Communication signal repeater system for a bottom hole assembly

A bottom hole assembly includes a cable to transmit power and communication signals. A first measurement-while-drilling tool is coupled with the cable. A second measurement-while-drilling tool is coupled with the cable. An adapter is coupled with the cable and positioned between the first and second measurement-while-drilling tools. The adapter includes a disconnect in the cable that prevents the power from being transmitted through the adapter. A repeater is coupled with the cable and amplifies the communication signals transmitted through the cable.

FIELD

Embodiments described herein generally relate to bottom hole assemblies. More particularly, such embodiments relate systems and methods for transmitting data signals in a wellbore.

BACKGROUND INFORMATION

A bottom hole assembly may be run into a wellbore. The bottom hole assembly may include a measurement-while-drilling (“MWD”) tool and a logging-while-drilling (“LWD”) tool. The MWD tool may evaluate physical properties in the wellbore such as pressure, temperature, and wellbore trajectory. The LWD tool may measure formation properties such as resistivity, porosity, sonic velocity, and gamma rays. The MWD tool may provide power to the LWD tool. In addition, the MWD tool may store measurements obtained by the MWD tool and the LWD tool. The measurements may then be encoded and transmitted from the MWD tool to the surface (e.g., through one or more wires or via pressure pulses).

In recent years, as drilling has progressed to greater depths, the length of the bottom hole assembly has increased to accommodate more advanced (and longer) MWD and LWD tools. This has resulted in the distance between the MWD tool and the LWD tool, or between two or more LWD tools, increasing, which causes the signals transmitted therebetween to become attenuated.

SUMMARY

A bottom hole assembly is disclosed. The bottom hole assembly includes a cable to transmit power and communication signals. First and second measurement-while-drilling tools are coupled with the cable. An adapter is coupled with the cable and positioned between the first and second measurement-while-drilling tools. The adapter includes a disconnect in the cable that prevents the power from being transmitted through the adapter. A repeater is coupled with the cable and amplifies the communication signals transmitted through the cable.

In another embodiment, the bottom hole assembly includes a cable to transmit power and communication signals. First and second measurement-while-drilling tools are coupled with the cable. First, second, and third logging-while-drilling tools are coupled with the cable. The first logging-while-drilling tool is positioned between the first measurement-while-drilling tool and the second measurement-while-drilling tool. The second measurement-while-drilling tool is positioned between the first logging-while-drilling tool and the second logging-while-drilling tool. The second logging-while-drilling tool is positioned between the second measurement-while-drilling tool and the third logging-while-drilling tool. An adapter is coupled with the cable and positioned between the first logging-while-drilling tool and the second measurement-while-drilling tool. The adapter includes a disconnect in the cable that prevents the power from being transmitted therethrough. A repeater is coupled with the cable and amplifies the communication signals transmitted through the communication line.

A method for amplifying a signal in a wellbore is also disclosed. The method includes measuring a first parameter using a logging-while-drilling tool. A first communication signal including the first parameter from the logging-while-drilling tool is transmitted to a first measurement-while-drilling tool. The logging-while-drilling tool receives power from the first measurement-while-drilling tool. The first communication signal is amplified using a repeater positioned between the logging-while-drilling tool and the first measurement-while-drilling tool. Power is prevented from being transmitted between the first measurement-while-drilling tool and a second measurement-while-drilling tool using an adapter that is positioned between the first measurement-while-drilling tool and the second measurement-while-drilling tool.

DETAILED DESCRIPTION

FIG. 1depicts a schematic view of an illustrative bottom hole assembly100, according to an embodiment. The bottom hole assembly100may include one or more MWD tools (two are shown:110,111) and one or more LWD tools (five are shown:120-124). As discussed above, the MWD tools110,111may evaluate physical properties in the wellbore such as pressure, temperature, and wellbore trajectory, and the LWD tools120-124may measure formation properties such as resistivity, porosity, sonic velocity, and gamma ray.

The MWD tools110,111and the LWD tools120-124may be coupled to a low power tool bus (“LTB”) bus130. As shown, the LTB bus130may include a power cable132and a communication cable134. Although shown as two separate cables132,134for illustrative purposes, in some embodiments, the bus130may include a single cable (or wire or conductor) that carries that carries both power (DC) and communication (AC). The MWD tools110,111may generate and transmit power (e.g., DC power) to the LWD tools120-124through the power cable132in the LTB bus130. In the example shown inFIG. 1, the MWD tool110may transmit power to the LWD tools120,121, and the MWD tool111may transmit power to the LWD tools122-124.

The LWD tools120-124may transmit data/communication signals (e.g., AC signals) to the MWD tools110,111through the communication cable134. The communication signals may include measurements taken by the LWD tools120-124. In another embodiment, the MWD tools110,111may transmit communication signals to the LWD tools120-124through the communication cable134. The communication signals may include instructions for which measurements to take, how often to take the measurements, etc.

The bottom hole assembly100may also include a dual MWD isolation adapter (“DMIA”)140. The DMIA140may facilitate the use of multiple MWD tools110,111that each power one or more LWD tools120-124. As shown, the DMIA140may include a disconnect in the power cable132that prevents power from being transmitted therethrough. Thus, each MWD tool110,111and its respective LWD tools120-124may be considered to be a standalone sub-BHA102,104in the bottom hole assembly100. The DMIA140may, however, allow communication signals to pass therethrough via the communication cable134.

FIG. 2depicts a cross-sectional view of an illustrative repeater200that may be inserted into the bottom hole assembly100, according to an embodiment. The repeater200may include a body210. The body210may include a first connector212proximate to a first end thereof and a second connector214proximate to a second, opposing end thereof. In one example, the first connector212may be a male connector, and the second connector214may be a female connector, or vice versa.

A chassis220may be positioned within the body210. One or more circuits230may also be positioned within the body210(e.g., mounted to the chassis220). The circuits230in the repeater200may receive the communication signals transmitted from the MWD tools110,111and/or the LWD tools120-124through the communication cable134, amplify the communication signals to a higher level or power, and re-transmit the amplified communication signals. As used herein, “amplify” refers to increasing, boosting, and/or regenerating the communication in the signals. This may allow the communication signals to be transmitted over longer distances. In at least one embodiment, the signals may be amplified within a predetermined frequency range but not amplified outside of that frequency range. The circuits230may have a form factor similar to that of the DMIA140or be integrated with the DMIA140. Illustrative circuits230(or portions thereof) are shown inFIGS. 5-9and described below.

FIG. 3depicts a schematic view of the bottom hole assembly100including the repeater200, according to an embodiment. The repeater200may be positioned at various locations within the bottom hole assembly100. As shown inFIG. 3, the repeater200may be coupled to and/or positioned within the DMIA140. In another embodiment, the repeater200may be positioned within one of the MWD tools110,111or the LWD tools120-124.

In other embodiments, however, the repeater200may be positioned elsewhere in the bottom hole assembly100. For example, as shown inFIG. 4, the repeater200may be in a sub that is positioned between a different pair of adjacent tools (e.g., LWD tools122,123) rather than positioned in the DMIA140. More particularly, the first connector212of the repeater200may be coupled to the portion of the communication cable134that transmits communication signals to and from the LWD tool122, and the second connector214of the repeater200may be coupled to the portion of the communication cable134that transmits data to and from the LWD tool123.

In yet another embodiment, the repeater200may be coupled to and/or positioned within an extender between two adjacent tools (e.g., LWD tools122,123). As used herein, an “extender” refers to a connector that enables real-time communication and power transfer between logging and measurement tools. Both functions may be performed by a single wire with a return path through the tool's collar. Extenders may be located uphole or downhole and provide a link between LWD tools and MWD tools in a drill string.

FIG. 5depicts a schematic view of a full duplex repeater circuit500that represents at least a portion of the circuit230shown inFIG. 2, according to an embodiment. The full duplex repeater circuit500may be a point-to-point system that is coupled (and in communication with) two or more tools. For example, the full duplex repeater circuit500may be coupled to and positioned between the LWD tools122,123, as shown inFIG. 4, and in communication with the MWD tools110,111and the LWD tools120-124.

The full duplex repeater circuit500may be configured to transmit communication signals in both directions one after another or simultaneously. For example, the full duplex repeater circuit500may be configured to transmit communication signals from the MWD tool111to the LWD tool123and from the LWD tool124to the MWD tool111simultaneously.

The full duplex repeater circuit500may include a message isolator module510and a repeater module520. The power cable132may run through the message isolator module510. As shown, in some embodiments, the message isolator module510may include an inductor512, and the DC power in the power cable132may run through the inductor512. The inductor512may have an impedance in the communication frequency band that is higher than the input impedance of the repeater520. In this way, the communication signal (AC) may be blocked, but the power signal (DC) may pass through. The repeater module520may include one or more receivers (two are shown:530,532), one or more transmitters (two are shown:540,542), and a message amplifier560.

A first communication signal may be received by the first receiver530. The first communication signal may be amplified by the message amplifier560and then transmitted (e.g., to the LWD tool123) by the first transmitter540. Before, after, or simultaneously with the first communication signal passing through the repeater module520, a second communication signal may pass through the repeater module520. The second communication signal may be at a different frequency than the first communication signal (i.e., frequency division multiplexing). In another embodiment, the second communication signal may occur at a different time slot than the first communication signal (i.e., time division multiplexing). The second communication signal may be received by the second receiver532. The second communication signal may be amplified by the message amplifier560and then transmitted (e.g., to the MWD tool111) by the second transmitter542. In at least one embodiment, in addition to amplifying/boosting the communication signal(s), the full duplex repeater circuit500may also analyze the communication signals (e.g., check for errors) and/or modify the communication signals (e.g., insert data such as signal to noise ratio, data error counts, etc.).

FIG. 6depicts a schematic view of a half duplex repeater circuit600that represents at least a portion of the circuit230shown inFIG. 2, according to an embodiment. The half duplex repeater circuit600may be a point-to-point system that is coupled (and in communication with) two or more tools. For example, the half duplex repeater circuit600may be coupled to and positioned between the LWD tools122,123, as shown inFIG. 4, and in communication with the MWD tools110,111and the LWD tools120-124. The half duplex repeater circuit600may be configured to transmit communication signals in both directions, but only one direction at a time (i.e., not simultaneously).

The half duplex repeater circuit600may include a message isolator module610and a repeater module620. The power cable132may run through the message isolator module610. As shown, in some embodiments, the message isolator module610may include an inductor612, and the DC power in the power cable132may run through the inductor612.

The repeater module620may include one or more receivers (two are shown:630,632), one or more transmitters (two are shown:640,642), one or more switches (two are shown:650,652), a message amplifier660, and a message direction detector670. The switches650,652, the message amplifier660, and/or the message direction detector670may function as a field programmable gate array (“FPGA”) that may have a digital modem implementation.

A first communication signal may be received by the first receiver630. When the message direction detector670determines that the first communication signal is travelling in a first direction (e.g., left to right), the message direction detector670may cause the first switch650to provide a path of communication from the first receiver630to the message amplifier660and cause the second switch652to provide a path of communication from the message amplifier660to the first transmitter640. The first communication signal may be amplified by the message amplifier660and then transmitted (e.g., to the LWD tool123) by the first transmitter640.

Before or after the first communication signal passes through the repeater module620, a second communication signal may pass through the repeater module620. More particularly, the second communication signal may be received by the second receiver632. When the message direction detector670determines that the second communication signal is travelling in a second, opposing direction (e.g., right to left), the message direction detector670may cause the first switch650to provide a path of communication from the second receiver632to the message amplifier660and cause the second switch652to provide a path of communication from the message amplifier660to the second transmitter642. The second communication signal may be amplified by the message amplifier660and then transmitted (e.g., to the MWD tool111) by the second transmitter642. As discussed above, in some embodiments, the communication signals may also be analyzed and/or modified before being re-transmitted.

FIG. 7depicts a schematic view of a half or full duplex repeater circuit700that represents at least a portion of the circuit230shown inFIG. 2, according to an embodiment. The repeater circuit700may include one or more receivers (two are shown:720,722), one or more transmitters (two are shown:730,732), one or more transformers (two are shown:740,742), and an FPGA750.

A first portion of the communication cable134-1may transmit a first communication signal in a first direction (e.g., left to right). For example, the first communication signal may be travelling from the MWD tool111to the LWD tool123(seeFIG. 4). The first communication signal may pass through the first transformer740and be received by the first receiver720. The first communication signal may then be demodulated and then re-modulated by the FPGA750and sent to the first transmitter730. The first transmitter730may transmit the first communication signal through the second transformer742and to the LWD tool123. A first portion of the power cable132-1may transmit the power (e.g., from the MWD tool111to the LWD tool123(seeFIG. 4), with the return power in power cable132-2. The power cable(s)132-1,132-2may include a first inductor760and a second inductor762.

A second portion of the communication cable134-2may transmit a second communication signal in a second direction (e.g., right to left). For example, the second communication signal may be travelling from the LWD tool124to the MWD tool111(seeFIG. 4). The second communication signal may pass though the second transformer742and be received by the second receiver722. The second communication signal may then be demodulated and then re-demodulated by the FPGA750and sent to the second transmitter732. The second transmitter732may transmit the second communication signal through the first transformer740and to the MWD tool111.

FIG. 8depicts a schematic view of a half or full duplex repeater circuit that represents at least a portion of the circuit shown inFIG. 2, according to an embodiment. The repeater circuit800may include one or more receivers (two are shown:820,822), one or more transmitters (two are shown:830,832), one or more transformers (two are shown:840,842), and one or more FPGAs (two are shown:850,852).

A first portion of the communication cable134-1may transmit a first communication signal in a first direction (e.g., left to right). For example, the first communication signal may be travelling from the MWD tool111to the LWD tool123(seeFIG. 4). The first communication signal may pass through the first transformer840and be received by the first receiver820. The first communication signal may then be demodulated by the first FPGA850and then re-modulated by the second FPGA852and sent to the first transmitter830. The first transmitter830may transmit the first communication signal through the second transformer842and to the LWD tool123. A first portion of the power cable132-1may transmit the power (e.g., from the MWD tool111to the LWD tool123(seeFIG. 4), with the return power in power cable132-2. The power cable(s)132-1,132-2may include a first inductor860and a second inductor862.

A second portion of the communication cable134-2may transmit a second communication signal in a second direction (e.g., right to left). For example, the second communication signal may be travelling from the LWD tool124to the MWD tool111(seeFIG. 4). The second communication signal may pass though the second transformer842and be received by the second receiver822. The second communication signal may then be demodulated by the second FPGA852and then re-modulated by the first FPGA850and sent to the second transmitter832. The second transmitter832may transmit the second communication signal through the first transformer840and to the MWD tool111.

FIG. 9depicts a schematic view of a half duplex repeater circuit900that represents at least a portion of the circuit230shown inFIG. 2, according to an embodiment. The circuit900may include one or more receivers (one is shown:920), one or more transmitters (one is shown:930), one or more transformers (one is shown:940), and one or more FPGAs (one is shown:950).

A first portion of the communication cable134-1may transmit a first communication signal in a first direction (e.g., left to right). For example, the first communication signal may be travelling from the MWD tool111to the LWD tool123(seeFIG. 4). The first communication signal may pass through switches971,974and the transformer940and be received by the receiver920. The first communication signal may then be demodulated and then re-demodulated by the FPGA950. At this point, the FPGA950may send a command to a control circuit970to open the switches971,974and close the switches972,973. The first communication signal may then be re-transmitted by the transmitter930, through the transformer940and switches972,973, to, for example, the LWD tool123. A first portion of the power cable132-1may transmit the power (e.g., from the MWD tool111to the LWD tool123(seeFIG. 4), with the return power in power cable132-2. The power cable(s)132-1,132-2may include a first inductor960and a second inductor962.

A second portion of the communication cable134-2may transmit a second communication signal in a second direction (e.g., right to left). For example, the second communication signal may be travelling from the LWD tool124to the MWD tool111(seeFIG. 4). The second communication signal may be transmitted before or after the first communication signal. The second communication signal may pass through switches972,973and the transformer940and be received by the receiver920. The second communication signal may then be demodulated and then re-demodulated by the FPGA950. At this point, the FPGA950may send a command to the control circuit970to open the switches972,973and close the switches971,974. The second communication signal may then be re-transmitted by the transmitter930, through the transformer940and switches971,974, to, for example, the MWD tool111.

As used herein, the terms “inner” and “outer”; “up” and “down”; “upper” and “lower”; “upward” and “downward”; “above” and “below”; “inward” and “outward”; and other like terms as used herein refer to relative positions to one another and are not intended to denote a particular direction or spatial orientation. The terms “couple,” “coupled,” “connect,” “connection,” “connected,” “in connection with,” and “connecting” refer to “in direct connection with” or “in connection with via one or more intermediate elements or members.”

Although the preceding description has been described herein with reference to particular means, materials, and embodiments, it is not intended to be limited to the particulars disclosed herein; rather, it extends to all functionally equivalent structures, methods, and uses, such as are contemplated within the scope of the appended claims. While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof.