1. Field of the Invention
The invention relates generally to drill string telemetry. More specifically, the present invention relates to a fault diagnosis and/or identification system for a downhole drilling operation.
2. Background Art
Downhole systems, such as Measurement While Drilling (MWD) and Logging While Drilling (LWD) systems, derive much of their value from their abilities to provide real-time information about borehole conditions and/or formation properties. These downhole measurements may be used to make decisions during the drilling process or to take advantage of sophisticated drilling techniques, such as geosteering. These techniques rely heavily on instantaneous knowledge of the formation that is being drilled. Therefore, it is important to be able to send large amounts of data from the MWD/LWD tool to the surface and to send commands from the MWD/LWD tools to the surface. A number of telemetry techniques have been developed for such communications, including wired drill pipe (WDP) telemetry.
The idea of putting a conductive wire in a drill string has been around for some time. For example, U.S. Pat. No. 4,126,848 issued to Denison discloses a drill string telemeter system, wherein a wireline is used to transmit the information from the bottom of the borehole to an intermediate position in the drill string, and a special drilling string, having an insulated electrical conductor, is used to transmit the information from the intermediate position to the surface. Similarly, U.S. Pat. No. 3,957,118 issued to Barry et al. discloses a cable system for wellbore telemetry, and U.S. Pat. No. 3,807,502 issued to Heilhecker et al. discloses methods for installing an electric conductor in a drill string.
For downhole drilling operations, a large number of drill pipes are used to form a chain between the surface Kelley (or top drive) and a drilling tool with a drill bit. For example, a 15,000 ft (5472 m) well will typically have 500 drill pipes if each of the drill pipes is 30 ft (9.14 m) long. In wired drill pipe operations, some or all of the drill pipes may be provided with conductive wires to form a wired drill pip (“WDP”) and provide a telemetry link between the surface and the drilling tool. With 500 drill pipes, there are 1000 joints, each of which may include inductive couplers such as toroidal transformers. The sheer number of connections in a drill string raises concerns of reliability for the system. A commercial drilling system is expected to have a minimum mean time between failure (MTBF) of about 500 hours or more. If one of the wired connections in the drill string fails, then the entire telemetry system fails. Therefore, where there are 500 wired drill pipes in a 15,000 ft (5472 m) well, each wired drill pipe should have an MTBF of at least about 250,000 hr (28.5 yr) in order for the entire system to have an MTBF of 500 hr. This means that each WDP should have a failure rate of less than 4×10 per hr. This requirement is beyond the current WDP technology. Therefore, it is necessary that methods are available for testing the reliability of a WDP and for quickly identifying any failure.
Currently, there are few tests that can be performed to ensure WDP reliability. Before the WDP are brought onto the rig floor, these pipes may be visually inspected and the pin and box connections of the pipes may be tested for electrical continuity using test boxes. It is possible that two WDP sections may pass a continuity test individually, but they might fail when they are connected together. Such failures might, for example result from debris in the connection that damages the inductive coupler. Once the WDPs are connected (e.g., made up into triples), visual inspection of the pin and box connections and testing of electrical continuity using test boxes will be difficult, if not impossible, on the rig floor. This limits the utility of the currently available methods for WDP inspection.
In addition, the WDP telemetry link may suffer from intermittent failures that would be difficult to identify. For example, if the failure is due to shock, downhole pressure, or downhole temperature, then the faulty WDP section might recover when conditions change as drilling is stopped, or as the drill string is tripped out of the hole. This would make it extremely difficult, if not impossible, to locate the faulty WDP section.
In view of the above problems, it is desirable to have techniques for performing diagnostics on and/or for monitoring the integrity of a WDP telemetry system.
In one aspect, embodiments of the invention relate to a wired drill pipe diagnostic system/module. A diagnostic module for wired drill pipe in accordance with the invention includes a line interface adapted to interface with a wired drill pipe telemetry section; a transceiver adapted to communicate signals between the wired drill pipe telemetry section and the diagnostic module; and a controller operatively connected with the transceiver and adapted to control the transceiver. The diagnostic module may further comprise a power supply, an acquisition module, a sensor module, and an isolation measurement circuitry.
In one aspect, embodiments of the invention relate to a wired drill pipe having a diagnostic module. A wired drill pipe in accordance with one embodiment of the invention includes an elongated tubular shank having an axial bore; a box end at a first end of the shank, the box end having a first toroidal transformer disposed therein; a pin end at a second end of the shank, the pin end having a second toroidal transformer disposed therein; a wire electrically coupling the first and the second toroidal transformers, wherein the first toroidal transformer, the second toroidal transformer, and the wire constitute a telemetry section of the wired drill pipe; and a diagnostic module electrically coupled to the telemetry section of the wired drill pipe, wherein the diagnostic module comprising a line interface adapted to interface with a wired drill pipe telemetry section; a transceiver adapted to communicate signals between the wired drill pipe telemetry section and the diagnostic module; and a controller operatively connected with the transceiver and adapted to control the transceiver.
In one aspect, embodiments of the invention relate to a wired drill pipe telemetry system. A wired drill pipe telemetry system in accordance with one embodiment of the invention includes a surface computer; and a drill string telemetry section comprising a plurality of wired drill pipes each having a telemetry section, at least one of the plurality of wired drill pipes having a diagnostic module electrically coupling the telemetry section and wherein the diagnostic module includes a line interface adapted to interface with a wired drill pipe telemetry section; a transceiver adapted to communicate signals between the wired drill pipe telemetry section and the diagnostic module; and a controller operatively connected with the transceiver and adapted to control the transceiver.
In one aspect, embodiments of the invention relate to a method for diagnosing a wired drill pipe telemetry system that includes a plurality of wired drill pipes, each having a telemetry section, and at least one of the plurality of the wired drill pipes having a diagnostic module. A method in accordance with one embodiment of the invention includes sending a polling signal from a surface computer to the wired drill pipe telemetry system, the polling signal including a selected identifier; receiving and processing the polling signal by the diagnostic module in the at least one of the plurality of wired drill pipes; and receiving by the surface computer a reply from a specific diagnostic module having the selected identifier.
In one aspect, embodiments of the invention relate to methods for determining coupling efficiencies of wired drill pipes in a drill string. A method in accordance with one embodiment of the invention includes instructing each of at least one diagnostic module of the wired drill pipes in the drill string to send a signal of a known magnitude to a surface computer; receiving the signal with a measured magnitude for the each of the at least one diagnostic module; and determining the coupling efficiencies of the wired drill pipes based on the measured magnitude of the signal.
Finally, in another aspect, the invention relates to a method of testing a telemetry section. The section comprises a drill pipe having a wire extending therethrough. The method comprises providing a telemetry section with a test pad and a resistor, the resistor having a known resistance, applying a voltage between a test pad and the drill pipe, measuring a test resistance passing between the test pad and the drill pipe, and detecting a difference between the test resistance and the known resistance whereby the condition of the wired drill pipe is determined.
Other aspects of the invention will become apparent from the following description, the drawings, and the claims.
Embodiments of the present invention relate to wired drill pipe (WDP) diagnostic systems/modules (DSM). A DSM in accordance with the invention may comprise, for example, a transceiver and a controller or a simple state machine integrated into a chip. Each DSM can respond to a poll from a surface computer and provide information, such as the status of the section of the WDP. Using embodiments of the invention, the connection to each WDP can be confirmed, and any failure in the drill string can be immediately located. In addition, the DSM may also include a unique identifier to facilitate identification, inventory and maintenance of the WDP. The identification system can also be used to provide an automatic tally book.
Drilling fluid or mud 26 is stored in pit 27 formed at the well site. Pump 29 delivers drilling fluid 26 to the interior of drill string 12 via a port in swivel 19, inducing the drilling fluid to flow downwardly through drill string 12 as indicated by directional arrow 9. The drilling fluid exits drill string 12 via ports in drill bit 15, and then circulates upwardly through the region between the outside of the drillstring and the wall of the wellbore, called the annulus, as indicated by direction arrows 32. In this manner, the drilling fluid lubricates drill bit 15 and carries formation cuttings up to the surface as it is returned to pit 27 for recirculation.
Drillstring 12 further includes a bottom hole assembly (BHA) 200 disposed near the drill bit 15. BHA 200 may include capabilities for measuring, processing, and storing information, as well as communicating with the surface (e.g., MWD/LWD tools). An Example of a communications apparatus that may be used in a BHA is described in detail in U.S. Pat. No. 5,339,037.
The communication signal from the BHA may be received at the surface by a transducer 31, which is coupled to an uphole receiving subsystem 90. The output of receiving subsystem 90 is then couple to processor 85 and recorder 45. The surface system may further include a transmitting system 95 for communicating with the downhole instruments. The communication link between the downhole instruments and the surface system may comprise, among other things, a drill string telemetry system that comprises a plurality of WDPs.
One type of WDP, as disclosed in U.S. Patent Application No. 2002/0193004 by Boyle et al. and assigned to the assignee of the present invention, uses inductive couplers to transmit signals across pipe joints. An inductive coupler in the WDPs, according to Boyle et al., comprises a transformer that has a toroid core made of a high permeability, low loss material such as Supermalloy (which is a nickel-iron alloy processed for exceptionally high initial permeability and suitable for low level signal transformer applications). A winding, consisting of multiple turns of insulated wire, winds around the toroid core to form a toroid transformer. In one configuration, the toroidal transformer is potted in rubber or other insulating materials, and the assembled transformer is recessed into a groove located in the drill pipe connection.
In this description, a “telemetry connection” defines a connection at a joint between two adjacent pipes, and a “telemetry section” refers to the telemetry components within a single piece of WDP. A “telemetry section” may include inductive coupler elements and the wire within a single WDP, as described above. However, in some embodiments, the inductive coupler elements may be replaced with some other device serving a similar function (e.g., direct electrical connections). In some embodiments of the invention, a WDP may further include a diagnostic module operatively coupled to one or more telemetry sections to facilitate diagnosis, inventory, and/or maintenance of the WDP. When a plurality of such WDPs are made up into a drill string, the telemetry components are referred to as a “telemetry link.” That is, a drill string “telemetry link” or a WDP “telemetry link” refers to an aggregate of a plurality of WDP “telemetry sections.” When other components such as a surface computer, an MWD/LWD tool, and/or routers are added to a WDP “telemetry link,” they are referred to as a “telemetry system.” A surface computer as used herein may comprise a computer, a surface transceiver, and/or other components.
As shown in
When the box end 22 of one WDP is assembled with the pin end 32″ of the adjacent WDP, a pipe and or telemetry connection is formed.
Also shown in
However, this potential problem can be minimized or prevented by placing a high impedance or a capacitive coupling (not shown) close to the DSM circuit 60.
In another embodiment shown in
Note that with either configuration shown in
The dimensions of the DSM electronic module are preferably small such that it may fit in the same groove (shown as 25 in
The power supply 61 provides the power needed to operate the DSM 60. As noted above, the DSM may draw power from the WDP toroidal transformer either by wrapping a secondary coil on the WDP toroid (
The line interface 62, which may include an input transformer, functions to bridge the DSM circuitry 60 with the WDP telemetry system 69. The transceiver 63 includes a transmitter 63a for transmitting identifier signals to the surface computer and a receiver 63b for receiving polling signals from the surface computers.
Normally, the DSM 60 will be in a low power listening mode (idle mode). When the surface computer (not shown) issues a poll for a specific identifier, every DSM in the WDP telemetry link may receive (via receiver 63b) and process the polling signal. However, only the DSM with the matching identifier would respond and transmit a reply to the surface computer (via transmitter 63a). Alternatively, each DSM may respond with its own identifier or some indicator signal (match or no match). The power consumption may increase during the brief transmission period.
One way to implement the communication between the WDP surface unit and the DSM, for example, would be to feed a selected level of power (e.g., 10 W to 100 W) from the surface computer to the WDP telemetry system and use a proper modulation scheme to control the uplink (communication from the DSM to the surface unit) and downlink (communication from the surface unit to the DSM) traffic. For example, the WDP surface unit may send an AC power to the WDP telemetry system and the commands sent to the DSM's may be encoded by modulating the line voltage using a technique such as amplitude modulation, frequency shift keying, and the like. The DSM would send data back to the surface computer by a different modulation scheme, e.g., by modulating the current drawn by the WDP using a transistor switch. One of ordinary skill in the art would appreciate that other ways of implementing the communication and signal modulation/encoding are possible and would not depart from the scope of the invention.
The controller 64, as shown in
In addition to the above components, the DSM 60 may also include an acquisition module 65 and a sensor module 66, which may be used to measure shocks, pressure, or temperature, for example. Downhole temperature normally will be related to the depth and the geothermal profile. However, friction between the drill pipe and formations or casing may result in abnormal temperatures. Thus, an unusually high temperature for a particular section of WDPs may indicate excessive friction, which would shorten the lifetime of the section. Similarly, shocks may also negatively impact the lifetime of a WDP. Shocks induced by harsh drilling could be detected by an accelerometer using predefined thresholds. The surface computer could poll the DSM's, and the DSM's may initiate such measurements and send the results to the surface computer in real time. It is also possible to store results in a permanent memory for later read-out. Such data may be used to schedule inspection and maintenance of the WDP, and to inform, in real-time, the operator of possible problems (high shock levels, high friction) that could damage the drill string.
In addition, the DSM 60 may also include other modules for other desired functions. For example, an isolation measurement circuitry 67 may be included in the DSM 60 for checking the isolation between the WDP wires and the pipe.
As shown in
An alternative solution is to connect a high ohmic resistor 73 (e.g., 1–10 M Ω) to the WDP toroid 52 or WDP wire 53 on one end and to a test pad 75 on the other end, as shown in
As noted above, with a high ohmic resistor 73, the test pad can be exposed to the environment. This greatly simplifies the design of WDPs.
An alternative approach to testing the isolation between the drill pipe and the WDP wire is to include an isolation measurement circuitry. As shown in
While the above description implies that the WDP telemetry system works in a simple series, this is not necessary. In fact, in a linear configuration, there may be a limitation on how many WDP DSM can respond directly to the surface computer.
Assuming a signal loss of 0.2 dB per connection, and a 15,000 ft (4572 m) drill string, the total attenuation for 500 WDP's is 100 dB. This problem can be solved by adding routers (which are relays and amplifiers) in the drill string to boost transmission
In a typical implementation, a router may be added every 100–200 pipes depending on the system efficiency. For example, in
A network may be configured in a bus topology (with the WDP surface unit 81 is the master and the DSMs are the slaves), a ring topology (e.g., “daisy-chain” of DSMs), or the like. In the embodiment shown in
In addition, the network communication may be reconfigured (by the user or transparently by the communication protocol) when communication errors occur at a particular WDP telemetry section. For example, if the WDP joint between DSM 60c and DSM 60d has high loss, DSMs 60d 60f will no longer be able to communicate through router 82a, as shown in
In addition to the bus topology shown in
In a network implementation, the WDP DSMs of the invention may be adapted to a variety of telemetry protocols (custom protocols or standard protocols). For example, the mode of transmission may be based on any modulation technique known in the art, such as amplitude modulation (AM), frequency shift keying (FSK), phase shift keying (PSK), and the like. The WDP DSM may be adapted to various transmission rates, e.g., from a few baud to tens of thousands of baud. Data transmission between the DSM and the surface computer may be encoded with any known encoding techniques, such as Manchester phase encoding, differential Manchester encoding, or any other encoding. Communications between the DSMs and the routers, or other components of the telemetry system, may be mediated by the WDP wires, by wireless communications, or by other suitable means (e.g., mud pulse telemetry).
The present invention has several advantages. Some of these advantages are illustrated in the following exemplary applications.
For example, the WDP DSMs of the invention may be used to monitor and log drill pipes as they are run in hole.
As shown in
Steps 1202–1204 are repeated (step 1206) until the drill string is complete, i.e., the tools reach the bottom of the borehole. This process establishes the relative position of each stand in the drill string. With the length of each WDP known and stored in a database, it becomes possible to locate the depth of each WDP in the borehole. This could be used to create an automatic tally book (step 1205). The automatic tally would reduce depth errors commonly associated with manual tally. This information may also be used later to locate any failure in the drill string. In the tally book, the WDP DSM may also log the time of each WDP in use and the temperature or shock exposure history of each WDP (e.g., using the acquisition module 65 and sensor module 66 shown in
Once the drill bit reaches the bottom of the hole, the WDP DSM system may be used to perform various diagnostic and measurement functions. For example, a process of verifying that each WDP is functioning properly during a logging operation is illustrated in
As shown in
In an alternative embodiment, if the DSM is too far removed from the surface computer to be heard, the MWD or LWD tools may serve as a relay to the surface computer. In this alternative embodiment, an MWD or LWD tool also listens for the response from DSM 20015. If it receives the response, it waits until the pre-set time period expires. Then, the MWD or LWD tool transmits a message to the surface computer indicating whether it detected the response from DSM 20015. This verifies whether the DSM is working and whether the transmission system is functional in both directions.
The surface computer polls the next DSM (e.g. 20039). This process is repeated (step 1306) until some or all of the WDP are polled. Note that it is not necessary to poll all of the WDP DSMs all the times. Strategic sampling of a few physically separated WDP DSMs is a better approach. Finally, the surface computer instructs the MWD or LWD tools to resume transmitting MWD and LWD data (step 1305).
Locating Failures During Well Site Operations
Certain circumstances would justify polling the WDP DSM. For example, the surface computer would poll the WDP DSM during the trip into the well run in hole (RIH) and when adding drill pipe while drilling ahead. The surface computer could also poll the WDP DSM periodically during drilling to verify their proper operation and the integrity of the transmission system, according to the method shown in
If there is a hard failure, the surface computer can communicate to all WDP DSMs down to the point of failure and thus locate it. If there are intermittent failures, then the surface computer can periodically poll WDP DSMs to locate the troublesome WDP, or it can poll as soon as a failure is detected. Once the failure is located, the drill string may be rapidly tripped out to the point of failure. Fast tripping with elevators may be preferred over a trip where the Kelley or top drive is attached to each stand of WDP. During such a fast trip, the surface transceiver would not be attached to the WDP string.
Another potential problem with WDP is that certain sections may suffer reduced coupling efficiencies but not a hard failure. For example, the transformer core might be damaged or the copper clad groove might be corroded, resulting in a loss greater than expected (e.g., >0.2 dB). Such losses might be affected by the downhole environment, making them difficult to find under surface conditions. However, with embodiments of the invention, the efficiency of each WDP connection can be monitored in real time, and any problem that exists only in the downhole environment may be easily identified.
One of ordinary skill in the art would appreciate that such analysis does not require that each DSM transmits a signal of the same amplitude. If the amplitudes of the signals from the WDP DSM are known before hand, then the signals received from the DSM can be normalized. Similarly, it is not necessary that each WDP section attenuates the signal to the same extent. Instead, as long as the attenuation of each WDP is known before hand, the received signal magnitudes may be normalized or compensated. Even if the attenuation of each WDP is not known before hand, it can be determined from the signal level of each WDP DSM as each new section of WDP is added to the drill string. Furthermore, even if the attenuation of each WDP is not known or determined, it is possible to monitor any changes in attenuation with time (or with the addition of more WDP) to detect the problematic WDP using embodiments of the invention.
Maintenance and Tracking of WDP
WDP including the DSM of the invention will be easily tracked or inventoried. Because each WDP is uniquely identified by its identifier, shipping and tracking WDP will be relatively simple. To identify or inventory such a WDP, a conventional test box may be used to activate the DSM and record the identifier into a database.
At the rig, the surface computer can automatically record into a database pumping hours, hours below rotary, RPM, GPM, temperature, and pressure for each WDP. This database can be used to schedule inspections, maintenance and repair for each WDP. In addition, the attenuation for each section of WDP can be measured (as discussed above in relation to
Pre-Job and Post-Job Testing
The electrical function of each section of WDP or each stand of WDP (e.g., a triple WDP) can be tested using the DSM in accordance with embodiments of the invention. Test boxes can be attached to the pin or box connection of a WDP. Such a test box would inject current directly across the recess containing the toroid or would induce current using the toroidal transformer. It would communicate to the DSM, thus verifying the integrity of the WDP transmission and the proper operation of the DSM. The test box would record the identifier and the test results. It is not necessary to connect a test box to the end of the WDP containing the DSM. Instead, the test box may be attached to either end for the testing because the DSM will not respond if there is a failure in the link. This makes it possible to test a stand of WDP without physically accessing both ends. This is a significant advantage on the rig where access to both ends of a WDP stand may not be readily available. For example, when a triple stand of WDP is racked in the derrick, it is possible to access the pin connection, but not the box connection, from the rig floor to test all three sections of WDP without leaving the rig floor.
While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as disclosed herein. For example, while the invention has been illustrated using WDP having toroidal inductive couplers, embodiments of the invention can be applied to other systems where there are many series connections. For clarity, the above description assumes that each WDP includes a diagnostic system/module. One of ordinary skill in the art would appreciate that the present invention is not limited to a drilling string, in which every WDP includes a DSM. Instead, drill strings in which some WDPs include DSMs and some do not are expressly within the scope of the invention. Furthermore, embodiments of the invention are not limited to MWD or LWD telemetry, but can also be used for completion strings, testing strings or permanent monitoring installations. Accordingly, the scope of the invention should be limited only by the attached claims.
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