None.
Disclosed embodiments relate generally to magnetic ranging methods and more particularly to methods for magnetic ranging while drilling (i.e., while the drill string is rotating).
In subterranean drilling operations the need frequently arises to determine the relative location of the wellbore being drilled (the drilling well) with respect to a pre-existing offset wellbore (a target well). This need may exist for the purpose of avoiding a collision or making an interception, or for the purpose of maintaining a specified separation distance between the wells (e.g., as in well twinning operations such as steam assisted gravity drainage operations). Magnetic ranging techniques are commonly employed to determine the relative location of the target well, for example, by making magnetic field measurements in the drilling well. The measured magnetic field may be induced in part by ferromagnetic material or an electromagnetic source (or sources) in the target well such that the measured magnetic field vector may enable the relative location of the target well to be computed.
Existing magnetic ranging techniques are similar to conventional static surveys in that they require drilling to be halted and the drill string to be held stationary in the drilling well while each magnetic survey is obtained. Magnetic ranging operations are therefore costly and time consuming. Moreover, magnetic ranging is similar to wellbore navigation in that the well path may be continuously adjusted in response to the ranging measurements. It may therefore be desirable to make ranging measurements as close to the bit as possible, in order to gain the earliest possible notification of required course adjustments. Owing to the rotation of the bit, measurements made close to the bit while drilling are made from a rotating platform (i.e., with rotating magnetic field sensors). There is a need in the art for magnetic ranging methods that employ magnetic field measurements made from a rotating platform (rotating sensors).
A method for magnetic ranging is disclosed. A downhole drilling tool is rotated in a drilling well in sensory range of magnetic flux emanating from a target well having an AC magnetic source deployed therein. The downhole tool includes a magnetic field sensor deployed therein. The magnetic field sensor measures a magnetic field vector while rotating. The measured magnetic field vector is processed to compute at least one of a distance and a direction from a drilling well to a target well.
The disclosed methods may enable magnetic ranging measurements to be acquired and processed while rotating the magnetic field sensors in the drilling well. The measurements may therefore be acquired and processed while drilling. Moreover, in embodiments in which the magnetic field sensors are mounted in a near-bit sensor sub below a mud motor, the ranging measurements may be acquired and processed while maintaining drilling fluid circulation.
This summary is provided to introduce a selection of concepts that are further described below in the detailed description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter.
For a more complete understanding of the disclosed subject matter, and advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:
It will be understood by those of ordinary skill in the art that the deployment illustrated on
Suitable accelerometers and magnetometers for use in sensors 55 and 57 may be chosen from among any suitable commercially available devices known in the art. For example, suitable accelerometers may include Part Number 979-0273-001 commercially available from Honeywell, and Part Number JA-5H175-1 commercially available from Japan Aviation Electronics Industry, Ltd. (JAE). Other suitable accelerometers may include micro-electro-mechanical systems (MEMS) solid-state accelerometers, available, for example, from Analog Devices, Inc. (Norwood, Mass.). Such MEMS accelerometers may be advantageous for certain near bit sensor sub applications since they tend to be shock resistant, high-temperature rated, and inexpensive. Suitable magnetic field sensors may include conventional ring core flux gate magnetometers or conventional magnetoresistive sensors, for example, Part Number HMC-1021D, available from Honeywell.
By further convention, the gravitational field is taken to be positive pointing downward (i.e., toward the center of the Earth) while the magnetic field is taken to be positive pointing towards magnetic north. Moreover, also by convention, the y-axis is taken to be the toolface reference axis (i.e., gravity toolface T equals zero when the y-axis is uppermost and magnetic toolface M equals zero when the y-axis is pointing towards the projection of magnetic north in the transverse (xy) plane). Those of ordinary skill in the art will readily appreciate that the magnetic toolface M is projected in the xy plane and may be represented mathematically as: tan M=Bx/By. Likewise, the gravity toolface T may be represented mathematically as: tan T=−Ax/−Ay. Those of skill in the art will understand that the negative sign in the gravity toolface expression arises owing to the convention that the gravity vector is positive in the downward direction while the toolface reference direction is the high side of the borehole (the side facing upward).
It will be understood that the disclosed embodiments are not limited to the above described conventions for defining the borehole coordinate system. It will be further understood that these conventions can affect the form of certain of the mathematical equations that follow in this disclosure. Those of ordinary skill in the art will be readily able to utilize other conventions and derive equivalent mathematical equations.
During rotation at 102, the transverse sensor (accelerometers Ax and Ay and magnetometers Bx and By) measurements may be expressed mathematically, for example, as follows:
Ax=−Axy·sin T (1)
Ay=−Axy·cos T (2)
Bx=Bxy·sin M (3)
By=Bxy·cos M (4)
where Axy represents the transverse component of the acceleration (e.g., due to gravity), Bxy represents the transverse component of the magnetic field, and T and M represent gravity and magnetic tool face as defined above. With reference to
Bx·Ay−By·Ax=Bxy·Axy·sin(T−M) (5)
Bx·Ax+By·Ay=−Bxy·Axy·cos(T−M) (6)
Equations 5 and 6 may be combined, for example, as follows to obtain the toolface offset (T−M):
which as illustrated in
Bxy=√{square root over ((Bx2+By2))} (8)
Bxy=√{square root over (2·σ(Bx)·σ(By))} (9)
where σ(Br) and σ(By) represent the standard deviations of Bx and By. Note that both the magnitude Bxy and direction (T−M) of the transverse field given in Equations 7, 8, and 9 are invariant under drill string rotation.
Accelerometer measurements made while rotating (particularly while drilling) are generally noisy owing to vibration of the drill string. Therefore, it may be advantageous to average the transverse accelerometer measurements over a time period such as several seconds in order to obtain an accurate measure of the toolface offset. Since the transverse accelerometer measurements vary with rotation it is desirable to compute an average toolface offset, for example, as follows:
where Σ(⋅) represents a summation of a number of accelerometer and magnetometer measurements (acquired over a period of time). In an embodiment in which the accelerometer and magnetometer measurements are acquired at 10 millisecond intervals, the measurements may be advantageously summed (averaged) over a time interval in a range from about 1 to about 300 seconds (e.g., about 30 seconds). The magnitude of the transverse component Bxy may be similarly averaged.
Turning to
The transverse magnetic field may alternatively and/or additionally be expressed in terms of high side BHS and right side BRS components, for example, as follows:
BHS=Bxy·cos(T−M) (11)
BRS=Bxy·sin(T−M) (12)
The axial magnetic field measurement and the axial acceleration component (measured by the Bz magnetometer and the Az accelerometer) may also be averaged as described above for the transverse measurements (e.g., over the same time interval). In embodiments utilizing a near-bit sensor sub (as depicted on
Based on the foregoing discussion, the three-dimensional magnetic field measured while rotating may be transformed from a tool based x/y/z coordinate system to a rotation invariant high side/right side/axial coordinate system. Alternatively, the three-dimensional magnetic field measured while rotating may be expressed as the magnitude of the transverse component Bxy, the toolface offset angle (T−M), and the magnitude of the axial component Bz. The three components of the rotation invariant magnetic field vector (e.g., BHS, BRS, and Bz) may be computed downhole as described above and transmitted to the surface using conventional telemetry techniques (e.g., via mud pulse or mud siren telemetry techniques). It may also be advantageous to transmit either the axial accelerometer measurement Az or the borehole inclination Inc, which may be computed from the axial accelerometer measurement, for example, as follows:
where G represents the local gravitational field of the Earth which may be determined from an external source or from the tri-axial accelerometer array during times in which the sensor sub is not rotating.
In certain embodiments the measured transverse magnetic field components may be perturbed by rotation of the drill string which can produce eddy currents in the electrically conductive collar. Such phenomenon has been disclosed, for example, in U.S. Pat. No. 5,012,412. In order to compensate for the effect of rotation induced eddy currents, it may also be desirable to transmit to the rotary speed (the rotation rate) of the sensor sub to the surface. The rotary speed rpm may be found, for example, as follows:
where the summation is over N samples acquired at s per second (e.g., 3000 samples acquired at 100 samples per second) and Mi represents the magnetic tool face of the ith sample.
Since the error in the direction of the transverse magnetic component caused by the conductive collar is approximately proportional to rotary speed, it may be represented by a fixed time delay between the accelerometer and magnetometer measurements. The effect may therefore be corrected by shifting the acquisition times for one set of sensors (either the accelerometers or magnetometers). This may be accomplished, for example, through the use of appropriate filters which delay the accelerometer signals with respect to the magnetometer signals. The methodologies disclosed in U.S. Pat. No. 7,650,269 and U.S. Patent Publications 2007/0203651 and 2010/0250207 may also optionally be employed to address any transverse magnetic field perturbations due to eddy currents in the drill collar.
The magnetic field components measured downhole represent the sum of the local Earth's magnetic field and the field from the target (as well as any magnetic interference from the drill string—which may be removed as described above). In order to obtain the target field from which magnetic ranging calculations are made, it may be necessary to remove the Earth's field components from the measured field. This may be represented mathematically, for example, as follows:
T=m−e (15)
where T represents the target magnetic field vector, m represents the measured magnetic field vector, and e represents the Earth's magnetic field vector. It will be understood that computing the target field vector may require that the measured magnetic field vector and the Earth's magnetic field vector be transformed into the same coordinate system (e.g., the rotation invariant system described above).
The magnetic field of the Earth (including both magnitude and direction components) is typically known, for example, from previous geological survey data or a geomagnetic model. However, for some applications it may be advantageous to measure the magnetic field in real time on site at a location substantially free from magnetic interference, e.g., at the surface of the well or in a previously drilled well. Measurement of the magnetic field in real time is generally advantageous in that it accounts for time dependent variations in the Earth's magnetic field, e.g., as caused by solar winds. However, at certain sites, such as an offshore drilling rig, measurement of the Earth's magnetic field in real time may not be practical. In such instances, it may be preferable to utilize previous geological survey data in combination with suitable interpolation and/or mathematical modeling (i.e., computer modeling) routines. Those of ordinary skill in the art will readily be able to transform the Earth's field to the above described high side/right side/axial reference frame, for example, using measured borehole inclination and borehole azimuth values.
Magnetic Ranging to a DC Target
The disclosed magnetic ranging embodiments may be utilized with a magnetic target including substantially any suitable DC magnetization. For example, the target well may include a magnetized casing string. The casing string may be intentionally magnetized so as to impart a known magnetic pattern to the string, for example, as disclosed in U.S. Pat. Nos. 7,538,650, 7,656,161, and 8,026,722, each of which is incorporated by reference herein in its entirety. In one embodiment commonly used in SAGD operations, the casing string may be magnetized such that each tubular in a premagnetized region of the casing includes a single pair of magnetically opposing poles (NN or SS) located at the approximate midpoint of the tubular. In this embodiment, the pairs of opposing poles are spaced at intervals about equal to the length of the tubulars, while the period of the magnetic field pattern (e.g., the distance from one a NN pair of opposing poles to the next) is about twice the length of the tubular.
When ranging to a target including premagnetized casing (also referred to as remanent magnetism), the magnetic field of the Earth e may be subtracted, for example, as described above with respect to Equation 15. Alternatively, periodic variations in the measured magnetic field along the length (axis) of the drilling well may be used to separate the Earth's field from the target field.
In embodiments in which the drilling well is a sufficient distance from the target well (e.g., greater than about one third of the axial distance between adjacent NN and SS opposing magnetic poles) the axial component Bz displays a single maximum or minimum between adjacent NN and SS poles. The maxima and minima of the axial component Bz correspond to the midpoints between the NN and SS poles where the target produces essentially no transverse magnetic field. Thus the values of BHS and BRS at these points may be taken to define the transverse component of the Earth's field. Conversely, maxima and minima of the transverse components BHS and BRS correspond to points opposite the NN and SS poles where the target produces essentially no axial magnetic field. Thus the value of the axial component Bz at these points may be taken to define the axial component of the Earth's field.
In embodiments in which the drilling well is closer to the target well (e.g., less than about one third of the axial distance between adjacent NN and SS opposing magnetic poles), the axial component Bz may display multiple maxima and/or minima between adjacent NN and SS poles (e.g., two maxima and one minimum or two minima and one maximum. In such embodiments, the single maximum or single minimum about which the axial component is symmetrical corresponds to the midpoints between the NN and SS poles where the target produces essentially no transverse magnetic field. Thus the values of BHS and BRS at these points may be taken to define the transverse component of the Earth's field.
Upon removing the Earth's magnetic field, the distance to the target wellbore may be computed from the target magnetic field vector and the known pole strengths imparted to the target well. For example, the magnitude of the transverse component of the target magnetic field may be processed in combination with an empirical or theoretical model of the magnetic field about the target to compute the distance. Moreover, the high side and right side components of the target magnetic field may be processed to compute the distance and/or direction to the target well. U.S. Pat. No. 7,617,049, which is incorporated by reference herein in its entirety, discloses other suitable methods for computing the distance and/or direction between a drilling well and a target well using magnetic ranging measurements.
The direction in the transverse plane to the target well may alternatively and/or additionally be obtained via plotting the high side and right side components BHS and BRS of the measured magnetic field.
The casing string may include a residual remanent magnetism imparted during a magnetic particle inspection of the threaded ends of the casing tubulars. Magnetic ranging to such residual remanent magnetism is commonly referred to in the art as passive ranging. Such passive ranging can be challenging as the residual remanent magnetism tends to be highly localized at the ends of the casing tubulars, and consequently at the casing joints within the target wellbore. Moreover, the magnetic field strengths of the poles can be weak and unknown; therefore resulting in a magnetic field pattern that also tends to be unknown. Notwithstanding, magnetic ranging to target wells including residual remanent magnetism may be required, for example, when attempting to intercept the target well with a relief well, particularly when a close approach is used in a non-conductive formation such as salt, which tends to prevent the use of active ranging techniques.
Owing to the relatively low magnitude of the target magnetic field, passive ranging is generally utilized at close distances (e.g., within five meters or less of the target). At close distances, each pole may present a signature such as that depicted on
where P represents the magnetic pole strength, d represents the radial distance to the target, z represents the axial position of the magnetic field sensor, and z0 represents the axial position of the magnetic source (e.g., the joint between adjacent casing tubulars). Equation 16 may be differentiated with respect to the axial direction, for example, as follows:
The axial positions of the maximum and minimum may be obtained by setting Equation 17 to zero which yields d2=2(z−z0)2. Assuming from
d=√{square root over (2)}(z−z0)=δz/√{square root over (2)} (18)
It will be understood that the methodology described above with respect to Equations 16-18 and
The target magnetic field may also be obtained by removing the Earth's magnetic field e, for example, as describe above with respect to Equation 15. The target magnetic field may then be processed to compute the distance and/or the direction (e.g., the TFT) to the target well, for example, using the one or more of the techniques disclosed in U.S. Pat. No. 6,985,814, which is incorporated by reference herein in its entirety.
The target well may alternatively and/or additionally include a direct current (DC) electromagnetic source deployed therein. The electromagnetic source, such as a solenoid, may be moved along the axis of the target during the drilling operation and may further be controlled during drilling, for example, via switching the source on or off, varying its intensity, or reversing its polarity.
The target magnetic field may be found, for example, from the difference between measurements taken with the source excited in two different states such as two opposing polarities (e.g., positively and negatively directed current in the solenoid). The three components of the target magnetic field vector (BHS, BRS, and Bz of the target) may be resolved into distance and direction by inversion of models or maps of the field around the target.
The Earth's field may be found from a measurement taken with the source switched off, or from the average of two measurements in which the source was excited with equal amplitude in two opposing polarities. Measurement of the Earth's field components in this way may be used to ascertain the attitude of the receiver by the use of standard relationships well known in magnetic wellbore surveying.
Magnetic Ranging to an AC Target
The disclosed magnetic ranging embodiments may be utilized with a magnetic target including substantially any suitable AC magnetization. In such operations the target well may include an electromagnet powered by an alternating current (AC) power source. The magnetic field about an AC target BT may be expressed mathematically, for example, as follows:
BT=BTa sin(ωt+ϕ) (19)
where BTa represents the amplitude of the magnetic field, ω represents the known frequency, and ϕ represents an arbitrary phase. When in sensory range of the target, the axial (z-axis) magnetic field Bz may be expressed as follows:
Bz=Bez+BTz (20)
where Bez represents the axial component of the Earth's field and BTz represents the axial component of the target AC field. It will be understood from Equation 20 that the mean value (the DC value) of Bz is equal to Bez and that the periodic variations from the mean may be used to compute the amplitude and phase of BTz. When magnetic field measurements are acquired over an interval of several cycles (preferably over an integer number of cycles—which may be readily achieved since the source frequency is known), the mean value of a set of measured Bz measurements represents the axial component of the Earth's field. Thus, subtracting the mean value from each individual Bz measurement gives the corresponding BTz. These operations may be expressed mathematically, for example, as follows:
where Bzm represents the mean value of a set of Bz measurements. The standard deviation of the set of Bz measurements represents the root mean square (rms) amplitude of BTz. The amplitude Bza of Bz may thus be found by multiplying the root mean square value by the square root of two and the phase information sin(ωt+ϕ) may be found by dividing BTz by Bza. These operations may be expressed mathematically, for example, as follows
where BTzrms represents the root mean square amplitude of Bz and σ(⋅) represents the standard deviation. While Equations 19, 24 and 25 may imply that the target field BT is sinusoidal, the disclosed embodiments are expressly not limited in this regard. In practice the target field may deviate from a sine wave, as nonlinearity and hysteresis of ferromagnetic materials in the solenoid core and target casing may distort the waveform of the magnetic field (even when the input AC current is perfectly sinusoidal). The deviation of the magnetic field from a sine wave may be modeled or measured and suitable corrections made, if necessary.
xy(ϕ)=exy+Txy(ϕ) (26)
With continued reference to
Bxy=√{square root over ((Bexy2+BTxy2−2BexyBTxy cos θ))} (27)
where Bexy represents the magnitude of the transverse component of the Earth's field, BTxy represents the magnitude of the transverse component of the target field, and θ represents the angle between the transverse components of the Earth's magnetic field vector and the target magnetic field vector. The direction of the transverse component of the measured magnetic field vector Bxy diverges from the transverse component Earth's magnetic field vector Bexy by the angle α where (using the law of sines):
It will thus be understood that both the amplitude and direction of the measured transverse component oscillate with the target field, for example, as follows:
BTxy=BTxya sin(ωt+ϕ) (29)
where BTxya represents the amplitude of the transverse magnetic field from the target and where at any time t the corresponding value of sin(ωt+ϕ) may be obtained from the axial measurement (even when the magnetic field is non-sinusoidal). The magnitude of the transverse component of the measured magnetic field can be computed from the x- and y-axis magnetometer measurements (e.g., Bxy2=Bx2 By2). Combining Equations 27 and 29 enables the magnitude of the transverse component of the measured magnetic field to be expressed as a quadratic function of the phase sin(ωt+ϕ), for example, as follows:
Bxy2=BTxya2 sin2(ωt+ϕ)−2BxyeBTxya cos θ sin(ωt+ϕ)+Bxye2 (30)
Since sin(ωt+ϕ) is known at any instant in time from the axial magnetic field measurements (Equation 25), and since corresponding values of Bxy are measured, a standard least-squares fit may be applied to determine the quadratic coefficients BTxya2, 2BxyeBTxya cos θ, and Bxye2, from which BTxya, Bexy, and θ may be determined. These parameters may then be used to obtain the distance and direction to the target well as described in more detail below.
The coefficients in a quadratic equation y=a·x2+b·x+c may be found, for example, as follows when x and y are known:
where y=Bxy2, x=sin(ωt+ϕ), and Σ(⋅) indicates a sum over a predetermined number of measurements. For example, measurements may be acquired at 10 millisecond intervals for 30 seconds to obtain 3000 accelerometer and magnetometer measurements. In an embodiment in which the AC frequency is 10 Hz these measurements span 300 cycles.
It will be understood that the foregoing discussion has assumed that the AC magnetic field emanating from the target is substantially sinusoidal. However, the disclosed embodiments are not limited in this regard. In practice, when ranging to an AC solenoid, the received magnetic field may be non-sinusoidal. While the solenoid may be driven by a sinusoidal current, nonlinear behavior of ferromagnetic materials in the solenoid core and/or in the casing may cause the emitted AC magnetic field to be non-sinusoidal. In particular, the magnetic field may contain a third harmonic corresponding to a depression of the peak values resulting from material nonlinearity as magnetic saturation is approached.
A non-sinusoidal magnetic field may result in biased ranging results unless compensation is made. The waveform of the target magnetic field can be determined from the measured axial component, or from measurements of transverse components during intervals of non-rotation of the magnetic sensors. Corrections for harmonics (such as the above described third harmonic) may then be made by modeling their effect or by experiments conducted at the surface. Alternatively, the solenoid may be driven by a non-sinusoidal current whose waveform is adjusted to produce a sinusoidal magnetic field at the receiver. The waveform may be determined by modeling, by experiments conducted at the surface, or by feedback from real-time measurements of the received magnetic waveforms. The disclosed embodiments are not limited in this regard.
For example, a method for magnetic ranging may include deploying a magnetic field sensor in sensory range of magnetic flux emanating from a ferromagnetic casing string having an AC magnetic source deployed therein. The casing may be deployed at the surface or in a target well. Magnetic field measurements may be processed to compute an amplitude of at least one higher order harmonic of the AC magnetic field. The AC magnetic source may then be energized with a non-sinusoidal input electrical current to reduce (or eliminate) the amplitude of the higher order harmonic.
The above described magnetic ranging technique tends to be effective when the magnitude of Bxy is a strong function of the target field; i.e., when the angle θ in
At each instant (i.e., at each magnetometer measurement interval—such as 10 millisecond), an apparent magnetic toolface may be computed, for example, as described above with respect to
where s represents the magnetometer sample rate (measurement interval). It will be understood that the magnetic toolface M is measured with respect to the transverse component of the measured magnetic field (i.e., xy). As described above with respect to
where rpmavg represents the average rotary speed determined, for example, via Equation 14 and ∂∝/∂t represents the rate of change of the angle α which may be evaluated by applying the law of sines to the diagram on
from which it follows that:
Differentiating Equation 35 yields:
From Equation 33 the deviation of the measured rotary speed from the average rotary speed Δrpm may be given as follows:
Substituting Equation 36 into Equation 37 yields:
In many magnetic ranging operations to an AC target, it may be assumed that the Earth's field Bexy is much larger than the target field BTxya such that Equation 37 may be simplified, for example, as follows:
Note that in Equation 39 the deviation (or variation) in the measured rotary speed Δrpm is sinusoidal (proportional to cos(ωt+ϕ)) at the AC excitation frequency ω with an amplitude equal to BTxya·sin θ/Bexy. The amplitude is proportional BTxya and may thus be related to the distance from the drilling well to the target well (e.g., using one or more of the above described methods). Moreover, the Earth's field Bexy may be known from other measurements.
In many ranging operations employing an AC target, it may be advantageous to employ both of the above described methodologies (the first based on the magnitude of Bxy described with respect to Equations 27-30 and the second based on the oscillating direction described with respect to Equations 31-38). For example, the first methodology may be employed to obtain values of BTxya and θ while the second methodology may be employed to obtain the sign (positive or negative) of sin θ which indicates whether the target is to the right or left of the drilling well. Alternatively, both methodologies may be employed simultaneously to provide a more robust solution for BTxya and θ (i.e., a solution having reduced noise).
The three components of the AC target magnetic field (BTxya, θ, and Bza of the target) may be resolved into distance and direction by inversion of models or maps of the field around the target. For example, the amplitude of the transverse component of the target field BTxya may be resolved into distance using an empirical or theoretical model or map of the target field and the angle θ between the Earth's field and the target field may be resolved into a toolface to target direction, for example, as follows:
TFT=θ+(T−M) (40)
where TFT represents the toolface to target direction in the transverse plane and (T−M) represents the above described toolface offset that may be measured, for example, using Equation 9 at times when the AC target is not energized.
It will be understood that while not shown in
A suitable controller may include a timer including, for example, an incrementing counter, a decrementing time-out counter, or a real-time clock. The controller may further include multiple data storage devices, various sensors, other controllable components, a power supply, and the like. The controller may also optionally communicate with other instruments in the drill string, such as telemetry systems that communicate with the surface or an EM (electro-magnetic) shorthop that enables the two-way communication across a downhole motor. It will be appreciated that the controller is not necessarily located in the sensor sub (e.g., sub 60), but may be disposed elsewhere in the drill string in electronic communication therewith. Moreover, one skilled in the art will readily recognize that the multiple functions described above may be distributed among a number of electronic devices (controllers).
Although magnetic ranging while rotating and certain advantages thereof have been described in detail, it should be understood that various changes, substitutions and alternations can be made herein without departing from the spirit and scope of the disclosure as defined by the appended claims.
Number | Name | Date | Kind |
---|---|---|---|
2596322 | Zumwalt | May 1952 | A |
2980850 | Cochran | Apr 1961 | A |
3117065 | Wootten | Jan 1964 | A |
3406766 | Henderson | Oct 1968 | A |
3670185 | Vermette | Jun 1972 | A |
3673629 | Casey et al. | Jul 1972 | A |
3725777 | Robinson et al. | Apr 1973 | A |
3731752 | Schad | May 1973 | A |
3862499 | Isham et al. | Jan 1975 | A |
4072200 | Morris et al. | Feb 1978 | A |
4458767 | Hoehn, Jr. | Jul 1984 | A |
4465140 | Hoehn, Jr. | Aug 1984 | A |
4525715 | Smith | Jun 1985 | A |
4646277 | Bridges et al. | Feb 1987 | A |
4672345 | Littwin et al. | Jun 1987 | A |
4710708 | Rorden et al. | Dec 1987 | A |
4730230 | Helfrick et al. | Mar 1988 | A |
4743849 | Novikov | May 1988 | A |
4812812 | Flowerdew et al. | Mar 1989 | A |
4813274 | DiPersio et al. | Mar 1989 | A |
4894923 | Cobern et al. | Jan 1990 | A |
4931760 | Yamaguchi et al. | May 1990 | A |
4933640 | Kuckes | Jun 1990 | A |
5012412 | Helm | Apr 1991 | A |
5025240 | La Croix | Jun 1991 | A |
5126720 | Zhou et al. | Jun 1992 | A |
5148869 | Sanchez et al. | Sep 1992 | A |
5230387 | Waters et al. | Jul 1993 | A |
5319335 | Huang et al. | Jun 1994 | A |
5428332 | Srail et al. | Jun 1995 | A |
5485089 | Kuckes | Jan 1996 | A |
5512830 | Kuckes | Apr 1996 | A |
5541517 | Hartmann et al. | Jul 1996 | A |
5589775 | Kuckes | Dec 1996 | A |
5657826 | Kuckes | Aug 1997 | A |
5675488 | McElhinney | Oct 1997 | A |
5725059 | Kuckes et al. | Mar 1998 | A |
5923170 | Kuckes | Jul 1999 | A |
RE36569 | Kuckes | Feb 2000 | E |
6060970 | Bell | May 2000 | A |
6310532 | Santa Cruz et al. | Oct 2001 | B1 |
6369679 | Cloutier et al. | Apr 2002 | B1 |
6466020 | Kuckes et al. | Oct 2002 | B2 |
6670806 | Wendt et al. | Dec 2003 | B2 |
6698516 | Van Steenwyk et al. | Mar 2004 | B2 |
6736222 | Kuckes et al. | May 2004 | B2 |
6937023 | McElhinney | Aug 2005 | B2 |
6985814 | McElhinney | Jan 2006 | B2 |
6991045 | Vinegar et al. | Jan 2006 | B2 |
7510030 | Kuckes et al. | Mar 2009 | B2 |
7538650 | Stenerson et al. | May 2009 | B2 |
7565161 | Sliva | Jul 2009 | B2 |
7568532 | Kuckes | Aug 2009 | B2 |
7617049 | McElhinney et al. | Nov 2009 | B2 |
7650269 | Rodney | Jan 2010 | B2 |
7656161 | McElhinney | Feb 2010 | B2 |
7671049 | Desai et al. | Mar 2010 | B2 |
7712519 | McElhinney et al. | May 2010 | B2 |
7755361 | Seydoux | Jul 2010 | B2 |
8010290 | Illfelder | Aug 2011 | B2 |
8026722 | McElhinney | Sep 2011 | B2 |
8049508 | Gorek | Nov 2011 | B2 |
8490717 | Bergstrom et al. | Jul 2013 | B2 |
20020062992 | Fredericks et al. | May 2002 | A1 |
20030188891 | Kuckes | Oct 2003 | A1 |
20040051610 | Sajan | Mar 2004 | A1 |
20040119607 | Davies et al. | Jun 2004 | A1 |
20040263300 | Maurer et al. | Dec 2004 | A1 |
20060106587 | Rodney | May 2006 | A1 |
20060131013 | McElhinney | Jun 2006 | A1 |
20070203651 | Blanz et al. | Aug 2007 | A1 |
20070289373 | Sugiura | Dec 2007 | A1 |
20080177475 | McElhinney | Jul 2008 | A1 |
20100126770 | Sugiura | May 2010 | A1 |
20100155139 | Kuckes | Jun 2010 | A1 |
20100250207 | Rodney | Sep 2010 | A1 |
20110036631 | Prill | Feb 2011 | A1 |
20110133741 | Clark | Jun 2011 | A1 |
20110282583 | Clark | Nov 2011 | A1 |
20110298462 | Clark et al. | Dec 2011 | A1 |
20120194195 | Wisler et al. | Aug 2012 | A1 |
20130069655 | McElhinney et al. | Mar 2013 | A1 |
20130073208 | Dorovsky | Mar 2013 | A1 |
20130151158 | Brooks et al. | Jun 2013 | A1 |
20140111210 | Fang et al. | Apr 2014 | A1 |
Number | Date | Country |
---|---|---|
2012134468 | Oct 2012 | WO |
2013101587 | Jul 2013 | WO |
Entry |
---|
International Search Report issued in related PCT application PCT/US2015/037875 dated Sep. 9, 2015, 3 pages. |
International Search Report issued in related PCT application PCT/US2015/037884 dated Sep. 21, 2015, 3 pages. |
Ex Parte Quayle Action issued in U.S. Appl. No. 14/318,327 on Jun. 16, 2017. 7 pages. |
International Preliminary Report on Patentability issued in related PCT application PCT/US2015/037884 dated Jan. 5, 2017. 11 pages. |
International Preliminary Report on Patentability issued in related PCT application PCT/US2015/037875 dated Jan. 5, 2017. 7 pages. |
Number | Date | Country | |
---|---|---|---|
20150378044 A1 | Dec 2015 | US |