any conventional compressor or intensifier system. Gel-liquid flow-through port 48 is supplied by a conventional high-pressure liquid pump through valve 52. Depending on the operator's selection, the system can automatically sequence the delivery of three different types of charges to breaker 59: foam, high-viscosity foam, and / or water. The PLC controls the state of supply valves 51-54 and 58, as well as the displacement of the internal hydraulic piston of foam generator 55. The system is also configured to allow the operator to selectively pre-load the crusher barrel with water. Low viscosity water can be supplied to the crusher barrel via port 50 and through valves 54 and 58 with the intent of initiating fracture at the bottom of the hole at low relative foam pressure.

[0037] PLC allows operators to customize the desired foam viscosity, injection pressure, and amount and type of foam charge depending on the fragmentation characteristics of the material being fractured. For example, operators can deliver additional foam charge to the fracturer, which has the effect of increasing the injection pressure at the bottom of the hole. Operators can also choose to simply charge the fracturer with a low-viscosity water charge, which is useful for breaking down tough, homogeneous, fine-grained, and low-porosity rocks.

[0038] Two electronic sensors 112 and 110 in Figure 10 monitor the air pad pressure and foam pad pressure. For safety reasons, the PLC is programmed to automatically open the foam release valve 62 if an overpressure or other fault condition is detected by the PLC and / or the operator.

[0039] One embodiment of the delivery system also includes a high-pressure regulator 60 between the high-pressure gas line 49 and the input to the foam generator air cylinder 48. The quality of the foam in the CFI breaker can be controlled from 50% to 0% quality (percent gas) by varying the pressure in the gas cylinder 48 through the pressure regulator 60. This regulator can lower the effective pressure in the gas cylinder relative to the pressure in the air pad section 78 of the breaker 59, resulting in lower pressure foam being delivered to the water / foam cylinder of the foam generator 55. When this foam is delivered to the breaker, it is compressed to the air pad pressure in the chamber 78. This compression in turn reduces the gas quality of the foam delivered to the breaker. Using lower quality foam at a given pressure for rock fracturing results in reduced air blast and flying stones.

[0040] The automatic foam generation and delivery system of Figure 8 can be mounted directly onto a rock or concrete crusher utilizing an on-board diesel / hydraulic or electric / hydraulic power source. Alternatively, the automatic foam generation and delivery system can be mounted on a separate "power pack" machine that incorporates the necessary power source and is attached or towed to the rear of the rock or concrete crushing unit and connected using high-pressure flexible piping and hoses.

[0041] Figure 9 shows a detailed cross-sectional side view of a compact, high-pressure foam generator. As described in detail in Patent No. 6,375,271, the foam generator consists of a coaxial outer cylinder assembly that houses an internal piston core. The cross-linked piston 63 and cylinder assembly 67 are housed internally, thereby reducing the foam generator's footprint and providing an additional safety margin in case of mechanical failure. In addition, embedded electronic position sensors 74 on both ends of the foam generator provide feedback of the piston core position to the PLC. The PLC controls both the direction of movement and the start and stop timing of the piston core.

[0042] A tubular rod 63 of small static diameter acts as a piston within a cylindrical cavity 67 and is used to inject the cross-linking liquid 47. A micrometering cylinder 67 is incorporated within the gel piston 64 and acts like a syringe, thereby delivering chemical liquid in proportion to the leftward displacement of the piston core.

[0043] Because the use of organic polymers was found to suffer from significant viscosity loss at high shear rates, other additives were investigated for the purpose of increasing foam viscosity. Several insoluble materials with small particle sizes and unique shapes were investigated. The effect of such particles is to prevent pressurized foam from escaping through narrow crevices. Both manufactured and naturally occurring materials were found to have this desired effect. Partial blockage of the crevices slows the dissipation of foam pressure, resulting in more uniform and thorough fracturing. The use of clay additives such as montmorillonite has been found to be very effective. The plate-like, lamellar geometry acts to improve grain-to-grain interlocking, thereby making the plugging of advancing cracks more easily achieved. Other equivalent clays or insoluble minerals may be used.

[0044] FIG. 10 is a schematic representation of the control system showing PLC 100 and its main sensors: foam pad pressure sensor 110, air pad pressure sensor 112, and hydraulic pressure sensor 114, foam generator left position sensor 116, and right position sensor 118.

[0045] The operator control panel 120 has button switches for sand sealing 122 , stopping 124 , seal grinding 126 , pressure adjustment 128 , water loading 132 , crosslinker loading 134 and foam loading 136 .

[0046] The seal button 122 initiates the sand seal delivery and placement cycle. The fire switch 140 sequences the burst discharge of the crusher to release the foam charge into the material being crushed. The crusher flush switch 142 initiates the water and pressurized air to remove the crushed sand seal. Two important electrohydraulic valves are the crusher tube extension and contraction valve 150 to crush and compact the sand seal, and the foam generator gel / water stroke valve 152 to displace the foam generator piston core to either side.

[0047] A PLC output 161 turns on a sand metering roller motor 162 and a switch 164 operates an air valve 166 which pressurizes the sand delivery system as set by a regulator 168 .

[0048] A barrel water valve 170 controls the pre-loading of the barrel with low viscosity fluid. A valve 172 opens and closes the supply of foam modifying material to the foam generator. The foam modifying material can be one or more chemicals, for example, a cross-linking chemical, or small particles that are feed or small charge propellants.

[0049] A gel close valve 174 controls the flow of gel to the foam generator. Air and water open valves 176, 178 control the high pressure air and water to the foam generator.

[0050] The fire valve 180 allows for the sudden release of poppet back pressure to release the foam charge within the crusher.

[0051] Although the present invention has been described with reference to particular embodiments, variations and modifications of the present invention may be made without departing from the scope of the invention as defined in the claims that follow. [Explanation of symbols]

[0052] 2 crusher barrels 3 Crushing tube 13 Grinding piston assembly, grinding tube piston 6 Oval opening, crushing tube opening, crushing access tube hole, crushing tube access hole 5 Nosecone 7 Washing port, nose cone access port 9. Sand Port 4 Sand grooves, barrel grooves, channels, 21 Lid 22 Sand Hopper 26 Sand Delivery Port 20, 28 inlet ports 8-hole nose cone access port 18 Sealing cavity, sand sealing 24 Measuring equipment, roller 27 Roller motor 23, 25 funnel 26 Compressed air, outlet port, sand line 19 Perforation walls, perforations, annular sealed cavities 14 Grinding tube cylinder 17 Host rock 1 Expanded end 10, 11 Engagement groove 16 Center plate 14 Hydraulic Cylinder 15 Barrel flange 81 Injection tube 82 injection cavity, chemical chamber 83 Injection Cylinder 84 Bubble Piston 86 High-pressure sealing 39 High-pressure bubbles, fluids 78 High-pressure air pad, crusher air pad compartment, air pad section, chamber 92 Throat 55 Foam generator 87 Fixed tube 59 Crusher 87 tube 88 Rear crusher plug 40 Main foam cylinder, crusher 75 Internal poppet cylinder 76 Annular poppet piston 77 Poppet Core 89 Access Port 80 Air Cavity 90 Access Port 36 Poppet outlet, throat 32 Stationary Core 33 Free Piston 34 Adapter cylinder, adapter flange 41 Valve seat 35 plug 43 Chamber, poppet piston 37, 38 Access ports 42 End 31 ports 30 ports 44 Floating piston, piston assembly 51~58 valves 59 Crusher 56 Check valve 46, 49 Gas inlet ports 48 Gel liquid through-flow port, air cylinder 112, 110 Electronic sensors 49 High-pressure gas line 60 High pressure regulator, pressure regulator 63 Cross-link piston and rod 67 Cylinder assembly, hollow, micro-measurement cylinder 74 Electronic Position Sensor 47 Crosslinking Agent 64 Gel Piston 100 PLC 110 Foam pad pressure sensor 112 Air pad pressure sensor 114 Hydraulic pressure sensor 116 Foam generator left position sensor 118 Foam generator right position sensor 120 Control Panel 122 Sand seals, sealing buttons 124 Stop 126 Sealing Crushing 128 Pressure Adjustment 132 Water loading 134 Crosslinker Loading 136 Foam loading 140 Fire Switch 142 Crusher sink switch 150 Grinding pipe extension / contraction valve 152 Foam Generator Gel / Water Stroke Valve 161 PLC output 162 Sand measuring roller motor 164 Switch 166 Air valve 168 Regulator 170 barrel water valve 172 Valve 174 Gel Closed Valve 176 Air Opening Valve 178 Water Opening Valve 180 Fire valve

Claims

1. 1. An apparatus comprising: A rock or concrete crusher, the rock or concrete crusher comprising: a barrel having a proximal end and a distal end; a conical end expansion extending radially from the distal end of the barrel and configured to fit within a borehole and press against an inner wall of the borehole, the proximal end of the conical end expansion being configured as a cone for capturing particulate sealing material and forcing it against the inner wall of the borehole; a grinding tube having a proximal end and a distal end and concentrically mounted on the outside of the barrel, the grinding tube configured to slide back and forth on the barrel with the distal end of the grinding tube variably spaced from the end upset on the distal end of the barrel to compact a particulate sealant material into an annular cavity formed between the barrel and the inner wall of the borehole and between the distal end of the grinding tube and the end upset; a groove extending longitudinally along an exterior surface of the barrel, the groove having a distal end and a proximal end; a nosecone having a proximal end and a distal end and configured to retain the proximal end of the barrel; a cylinder mounted within the nosecone with an internal piston configured to receive and secure the proximal end of the grinding tube and drive the grinding tube back and forth between extended and retracted positions on an outer surface of the barrel; first and second inlets in the nosecone, the first inlet configured to connect with the proximal end of the groove when the comminution tube is in the retracted position, and the second inlet located in the nosecone and configured to connect with the groove when the comminution tube is in an at least partially extended position; a particulate sealing material and a delivery fluid selectively connected and disconnected to the first inlet, the particulate sealing material being configured to be supplied by the delivery fluid to and through the first inlet, through the groove, and out of the groove into the annular cavity formed between the barrel and the inner wall of the bore, the annular cavity being longitudinally restricted by the distal end of the grinding tube and the conical end enlargement, the particulate sealing material being confined within the annular cavity by the distal end of the grinding tube and the conical end enlargement and a piston connected to the proximal end of the grinding tube adapted to reciprocate the grinding tube toward and away from the conical end enlargement, compacting the particulate sealing material radially outward, thereby forming a tight annular seal of highly crushed and compacted particulate sealing material within the annular cavity; a cleaning fluid selectively connected and disconnected to the second inlet, the cleaning fluid being configured to deliver cleaning fluid through the second inlet and the groove during at least a portion of movement of the comminution tube relative to the barrel to clean the inner wall of the bore, the barrel, the distal end of the comminution tube, and the annular cavity between the conical end expansion; The apparatus further comprises:

2. 10. The apparatus of claim 1, wherein the particulate encapsulant material is in a hopper that holds the particulate encapsulant material, the delivery fluid is connected to the hopper, a metering chamber is connected to the hopper, and a first conduit connects an outlet of the metering chamber to the first inlet of the nosecone.

3. 3. The apparatus of claim 2, further comprising a metering roller within the metering chamber; and a delivery fluid inlet connected to the delivery fluid and the metering chamber for directing a delivery fluid through the conduit, the first inlet, and the groove, with or without the particulate encapsulant material.

4. The device of claim 2 , wherein the delivery fluid is compressed air.

5. 2. The apparatus of claim 1, wherein the cleaning fluid further comprises compressed air and water, and further comprising a conduit connected to the compressed air and water and the second inlet of the nosecone for delivering the compressed air and water as cleaning fluid through a second conduit, the second inlet, and the groove of the barrel to the annular cavity.

6. The device of claim 1 , wherein the particulate sealing material is sand and the delivery fluid is compressed air.

7. a foam cylinder having a first foam chamber and a second drive chamber; a piston separating the first foam chamber and the second drive chamber, the first chamber connected to the barrel; and a foam generating device connected to the first chamber, the foam generating device adapted to fill the first chamber with foam; a pressure conduit connected to the second chamber adapted to drive the piston toward the barrel and compress the first chamber; a small injection cylinder connected to the piston and extending into the second chamber; a small injection tube mounted within the injection cylinder and functioning as an injection piston, the injection tube having first and second ends; the first end of the injection tube is connected to a poppet valve having a connection to the barrel; an injection tube, the second end of which is mounted within the injection cylinder and adapted to provide pressurized foam modifier from the injection cylinder through the poppet valve as the piston and the injection cylinder are moved toward the first end of the foam cylinder; The apparatus of claim 1 further comprising:

8. 8. The device of claim 7, wherein the poppet valve comprises an annular poppet cylinder, an annular poppet piston within the poppet cylinder, and a poppet core having a through hole connected to the barrel, the poppet piston being held closed by pressurized air, and the poppet valve is adapted to open and deliver foam from the first end of the foam cylinder through the poppet valve and the core to the barrel when the air pressure holding the poppet valve closed is reduced by an external valve, and simultaneously, movement of the injection cylinder within the second drive chamber increases pressure in the small injection tube to open a check valve and deliver the foam modifier under pressure to the through hole in the poppet core.

9. the poppet valve is configured to deliver the foam under pressure from the injection cylinder through the barrel and into the bore; The poppet valve is an annular poppet cylinder; an annular poppet piston within the poppet cylinder; a poppet core located inside the annular poppet piston; an open throat in the poppet core; an access port closed by the annular poppet piston and configured to prevent communication between the foam cylinder and the open throat in the poppet core; The apparatus of claim 7 further comprising:

10. 10. The apparatus of claim 9, further comprising an annular cavity, wherein the annular poppet piston is held closed until pressure is relieved by an external valve.

11. providing a barrel having a conical end enlargement configured for insertion into a borehole drilled in rock or concrete to break up the rock or concrete; providing a grinding tube slidable on said barrel, said grinding tube having a distal end spaced from said conical end upset; providing a longitudinal groove along an outer surface of the barrel; providing a nosecone adapted to hold a cylinder against a center plate adapted to hold the barrel and allow the proximal end of the grinding tube to slide through the nosecone on the barrel; providing first and second passages in the nosecone; supplying pressurized sand and air through the first passageway of the nose cone and a groove along the outer surface of the barrel into a gap between the end upset and the distal end of the grinding tube; closing the first passage and advancing the grinding tube on the barrel to move the distal end of the grinding tube toward the end upset; grinding the sand between the end upset and the distal end of the grinding tube, thereby forming a ground sand seal between the barrel and an interior wall of the borehole; forming a sand seal, the sand being trapped within a seal cavity by the end of the grinding tube and the conical end enlargement; and supplying foam and a cross-linking agent through the hole in the barrel and into the bottom of the sealed borehole.

12. 12. The method of claim 11, further comprising introducing water and compressed air through the second passage and the groove into the crushed sand seal to erode the sand seal to facilitate removal of the barrel from the borehole.

13. 13. The method of claim 12, further comprising reciprocating the grinding tube to further facilitate erosion and removal of the sand seals.

14. providing the pressurized sand and air; Providing a sand hopper; Supplying sand into the sand hopper; Providing a measuring roller below the sand hopper; providing a flow of pressurized air beneath the metering roller through the first path and the groove along the barrel, thereby keeping the first path and the groove free of debris, moisture, and sand; The method of claim 11 further comprising:

15. 15. The method of claim 14, further comprising: forcing pressurized air into the sand hopper, rotating the metering roller, and forcing the sand and pressurized air from the sand hopper, through the first passage and the groove, and into the annular cavity between the end upset and the distal end of the comminution tube.

16. providing a foam cylinder; supplying foam from the foam cylinder through a poppet valve to the barrel; providing the poppet valve with an annular poppet chamber, an annular poppet piston within the annular poppet chamber, and a poppet core having a throat adapted to connect to a bore in the barrel; providing a passageway in the poppet valve from the foam cylinder to the throat; providing an annular air chamber behind the annular poppet piston, and closing the passage with the poppet piston while air pressure is present in the air chamber; using an external valve to reduce the air pressure holding the poppet valve closed, thereby allowing injection of high pressure foam into the bore of the barrel and out through the distal end of the barrel; The method of claim 11 further comprising:

17. supplying foam modifier to the foam in the throat and the barrel by extending an injection cylinder from the foam piston into an air drive chamber on an opposite side of the foam piston from the foam chamber; extending a hollow injection piston from said poppet valve through said foam chamber, through said foam piston, and into a crosslinker cylinder; using the foam piston to move the injection cylinder onto the hollow injection piston to increase pressure on the cross-linking agent within the hollow injection piston; opening a one-way valve in the poppet valve with the increased crosslinker pressure; Discharging the foam modifier from the hollow injection piston into the throat; 17. The method of claim 16, further comprising:

18. 20. The method of claim 17, wherein releasing the foam modifier further comprises releasing one or more foam cross-linking chemicals.

19. 20. The method of claim 17, wherein releasing the foam modifier further comprises releasing particles, microparticles, or nanoparticles.

20. 20. The method of claim 17, wherein discharging the foam modifier further comprises discharging a combination of a foam cross-linking chemical and microparticles into the throat.

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