Patent Application
20080156477
Not applicable.
Not applicable.
1. Field of the Invention
The invention relates generally to the field of well logging instrument conveyance devices. More specifically, the invention relates to devices used to move a well logging instrument through the interior of a pipe string so that the well logging instrument can be deployed in a wellbore.
2. Background Art
Well logging instruments are used, among other purposes, to make measurements of physical properties of Earth formations that have been penetrated by a wellbore. Well logging instruments typically include one or more types of sensors to make the measurements of the physical properties. Signals from the sensors may be communicated to the Earth's surface by various forms of signal telemetry, and/or may be stored in various types of recording device disposed within the well logging instrument.
As the well logging instrument is moved along the wellbore, a record of the signals generated by the sensors is made with respect to time and/or depth of the sensors within the wellbore. There are a number of different devices known in the art for moving the well logging instrument along the wellbore. The instrument may be affixed to the end of an armored electrical cable, which is unwound from w winch or similar spooling device to extend the instrument into the wellbore by the action of Earth's gravity. The instrument is withdrawn by rewinding the cable onto the winch. The well logging instrument may be moved along the wellbore by coupling it to the end of a coiled tubing, and unspooling and spooling the coiled tubing to move the instrument into and out of the wellbore. The instrument may also be coupled to the end of a threadedly coupled pipe, called a pipe “string.” The pipe string with the instrument attached to the lower end thereof is extended into the wellbore by threadedly coupling segments of pipe end to end. The pipe string is withdrawn from the wellbore by threadedly uncoupling segments of pipe.
U.S. patent application Publication No. 2004/0074639 filed by Runia discloses another device for moving the well logging instrument along the wellbore. The system comprises a tubular conduit or pipe extending from the Earth's surface into the wellbore containing a body of wellbore fluid. A well logging instrument string is included that is capable of passing from a position within the conduit to a position outside the conduit at a lower end part thereof and capable of being suspended by the conduit in said position outside the conduit. In some embodiments the well logging instrument may include a pressure pulse device arranged within the conduit in a manner that the pressure pulse device is in data communication with the logging tool. The pressure pulse device is capable of generating pressure pulses in the body of wellbore fluid, the pressure pulses representing data communicated by the logging tool string to the pressure pulse device during logging of Earth formation by the logging tool string.
In using the device disclosed in the Runia '639 publication it has been found desirable to be able to control the speed of movement of the well logging instrument inside the conduit, particularly when the conduit is disposed in a vertical or nearly vertical wellbore. Conversely, it is necessary to provide some mechanism to move the well logging instrument along the interior of the conduit when the wellbore is highly inclined form vertical such that Earth's gravity is incapable of moving the well logging instrument sufficiently.
A deployment device for controlling rate of movement of an instrument inside a conduit according to one aspect of the invention includes a mandrel having a coupling to affix the deployment device to the instrument and a controllable brake disposed in the mandrel, the brake controllably actuatable to maintain the mandrel and instrument at a selected speed within the conduit.
Other aspects and advantages of the invention will be apparent from the following description and the appended claims.
It is to be clearly understood that the FT tool 14 shown in
The fluid pressure pulse device 18 has a variable flow restriction (not show) which is controlled by electric signals transmitted by the FT tool 14 to the pressure pulse device 18, which signals represent part of the data produced by the FT tool 14 during the making of measurements of the earth formation 2. The upper end of the deployment device 12A may be provided with a latch 20 for latching of an armored electrical cable (not shown) to the device 12A for retrieval from the bottom of the drill string 9.
A wellhead 22 is typically connected to the upper end of the casing 4 and is provided with an outlet conduit 24 terminating in a drilling fluid reservoir 26 provided with a suitable sieve means (not shown) for removing drill cuttings from the drilling fluid. A pump 28 having an inlet 30 and an outlet 32 is arranged to pump drilling fluid from the fluid reservoir 26 into the upper end of the drill string 9.
A control system 34 located at the Earth's surface is connected to the drill string 9 for sending or receiving fluid pressure pulses in the body of drilling fluid 10 to or from the fluid pressure pulse device 18.
A second embodiment shown in
The closure element 46 has a latching mechanism (not shown) for latching the closure element 46 to the drill bit 40. The latching mechanism is arranged to co-operate with the latching members 48a, 48b in a manner that the closure element 46 unlatches from the drill bit 40 upon latching of latching member 48a to latching member 48b, and that the closure element 46 latches to the drill bit 40, and thereby closes passage 44, upon unlatching of latching member 48a from latching member 48b.
In
During normal operation of the embodiment of
Simultaneously with operating the logging instrument 12, drilling fluid is pumped by pump 28 from the fluid reservoir 26 into the drill string 9 via inlet 30 and outlet 32. The controlled variations of the variable flow restriction induce corresponding pressure pulses in the body of drilling fluid present in the drill string 9, which pressure pulses are monitored by the control system 34. In this manner the system operator can monitor the well logging operation and can take corrective action if necessary. For example, incorrect deployment of the arms 16 of the RFT tool can be detected in this manner at an early stage.
After the logging run has been completed, the logging instrument 12 may retrieved through the drill string 9 to surface by wireline connected to latch 20. Optionally the drill string 9 is then removed from the wellbore 1.
During normal operation of the embodiment of
When it is desired to log the earth formation 2 surrounding the open wellbore portion 7, the logging tool string 12 is pumped down the drill string 9 using pump 28 until the logging tool string 12 latches to the MWD device 42 by means of latching members 48a, 48b. During lowering of the string 12, the arms 16 of the FT tool 14 are retracted. Then the drill string 9 is raised a selected distance until there is sufficient space below the drill string for the FT tool 14, the MWD device 42 and the closure element 46 to extend below the drill bit 40. Upon latching of latching member 48a to latching member 48b, the closure element 46 unlatches from the drill bit 40. Continuous operation of pump 28 causes further downward movement of the combined logging tool string 12, MWD device 42 and closure element 46 until the logging tool string 12 becomes suspended by the drill string. In this position (shown in
The arms 16 are then extended against the wall of the wellbore and the FT tool 14 is operated to measure the Earth formation 2. The measurement data are stored in the electronic memory, and part of the data are transmitted by the FT device 14 in the form of electrical signals to the pressure pulse device 18, which signals induce controlled variations of the variable flow restriction of the MWD device 42.
Simultaneously with operating the logging tool string 12, drilling fluid is pumped by pump 28 from the fluid reservoir 26 into the drill string 9 via inlet 30 and outlet 32. The controlled variations of the variable flow restriction induce corresponding pressure pulses in the body of drilling fluid present in the drill string 9, which pressure pulses are monitored by the control system 34. Thus, the operator is in a position to monitor the logging operation and to take corrective action if necessary (similarly to the embodiment of
After measuring has been completed, the instrument 12 may be retrieved to surface through the drill string 9 by wireline connected to latch 20 at the top of the deployment device 12A. During retrieval the closure element 46 latches to the drill bit 40 (thereby closing the passage 44) and the latching members 48a, 48b unlatch. Alternatively the instrument 12 can be retrieved to surface by reverse pumping of drilling fluid, i.e. pumping of drilling fluid down through the annular space between the drill string 9 and the wellbore wall and into the lower end of the drill string 9. Optionally a further wellbore section then can be drilled, or the drill string 9 can be removed from the wellbore 1.
As will be readily appreciated by those skilled in the art, during deployment of the well logging instrument 12 into the drill string 9, and during removal therefrom, it is desirable to be able to control the speed of movement of the instrument 12 within the drill string. A deployment device 12A according to the invention is configured to control the speed of motion of the instrument 12 along the interior of the drill string 9, and where appropriate, can provide motive power to move the instrument 12 along the interior of the drill string 9 during deployment or withdrawal of the instrument 12.
One embodiment of the deployment device 12A will now be explained with reference to
In the present embodiment, the motor driver 60 can generate alternating current used to operate drive motors, as will be further explained. The motor driver 60 may also induce alternating current in such drive motors such that the motors provide electrically regenerative braking. The controller 58 can provide control signals to operate the motor driver 60 such that a substantially constant, or other controlled speed of movement of the deployment device 12A along the interior of the drill string can be maintained.
In the present embodiment, the drive motors can be induction motors formed by combination of high magnetic permeability steel traction wheels 66 that are held in frictional contact with the interior wall of the drill string (or other conduit) by a biasing device such as bow springs 64 acting on the wheels' axles. The wheels 66 may each be disposed proximate to a corresponding induction coil 68. One or more of the wheels 66 may include embedded permanent magnets 67 to assist in regenerative braking, as will be further explained. The particular biasing device shown in this embodiment is not intended to limit the scope of the invention. Alternative biasing devices may be used in other embodiments, such as pressurized hydraulic or pneumatic cylinders, coil springs, and shape memory metal springs, for example.
As the deployment device 12A moves downward inside the pipe or conduit by gravity, the rate of descent may be controlled by suitable current being passed through the induction coils 68 by the motor driver 60 so as to electrically brake the wheels 66. Electrical power may be generated by such braking, and the generated power may be conditioned and supplied to the battery 62 to maintain its charge. Conversely, when it is necessary to supply motive power to move the device 12A and the well logging instrument (12 in
The present embodiment includes components intended to cause the wheels 66 to act as the rotors in an induction motor. It will be appreciated by those skilled in the art that the wheels 66 may be driven by alternative arrangements of a motor rotationally coupled to the wheels 66.
Another arrangement is shown in
An alternative type of motor that may be used in embodiments such as shown in
When it is determined that braking force is needed, the three-way valve 94 is moved to the leftmost position in
When it is determined that motive force is required for the deployment device, the three way valve 94 may be moved to the right hand position in
In some embodiments, pressure charge may be maintained in the accumulator 90 by a separate pump 73C which may be driven by a separate motor, or a turbine exposed to flow of fluid in the wellbore or other type of drive mechanism. The pump 73C transfers fluid from the reservoir 92 to the accumulator 90 to maintain pressure therein. The outlet line of the pump 73C may include a check valve 98 to prevent leak off of pressure through the pump 73C when the pump is not operating.
Another embodiment of a braking mechanism that may be used in substitution of or in addition to the inductive traction device explained above will now be explained with reference to
It will be readily appreciated by those skilled in the art that other forms of regenerative braking may be used to control the speed of motion under gravity of a logging instrument inside a conduit. Such regenerative braking may include rotating a hydraulic pump to convert motion into hydraulic pressure, for example.
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. Accordingly, the scope of the invention should be limited only by the attached claims.
