Configurable beacon and method

A monitoring system is used to monitor the location and orientation of a downhole tool assembly by detecting an output signal. The downhole tool assembly has a beacon assembly with one or more configurable operation parameters. A transmitting assembly transmits an operation instruction signal to the beacon assembly to configure the operation parameters. The detected operation instruction signal is processed by the beacon assembly and the operation parameter is configured. The transmitting assembly may be separate from the monitoring system and have an input assembly. The input assembly allows the operator to input predetermined operation parameters into the transmitting assembly that are then transmitted to the beacon assembly. In a preferred embodiment, the configurable operation parameters may include the intensity and/or frequency of the output signal, the calibration and resolution of orientation sensors, and the rate at which data is transmitted from the beacon assembly.

FIELD OF THE INVENTION

The present invention relates generally to the field of determining the location and orientation of underground objects, and in particular to the configuration of beacons and sensors used to monitor the orientation and location of a downhole tool assembly.

SUMMARY OF THE INVENTION

The present invention is directed to a horizontal directional drilling system. The horizontal directional drilling system comprises a horizontal directional drilling machine, a drill string, a downhole tool assembly, a transmitting assembly and a beacon assembly. The drill string is operatively connected to the horizontal directional drilling machine and the downhole tool assembly is supported on the drill string. The transmitting assembly comprises a transmitter adapted to transmit at least an operation instruction signal. The beacon assembly is supported by the downhole tool assembly and comprises at least a configurable operation parameter.

The beacon assembly further comprises a receiver, a processor, and a transmitter. The receiver is adapted to detect the operation instruction signal from the transmitting assembly and to communicate the detected operation instruction signal. The processor is supported by the beacon assembly and is adapted to receive the detected operation instruction signal from the receiver. Further, the processor is adapted to configure the operation parameter of the beacon assembly in response to the detected operation instruction signal. The transmitter transmits an output signal from the beacon assembly.

The invention further includes a beacon assembly having at least a configurable operation parameter for use with a horizontal directional drilling system having a transmitting assembly. The transmitting assembly comprises a transmitter adapted to transmit an operation instruction signal. The beacon assembly comprises a receiver, a processor, and a transmitter. The receiver is adapted to detect the operation instruction signal from the transmitting assembly and to transmit the detected operation instruction signal. The processor is adapted to receive the detected operation instruction signal from the receiver. Further, the processor is adapted to process the operation instruction signal and to configure the operation parameter of the beacon assembly in response to the detected operation instruction signal. The transmitter is adapted to transmit an output signal.

Still yet, the present invention is directed to a method for monitoring the location and orientation of a downhole tool assembly using a monitoring system. The downhole tool assembly has a beacon assembly comprising at least a configurable operation parameter. The method comprises transmitting an output signal from the beacon assembly indicative of the configurable operation parameter, detecting the output signal, processing the output signal to determine a value for the configurable operation parameter. Using the determined value, an operation instruction is transmitted to the beacon assembly to alter the configurable operation parameter of the beacon assembly to obtain a desired operation parameter.

Further still, the present invention is directed to a method of determining the distance between a downhole tool assembly and a monitoring system. The method comprises positioning the downhole tool assembly and monitoring system a known distance from each other. Next, a proportionality constant value is selected. The magnetic field is then transmitted from the downhole tool assembly and detected. An estimated distance between the monitoring system and the downhole tool assembly is calculated based upon the detected intensity of the magnetic field and the selected proportionality constant value. An operation instruction is transmitted to the downhole tool assembly. The operation instruction signal is indicative of the estimated distance between the downhole tool assembly and the monitoring system. The intensity or signal strength of the magnetic field transmitted by the downhole tool assembly is changed so that the estimated distance calculated by the monitoring system is substantially equal to the known distance.

In yet another embodiment, the present invention is directed to a method for monitoring the location and orientation of a beacon assembly located below ground, the beacon assembly comprising at least a configurable operation parameter. The method comprises sensing a configurable operation parameter of the beacon assembly, processing the configurable operation parameter, transmitting an operation instruction to the beacon assembly, and altering the configurable operation parameter of the beacon assembly in response to the operation instruction.

BRIEF DESCRIPTION OF THE INVENTION

Horizontal directional drilling (“HDD”) permits the installation of utility services or other products underground in an essentially trenchless manner, eliminating surface disruption along the length of the project and reducing the likelihood of damaging previously buried products. The typical HDD borepath begins from the ground surface as an inclined segment that is gradually leveled off as the desired product installation depth is neared. This depth is maintained—or a near horizontal path may be desirable instead—for the specified length of the product installation. The presence of previously buried products has given rise to a need for methods and systems that allow for steering of a boring tool as it moves along the borepath.

To steer the boring tool, it is important to know the location and orientation (roll, pitch and yaw) of the downhole tool assembly. Various beacon assemblies have been developed to provide the operator with information concerning the location and orientation of the downhole tool assembly. To provide accurate location and orientation information it is important that the beacon assembly is properly calibrated and configured.

The present invention provides the ability to configure certain and various operation parameters of the beacon assembly so that the downhole tool assembly may be located and steered during the boring operation. The present invention provides the ability to configure the orientation of the beacon assembly to match the orientation of the downhole tool assembly without concern for the actual orientation of the beacon assembly supported within the downhole tool assembly or with the type of connection between the boring tool and the tool assembly. With the present invention, the orientation of the receiver may be electronically adjusted without the need for removing the boring tool from the housing or repositioning the orientation sensors within the housing of the tool assembly. Additionally, various other beacon assembly operation parameters may be electronically configured i.e., intensity or signal strength of the magnetic field, orientation sensor resolution, transmitted frequency, and the rate at which data is transmitted from the beacon assembly. While the preferred application of this invention is to near surface HDD, the systems and methods of this invention may be applied to other machines and devices which require knowing the orientation and location of a device.

With reference now to the drawings in general andFIG. 1in particular, there is shown therein a HDD system10suitable for the subsurface placement of utility services.FIG. 1illustrates the usefulness of near surface HDD by illustrating that a borehole12can be made without disturbing an above-ground structure, namely the roadway as denoted by reference numeral14.FIG. 1also illustrates the present invention by showing the use of a monitoring system16to monitor the location and orientation of a downhole tool assembly18, comprising a directional boring tool20, supported on a drill string22. The monitoring system16may include a transmitting assembly, as shown inFIG. 4, that comprises a transmitter adapted to transmit at least an operation instruction signal. As used herein, directional boring tool20is intended to refer to any drilling bit or boring tool which may cause deviation of the tool from a straight path. A directional boring tool, when operated in accordance with the present invention, will have a steering capability to enable the downhole tool assembly18to direct the path of the borehole12.

Referring still toFIG. 1, the HDD system10generally comprises an HDD machine24, the drill string22, the monitoring system16, the downhole tool assembly18, and an earth anchor26. The HDD machine24comprises a rotary drive system28movably supported on a frame30between a first position and a second position. Movement of the rotary drive system28by way of an axial advancement means (not shown) between the first position and the second position, axially advances the drill string22, downhole tool assembly18, and directional boring tool20through the earth to create the borehole12. The earth anchor26is driven into the earth to stabilize the frame30against the axial force exerted by the movement of the axial advancement means during the axial advancement of the downhole tool assembly18and directional boring tool20.

The drill string22is operatively connected to the rotary drive system28of the HDD machine24at a first end32. The downhole tool assembly18is operatively connected to a downhole second end34of the drill string22. The drill string22transmits torque and thrust to the downhole tool assembly18and directional boring tool20to drill the subsurface borehole12.

Turning now toFIG. 2, there is shown therein the downhole tool assembly18constructed in accordance with the present invention. The downhole tool assembly18comprises a housing36and the directional boring tool20. The housing36comprises a chamber38for supporting the beacon assembly40. The housing36is operably connected at a rear end42to the drill string22. Preferably, the connection between the rear end42of the housing36and the drill string22is a threaded connection.

As discussed above, the beacon assembly40is supported by the downhole tool assembly18and comprises at least a configurable operation parameter. Further, the beacon assembly40may comprise an electromagnetic transmitter44that emits an output signal46(FIG. 1) that may be a magnetic field that is modulated to communicate information indicative of the location, orientation, and condition of the beacon assembly40. Preferably, a beacon assembly40for use with the present invention will also include a receiver49supported by the beacon assembly and adapted to detect the operation instruction signal from the transmitting assembly. The receiver49is also adapted to communicate the detected operation instruction signal to a processor50.

The processor50is supported by the beacon assembly40and is adapted to receive the detected operation instruction signal from the receiver49and to configure the operation parameter of the beacon assembly. Further, the processor50can attach orientation information received from the orientation sensor48, by well-known amplitude, phase, or frequency modulation techniques, onto an output signal46(FIG. 1) transmitted by the electromagnetic transmitter44to the monitoring system16(shown inFIG. 1). The signal46is processed by the monitoring system16to determine the location and orientation of the downhole tool assembly18and condition of the beacon assembly40.

As shown inFIG. 2, the housing36has a side-entry opening52to receive the beacon assembly40, which is held therein by a retaining cover54. It should be noted that a front-loading or end-loading housing could also be utilized without departing from the spirit of the invention. The beacon assembly40could also be an integral part of the housing36. Preferably, the beacon assembly40and orientation sensors48are maintained in substantially parallel axial alignment with respect to the central axis of the housing36. Beacon assemblies and associated internal orientation sensors suitable for use with the present invention are disclosed in U.S. Pat. No. 5,264,795, issued to Rider, U.S. Pat. No. 5,703,484, issued to Bieberdorf, et al., U.S. Pat. No. 5,850,624, issued to Gard, et al., and U.S. Pat. No. 5,880,680, issued to Wisehart, et al., the contents of which are incorporated herein by reference.

The directional boring tool20is attached to the front end56of the housing36. As shown in the embodiment ofFIG. 2, the front end56of the housing36may be configured for the attachment of a boring tool comprising a flat blade drill bit58. Preferably, the flat blade drill bit58is bolted onto the housing36at an acute angle of approximately 10° to the central axis of the housing36. While the flat blade drill bit58is shown herein, it should be noted that any other directional boring tool or mechanisms which may cause deviation of the drill string may be used with the present invention. Such boring tools and mechanisms include single roller cone bits, carbide studded cobble drilling bits, replaceable tooth rock drilling bits, and bent-sub assemblies. Directional boring tools and mechanisms suitable for use with the present invention are described in U.S. Pat. No. 5,490,569 issued to Brotherton et al., U.S. Pat. No. 5,799,740, issued to Stephenson, et al., U.S. Pat. No. 6,109,371, issued to Kinnan, and U.S. Pat. No. 6,311,790, issued to Beckwith et al., the contents of which are incorporated herein by reference.

Turning now toFIG. 3, the beacon assembly40constructed in accordance with the present invention is shown therein. The beacon assembly40comprises the receiver49, the processor50, and the electromagnetic transmitter44. Additionally, the beacon system may comprise an orientation sensor48, an analog to digital (“A/D”) converter64, a temperature sensor68, a battery condition sensor (not shown), and an optional Digital Signal Processor70. A power supply66and power regulator69are provided to normalize the voltage input into the various beacon assembly components.

The orientation sensor48may comprise one or more accelerometers adapted to sample changes in the angular orientation of the beacon assembly40. For example, the orientation sensor48may comprise pitch or roll sensors that are capable of sampling data indicative of the pitch and roll orientation of the beacon assembly40. A pitch sensor is generally aligned so that its sensitive axis is parallel to and coaxial with the longitudinal axis of the beacon assembly40. Placing the pitch sensor in this orientation provides the greatest sensitivity to changes in the pitch orientation of the beacon assembly while minimizing the effect of changes in roll orientation. Additionally, the orientation sensor48may also comprise a magnetometer or similar device for sensing the azimuth of the housing36. Preferably, the orientation sensor48will be operable alternatively in a low resolution mode or a high resolution mode.

The orientation data is sent from the orientation sensor48to the A/D converter64. The A/D converter64takes the analog data received from the orientation sensor48and converts it into a digital format for use by the processor50. It will be appreciated that an orientation sensor that outputs digital data directly to the processor50may be used in accordance with the present invention.

The temperature sensor68is provided to monitor the temperature of the beacon assembly40and transmit the results of temperature readings to the processor50in a temperature signal. In the event that the temperature readings transmitted from the temperature sensor68exceed safe operating parameters, the processor50is programmed to turn off the beacon assembly40and its associated electronics.

The processor50contains the programming and memory required to use the raw data from the orientation sensor48and the temperature sensor68to determine the spatial orientation of the beacon assembly40. The processor50processes the data, performs any necessary calculations and corrections, and communicates the results to the transmitter44.

The processor50applies filtering to the orientation data received from the orientation sensor48. Filtering is used so that the orientation can be measured effectively while the downhole tool assembly18(FIG. 2) is rotating. Filtering reduces vibration noise and other electrical noise and provides a clean signal to the transmitter44.

The electromagnetic transmitter44is coupled to the processor50for encoding orientation, temperature, and battery condition information on a carrier for transmitting to the monitoring system16in a known manner. The transmitter44may comprise a solenoid driver circuit76, a transmitting solenoid78, and an antenna feedback circuitry80as described in U.S. Pat. No. 5,872,703, the contents of which are incorporated herein by reference. The solenoid driver circuit drives operation of the transmitting solenoid. The transmitting solenoid is adapted to emit a carrier signal that is capable of communicating orientation, signal strength, temperature information, and battery condition to the monitoring system16. The antenna feedback circuitry normalizes the signal strength of the transmitter's44output signal so that the downhole tool assembly18may be properly located using the monitoring system16.

The receiver49is supported by the beacon assembly40and adapted to detect an operation instruction signal from a transmitting assembly (discussed hereinafter) and to communicate the detected operation instruction signal to the processor50. The receiver49may comprise an antenna assembly72comprising at least one ferrite core receiving antenna. The antenna assembly72, as previously discussed, detects the operation instruction signals emanating from the transmitting assembly106(FIG. 4). The antenna assembly72may also provide initial amplification and conditioning of the detected operation instruction signals using gain and decoding circuitry74known to one skilled in the art.

Turning now toFIG. 4, there is shown therein an embodiment of the monitoring system16of the present invention. The monitoring system16is adapted to monitor the location and orientation of the downhole tool assembly18(shown inFIGS. 1 & 2) by detecting the output signal46. The monitoring system16ofFIG. 4comprises a receiver antenna assembly82adapted to detect the output signal46from the electromagnetic transmitter44and to communicate the detected signal to a yet to be described monitoring system processor. InFIG. 4, the monitoring system is shown to have a frame84comprising a handheld unit having an upper portion86and a lower portion88.

The upper portion86includes a battery compartment90, a visual display92, an input assembly94for inputting predetermined operation parameters into the monitoring system16, and a handle96for carrying the monitoring system. The battery compartment90is used to secure a power supply within the frame84during operation of the monitoring system16. The visual display92, such as a liquid crystal display, is adapted to visually communicate various operational parameters to the operator (not shown), including the orientation of the downhole tool assembly18.

The antenna assembly82is adapted to detect the output signal46(FIG. 1) transmitted by the beacon assembly40(shown inFIGS. 2 and 3) and to communicate the detected signals to a processor. The antenna assembly82may comprise a plurality of antennas operatively connected to a circuit board98and adapted to detect the output signal46transmitted from the beacon assembly40. Antennas100,102, and104are shown to illustrate one possible antenna configuration capable of detecting the output signal46transmitted by the beacon assembly40. Antennas100,102, and104may individually comprise antennas with center-tapped coils including a ferrite rod to increase the magnetic flux through the coil. Antennas suitable for use with the present invention are described in U.S. Pat. No. 5,264,795, issued to Rider, the contents of which are incorporated by reference herein. Alternatively, air cored antennas would also be suitable for use with the present invention.

The monitoring system16may also comprise a transmitting assembly106supported on the frame84of the monitoring system16. The transmitting assembly106may comprise a transmitting antenna108that is adapted to transmit the operation instruction signal to the receiver49(FIG. 3). The transmitting antenna108may comprise a coil wound on a ferrite rod. The transmitting antenna108is coupled to a yet to be described transmitting assembly processor that generates operation instruction signals that are transmitted to the receiver49.

With reference now toFIG. 5, a block diagram of the components comprising the monitoring system16are shown therein. As previously discussed, the monitoring system16comprises the antenna assembly82, the visual display92, the input assembly94, the transmitting assembly106, and the monitoring system processor110. Additionally, the monitoring system16may comprise a wireless communication system112that is capable of transmitting location and orientation information from the monitoring system16to a location distant from the monitoring system, such as to the HDD machine24. The monitoring system16ofFIG. 5is shown with the transmitting assembly106. However, it will be appreciated that the monitoring system16may be adapted to comprise a communications link114that is used to communicate with a transmitting assembly106A & B (FIGS. 6 & 10) that are separate from the monitoring system. As shown inFIG. 5, the communications link114may communicate with the separate transmitter assembly using radio communications.

The antenna assembly82, as previously discussed, detects the output signal46(FIG. 1) emanating from the downhole tool assembly18. The antenna assembly82may also provide initial amplification and conditioning of the detected signals using gain circuitry116. The antenna assembly82is adapted to transmit the detected signals to the monitoring system processor110.

The monitoring system processor110is programmed to control many of the monitoring system16functions and may also be programmed to cause the transmitter assembly106to send operation instruction signals to the receiver49. For example, the processor110may be programmed to send an operation instruction signal to the receiver49that causes the intensity or signal strength of the output signal46to increase or decrease.

Turning now toFIG. 6there is illustrated therein an alternative transmitting assembly106A that is separate from the monitoring system16. The transmitting assembly106A has a transmitter117adapted to transmit at least an operation instruction signal to the receiver49of the beacon assembly40(shown inFIGS. 2 & 3). The transmitting assembly106A comprises a case118that is generally cubic and adapted to support the transmitter117and a face plate120.

The face plate120supports an input assembly122, a visual display124, and a radio transceiver126. The input assembly122is adapted to receive a predetermined operation parameter and to communicate the predetermined operation parameter data to the processor128. The input assembly122may comprise a keypad that is coupled to the transmitting assembly processor128. As used herein, predetermined operation parameter may comprise the signal strength of the output signal46(FIG. 1), offset and resolution of the orientation sensor48, the frequency of the output signal, the rate at which data is transmitted from the beacon assembly40(FIGS. 2 and 3), and timed power down of the beacon assembly. The visual display124is used to communicate operation parameters and information received from the monitoring system16to the operator. The radio transceiver126may receive the predetermined operation parameters from the monitoring system16wireless communication system112and thus eliminate the need for the input assembly122.

The transmitting assembly processor128is supported by the transmitting assembly case118. The transmitting assembly processor128is programmed to receive the predetermined operation parameter data from the input assembly122. The input assembly122communicates the operation parameter data to the transmitting assembly processor128which processes the predetermined operation parameter data to produce the operation instruction signal. The processor128can transmit the predetermined operation parameter in the form of an operation instruction signal using either the radio transceiver126or the input assembly122.

Turning now toFIG. 7, a routine for predetermining a calibration factor indicative of the actual orientation of the beacon assembly40relative to a known downhole tool assembly18orientation is shown. The calibration factor is determined in response to the operation instruction signal sent from the transmitting assembly106and detected by the receiver49. The detected operation instruction signal is processed according to the predetermined calibration factor to determine the actual orientation of the downhole tool assembly18. The actual orientation of the downhole tool assembly18is determined by the processor50using the actual orientation of the receiver49and the calibration factor.

The calibration factor is indicative of the angle offset between the beacon assembly40and the downhole tool assembly18. For purposes of illustration, the routine shown inFIG. 7is used to calibrate the orientation sensor48comprising a roll sensor. The roll angle calibration routine is performed with the downhole tool assembly18(FIG. 2) at a known orientation. The orientation sensor48comprising the roll sensor (FIG. 2) transmits roll data to the beacon assembly processor50.

The roll calibration begins (step200), and the downhole tool assembly18is set to a known orientation (step202). Preferably, the downhole tool assembly18is set so that the directional boring tool20orientation corresponds to a desired steering position. Typically, the desired position is with the boring tool oriented to cause the drill string to move in an upward direction, normally referred to as zero (0) degrees, or the twelve (12) o'clock position. However, it will be appreciated that the boring tool20and downhole tool assembly may be set at any other known orientation.

With the downhole tool assembly18at the known orientation, the transmitting assembly106transmits the operation instruction signal to the receiver49(step204). During the roll calibration routine the operation instruction signal comprises a command from the transmitter assembly106to adjust the orientation information output from the processor50to the known roll orientation. The roll data communicated to the beacon assembly processor50contains the actual roll orientation of the roll sensor. The processor50assumes that the downhole tool assembly18has been set at a known reference orientation, as described above, and computes the calibration factor (step206) as being equal to the offset of the roll orientation relative to the known orientation of the downhole tool assembly. The beacon assembly processor50then stores the calibration factor in memory (step208) and the roll calibration is ended (step210).

The stored calibration factor is then later accessed when the operator wishes to determine the actual orientation of the downhole tool assembly18by performing a roll adjustment routine. The roll adjustment routine of the beacon assembly40is illustrated inFIG. 8. When the roll adjustment routine is implemented (step302), the roll sensor samples the roll orientation of the beacon assembly40and communicates the roll orientation data to the beacon assembly processor50(step304). The processor50reads the orientation data from the roll orientation sensor to determine the actual orientation of the beacon assembly40. The stored calibration factor is then subtracted from the actual orientation of the beacon assembly40to get an intermediate roll value for the downhole tool assembly18(step306).

The intermediate roll value is either a positive or a negative value, giving the intermediate roll value either a positive sign or a negative sign. If the intermediate roll value is less than zero (step308), then the actual orientation of the downhole tool assembly is equal to the intermediate roll plus three hundred and sixty degrees (360°) (step310). If the intermediate roll value is not less than zero (step308), then the actual orientation of the downhole tool assembly18is equal to the intermediate roll value (step312). The roll adjustment routine is then complete (step314) and the actual orientation of the downhole tool assembly18is communicated to the monitoring system16via the output signal46.

While the above routines have been described with reference to the calibration of roll sensors, it will be appreciated that one of skill in the art may adjust the above routines for use with known pitch and yaw sensors used to measure the pitch and yaw orientation of the downhole tool assembly18. An alternative method and apparatus for calibrating a beacon assembly is disclosed in pending U.S. patent application titled Electronically Calibrated Beacon for a Horizontal Directional Drilling Machine, Ser. No. 10/365,596, filed Feb. 12, 2003, assigned to The Charles Machine Works, Inc., the contents of which is incorporated herein by reference.

Turning now toFIG. 9, there is shown a routine that is followed to adjust the intensity or signal strength of the output signal46of the transmitter44. Generally, the monitoring system16is calibrated to the output signal's46constant magnetic field strength by solving the following equation for “z”:
H=z/d3(1)
Where the variable “H” represents the strength of the magnetic field detected by the monitoring system antenna assembly82and “d” is the distance between the downhole tool assembly18and the monitoring system16. The value for “z” is stored by the monitoring system16and used in subsequent measurements of the magnetic field to determine the distance between the downhole tool assembly18and the monitoring system.

The present invention is directed to a method and apparatus that is capable of configuring the signal strength of the output signal46to calibrate the beacon assembly40. In a preferred method of configuring the signal strength of the output signal46, the monitoring system16and downhole tool assembly are positioned a known distance, preferably ten (10) feet, from each other. The downhole tool assembly18supporting the beacon assembly40is manipulated at this distance until a maximum signal strength reading is shown on the monitoring system's visual display92. Once the monitoring system16and downhole tool assembly18are properly positioned the signal strength adjustment routine may be implemented (step402).

Using the input assembly94the operator may enter the greatest anticipated depth that the downhole tool assembly18will reach during the upcoming boring operation (step404). Additionally, the operator may input the noise floor of the area in which the boring operation will be conducted. Based upon the anticipated depth and noise floor, the monitoring system processor110will calculate a predetermined calibration parameter. The predetermined calibration parameter may comprise a “best-fit” constant “z” for use in the above equation to make distance calculations (step406).

Next, the antenna assembly82of the monitoring system16detects the signal strength of the output signal46transmitted from the beacon assembly transmitter44and communicates the detected signal to the monitoring system processor110. The monitoring system processor110processes the signal strength of the output signal46“H”, and calculates an estimated distance between the monitoring system16and the downhole tool assembly18using the best-fit constant “z” (step408). The estimated distance between the monitoring system16and the downhole tool assembly18may be generally greater than the known distance or less than the known distance between the monitoring system and the downhole tool assembly (step410).

If the estimated distance is less than the known distance the monitoring system processor110determines an output signal strength adjustment factor and communicates the adjustment factor to the transmitting assembly106. The transmitting assembly106receives and processes the intensity adjustment factor and generates an operation instruction signal that is transmitted to the receiver49. The operation instruction signal is generally indicative of the estimated distance between the downhole tool assembly18and the monitoring system16. The beacon assembly processor50receives the operation instruction signal and decreases the strength of the output signal (step412). The process is repeated until the estimated distance is substantially equal to the known distance between the downhole tool assembly18and the monitoring system16. Once the estimated distance and known distance are substantially equal, the transmitting assembly106transmits an operation instruction signal to the beacon assembly instructing the beacon assembly to maintain the proper strength until instructed otherwise (step414).

If the estimated distance is not less than the known distance, but the two are not equal (step416), the transmitting assembly106transmits and operation instruction signal to the beacon assembly40instructing the beacon assembly to increase the strength of the output signal46(step418). The instruction is repeated until the estimated distance is substantially equal to the known distance between the downhole tool assembly18and the monitoring system16. Once the estimated distance and known distance are substantially equal, the transmitting assembly106transmits an operation instruction signal to the beacon assembly instructing the beacon assembly to maintain the proper strength until instructed otherwise (step414). However, if at Step416the estimated distance and the known distance are substantially equal, the maintain signal strength operation instruction signal is sent to the beacon assembly40without requiring the step of increasing the strength. The output signal strength adjustment routine is then ended and the distance thereafter calculated by the monitoring system processor110is indicative of the actual distance between the monitoring system16and the downhole tool assembly18.

Turning now toFIG. 10there is shown therein a diagrammatic representation of an alternative transmitting assembly106B that is adapted to directly connect the beacon assembly40to the transmitting assembly through the housing36. Transmitting assembly106B comprises a base130having a generally elongate v-groove or concave groove132for supporting the housing36. The base also supports the visual display124, input assembly122, and associated electronics discussed with reference to transmitting assemblies106and106A ofFIGS. 5 and 6. The transmitter134of transmitting assembly106B is supported within the groove132and adapted to transmit operation instruction signals to the beacon assembly40. Accordingly, the beacon assembly40shown inFIG. 10comprises the receiver49, the transmitter44and electronics136that are electrically connected to the housing36. The electronics136are adapted to receive operation instruction signals transmitted through the housing36and communicate the signals to the beacon assembly40. The present embodiment is advantageous because the transmitting assembly106B may transmit data to the beacon assembly40at a high rate.

The present invention also comprises a method for monitoring the location and orientation of the downhole tool assembly18. In accordance with the method of the present invention, the location and orientation of the downhole tool assembly18is monitored using the monitoring system16. The downhole tool assembly18has a beacon assembly40that comprises one or more of the configurable operation parameters described above.

The beacon assembly40transmits an output signal46indicative of one or more to the configurable operation parameters to the antenna assembly82of the monitoring system16. The detected output signal may be processed to determine a value for the configurable operation parameter by either the monitoring system processor110or by the transmitting assembly processor128(FIG. 6). Using the determined value of the configurable operation parameter, the transmitting assembly transmits an operation instruction signal to the beacon assembly40to alter the configurable operation parameter of the beacon assembly. The beacon assembly40receives the operation instruction signal and processes it to alter the configurable operation parameter. The configured operation parameter is then maintained by the beacon assembly40until a new operation instruction signal is received by the beacon assembly.

The present invention also comprises a method for calibrating and determining the distance between the downhole tool assembly18and the monitoring system16. The method comprises positioning the downhole tool assembly18and monitoring system16a known distance apart and at known orientations relative to each other. The downhole tool assembly18comprises the beacon assembly40that is adapted to transmit a magnetic field output signal.

The monitoring system16may comprise an antenna assembly82and processor110that are capable of detecting the signal strength of the magnetic field transmitted from the beacon assembly40. The processor110calculates an estimated distance between the monitoring system16and the downhole tool assembly18based upon the detected signal strength of the magnetic field.

Based upon the relationship between the estimated distance and the known distance between the downhole tool assembly18and the monitoring system16, an operation instruction is transmitted to the beacon assembly40. In response to operation instructions, the beacon assembly40changes the signal strength of the magnetic field until the known distance between the monitoring system16and the downhole tool assembly18is substantially equal to the estimated distance calculated by the monitoring system processor10. The monitoring system16can then be used at unknown distances from the downhole tool assembly18to calculate the distance from the monitoring system to the tool assembly based on the signal strength detected by the monitoring system.

Various modifications can be made in the design and operation of the present invention without departing from the spirit thereof. Thus, while the principal preferred construction and modes of operation of the invention have been explained in what is now considered to represent its best embodiments, which have been illustrated and described, it should be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.