Patent Application
20130098684
1. Field of the Invention
This invention relates to earth bits for drilling.
2. Description of the Related Art
An earth bit is commonly used for boring through a formation to form a borehole. Such boreholes may be formed for many different reasons, such as drilling for oil, minerals and geothermal steam. There are several different types of earth bits that are used forming a borehole. One type is a tri-cone rotary earth bit and, in a typical setup, it includes three earth bit cutting cones rotatably mounted to separate lugs. The lugs are joined together through welding to form a bit body. The earth bit cutting cones rotate in response to contacting the formation as the earth bit body is rotated in the borehole. Several examples of rotary earth bits are disclosed in U.S. Pat. Nos. 3,550,972, 3,847,235, 4,136,748, 4,427,307, 4,688,651, 4,741,471 and 6,513,607.
Some attempts have been made to form boreholes at a faster rate, as discussed in more detail in U.S. Pat. Nos. 3,250,337, 3,307,641, 3,807,512, 4,502,552, 5,730,230, 6,371,223 and 6,986,394, as well as in U.S. Patent Application No. 20050045380. Some of these references disclose using a percussion hammer to apply an overstrike force to the earth bit. However, it is desirable to increase the boring rate when using the percussion hammer, and to reduce the amount of damage to the earth bit in response to the overstrike force.
The present invention is directed to a percussion assisted rotary earth bit, and method of operating the same. The novel features of the invention are set forth with particularity in the appended claims. The invention will be best understood from the following description when read in conjunction with the accompanying drawings.
These and other features, aspects, and advantages of the present invention will become better understood with reference to the following drawings and description.
a is a perspective view of a rotary drill system coupled to the drill string of
b is a cut-away side view of the rotary drill system of
a is a perspective view of a rotary tool joint included with the hammer assembly of
b is a perspective view of a hammer casing included with the hammer assembly of
c is a perspective view of a flow control tube included with the hammer assembly of
d is a perspective view of a piston included with the hammer assembly of
e is a perspective view of a drive chuck included with the hammer assembly of
f is a perspective view of an adapter sub included with the hammer assembly of
a and 4b are close-up side views of the hammer assembly of
a and 5b are side views of the rotary drilling system of
a is a perspective view of the adapter sub and rotary earth bit of
b and 7c are cross-sectional views of adapter sub and rotary earth bit of
d is a side view of trapezoidal rotary earth bit threads of the rotary earth bit of
e is a side view of trapezoidal tool joint threads of the adapter sub of
a and 8b are flow diagrams of methods of boring a hole.
c and 8d are flow diagrams of methods of manufacturing a rotary drill system.
a, 9b and 9c are flow diagrams of methods of boring through a formation.
Tower 164 generally carries a feed cable system (not shown) attached to a rotary head 167, wherein the feed cable system allows rotary head 167 to move between raised and lowered positions along tower 164. The feed cable system moves rotary head 167 to the raised and lowered positions by moving it towards tower crown 164b and tower base 164a, respectively.
Rotary head 167 is moved between the raise and lowered positions to raise and lower, respectively, drill string 106 through a borehole. Further, rotary head 167 is used to rotate drill string 106, wherein drill string 106 extends through tower 164. Drill string 106 generally includes one or more drill pipes connected together in a well-known manner. The drill pipes of drill string 106 are capable of being attached to an earth bit, such as a tri-cone rotary earth bit.
a is a perspective view of a rotary drill system 100 coupled to drill string 106, and
The value of dimension D1 corresponds to the value of dimension D2. For example, dimension D1 increases and decreases in response to increasing and decreasing dimension D2, respectively. It should be noted that the cross-sectional shapes of borehole 105 and rotary drill system 100 are determined by forming a cut-line through borehole 105 and rotary drill system 100, respectively, in a direction along radial line 169.
In this embodiment, rotary drill system 100 includes a rotary earth bit 102 coupled to a hammer assembly 103. Rotary earth bit 102 is repeatably moveable between coupled and decoupled conditions with hammer assembly 103, as will be discussed in more detail below with
In this embodiment, hammer assembly 103 includes a rotary tool joint 107 with a central opening 104 (
The connection between drill string 106 and rotary tool joint 107 is often referred to as a threaded box connection. Drill string 106 is coupled to rotary drill system 100 so that drill string 106 is in fluid communication with rotary earth bit 102 through hammer assembly 103. Drill string 106 provides fluid to hammer assembly 103 through a drill string opening 108 and central opening 104 of tool joint 107. Drilling machine 160 flows the fluid to earth bit 102 and hammer assembly 103 through rotary head 167 and drill string 106. Rotary earth bit 102 outputs some of the fluid so that cuttings are lifted upwardly through borehole 105. Drilling machine 160 provides the fluid with a desired pressure to clean rotary earth bit 102, as well as to evacuate cuttings from borehole 105. As will be discussed in more detail below, drilling machine 160 provides the fluid with the desired pressure to actuate hammer assembly 103.
The fluid can be of many different types, such as a liquid and/or gas. The liquid can be of many different types, such as oil, water, drilling mud, and combinations thereof. The gas can be of many different types, such as air and other gases. In some situations, the fluid includes a liquid and gas, such as air and water. It should be noted that drilling machine 160 (
It should also be noted that drill string 106 is typically rotated by rotary head 167, and rotary drill system 100 rotates in response to the rotation of drill string 106. Drill string 106 can be rotated at many different rates. For example, in one situation, rotary head 167 rotates drill string 106 at a rate less than about one-hundred and fifty revolutions per minute (150 RPM). In one particular situation, rotary head 167 rotates drill string 106 at a rate between about fifty revolutions per minute (50 RPM) to about one-hundred and fifty revolutions per minute (150 RPM). In some situations, rotary head 167 rotates drill string 106 at a rate between about forty revolutions per minute (40 RPM) to about one-hundred revolutions per minute (100 RPM). In another situation, rotary head 167 rotates drill string 106 at a rate between about one-hundred revolutions per minute (100 RPM) to about one-hundred and fifty revolutions per minute (150 RPM). In general, the penetration rate of rotary drill system 100 increases and decreases as the rotation rate of drill string 106 increases and decreases, respectively. Hence, the penetration rate of rotary drill system 100 is adjustable in response to adjusting the rotation rate of drill string 106.
In most embodiments, earth bit 102 operates with a weight-on-bit applied thereto. In general, the penetration rate of rotary drill system 100 increases and decreases as the weight-on-bit increases and decreases, respectively. Hence, the penetration rate of rotary drill system 100 is adjustable in response to adjusting the weight-on-bit.
The weight-on-bit is generally applied to earth bit 102 through drill string 106 and hammer assembly 103. The weight-on-bit can be applied to earth bit 102 through drill string 106 and hammer assembly 103 in many different ways. For example, drilling machine 160 can apply the weight-on-bit to earth bit 102 through drill string 106 and hammer assembly 103. In particular, rotary head 167 can apply the weight-on-bit to earth bit 102 through drill string 106 and hammer assembly 103. The value of the weight-on-bit depends on many different factors, such as the ability of earth bit 102 to withstand the weight-on-bit without failing. Earth bit 102 is more likely to fail if the applied weight-on-bit is too large.
The weight-on-bit can have weight values in many different ranges. For example, in one situation, the weight-on-bit is less than ten-thousand pounds per square inch (10,000 psi) of borehole diameter. In one particular situation, the weight-on-bit is in a range of about one-thousand pounds per square inch (1,000 psi) of borehole diameter to about ten-thousand pounds per square inch (10,000 psi) of borehole diameter. In one situation, the weight-on-bit is in a range of about two-thousand pounds per square inch (2,000 psi) of borehole diameter to about eight-thousand pounds per square inch (8,000 psi) of borehole diameter. In another situation, the weight-on-bit is in a range of about four-thousand pounds per square inch (4,000 psi) of borehole diameter to about six-thousand pounds per square inch (6,000 psi) of borehole diameter. It should be noted that the borehole diameter of the weight-on-bit corresponds to dimension D1 of borehole 105, which corresponds to dimension D2 of rotary drill system 100, as discussed in more detail above.
The weight-on-bit can also be determined using units other than the number of pounds per square inch of borehole diameter. For example, in some situations, the weight-on-bit is less than about one-hundred and thirty thousand pounds (130,000 lbs). In one particular situation, the weight-on-bit is in a range of about thirty-thousand pounds (30,000 lbs) to about one-hundred and thirty thousand pounds (130,000 lbs). In one situation, the weight-on-bit is in a range of about ten-thousand pounds (10,000 lbs) to about sixty-thousand pounds (60,000 lbs). In another situation, the weight-on-bit is in a range of about sixty-thousand pounds (60,000 lbs) to about one-hundred and twenty thousand pounds (120,000 lbs). In one situation, the weight-on-bit is in a range of about ten-thousand pounds (10,000 lbs) to about forty-thousand pounds (40,000 lbs). In another situation, the weight-on-bit is in a range of about eighty-thousand pounds (80,000 lbs) to about one-hundred and ten thousand pounds (110,000 lbs).
During operation, hammer assembly 103 applies an overstrike force to rotary earth bit 102. It should be noted, however, that the overstrike force can be applied to rotary earth bit 102 in many other ways. For example, in one embodiment, the overstrike force is applied to earth bit 102 by a spring actuated mechanical tool. In another embodiment, the overstrike force is applied to earth bit 102 by a spring actuated mechanical tool instead of an air operated hammer. In some embodiments, the overstrike force is applied to earth bit 102 by an electromechanical powered tool. some embodiments, the overstrike force is applied to earth bit 102 by an electromechanical powered tool instead of an air operated hammer.
In the embodiment of
In operation, hammer assembly 103 is actuated as the cutting cone(s) of rotary earth bit 102 make contact with a formation. Hammer assembly 103 applies the overstrike force to rotary earth bit 102 and, in response, rotary earth bit 102 advances into the formation as the cutting cone(s) fracture it. The rate at which the formation is fractured is influenced by the magnitude and frequency of the force provided by hammer assembly 103 in response to being actuated. In this way, hammer assembly 103 drives rotary earth bit 102 into the formation, and borehole 105 is formed. It should be noted that the magnitude of the overstrike force typically corresponds with the absolute value of the amplitude of the overstrike force.
As mentioned above, hammer assembly 103 includes rotary tool joint 107 with central opening 104 extending therethrough, wherein rotary tool joint 107 is shown in a perspective view in
In this embodiment, hammer assembly 103 includes a hammer casing body 110, which is shown in a perspective view in
Rotary tool joint 107 can be coupled to hammer casing body 110 in many different ways. In this embodiment, rotary tool joint 107 is coupled to hammer casing body 110 with a backhead 114 (
In this embodiment, hammer assembly 103 includes a flow control tube 118, which is shown in a perspective view in
In this embodiment, hammer assembly 103 includes a piston 124, which is shown in a perspective view in
In this embodiment, piston body 126 includes opposed drive piston ports 132a and 132b and opposed return piston ports 132c and 132d. Drive piston ports 132a and 132b and return piston ports 132c and 132d extend between central opening 125 and the outer periphery of piston body 126. Drive piston ports 132a and 132b and return piston ports 132c and 132d can extend through piston body 126 in many different ways. In this embodiment, drive piston ports 132a and 132b are angled towards drive surface 128. Drive piston ports 132a and 132b are angled towards drive surface 128 so that drive piston ports 132a and 132b are not parallel to radial line 169. Drive piston ports 132a and 132b are angled towards drive surface 128 so that drive piston ports 132a and 132b are not parallel to centerline 147. Further, return piston ports 132c and 132d are angled towards return surface 130. Return piston ports 132c and 132d are angled towards drive surface 130 so that return piston ports 132c and 132d are not parallel to radial line 169. Return piston ports 132c and 132d are angled towards drive surface 130 so that return piston ports 132c and 132d are not parallel to centerline 147.
As will be discussed in more detail below, piston body 126 is repeatably moveable, along sleeve portion 123, between a first position wherein drive piston ports 132a and 132b are in fluid communication with central channel 112 through drive guide ports 122a and 122b, respectively, and a second position wherein return piston ports 132c and 132d are in fluid communication with central channel 112 through return guide ports 122c and 122d, respectively. It should be noted that, in the first position, return piston ports 132c and 132d are not in fluid communication with central channel 112 through return guide ports 122c and 122d. Further, in the second position, drive piston ports 132a and 132b are not in fluid communication with central channel 112 through drive guide ports 122a and 122b. Hence, in the first position, material from central channel 112 is restricted from flowing through return piston ports 132c and 132d by piston body 126. Further, in the second position, material from central channel 112 is restricted from flowing through drive piston ports 132a and 132b by piston body 126. The flow of material through the ports of hammer assembly 103 is discussed in more detail with
In this embodiment, hammer assembly 103 includes a drive chuck 134, which is shown in a perspective view in
In this embodiment, hammer assembly 103 includes an adapter sub 136, which is shown in a perspective view in
As mentioned above, rotary drill system 100 includes rotary earth bit 102 coupled to hammer assembly 103. Rotary earth bit 102 can be coupled to hammer assembly 103 in many different ways. In this embodiment, rotary earth bit 102 is coupled to hammer assembly 103 by coupling it to adapter sub 136. In this embodiment, rotary earth bit 102 is coupled to adapter sub 136 by extending it through rotary earth bit opening 138 and coupling it to tool joint 139. Rotary earth bit 102 is repeatably moveable between coupled and decoupled conditions with adapter sub 136, as will be discussed in more detail with
It should be noted that rotary earth bit 102 can slide relative to drive chuck 134 because it is coupled to adapter sub 136, which is slidingly coupled to drive chuck 134. Hence, rotary earth bit 102 slides relative to drive chuck 134 in response to adapter sub 136 sliding relative to drive chuck 134. In this way, adapter sub 136 and rotary earth bit 102 can slide relative to drive chuck 134 and hammer casing body 110.
As will be discussed in more detail with
a and 4b are close-up side views of hammer assembly 103 showing piston 124 in the first and second positions, respectively. Further,
In this embodiment, hammer assembly 103 includes drive exhaust ports 142a and 142b in fluid communication with drive chamber 141. Further, hammer assembly 103 includes return exhaust ports 142c and 142d in fluid communication with return chamber 140. Drive exhaust ports 142a and 142b allow material to flow from drive chamber 141 to a region external to hammer assembly 103. Further, return exhaust ports 142c and 142d allow material to flow from return chamber 140 to a region external to hammer assembly 103. The flow of material from return chamber 140 and drive chamber 141 will be discussed in more detail with
In this embodiment, piston 124 is repeatably moveable between the first and second positions. In the first position, piston 124 is disengaged from adapter sub 136 and, in the second position, piston 124 is engaged with adapter sub 136. In the disengaged position, piston body 126 is positioned so that drive piston ports 132a and 132b are in fluid communication with central channel 112 through drive guide ports 122a and 122b, respectively. In the disengaged position, piston body 126 is positioned so that return piston ports 132c and 132d are not in fluid communication with central channel 112 through return guide ports 122c and 122d. In the disengaged position, piston body 126 restricts the flow of material through return guide ports 122c and 122d. Further, in the disengaged position, piston body 126 is positioned so that return chamber 140 is in fluid communication with return exhaust ports 142c and 142d and drive chamber 141 is not in fluid communication with drive exhaust ports 142a and 142b.
In the engaged position, piston body 126 is positioned so that drive piston ports 132a and 132b are not in fluid communication with central channel 112 through drive guide ports 122a and 122b. In the engaged position, piston body 126 is positioned so that return piston ports 132c and 132d are in fluid communication with central channel 112 through return guide ports 122c and 122d, respectively. In the engaged position, piston body 126 restricts the flow of material through drive guide ports 122a and 122b. Further, in the engaged position, piston body 126 is positioned so that return chamber 140 is not in fluid communication with return exhaust ports 142c and 142d and drive chamber 141 is in fluid communication with drive exhaust ports 142a and 142b.
In one situation, piston 124 is in the disengaged position, as shown in
Piston body 126 moves, in response to overstrike force F applied to drive surface 128, towards adapter sub 136, wherein return surface 130 engages impact surface 131. Adapter sub 136 slides relative to drive chuck 134 in response to return surface 130 engaging impact surface 131. As mentioned above, rotary earth bit 102 is coupled to adapter sub 136. Hence, rotary earth bit 102 also slides in response to return surface 130 engaging impact surface 131, wherein rotary earth bit slides so it is moved from a retracted position (
In the retracted position, adapter sub 136 is engaged with drive chuck 134, as indicated by an indication arrow 148 in
In another situation, piston 124 is in the engaged position, as shown in
Piston body 126 moves, in response to overstrike force F applied to return surface 130, away from adapter sub 136, wherein return surface 130 is disengaged from impact surface 131. Adapter sub 136 slides relative to drive chuck 134 in response to return surface 130 being disengaged from impact surface 131. As mentioned above, rotary earth bit 102 is coupled to adapter sub 136. Hence, rotary earth bit 102 also slides in response to return surface 130 being disengaged from impact surface 131, wherein rotary earth bit slides so it is moved from the extended position (
In another embodiment, piston body 126 moves away from adapter sub 136 as a result of a rebound, wherein the rebound includes the portion of the impact energy not transmitted through adapter sub 136 and earth bit 102 to the formation. In this embodiment, adapter sub 136 moves relative to drive chuck 134 in response to the impact of piston body 126 with the surface 131 of adapter sub 136. In this way, overstrike force F is imparted to adapter sub 136 and the motion of piston body 126 is in response to a reaction force applied to it by adapter sub 136.
Hence, piston 124 is moved between the engaged and disengaged positions by adjusting the fluid pressure in return chamber 140 and drive chamber 141. The fluid pressure in return chamber 140 and drive chamber 141 is adjusted so that oscillating forces are applied to return surface 130 and drive surface 128 and piston 124 is moved towards and away from impact surface 131.
Rotary earth bit 102 typically operates with a threshold inlet pressure of about 40 pounds per square inch (psi). However, most drilling machines provide a supply pressure of between about 50 psi to 100 psi. Hence, only about 10 psi to 60 psi will be available to operate hammer assembly 103 if hammer assembly 103 and rotary earth bit 102 are coupled together in series. In accordance with the invention, hammer assembly 103 is capable of operating at full system pressure so that piston 124 can apply more percussive power to adapter sub 136 and rotary earth bit 102. Hence, the fluid pressure at which hammer assembly 103 operates is driven to equal the fluid pressure at which rotary earth bit 102 operates.
As mentioned above, drill string 106 provides fluids to hammer assembly 103 through drill string opening 108, and the fluids can be of many different types, such as air or other gases, or a combination of gases and liquids, such as oil and/or water. In one embodiment, the fluid includes air and the air is flowed through drill string 106 at a rate less than about 5,000 cubic feet per minute (cfm). For example, in one embodiment, the air is flowed at a rate in a range of about 1,000 cfm to about 4,000 cfm. In another embodiment, the fluid includes air and the air flowed through drill string 106 is provided at an air pressure less than about one-hundred pounds per square inch (100 psi). For example, in one embodiment, the pressure of the air flowing through drill string 106 is at a pressure in a range of about 40 psi to about 100 psi. In another embodiment, the pressure of the air flowing through drill string 106 is at a pressure in a range of about 40 psi to about 80 psi. In accordance with the invention, the pressure of the air used to operate hammer assembly 103 is driven to equal the pressure of the air used to operate rotary earth bit 102. In general, the penetration rate of earth bit 102 increases and decreases as the air pressure increases and decreases, respectively.
Overstrike force F is typically applied to earth bit 102 with an amplitude and frequency. When overstrike force F is applied to earth bit 102 with a frequency, its amplitude changes as a function of time. In this way, overstrike force F is a time-varying overstrike force. The frequency of overstrike force F is typically periodic, although it can be non-periodic in some situations. The frequency of overstrike force F corresponds with the number of times that piston 124 impacts adapter sub 136. As mentioned above, the magnitude of overstrike force F typically corresponds with the absolute value of the amplitude of overstrike force F.
Overstrike force F can have magnitude values in many different ranges. However, overstrike force F is typically less than about five foot-pounds per square inch (5 ft-lb/in2). In one embodiment, overstrike force F is in a range of about 1 ft-lb/in2 to about 4 ft-lb/in2. In one embodiment, overstrike force F is in a range of about 1 ft-lb/in2 to about 5 ft-lb/in2.
In another embodiment, overstrike force F is in a range of about 1.2 ft-lb/in2 to about 3.6 ft-lb/in2. In general, the penetration rate of earth bit 102 increases and decreases as overstrike force F increases and decreases, respectively. However, it is typically undesirable to apply an overstrike force to earth bit 102 with a value that will damage earth bit 102. It should be noted that the area over which overstrike force F is applied can be many different areas. For example, in one embodiment, the area over which overstrike force F is applied corresponds to the area of impact surface 131 of adapter sub 136 (
The frequency of overstrike force F can have many different values. For example, in one embodiment, overstrike force F is applied to earth bit 102 at a rate less than about 1500 times per minute. In one particular embodiment, overstrike force F is applied to earth bit 102 at a rate in a range of about 1100 times per minute to about 1400 times per minute.
The frequency and amplitude of overstrike force F can be adjusted. The frequency and amplitude of overstrike force F can be adjusted for many different reasons, such as to adjust the penetration rate of earth bit 102 into the formation. In one embodiment, the amplitude and/or frequency of overstrike force F are adjusted in response to an indication of a penetration rate of earth bit 102 through the formation. The indication of the penetration rate of earth bit 102 through the formation can be provided in many different ways. For example, the penetration rate of earth bit 102 through the formation is typically monitored with equipment included with the drilling machine.
The penetration rate of earth bit 102 through the formation is adjusted by adjusting at least one of an amplitude and frequency of overstrike force F. For example, in one embodiment, the penetration rate of earth bit 102 through the formation is adjusted by adjusting the amplitude of overstrike force F. In another example, the penetration rate of earth bit 102 through the formation is adjusted by adjusting the frequency of overstrike force F. In another example, the penetration rate of earth bit 102 through the formation is adjusted by adjusting the frequency and amplitude of overstrike force F.
In one embodiment, the amplitude of overstrike force F is adjusted in response to the indication of the penetration rate of earth bit 102 through the formation. In another embodiment, the frequency of overstrike force F is adjusted in response to the indication of the penetration rate of earth bit 102 through the formation. In one embodiment, the frequency and amplitude of overstrike force F are both adjusted in response to the indication of the penetration rate of earth bit 102 through the formation. In this way, overstrike force F is adjusted in response to an indication of a penetration rate of earth bit 102 through the formation.
In general, overstrike force F is adjusted to drive the penetration rate of earth bit 102 through the formation to a desired penetration rate. The frequency and/or amplitude of the overstrike force are typically increased to increase the penetration rate of earth bit 102 through the formation. Further, the frequency and/or amplitude of the overstrike force are typically decreased to decrease the penetration rate of earth bit 102 through the formation. Further, overstrike force F is typically adjusted to reduce the likelihood of earth bit 102 experiencing any damage.
The frequency and amplitude of overstrike force F can be adjusted in many different ways. In one embodiment, the frequency and amplitude of overstrike force F are adjusted in response to adjusting the fluid flow through drill string 106. The frequency and amplitude of overstrike force F are typically increased and decreased in response to increasing and decreasing, respectively, the fluid flow through drill string 106. For example, in one embodiment, the frequency and amplitude of overstrike force F are increased and decreased in response to increasing and decreasing, respectively, the pressure of the air flowing through drill string 106.
It should be noted that, in some embodiments, the frequency and amplitude of overstrike force F are adjusted automatically by the equipment of the drilling machine by adjusting the fluid flow. In other embodiments, the fluid flow is adjusted manually to adjust the frequency and amplitude of overstrike force F.
The material being exhausted from drive chamber 141 and return chamber 140 can be flowed to the external region of hammer assembly 103 in many different ways, one of which is shown in
As discussed above, overstrike force F is applied by piston 124 to rotary earth bit 102 through adapter sub 136. The magnitude of overstrike force F can be controlled in many different ways. In one way, the amount of overstrike force is controlled by choosing adapter sub 136 to have a desired mass. As the mass of adapter sub 136 increases, less overstrike force is transferred from piston 124 to rotary earth bit 102 in response to return surface 130 engaging impact surface 131. Further, as the mass of adapter sub 136 decreases, more overstrike force is transferred from piston 124 to rotary earth bit 102 in response to return surface 130 engaging impact surface 131. Another way the amount of overstrike force is controlled is by choosing piston 124 to have a desired mass. As the mass of piston 124 is increased, more of the overstrike force is transferred by it to rotary earth bit 102. Further, as the mass of piston 124 is decreased, less of the overstrike force is transferred from it to rotary earth bit 102.
The overstrike force applied by piston 124 can be controlled by controlling the size of cylinder 113. As the size of cylinder 113 increases, the overstrike force increases because piston 124 is moved over a longer distance before engaging adapter sub 136. As the size of cylinder 113 decreases, the overstrike force decreases because piston 124 is moved over a shorter distance before engaging adapter sub 136.
Overstrike force F applied by piston 124 can be controlled by controlling the size of drive chamber 141. As the size of drive chamber 141 increases, overstrike force F increases because the pressure of the fluid in drive chamber 141 increases more gradually, which increases the length of travel of piston 124. A longer length of travel allows the pressure of the fluid of drive chamber 141 to increasingly accelerate piston 124, which increases overstrike force F. As the size of drive chamber 141 decreases, overstrike force F decreases because the upward motion of piston 124 is retarded by a more rapidly increasing pressure of the fluid of drive chamber 141, which shortens the length of piston travel and overstrike force F.
Overstrike force F applied by piston 124 can also be controlled by controlling the size of return chamber 140. As the size of return chamber 140 increases, overstrike force F increases because the pressure of the fluid of return chamber 140 increases more gradually on the forward stroke of piston 124, which allows greater acceleration of piston 124. As the size of return chamber 140 decreases, overstrike force F decreases because the more rapidly increasing pressure of the fluid of return chamber 140 increasingly decelerates piston 124, which reduces overstrike force F.
The overstrike force applied by piston 124 can be controlled by controlling the size of drive guide ports 122a and 122b. As the size of drive guide ports 122a and 122b increase, piston 124 applies a larger overstrike force to adapter sub 136 because more fluid can flow at a faster rate from central channel 112 to drive chamber 141. As the size of drive guide ports 122a and 122b decrease, piston 124 applies a smaller overstrike force to adapter sub 136 because less fluid can flow at a slower rate from central channel 112 to drive chamber 141.
The frequency of overstrike force F applied by piston 124 to rotary earth bit 102 through adapter sub 136 can be controlled in many different ways. The frequency of overstrike force F increases as overstrike force F is applied by piston 124 to rotary earth bit 102 more often, and the frequency of overstrike force F decreases as overstrike force F is applied by piston 124 to rotary earth bit 102 less often.
The frequency that overstrike force F is applied to adapter sub 136 can be controlled by controlling the size of return guide ports 122c and 122d. As the size of return guide ports 122c and 122d increase, the frequency increases because fluid from central channel 112 can be flowed into return chamber 140 at a faster rate. As the size of return guide ports 122c and 122d decrease, the frequency decreases because fluid from central channel 112 can be flowed into return chamber 140 at a slower rate.
The frequency that overstrike force F is applied to adapter sub 136 can be controlled by controlling the size of return exhaust ports 142c and 142d. As the size of return exhaust ports 142c and 142d increase, the frequency increases because fluid from return chamber 140 can be flowed out of return chamber 140 at a faster rate. As the size of return exhaust ports 142c and 142d decrease, the frequency decreases because fluid from return chamber 140 can be flowed out of return chamber 140 at a slower rate.
Hammer assembly 103 provides many advantages. One advantage provided by hammer assembly 103 is that piston 124 applies low energy and high frequency power to rotary earth bit 102. This is useful to reduce the amount of stress experienced by rotary earth bit 102. Another advantage provided by hammer assembly 103 is that there are parallel supply and exhaust flow paths which enable improved air and power control without having to increase the pressure of the fluid provided by drill string 106. Further, the amount of power provided by hammer assembly 103 to rotary earth bit 102 can be adjusted by adjusting throttle plate 116 and/or check valve 115. In this way, the amount of power provided by hammer assembly 103 can be adjusted without having to adjust the pressure of the fluid provided by drill string 106. Another advantage is that the exhaust of hammer assembly 103 is flowed out of hammer assembly 103 towards its rearward end and is directed upwardly through borehole 105. In this way, the exhaust of hammer assembly 103 assists in clearing debris from borehole 105.
a is a perspective view of adapter sub 136 and rotary earth bit 102 in a decoupled condition. Adapter sub 136 and rotary earth bit 102 are in a coupled condition in
Adapter sub 136 and rotary earth bit 102 are repeatably moveable between the coupled and decoupled conditions. Rotary earth bit 102 can be coupled to adapter sub 136 in many different ways. In this embodiment, tool joint 139 and rotary earth bit 102 include trapezoidal tool joint threads 143 and trapezoidal rotary earth bit threads 144, respectively. Adapter sub 136 and rotary earth bit 102 are moved to the coupled condition by threadingly engaging trapezoidal tool joint threads 143 and trapezoidal rotary earth bit threads 144. Further, adapter sub 136 and rotary earth bit 102 are moved to the decoupled condition by threadingly disengaging trapezoidal tool joint threads 143 and trapezoidal rotary earth bit threads 144. In this way, adapter sub 136 and rotary earth bit 102 are repeatably moveable between coupled and decoupled conditions.
It should be noted that a central channel 151 of rotary earth bit 102 is in fluid communication with central channel 112 when rotary earth bit 102 and adapter sub 136 are coupled to each other. In this way, fluid flows from drill string 106 through drill string nozzle 108 and central channel 112 to central channel 151 of rotary earth bit 102 (
The threads of adapter sub 136 and rotary earth bit 102 are complementary to each other, which allows rotary earth bit 102 and adapter sub 136 to be repeatably moveable between coupled and decoupled conditions. Adapter sub 136 and rotary earth bit 102 can include many other types of threads besides trapezoidal threads. For example, as indicated by an indication arrow 149a, adapter sub 136 can include v-shaped threads 143a and rotary earth bit 102 can include complementary v-shaped threads. As indicated by an indication arrow 149b, adapter sub 136 can include buttressed threads 143b and rotary earth bit 102 can include complementary buttressed threads. Further, as indicated by an indication arrow 149c, adapter sub 136 can include rope threads 143c and rotary earth bit 102 can include complementary rope threads. More information regarding threads that can be included with rotary earth bit 102 and adapter sub 136 is provided in U.S. Pat. Nos. 3,259,403, 3,336,992, 4,600,064, 4,760,887 and 5,092,635, as well as U.S. Patent Application Nos. 20040251051, 20070199739 and 20070102198.
b is a cross-sectional view of adapter sub 136 and rotary earth bit 102 in coupled conditions. In this embodiment, a reference line 192 extends through tool joint threads 143 and rotary earth bit threads 144 when tool joint 139 and rotary earth bit 102 are in the coupled condition, wherein reference line 192 is at an angle φ relative to centerline 147. In this way, tool joint 139 includes a threaded surface which extends at angle φ relative to centerline 147. Tool joint 139 is included with adapter sub 136 so that adapter sub 136 includes a threaded surface which extends at angle φ relative to centerline 147. Further, rotary earth bit 102 includes a threaded surface which extends at angle φ relative to centerline 147.
Angle φ can have many different angular values. In some embodiments, angle φ is in a range between about one degree (1°) to about nine degrees (9°). In some embodiments, angle φ is in a range between about one and one-half degrees (1.5°) to about eight degrees (8°). In some embodiments, angle φ is in a range between about three degrees (3°) to about five degrees (5°). In one particular embodiment, angle φ is about four and three-quarters of a degree (4.75°).
Angle φ is generally chosen so that rotary earth bit 102 is aligned with adapter sub 136 in response to moving rotary earth bit 102 and adapter sub 136 from the disengaged condition to the engaged condition. In this way, rotary earth bit 102 experiences less wobble in response to the rotation of hammer assembly 103 and drill string 106. It should be noted that the value of angle φ affects the amount of rotational energy transferred between drill string 106 and rotary earth bit 102 through adapter sub 136. The amount of rotational energy transferred between drill string 106 and rotary earth bit 102 increases and decreases as the value of angle φ increases and decreases, respectively.
In this embodiment, annular surfaces 158 and 159 are spaced apart from each other in response to rotary earth bit 102 and adapter sub 136 being in the coupled condition. Annular surfaces 158 and 159 are spaced apart from each other so that overstrike force F does not flow between adapter sub 136 and rotary earth bit 102 through annular surfaces 158 and 159. Instead, a first portion of overstrike force F flows between adapter sub 136 and rotary earth bit 102 through trapezoidal tool joint threads 143 and trapezoidal rotary earth bit threads 144.
Adapter sub 136 and rotary earth bit 102 are coupled to each other so that radial surfaces 153 and 154 (
It should be noted that overstrike force F flows more efficiently between adapter sub 136 and rotary earth bit 102 through surfaces 153 and 154 than through trapezoidal tool joint threads 143 and trapezoidal rotary earth bit threads 144. Overstrike force F experiences more attenuation in response to flowing through trapezoidal tool joint threads 143 and trapezoidal rotary earth bit threads 144 than through surfaces 153 and 154. Overstrike force F experiences less attenuation in response to flowing through surfaces 153 and 154 than through trapezoidal tool joint threads 143 and trapezoidal rotary earth bit threads 144. In this way, overstrike force F flows more efficiently through surfaces 153 and 154 than through trapezoidal tool joint threads 143 and trapezoidal rotary earth bit threads 144.
It should be noted, however, that the efficiency in which overstrike force F flows through trapezoidal tool joint threads 143 and trapezoidal rotary earth bit threads 144 increases and decreases as angle φ increases and decreases, respectively. It should also be noted that the interface between adapter sub 136 and rotary earth bit 102 can have many other shapes, one of which will be discussed in more detail presently.
c is a cross-sectional view of adapter sub 136 and rotary earth bit 102 in coupled conditions. In this embodiment, annular surfaces 158 and 159 are engaged with each other in response to rotary earth bit 102 and adapter sub 136 being in the coupled condition. Annular surfaces 158 and 159 are engaged with each other so that a third portion of overstrike force F does flow between adapter sub 136 and rotary earth bit 102 through annular surfaces 158 and 159. As mentioned above, the first portion of overstrike force F flows between adapter sub 136 and rotary earth bit 102 through trapezoidal tool joint threads 143 and trapezoidal rotary earth bit threads 144.
In this embodiment, adapter sub 136 and rotary earth bit 102 are coupled to each other so that an outer radial surface 153a faces an outer radial surface 154a and, and an outer radial surface 153b faces an outer radial surface 154b. Surfaces 153a, 153b, 154a and 154b are radial surfaces because they extend radially relative to centerline 147. Further, surfaces 153a and 154a are outer surfaces because they are positioned away from centerline 147. Surfaces 153a and 154a are positioned away from centerline 147 because they are positioned further away from centerline 147 than surfaces 153b and 154b. Surfaces 153b and 154b are inner surfaces because they are positioned towards centerline 147. Surfaces 153b and 154b are positioned towards centerline 147 because they are positioned closer to centerline 147 than surfaces 153a and 154a.
Surfaces 153a and 153b are spaced apart from each other to form an annular shoulder 156, and surfaces 154a and 154b are spaced apart from each other to form an annular shoulder 157. Annular shoulders 156 and 157 are positioned towards inner surfaces 153b and 154b, respectively. Annular shoulders 156 and 157 are positioned away from inner surfaces 153a and 154a, respectively. Inner surfaces 153b and 154b are spaced apart from each other, and annular shoulders 156 and 157 are spaced apart from each other to form an annular groove 155.
Surfaces 153a and 154a are spaced apart from each other when adapter sub 136 and rotary earth bit 102 are in the engaged condition, so that overstrike force F does not flow between adapter sub 136 and rotary earth bit 102 through surfaces 153a and 154a. In this way, overstrike force F is restricted from flowing between adapter sub 136 and rotary earth bit 102 through surfaces 153a and 154a. Further, surfaces 153b and 154b are spaced apart from each other when adapter sub 136 and rotary earth bit 102 are in the engaged condition, so that overstrike force F does not flow between adapter sub 136 and rotary earth bit 102 through surfaces 153b and 154b. In this way, overstrike force F is restricted from flowing between adapter sub 136 and rotary earth bit 102 through surfaces 153b and 154b.
Overstrike force F flows more efficiently between adapter sub 136 and rotary earth bit 102 through surfaces 158 and 159 than through trapezoidal tool joint threads 143 and trapezoidal rotary earth bit threads 144. Overstrike force F experiences more attenuation in response to flowing through trapezoidal tool joint threads 143 and trapezoidal rotary earth bit threads 144 than through surfaces 158 and 159. Overstrike force F experiences less attenuation in response to flowing through surfaces 158 and 159 than through trapezoidal tool joint threads 143 and trapezoidal rotary earth bit threads 144. In this way, overstrike force F flows more efficiently through surfaces 158 and 159 than through trapezoidal tool joint threads 143 and trapezoidal rotary earth bit threads 144.
d is a side view of trapezoidal rotary earth bit threads 144 in a region 145 of
As shown in
In this embodiment, earth bit thread root 180 includes a longitudinal wall 183 and tapered sidewall 182. Tapered sidewall 182 extends from an end of longitudinal wall 185 opposed to tapered sidewall 184 and towards centerline 147 (
Rotary earth bit threads 144 have a pitch L2, wherein pitch L2 is a length along longitudinal reference line 192 that earth bit thread root 180 and earth bit thread crest 181 extend. More information regarding the pitch of a thread can be found in the above-referenced U.S. Patent Application No. 20040251051. As pitch L2 increases and decreases the number of threads per unit length of trapezoidal rotary earth bit threads 144 increases and decreases, respectively. As pitch L2 increases and decreases the number of earth bit thread roots 180 per unit length increases and decreases, respectively. Further, as pitch L2 increases and decreases the number of earth bit thread crests 181 per unit length increases and decreases, respectively.
Thread pitch L2 can have many different length values. In some embodiments, thread pitch L2 has a length value in a range between about one-quarter of an inch to about one inch. In some embodiments, thread pitch L2 has a length value in a range between about one-half of an inch to about one inch. In one particular, embodiment, thread pitch L2 has a length value of one-eighth of an inch.
As mentioned above, the tapered sidewalls of trapezoidal rotary earth bit threads 144 extend at a non-parallel angle relative to longitudinal reference line 192. For example, in this embodiment, tapered sidewall 182 extends at an angle θ3 relative to radial reference line 191. Further, tapered sidewall 184 extends at an angle θ4 relative to radial reference line 161. It should be noted that the tapered sidewalls of trapezoidal rotary earth bit threads 144 extend at the same angle magnitude relative to longitudinal reference line 192.
Angles θ3 and θ4 can have many different angular values. In some embodiments, angles θ3 and θ4 are in a range between about one degree (1°) to about nine degrees (9°). In some embodiments, angles θ3 and θ4 are in a range between about one and one-half degrees (1.5°) to about eight degrees (8°). In some embodiments, angles θ3 and θ4 are in a range between about three degrees (3°) to about five degrees (5°). In one particular embodiment, angles θ3 and θ4 are each equal to about four and three-quarters of a degree (4.75°). In some embodiments, angles θ3 and θ4 are equal to each other and, in other embodiments, angles θ3 and θ4 are not equal to each other. In some embodiments, angles θ3 and θ4 are each equal to angle φ and, in other embodiments, angles θ3 and θ4 are not equal to angle φ. It should be noted that the values for angles θ3 and θ4 are not shown to scale in
In general, angles θ3 and θ4 are chosen to reduce the likelihood that rotary earth bit 102 and adapter sub 136 will over-tighten with each other. Further, angles θ3 and θ4 are chosen to increase the efficiency in which overstrike force F is transferred from hammer assembly 103 to rotary earth bit 102 through adapter sub 136. In general, the efficiency in which overstrike force F is transferred from hammer assembly 103 to rotary earth bit 102 through adapter sub 136 increases and decreases as angles θ3 and θ4 decrease and increase, respectively.
It should be noted that the helix angle of trapezoidal rotary earth bit threads 144 can have many different angular values. More information regarding the helix angle of a thread can be found in the above-references U.S. Patent Application No. 20040251051. In some embodiments, the helix angle of trapezoidal rotary earth bit threads 144 is in a range between about one degree (1°) to about ten degrees (10°). In some embodiments, the helix angle of trapezoidal rotary earth bit threads 144 is in a range between about one and one-half degrees (1.5°) to about five degrees (5°). In one particular embodiment, the helix angle of trapezoidal rotary earth bit threads 144 is about two and one-half degrees (2.5°).
As shown in
In this embodiment, tool joint thread root 170 includes a longitudinal wall 173 and tapered sidewall 172. Tapered sidewall 172 extends from an end of longitudinal wall 175 opposed to tapered sidewall 174 and towards centerline 147 (
Trapezoidal tool joint threads 143 have a pitch L1, wherein pitch L1 is a length along longitudinal reference line 192 that tool joint thread root 170 and tool joint thread crest 171 extend. As pitch L1 increases and decreases the number of threads per unit length of trapezoidal tool joint threads 143 increases and decreases, respectively. As pitch L1 increases and decreases the number of tool joint thread roots 170 per unit length increases and decreases, respectively. Further, as pitch L1 increases and decreases the number of tool joint thread crests 171 per unit length increases and decreases, respectively.
Thread pitch L1 can have many different length values. In some embodiments, thread pitch L1 has a length value in a range between about one-quarter of an inch to about one inch. In some embodiments, thread pitch L1 has a length value in a range between about one-half of an inch to about one inch. In one particular, embodiment, thread pitch L1 has a length value of one-eighth of an inch. It should be noted that thread pitches L1 and L2 are generally the same to facilitate the ability to repeatably move adapter sub 136 and rotary earth bit 102 between coupled and decoupled conditions.
As mentioned above, the tapered sidewalls of trapezoidal tool joint threads 143 extend at a non-parallel angle relative to longitudinal reference line 192. For example, in this embodiment, tapered sidewall 174 extends at an angle θ1 relative to radial reference line 190. Further, tapered sidewall 176 extends at an angle θ2 relative to radial reference line 190. It should be noted that the tapered sidewalls of trapezoidal tool joint threads 143 extend at the same magnitude angle relative to longitudinal reference line 192. Further, the tapered sidewalls of trapezoidal tool joint threads 143 generally extend at the same magnitude angle relative to longitudinal reference line 192 as the tapered sidewalls of trapezoidal rotary earth bit threads 144 to facilitate the ability to repeatably move adapter sub 136 and rotary earth bit 102 between coupled and decoupled conditions.
Angles θ1 and θ2 can have many different angular values. In some embodiments, angles θ1 and θ2 are in a range between about one degree (1°) to about nine degrees (9°). In some embodiments, angles θ1 and θ2 are in a range between about one and one-half degrees (1.5°) to about eight degrees (8°). In some embodiments, angles θ1 and θ2 are in a range between about three degrees (3°) to about five degrees (5°). In one particular embodiment, angles θ1 and θ2 are each equal to about four and three-quarters of a degree (4.75°). In some embodiments, angles θ1 and θ2 are equal to each other and, in other embodiments, angles θ1 and θ2 are not equal to each other. In some embodiments, angles θ1 and θ2 are each equal to angle γ and, in other embodiments, angles θ1 and θ2 are not equal to angle φ. It should be noted that the values for angles θ1 and θ2 are not shown to scale in
In general, angles θ1 and θ2 are chosen to reduce the likelihood that rotary earth bit 102 and adapter sub 136 will over-tighten with each other. Further, angles θ1 and θ2 are chosen to increase the efficiency in which overstrike force F is transferred from hammer assembly 103 to rotary earth bit 102 through adapter sub 136. In general, the efficiency in which overstrike force F is transferred from hammer assembly 103 to rotary earth bit 102 through adapter sub 136 increases and decreases as angles θ1 and θ2 decrease and increase, respectively. It should be noted that angles θ1, θ2, θ3 and θ4 generally have the same magnitude angular value to facilitate the ability to repeatably move adapter sub 136 and rotary earth bit 102 between coupled and decoupled conditions.
It should also be noted that the helix angle of trapezoidal tool joint threads 143 can have many different angular values. In some embodiments, the helix angle of trapezoidal tool joint threads 143 is in a range between about one degree (1°) to about ten degrees (10°). In some embodiments, the helix angle of trapezoidal tool joint threads 143 is in a range between about one and one-half degrees (1.5°) to about five degrees (5°). In one particular embodiment, the helix angle of trapezoidal tool joint threads 143 is about two and one-half degrees (2.5°). It should be noted that the helix angle of trapezoidal tool joint threads 143 and trapezoidal rotary earth bit threads 144 are generally the same to facilitate the ability to repeatably move adapter sub 136 and rotary earth bit 102 between coupled and decoupled conditions.
a is a flow diagram of a method 200, in accordance with the invention, of boring a hole. In this embodiment, method 200 includes a step 201 of providing a rotary drill system, wherein the rotary drill system includes a drive chuck and adapter sub slidingly engaged together, a rotary earth bit coupled to the adapter sub, and a piston repeatably moveable between engaged and disengaged positions with the adapter sub. The adapter sub slides relative to the drive chuck in response to the piston moving between the disengaged and engaged positions.
Method 200 includes a step 202 of flowing a fluid through the rotary drill system so that the piston moves between the engaged and disengaged positions. In this way, the piston moves between the engaged and disengaged positions in response to being actuated by a fluid. The rotary earth bit moves between extended and retracted positions in response to the piston moving between the engaged and disengaged positions.
b is a flow diagram of a method 210, in accordance with the invention, of boring a hole. In this embodiment, method 210 includes a step 211 of providing a rotary drill system, wherein the rotary drill system includes a drive chuck and adapter sub slidingly engaged together, a rotary earth bit coupled to the adapter sub, and a piston repeatably moveable between engaged and disengaged positions with the adapter sub. The adapter sub slides relative to the drive chuck in response to the piston moving between the disengaged and engaged positions.
In this embodiment, the piston includes a return piston port positioned away from the adapter sub and a drive piston port positioned proximate to the adapter sub. Further, the rotary drill system can include a flow control tube with a return guide port and a drive guide port. The return guide port is repeatably moveable between a first position in communication with the return piston port and a second position not in communication with the return piston port. Further, the drive guide port is repeatably moveable between a first position in communication with the drive piston port and a second position not in communication with the drive piston port.
Method 210 includes a step 212 of flowing a fluid through the ports of the piston so it moves between the engaged and disengaged positions. In this way, the piston moves between the engaged and disengaged positions in response to being actuated by a fluid. The rotary earth bit moves between extended and retracted positions in response to the piston moving between the engaged and disengaged positions.
c is a flow diagram of a method 220, in accordance with the invention, of manufacturing a rotary drill system. In this embodiment, method 220 includes a step 221 of providing a rotary earth bit and a step 222 of coupling a hammer assembly to the rotary earth bit. In accordance with the invention, the hammer assembly includes a drive chuck and adapter sub slidingly engaged together, and a piston repeatably moveable between engaged and disengaged positions with the adapter sub. The adapter sub slides relative to the drive chuck in response to the piston moving between the disengaged and engaged positions. The rotary earth bit is coupled to the adapter sub so that it slides in response to the adapter sub sliding.
A drill string is coupled to the hammer assembly and flows a fluid therethrough. The piston moves between the engaged and disengaged positions in response to the flow of the fluid. In this way, the piston moves between the engaged and disengaged positions in response to being actuated with a fluid. Further, the rotary earth bit moves between extended and retracted positions in response to the piston moving between the engaged and disengaged positions.
d is a flow diagram of a method 230, in accordance with the invention, of manufacturing a rotary drill system. In this embodiment, method 230 includes a step 231 of providing a rotary earth bit and a step 232 of coupling a hammer assembly to the rotary earth bit. In this embodiment, the hammer assembly includes a drive chuck and adapter sub slidingly engaged together and a piston repeatably moveable between engaged and disengaged positions with the adapter sub. The adapter sub slides relative to the drive chuck in response to the piston moving between the disengaged and engaged positions.
In this embodiment, the piston includes a drive piston port positioned away from the adapter sub and a drive piston port positioned proximate to the adapter sub. Further, the rotary drill system can include a flow control tube with a return guide port and a drive guide port. The return guide port is repeatably moveable between a first position in communication with the return piston port and a second position not in communication with the return piston port. Further, the drive guide port is repeatably moveable between a first position in communication with the drive piston port and a second position not in communication with the drive piston port.
In operation, the piston moves between the engaged and disengaged positions in response to a fluid flowing through the rotary drill system. In this way, the piston moves between the engaged and disengaged positions in response to being actuated by a fluid. The rotary earth bit moves between extended and retracted positions in response to the piston moving between the engaged and disengaged positions.
It should be noted that method 200 can include many other steps, several of which are discussed in more detail with method 210. Further, method 220 can include many other steps, several of which are discussed in more detail with method 230. Also, it should be noted that the steps in methods 200, 210, 220 and 230 can be performed in many different orders.
a is a flow diagram of a method 240, in accordance with the invention, of boring through a formation. In this embodiment, method 240 includes a step 241 of providing an earth bit operatively coupled to a drilling machine with a drill string, wherein the drilling machine applies a weight-on-bit to the earth bit through the drill string. Method 240 includes a step 242 of applying an overstrike force to the earth bit, wherein the overstrike force is in a range of about one foot-pound per square inch (1 ft-lb/in2) to about four foot-pounds per square inch (4 ft-lb/in2).
The weight-on-bit can be in many different ranges. For example, in one embodiment, the weight-on-bit is in a range of about 1,000 pounds per inch of hole diameter to about 10,000 pounds per square inch of hole diameter. The overstrike force can be applied to the earth bit in many different ways. For example, in some embodiments, the overstrike force is applied to the earth bit with a hammer assembly. In these embodiments, the hammer assembly operates in response to a flow of fluid through the drill string.
It should be noted that method 240 can include many other steps. For example, in some embodiments, method 240 includes a step of applying the overstrike force to the earth bit at a rate in a range of about 1100 times per minute to about 1400 times per minute. In some embodiments, method can include a step of adjusting the overstrike force in response to adjusting a fluid flow through the drill string. Method 240 can include a step of adjusting an amplitude and/or frequency of the overstrike force in response to an indication of a penetration rate of the earth bit through the formation. Method 240 can include a step of providing an air flow through the drill string at a rate in a range of about 1,000 cubic feet per minute (cfm) to about 4,000 cubic feet per minute (cfm). Method 240 can include a step of providing an air flow through the drill string at a pressure in a range of about forty pounds per square inch (40 psi) to about eighty pounds per square inch (80 psi).
b is a flow diagram of a method 250, in accordance with the invention, of boring through a formation. In this embodiment, method 250 includes a step 251 of providing a drilling machine and drill string and a step 252 of operatively coupling an earth bit to the drilling machine through the drill string. Method 250 includes a step 253 of providing an air flow through the drill string at an air pressure in a range of about forty pounds per square inch (40 psi) to about eighty pounds per square inch (80 psi) and a step 254 of applying an overstrike force to the earth bit, wherein the overstrike force is less than about five foot-pounds per square inch (5 ft-lb/in2).
The overstrike force can be in many different ranges. For example, in one embodiment, the overstrike force is in a range of about 1 ft-lb/in2 to about 4 ft-lb/in2.
It should be noted that method 250 can include many other steps. For example, in some embodiments, method 250 includes a step of adjusting the overstrike force in response to an indication of a penetration rate of the earth bit through the formation. In some embodiments, method 250 includes a step of adjusting the overstrike force to drive the penetration rate of the earth bit through the formation to a desired penetration rate. Method 250 can include a step of adjusting the penetration rate of the earth bit through the formation by adjusting at least one of an amplitude and frequency of the overstrike force. Method 250 can include a step of applying a weight-on-bit to the earth bit through the drill string, wherein the weight-on-bit is in a range of about 30,000 pounds to about 130,000 pounds.
c is a flow diagram of a method 260, in accordance with the invention, of boring through a formation. In this embodiment, method 260 includes a step 261 of providing an earth bit operatively coupled to a drilling machine with a drill string, wherein the drilling machine applies a weight-on-bit to the earth bit and a step 262 of providing an air flow through the drill string at an air pressure less than about eighty pounds per square inch (80 psi). Method 260 includes a step 263 of applying a time varying overstrike force to the earth bit, wherein the time varying overstrike force is less than about five foot-pounds per square inch (5 ft-lb/in2). The time varying overstrike force can have many different values. For example, in one embodiment, the time varying overstrike force is in a range of about 1.2 ft-lb/in2 to about 3.6 ft-lb/in2.
The time varying overstrike force can be applied to the earth bit in many different ways. For example, in some embodiments, the time varying overstrike force is applied to the earth with a hammer assembly.
It should be noted that method 260 can include many other steps. For example, in some embodiments, method 260 includes a step of adjusting an amplitude of the time varying overstrike force in response to an indication of a penetration rate of the earth bit through the formation. In some embodiments, method 260 includes adjusting a frequency of the time varying overstrike force in response to an indication of a penetration rate of the earth bit through the formation.
While particular embodiments of the invention have been shown and described, numerous variations and alternate embodiments will occur to those skilled in the art. Accordingly, it is intended that the invention be limited only in terms of the appended claims.
This application is a continuation of U.S. patent application Ser. No. 12/536,424, filed on Aug. 5, 2009 by the same inventors, now pending, which claims priority to U.S. Provisional Application No. 61/086,740, filed on Aug. 6, 2008 by the same inventors, the contents of which are incorporated by reference as though fully set forth herein.
| Number | Date | Country | |
|---|---|---|---|
| 61086740 | Aug 2008 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 12536424 | Aug 2009 | US |
| Child | 13709962 | US |
