The present disclosure relates generally to downhole well-logging tools and, more particularly, to wireless communication for downhole well-logging tools.
This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present techniques, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
A variety of downhole tools are used to obtain wellbore measurements. In general, downhole tools include sensors to measure the parameters of the rock formation surrounding the wellbore. Some downhole tools may obtain wellbore measurements by emitting radiation into the surrounding rock formation and detecting radiation that returns to the tool. These nuclear downhole tools may emit radiation using radioisotope sources or electronic nuclear radiation generators.
A downhole tool string may house one or more downhole tools. Typically, the downhole tool string includes a data storage device and/or a controller (often collectively referred to as a recorder). Communication with the downhole tool string via the data storage device and/or the controller may require an electrical connection to certain communication ports in the downhole tool string. The design of these electrical connectors may be prohibited by a variety of factors. Among other things, the mechanical constraints of the pressure housing of the downhole tool string may prohibit the use of these electrical connectors. Certain government regulations, such as the European ATEX (ATmospheres EXplosibles) regulations, may also proscribe the use of such electrical connectors at a producing wellsite.
Given these constraints on wired communication, certain wireless communication approaches have been attempted. Even conventional wireless communication approaches, however, may not be effective in many common well-logging circumstances. In one approach, a sonic device such as a buzzer may be used to relay information between the downhole tool string and a human operator. The buzzer may communicate with the tool operator with a series of high-volume beeps of selected timing and duration. Though effective under some circumstances, the sonic buzzer may be difficult to hear on a typical rig floor, since an operating rig may have a number of very high-volume sound sources. Not only does external noise interfere, but the sound penetration through the typical downhole tool string housing may also be limited. Furthermore, the range of information that can be transferred through the sonic device or buzzer is minimal due to the inconsistency of sound communications in such an uncontrolled environment. Finally, the transmission of information is unidirectional in this approach—from the sound buzzer in the downhole tool string to the human operator—meaning this manner of communication cannot be used to reprogram the downhole tool string once it has been lowered into the well.
In another wireless communication technique, an optical communication port in the housing downhole tool string may communicate by sending and receiving light signals. Optical communication in this way may depend on a direct, unimpeded view of the optical communication port. Thus, communication may be effective when the downhole tool string is in plain view of an external optical transceiver. When the downhole tool string is deployed through a pressure riser of a well, however, conventional wireless optical communication may be precluded.
Various refinements of the features noted above may exist in relation to various aspects of the present disclosure. Further features may also be incorporated in these various aspects as well. These refinements and additional features may exist individually or in any combination. For instance, various features discussed below in relation to one or more of the illustrated embodiments may be incorporated into any of the above-described aspects of the present disclosure alone or in any combination. Again, the brief summary presented above is intended only to familiarize the reader with certain aspects and contexts of embodiments of the present disclosure without limitation to the claimed subject matter.
The present disclosure relates to systems, methods, and devices for two-way communication with a downhole tool string. In one example, a method may include placing a downhole tool string into a pressure riser of a well while at least one component of the downhole tool string is not activated. Thereafter, a wireless control signal may be issued through the pressure riser to the downhole tool to cause the downhole tool string to activate the component. The wireless control signal may involve an acoustic signal, an optical signal, and/or an electromagnetic signal such as electrical dipole coupling or magnetic dipole coupling.
In another example, a system may involve a downhole tool string with a first wireless communication device and a logging unit with a communication link to a second wireless communication device. The second wireless communication device may be disposed on and/or embedded in a stuffing box and/or a pressure riser. The logging unit may also convey the downhole tool string through the stuffing box into the pressure riser of the well. Using the first wireless communication device and the second wireless communication device, the logging unit and the downhole tool string may intercommunicate while the downhole tool string is located in the pressure riser.
In another example, a downhole tool string may include a first magnetic dipole antenna to transmit and/or receive wireless signals via magnetic dipole coupling with a second magnetic dipole antenna external to the downhole tool string.
In another example, a method may involve raising a downhole tool string out of a borehole of a well and into a pressure riser of the well while a downhole tool of the downhole tool string is in a first operational state. While the downhole tool string is in the pressure riser, a wireless control signal may be issued to the downhole tool string to cause the downhole tool to exit the first operational state and enter a second operational state.
Various refinements of the features noted above may exist in relation to various aspects of the present disclosure. Further features may also be incorporated in these various aspects as well. These refinements and additional features may exist individually or in any combination. For instance, various features discussed below in relation to one or more of the illustrated embodiments may be incorporated into any of the above-described aspects of the present disclosure alone or in any combination. Again, the brief summary presented above is intended only to familiarize the reader with certain aspects and contexts of embodiments of the present disclosure without limitation to the claimed subject matter.
Various aspects of this disclosure may be better understood upon reading the following detailed description and upon reference to the drawings in which:
One or more specific embodiments of the present disclosure will be described below. These described embodiments are only examples of the presently disclosed techniques. Additionally, in an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.
When introducing elements of various embodiments of the present disclosure, the articles “a,” “an,” and “the” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Additionally, it should be understood that references to “one embodiment” or “an embodiment” of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.
The present disclosure describes two-way wireless communication between a downhole tool string and a surface-based logging unit. In certain examples discussed below, a logging unit may intercommunicate with a downhole tool string even while the downhole tools string is deployed in a conductive metal pressure riser. In one example, the downhole tool string may include a magnetic dipole antenna. The logging unit may include a similar magnetic dipole antenna. By communicating signals at sufficiently low frequencies (where the skin depth is relatively large), it is possible to transmit and receive signals through magnetic dipole coupling over suitable distances through the pressure riser. The magnetic dipole antennas may have magnetic cores to enhance magnetic dipole coupling through the pressure riser.
Additionally or alternatively, the downhole tool string and the logging unit may intercommunicate using electric dipole antennas, acoustic transducers, or optical communication devices. For instance, an acoustic transducer attached to the outer wall of the pressure riser may send and receive sound signals to an acoustic device in the downhole tool string. In another example, an optical communication device may send and receive light through a transparent window in the pressure riser to an optical communication device in the downhole tool string. A magnetic dipole antenna, electrical dipole antenna, an acoustic transducer, or an optical communication device may also be embedded in the pressure riser or a stuffing box above the pressure riser to communicate with the downhole tool string while the downhole tool string is within the pressure riser.
Two-way communication through the pressure riser provides greater control of the downhole tool string. For instance, a component of the downhole tool string (e.g., a battery sub or a nuclear downhole tool) may be in a deactivated or partially deactivated state while at the surface. The downhole tool string may be placed into the pressure riser while the component is deactivated. Once in the pressure riser, the logging unit may issue a command to cause the component to enter an activated state to permit well-logging. Additionally or alternatively, the logging unit may conduct an operational check of the downhole tool to ensure the downhole tool is operating correctly. The logging unit may request the status of the downhole tool, which may reply with some feedback signal that verifies the downhole tool is operative.
One example of a well-logging system 10 that can conduct two-way wireless communication appears in
In general, the pressure riser 18 may maintain pressure control over the well when an instrument is placed in the well 12. The stuffing box 16 serves as a cap on the pressure riser 18. The stuffing box 16, pressure riser 18, and wellhead valve 20 may be located underwater (e.g., in an offshore well 12) or on land (e.g., in an onshore well 12). The logging unit 14 may be understood to be “at the surface.” As such, the logging unit 14 may be located, for example, on an offshore platform above the well 12 or on a truck near the well 12. A rock formation surrounds a wellbore 22 of the well 12. Different characteristics of the rock formation surrounding the wellbore 22 may indicate the likely presence or absence of hydrocarbons such as oil or gas. By logging the well 12, characteristics of the rock formation surrounding the wellbore 22 can be detected and valuable information about the well 12 may be determined.
A downhole tool string 24 may be used for such well-logging purposes. The downhole tool string 24 may be lowered through the stuffing box 16 and pressure riser 18 using any suitable means of conveyance, such as a slick line 26. Other suitable means of conveyance may include, for example, conveyance within a drill string or other jointed pipe string, on coiled tubing, or on armored electrical cable, to name a few examples. The slick line 26 may be a strong wire, sometimes referred to as a piano wire, that mechanically supports the downhole tool string 24. A motor 28 may raise or lower the downhole tool string 24, using the weight of the downhole tool string 24 to send it downhole in the same manner of other wireline tools. Because the slick line 26 may not provide power or telemetry, the downhole tool string 24 may not communicate over the slick line 26. Instead, the downhole tool string 24 may communicate with the logging unit 14 using two-way wireless communication. Various ways of such two-way wireless communication will be discussed in greater detail below.
The downhole tool string 24 may include several components. A rope socket 30 may join the slick line 26 to the other components of the downhole tool string 24. A battery sub (B) 32 may provide power for a recorder (R) 34 and, in the example of
In some cases, the downhole tools (T1) 36A and/or (T2) 36B may include electronic nuclear radiation generators, such as neutron generators or x-ray generators. By way of example, such an electronic neutron generator may be a model of the Minitron™ by Schlumberger Technology Corporation. A Minitron™ may produce pulses of neutrons through deuteron-deuteron (d-D) and/or deuteron-triton (d-T) reaction. By way of example, the emitted neutrons may have energies of around 2 MeV or 14 MeV. In other cases, the downhole tools (T1) 36A and/or (T2) 36B may include an electronic x-ray generator. Such an x-ray generator may be a high-voltage x-ray generator such as that disclosed in U.S. Pat. No. 7,564,948, “HIGH VOLTAGE X-RAY GENERATOR AND RELATED OIL WELL FORMATION ANALYSIS APPARATUS AND METHOD,” which is assigned to Schlumberger Technology Corporation and incorporated by reference herein in its entirely. X-rays emitted by such an X-ray generator may have a maximum energy of greater than 250 keV.
Regardless of whether the downhole tools (T1) 36A and/or (T2) 36B employ such electronic nuclear radiation generators, the downhole tools (T1) 36A and/or (T2) 36B may remain at least partially deactivated while the downhole tool string 24 is being assembled at the well 12. As will be described further below, the downhole tools (T1) 36A and/or (T2) 36B may remain deactivated until the downhole tool string 24 has been lowered into the pressure riser 18. In addition, in a producing oilfield, the European ATEX directive often applies. In accordance with the ATEX directive, two electrically active pieces of equipment may not be connected in certain situations. Therefore, when the downhole tool string 24 is assembled at the surface, the battery sub (B) 32 may be off or may be controlled by the recorder (R) 34 not to supply power to certain components of the downhole tool string 24. The downhole tools (T1) 36A and (T2) 36B therefore may be off by default, since the battery sub may not be supplying power to all of the components of the downhole tool string 24.
In many situations, the battery sub (B) 32 and the recorder (R) 34 may be pre-assembled in an area where ATEX is not in effect. The recorder (R) 34 may control the battery sub (B) 32 such that power is turned off to the downhole tools (T1) 36A and (T2) 36B. Thus, when the downhole tool string 24 is assembled at the surface, the downhole tools (T1) 36A and (T2) 36B may be off by default. All connections made during the assembly of the downhole tool string 24 may not be electrically active. In this way, compliance with ATEX may be achieved.
Even though the downhole tool string 24 is not fully active upon assembly, the components of the downhole tool string 24 may be made active afterward. Namely, the logging unit 14 may cause the downhole tool string 24 to become activated once the downhole tool string 24 has been lowered into the pressure riser 18. A communication device 38 in the logging unit 14 may issue a control signal 40 to the downhole tool string 24. A corresponding communication device disposed within the downhole tool string 24 may receive the control signal 40. The control signal 40 may cause the battery sub (B) 32 to become activated, to cause the recorder (R) 34 to cause the battery sub (B) 32 to supply power to other components of the downhole tool string 24, and/or the downhole tools (T1) 36A and/or (T2) 36B to become activated. Additionally or alternatively, the control signal 40 may cause the downhole tool string 24 (e.g., the recorder (R) 34) to conduct an “operational check” to ensure the downhole tool string 24 is working properly. The downhole tool string 24 may reply with data 42. This data 42 could include a feedback signal indicating that the downhole tool string 24 is fully activated and ready to log the well 12. Based on such a data 42 signal, the logging unit 14 may begin to convey the downhole tool string 24 down into the wellbore 22 to log the well 12.
After the downhole tool string 24 has logged the well 12 and returned to the pressure riser 18, the logging unit 14 may issue other control signals 40. The control signals 40 issued after well-logging may instruct the downhole tool string 24 to provide well-logging data or may cause the downhole tool string 24 to become at least partially deactivated. In response, the data 42 may include the well-logging data and/or a feedback signal confirming that components of the downhole tool string 24 have been deactivated. The data 42 may indicate, for instance, that the downhole tools (T1) 36A and/or (T2) 36B are no longer emitting nuclear radiation.
It may be appreciated that the opaque, conductive metal pressure riser 18 may impede conventional wireless communication. As such, the control signals 40 and the data signals 42 may be transmitted beyond the conductive metal pressure riser 18 in a variety of ways. For example, the control signals 40 and data signals 42 may be transmitted by magnetic dipole coupling or electric dipole coupling through the pressure riser 18 (e.g., as discussed below with reference to
The communication device 38 may be controlled by a processor 44 of the logging unit 14. The processor 44 may be operably coupled to memory 46 and/or storage 48 to carry out the techniques described herein. The processor 44 and/or other data processing circuitry may carry out instructions stored on any suitable article of manufacture with one or more tangible, computer-readable media at least collectively storing such instructions. The memory 46 and/or the nonvolatile storage 48 may represent such an article of manufacture. Among other things, the memory 46 and/or the nonvolatile storage 48 may represent random-access memory, read-only memory, rewriteable-memory, hard drive, or optical discs.
In one particular example shown in
The magnetic dipole antennas 60A and 60B may be identical or may be of different. For instance, the magnetic dipole antenna 60A located outside of the pressure riser 18 may have proportionally larger coils than the magnetic dipole antenna 60B. In any case, communication between the magnetic dipole antennas 60A and 60B may occur via magnetic dipole coupling 62. In the example of
In another example, shown in
The communication device 38 of the logging unit 14 may include wired surface transmit/receive (TX/RX) circuitry 70. The surface TX/RX circuitry 70 may provide signals over a communication cable 72. The communication cable 72 may couple to the magnetic dipole antenna 60A, which may be embedded within the pressure riser 18, using a pressure feed-through 74. The pressure feed-through 74 may allow electrical connections to components embedded within the pressure riser 18 without compromising the integrity of the pressure riser 18.
The magnetic dipole antenna 60A embedded in the pressure riser 18 may include any suitable size and number of windings around the interior diameter of the pressure riser 18. The magnetic dipole antenna 60A of the example of
The magnetic dipole antenna 60A may also be located within the stuffing box 16 adjacent to the pressure riser 18, as shown in
The communication device 38 of the logging unit 14 may include wired surface transmit/receive (TX/RX) circuitry 70 in substantially the same manner as described with reference to
In the examples of
An electric dipole can be generated using a toroidal winding, as generally represented in electric dipole antennas 80A and 80B. To obtain a sufficient signal to noise ratio (SNR), a toroidal electric dipole antenna 80A located outside of the pressure riser 18 may be proportional to, but larger than, the toroidal electric dipole antenna 80B located in the downhole tool string 24. Specifically, as with the magnetic dipole examples of
Alternatively, the electric dipole antenna 80B may be embedded within the pressure riser 18 or the stuffing box 16. For example, as shown in
The communication device 38 of the logging unit 14 may include the wired surface transmit/receive (TX/RX) circuitry 70. The surface TX/RX circuitry 70 may provide signals over a communication cable 72. The communication cable 72 may couple to the toroidal electric dipole antenna 80A, which may be embedded within the pressure riser 18, using a pressure feed-through 74. The pressure feed-through 74 may allow electrical connections to components embedded within the pressure riser 18 without compromising the integrity of the pressure riser 18.
The electric dipole antenna 80A embedded in the pressure riser 18 may include any suitable size and number of toroidal windings within the pressure riser 18. The electric dipole antenna 80A of the example of
In another example, the electric dipole antenna 80A may be located within the stuffing box 16 adjacent to the pressure riser 18, as shown in
The communication device 38 of the logging unit 14 may include wired surface transmit/receive (TX/RX) circuitry 70 in substantially the same manner as described above. The surface TX/RX circuitry 70 may provide signals over a communication cable 72. The communication cable 72 may couple to the electric dipole antenna 80A, which may be embedded within the stuffing box 16 associated with the pressure riser 18, using a pressure feed-through 74. The pressure feed-through 74 may allow electrical connections to components embedded within the stuffing box 16 without compromising the integrity of the stuffing box 16. It should be noted that, in the example of
Two-way communication with the downhole tool string 24 may also take place via acoustic and/or optical communication. For example,
The acoustic transducers 90A and 90B facilitate communication through sound waves 92 passing between the conductive wall of the pressure riser 18 and the borehole fluid within the pressure riser 18. It should be appreciated that the sound waves 92 can pass through a solid, electrically conductive wall, albeit with some attenuation. Since the distance between the acoustic transducers 90A and 90B is relatively short, however, sufficient signal intensity may allow communication via the sound waves 92.
In the example of
In another example, shown in
The light 102 emitted and detected by the optical communication devices 100A and 100B may be of any suitable wavelength(s). For instance, the optical communication devices 100A and 100B may employ light emitting diodes (LEDs) of ultra violet (UV) to infrared (IR) wavelengths. The optical communication devices 100A and/or 100B may use lasers (e.g., LED lasers) to emit the light. Unlike the magnetic dipole coupling, electric dipole coupling, and acoustic communication approaches discussed above, optical transmission cannot pass through the opaque outer wall of the pressure riser 18 without the optically transmissive window 104. Alternatively, the optically transmissive window 104 may be avoided by placing the optical communication device 100A within or embedded in the pressure riser 18, and using a pressure feed-through 74 in the manner discussed above with reference to
In several examples discussed above, magnetic dipole coupling provides two-way communication between the logging unit 14 and the downhole tool string 24 (e.g.,
As seen in
The cross-sectional view of
Considering the case of magnetic dipole coupling in particular, two magnetic dipole antennas 60 can communicate in the manner shown in
To begin, the RX-TX induction coupling tensor between two points in space can be expressed as the following matrix:
where (zx) denotes the coupling when the magnetic dipole antenna 60B aligns with the Z-axis and the magnetic dipole antenna 60A aligns with the X-axis.
A received signal VR can be expressed as a product of matrices as shown below:
where AT is the transmitter effective area of the magnetic dipole antenna 60A, AR is the receiver effective area of the magnetic dipole antenna 60B, and IT is the transmitter current of the magnetic dipole antenna 60A.
In an infinite homogeneous formation, the coupling matrix can be written as:
where μ is the permeability (H/m),
is the propagation factor (1/m),
is the skin depth (m), and σ is the formation conductivity (S/m). In air, μ=μ0=4π×10−7 H/m. The σ of air ranges from 3 to 8×10-15 (S/m).
In air, term kS and k2S2 are small. By ignoring them, the coupling matrix in air can be simplified as the following:
Therefore, in air, the received signal VR can be written as follows:
When the downhole tool string 24 is pressure deployed, the downhole tool string 24 may be within the pressure riser 18 at certain points. Thus, either the transmitter or receiver magnetic dipole antenna 60A or 60B may be inside a steel pipe. The received magnetic dipole coupling 62 signal thus will be attenuated by the steel pipe. This attenuation is related to the skin depth of the metal pressure riser at the nominal frequency. The following equation illustrates the received signal attenuation:
where w is the wall thickness of the steel of the pressure riser 18 (m),
is the skin depth (m), μs is the steel pipe permeability of the pressure riser 18 (H/m), and σs is the steel pipe conductivity of the pressure riser 18 (S/m). In air, μs=μ0=4π×10−7 H/m. The σs of steel is typically about 1.6×106 (S/m).
Choosing w=0.5″ and μs=200μ0, the signal attenuation at 25 Hz is about 19.6 dB. The received signal thus could be calculated as:
Regardless of whether magnetic dipole coupling, electric dipole coupling, acoustic communication, or optical communication is used, two-way communication through the pressure riser 18 may allow for improved operation of the downhole tool string 24 when deployed under pressure. In a flowchart 130 of
When the downhole tool string 24 is placed into the pressure riser 18, at least one component of the downhole tool string 24 may not be active. For example, under the European ATEX directive, it may not be possible to connect certain electrically active components. When operating under the ATEX directive, the downhole tool string 24 may be assembled while the battery sub (B) 32 is not supplying power to the other components of the downhole tool string 24. As such, in some cases, the recorder (R) 34 and the downhole tools (T1) 36A and/or (T2) 36B may not be active when the downhole tool string 24 is placed into the pressure riser 18 of the well. In other cases, the recorder (R) 34 and the battery sub (B) 32 may be assembled off-site where ATEX does not apply. Other components of the downhole tool string 24 (e.g., the downhole tools (T1) 36A and/or (T2)) may be coupled to the recorder (R) 34 and/or battery sub (B) 32 while the recorder (R) 34 is controlling the battery sub (B) 32 not to supply power to the other components. In another example, regardless of whether the European ATEX directive applies in a given setting, an electronic nuclear radiation generator in the downhole tools (T1) 36A and/or (T2) 36B may be deactivated while at the surface.
The downhole tool string 24 may not be able to log the well 12 until the various components of the downhole tool string 24 become activated. Furthermore, in the case whether the downhole tool (T1) 36A and/or (T2) 36B are nuclear downhole tools with electronic nuclear radiation generators, the downhole tools (T1) 36A and/or (T2) 36B may not be able to log a well until the nuclear radiation generator(s) are activated and begin to emit nuclear radiation, or alternatively, the radiation generator(s) are armed for downhole activation using various interlock methods (such as described in U.S. Pat. No. 6,649,906, “Method and apparatus for safely operating radiation generators in while-drilling and while-tripping applications,” which is assigned to Schlumberger Technology Corp. and incorporated by reference herein in its entirety) that prevent generation of radiation at the surface. Once the downhole tool string 24 has been placed in the pressure riser 18, the logging unit 14 may take steps to activate the downhole tool string 24 and verify it is operative before logging the well 12 in earnest.
In particular, the logging unit 14 may issue a control signal 40 to the downhole tool string through the pressure riser 18 (block 134). The control signal 40 may reach the downhole tool string 24 via magnetic dipole coupling, electric dipole coupling, acoustic communication, and/or optical communication in the manners described above. Upon receipt of the control signal 40, the downhole tool string 24 may cause the deactivated component(s) of the downhole tool string 24 to become activated. In one example, the recorder (R) 34 may control the downhole tool string 24 such that power is provided to the other components of the downhole tool string 24. In another example, a deactivated battery sub (B) 32 may begin supplying power to the recorder (R) 34 and downhole tools (T1) 36A and/or (T2) 36B. In other examples, the downhole tools (T1) 36A and/or (T2) 36B may begin to emit nuclear radiation, or alternatively, the radiation generator may be armed for downhole activation using various interlock methods, such as those mentioned above, that prevent generation of radiation at the surface.
The downhole tool string 24 may reply with a wireless feedback data 42 signal (block 136). When the feedback data 42 signal indicates the previously deactivated component of the downhole tool string 24 has been activated (decision block 138) the logging unit 14 may lower the downhole tool string 24 into the wellbore 22 of the well 12 to log the well 12 (block 140). Otherwise, if the feedback data 42 signal does not indicate that the previously deactivated component of the downhole tool string 24 has become activated (decision block 138), the logging unit 14 may continue to issue the wireless command to activate the component (block 134). Without such an “operational check” of the downhole tool string 24, an operator of the logging unit 14 may choose not to expend the resources to attempt to log the well 12 until confirmation has been received that the downhole tool string 24 will be able to do so.
Two-way wireless communication may also allow at least one component of the downhole tool string 24 to be verifiably deactivated while in the pressure riser 18. For example, in a flowchart 150 of
As mentioned above, under the European ATEX directive, it may not be possible to connect or disconnect certain electrically active components. When operating under the ATEX directive, the downhole tool string 24 may be disassembled while the battery sub (B) 32 is not supplying power to the other components of the downhole tool string 24. As such, in some embodiments, the recorder (R) 34 may cause power not to be provided to the various components that are to be disassembled at the surface (e.g., the recorder (R) 34 and the battery sub (B) 32 may remain connected at the surface and disassembled off-site, so the recorder (R) 34 may remain powered). In other embodiments, the battery sub (B) 32 of the downhole tool string 24 may be deactivated or may stop providing power to the other components of the downhole tool string 24 before reaching the surface. Likewise, any electronic nuclear radiation generators in the downhole tools (T1) 36A and/or (T2) 36B may be deactivated so as not to be emitting radiation when the downhole tool string 24 is raised out of the pressure riser 18.
Specifically, the logging unit 14 may issue a control signal 40 to the downhole tool string through the pressure riser 18 (block 154). The control signal 40 may reach the downhole tool string 24 via magnetic dipole coupling, electric dipole coupling, acoustic communication, and/or optical communication in the manners described above. Upon receipt of the control signal 40, the downhole tool string 24 may cause certain active components of the downhole tool string 24 to become deactivated. In one example, an active battery sub (B) 32 may stop supplying power to the recorder (R) 34 and downhole tools (T1) 36A and/or (T2) 36B. In another example, the downhole tools (T1) 36A and/or (T2) 36B may stop emitting nuclear radiation.
The downhole tool string 24 may reply with a wireless feedback data 42 signal (block 156). When the feedback data 42 signal indicates the previously activated component of the downhole tool string 24 has been deactivated (decision block 158), the logging unit 14 may remove the downhole tool string 24 out of the pressure riser 18 to the surface (block 160). Otherwise, if the feedback data 42 signal does not indicate that the previously activated component of the downhole tool string 24 has become deactivated (decision block 158), the logging unit 14 may return to reissue the wireless command to deactivate the component (block 154). Without such a “confirmation signal” of the downhole tool string 24, an operator of the logging unit 14 may choose not to raise the downhole tool string 24 out of the well 12 until confirmation has been received that the downhole tool string 24 is off and/or not emitting radiation.
Technical effects of the present disclosure include, among other things, the ability to perform an “operational check” on a downhole tool string even while the downhole tool string is in a pressure riser. Thus, through magnetic dipole coupling, electrical dipole coupling, acoustic communication, or optical communication, a logging unit may control a downhole tool string while the downhole tool string is in a pressure riser. In addition, the downhole tool string may be assembled in accordance with the European ATEX directive in an at least partially deactivated state at the surface. When the assembled, but deactivated, downhole tool string has been lowered into a pressure riser, the downhole tool string may be verifiably activated. Likewise, when the active downhole tool string is raised into the pressure riser after logging the well, the downhole tool string may be verifiably deactivated before being raised out to the surface.
The specific embodiments described above have been shown by way of example, and it should be understood that these embodiments may be susceptible to various modifications and alternative forms. It should be further understood that the claims are not intended to be limited to the particular forms disclosed, but rather to cover all modifications, equivalents, and alternatives falling within the spirit and scope of this disclosure.
The present disclosure claims the benefit of U.S. Provisional Application No. 61/581,292, titled “WIRELESS TWO-WAY COMMUNICATION FOR DOWNHOLE TOOLS” and filed Dec. 29, 2011, which is incorporated by reference herein in its entirety.
Number | Date | Country | |
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61581292 | Dec 2011 | US |