Patent Application
20160326869
This invention relates generally to the field of telemetry systems, and more particularly, but not by way of limitation, to acoustic signal generators used in wellbore drilling operations.
Wells are often drilled for the production of petroleum fluids from subterranean reservoirs. In many cases, a drill bit is connected to a drill string and rotated by a surface-based drilling rig. Drilling mud is circulated through the drill string to cool the bit as it cuts through the subterranean rock formations and to carry cuttings out of the wellbore.
As drilling technologies have improved, “measurement while drilling” techniques have been enabled that allow the driller to accurately identify the location of the drill string and bit and the conditions in the wellbore. MWD equipment often includes one or more sensors that detect an environmental condition or position and relay that information back to the driller at the surface. This information can be relayed to the surface using acoustic signals that carry encoded data about the measured condition.
Prior art systems for emitting these acoustic signals make use of wave generators that create rapid changes in the pressure of the drilling mud. The rapid changes in pressure create pulses that are carried through the drilling mud to receivers located at or near the surface. Prior art pressure pulse generators include the use of rotary “mud sirens” and linearly-acting valves that interrupt the flow of mud through the pulse generator. The temporary flow disruption can be used to create a pattern of pressure pulses that can be interpreted and decoded at the surface.
Although generally effective, prior art piston-based pulsers suffer from several deficiencies. In particular, the prior art pistons have a tight tolerance within the pulser tool. The tight tolerance accelerates wear and can lead to premature failure of the pulser. In certain situations, the tight tolerance between the piston and the receiving bore can cause the piston to become pressure-locked within the bore. Once locked, the pulser will no longer function. Accordingly, there remains a need for an improved piston pulser design that overcomes these deficiencies in the prior art.
In various embodiments, the present invention includes an acoustic pulse generating component for use in connection with a downhole drilling tool. The acoustic pulse generating module includes a piston assembly and a drive assembly configured to move the piston assembly. The piston assembly includes a piston having a low friction wear ring.
In another aspect, the present invention includes a drilling tool that has a sensor, an encoder operably connected to the sensor and a pulser operably connected to the encoder. The pulser includes a piston assembly and a drive assembly configured to move the piston assembly. The piston assembly includes a piston having a low friction wear ring.
In yet another aspect the present invention includes a measurement while drilling (MWD) tool that includes at least one sensor configured to output a measurement signal representative of a measurement of a condition selected from the group consisting of torque, inclination, magnetic direction and position. The MWD tool further includes an encoder configured to encode the measurement signal into a command signal and a pulser operably connected to the encoder and configured to transmit an acoustic signal through a fluid medium in response to the command signal. The pulser includes a piston assembly and a drive assembly configured to move the piston assembly. The piston assembly includes a piston having a wear ring.
In accordance with an embodiment of the present invention,
The MWD tool 108 includes one or more sensors 110, an encoder module 112 and an acoustic pulse generating module, or pulser 114. It will be appreciated that the MWD tool 108 may include additional components, such as centralizers. The sensors 110 are configured to measure a condition on the drilling system 100 or in the wellbore 102 and produce a representative signal for the measurement. Such measurements may include, for example, temperature, pressure, vibration, torque, inclination, magnetic direction and position. The signals from the sensors 110 are encoded by the encoder module 112 into command signals delivered to the pulser 114.
Based on the command signals from the encoder module 112, the pulser 114 controllably adjusts the flow of fluid through the pulser 114. The rapid variation in the size of the flow path through the pulser 114 increases and decreases the pressure of drilling mud flowing through the MWD tool 108. The variation in pressure creates acoustic pulses that include the encoded signals from the sensors 110. The pressure pulses are transmitted through the wellbore 102 to a receiver 116 and processed by surface facilities to present the driller or operator with information about the drilling system 100 and wellbore 102.
The sensors 110, encoder module 112 and pulser 114 of the MWD tool 108 are operated using electricity. The electricity can be provided through an umbilical from the surface, from an onboard battery pack, through the operation of a generator or through some combination of batteries, generators and umbilicals.
Turning to
The piston assembly 124 includes a piston shaft 128, a piston 130 and a poppet valve 132. The piston 130 and poppet valve 132 are connected to, and configured for movement with, the piston shaft 128. The piston 130 is sized to fit in close proximity within the central bore 122. The piston assembly 124 is driven by a drive assembly 134 that produces the selective, rapid and bidirectional movement of the piston shaft 128, piston 130 and poppet valve 132 within the central bore 122. In some embodiments, the drive assembly 134 includes one or more solenoids that are configured to selectively reciprocate the piston shaft 128 in response to the application of electrical control signals.
When deployed, the piston shaft 128 extends and forces the poppet valve 132 into the orifice 126 to reduce flow through the pulser 114. When withdrawn, the piston shaft 128 retracts and removes the poppet valve 132 from the orifice 126 to increase flow through the pulser 114. The sequenced reduction and increase of flow through the pulser 114 creates pressure waves that carry encoded information from the sensors 110. It will be understood that the piston assembly 124 will reciprocate rapidly within the central bore 122 for extended periods of time during use.
Turning to
It is to be understood that even though numerous characteristics and advantages of various embodiments of the present invention have been set forth in the foregoing description, together with details of the structure and functions of various embodiments of the invention, this disclosure is illustrative only, and changes may be made in detail, especially in matters of structure and arrangement of parts within the principles of the present invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed. It will be appreciated by those skilled in the art that the teachings of the present invention can be applied to other systems without departing from the scope and spirit of the present invention.
This application claims the benefit of U.S. Provisional Patent Application No. 62/159,131, filed May 8, 2015, entitled “Improved Piston Design for Downhole Pulse,” the disclosure of which is incorporated herein.
| Number | Date | Country | |
|---|---|---|---|
| 62159131 | May 2015 | US |
