Servo-driven mud pulser
First Claim
1. A pulser apparatus responsive to a signal from a downhole sensor for creating a positive pressure pulse in a column of drilling fluid being circulated through a drill string to a drill bit, said apparatus comprising:
- a wire-line retrievable assembly adapted to be received within the bore of the drill string;
seating means on the retrievable assembly for seating the assembly in the lower portion of the drill string, above the drill bit, in a position substantially blocking the flow of drilling fluid around said assembly, so that a major portion of the drilling fluid which flows to said drill bit will flow through an annulus between said assembly and said drill string and through a fluid passageway in said assembly, before being supplied to said drill bit;
a main bore in the assembly having an inlet and outlet through which a major portion of the drilling fluid which flows to said bit may flow, said inlet for said main bore being in communication with said annulus and the outlet of said main bore being in communication with said drill string below said assembly;
main valve means in said assembly for selectively restricting the flow of drilling fluid through said main bore, said main valve means comprising,orifice means defining a main orifice in said main bore,a valve tip in said main bore above said main orifice and adjustable toward and away from said main orifice to adjust the amount of drilling fluid flowing through said main bore;
a main valve spring for urging said main valve tip toward said main orifice,a main valve piston connected to said main valve tip by a main valve stem,a cylinder in surrounding relationship to said main valve piston and comprising an upper chamber above said main valve piston and a lower chamber below said main valve piston;
a first fluid passageway in said assembly having an inlet in communication with said main bore and an outlet in communication with said upper cylinder chamber for supplying drilling fluid at a pressure substantially equal to the pressure in said main bore below said main valve tip to said upper cylinder chamber;
a second fluid passageway in said assembly having an inlet in communication with said annulus and an outlet in communication with said upper cylinder chamber for supplying drilling fluid at a pressure substantially equal to that of the drilling fluid in said annulus to said upper cylinder chamber;
pilot valve means in said assembly for selectively closing said second fluid passageway responsive to a signal from said sensor; and
a third fluid passageway having an inlet in communication with said annulus and an outlet in communication with said lower cylinder chamber for supplying drilling fluid at a pressure substantially equal to the pressure in said annulus to said lower cylinder chamber;
said main bore, said inlet to said main bore, said main valve tip and said orifice means being so configured, and said main valve tip being adapted to be so positioned with respect to said orifice means, when said main valve means is open, that the flow of drilling fluid through said inlet to said main bore, around said main valve tip and through said orifice means produces a first fluid pressure in said main bore at said inlet to said first fluid passageway, which first fluid pressure is lower than the annulus fluid pressure at said inlets to said second and third fluid passageways,whereby, when said pilot valve is closed, said first fluid pressure will be communicated through said first fluid passageway to the said upper chamber of said cylinder while said higher annulus fluid pressure will be communicated through said third fluid passageway to said lower cylinder chamber, creating a pressure differential across the main valve piston which is sufficient to overcome the closing effect of said main valve spring, so as to retain said main valve open and, when said pilot valve is opened responsive to said signal, said annulus fluid pressure will be transmitted through said second fluid passageway to said upper cylinder chamber, reducing the pressure differential across said main valve piston sufficiently to permit said main valve spring to cause said main valve tip to move toward said main orifice, so as to reduce the flow of drilling fluid through said main bore and create a positive pressure pulse in said drilling fluid in said drill string above said assembly.
4 Assignments
0 Petitions
Accused Products
Abstract
An improved servo-driven pulser is disclosed, for use in measurement while drilling applications. In the pulser, a battery powered on-board DC electric motor is used to operate a servo-valve, which in turn adjusts internal tool fluid pressures to cause operation of a main valve to substantially reduce mud flow to a drill bit, thereby creating a positive pressure pulse detectable at the surface. De-energizing the motor driving the pilot valve results in re-adjustment of internal fluid pressures, causing the main valve to reopen, thereby terminating the pressure pulse.
156 Citations
34 Claims
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1. A pulser apparatus responsive to a signal from a downhole sensor for creating a positive pressure pulse in a column of drilling fluid being circulated through a drill string to a drill bit, said apparatus comprising:
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a wire-line retrievable assembly adapted to be received within the bore of the drill string; seating means on the retrievable assembly for seating the assembly in the lower portion of the drill string, above the drill bit, in a position substantially blocking the flow of drilling fluid around said assembly, so that a major portion of the drilling fluid which flows to said drill bit will flow through an annulus between said assembly and said drill string and through a fluid passageway in said assembly, before being supplied to said drill bit; a main bore in the assembly having an inlet and outlet through which a major portion of the drilling fluid which flows to said bit may flow, said inlet for said main bore being in communication with said annulus and the outlet of said main bore being in communication with said drill string below said assembly; main valve means in said assembly for selectively restricting the flow of drilling fluid through said main bore, said main valve means comprising, orifice means defining a main orifice in said main bore, a valve tip in said main bore above said main orifice and adjustable toward and away from said main orifice to adjust the amount of drilling fluid flowing through said main bore; a main valve spring for urging said main valve tip toward said main orifice, a main valve piston connected to said main valve tip by a main valve stem, a cylinder in surrounding relationship to said main valve piston and comprising an upper chamber above said main valve piston and a lower chamber below said main valve piston; a first fluid passageway in said assembly having an inlet in communication with said main bore and an outlet in communication with said upper cylinder chamber for supplying drilling fluid at a pressure substantially equal to the pressure in said main bore below said main valve tip to said upper cylinder chamber; a second fluid passageway in said assembly having an inlet in communication with said annulus and an outlet in communication with said upper cylinder chamber for supplying drilling fluid at a pressure substantially equal to that of the drilling fluid in said annulus to said upper cylinder chamber; pilot valve means in said assembly for selectively closing said second fluid passageway responsive to a signal from said sensor; and a third fluid passageway having an inlet in communication with said annulus and an outlet in communication with said lower cylinder chamber for supplying drilling fluid at a pressure substantially equal to the pressure in said annulus to said lower cylinder chamber; said main bore, said inlet to said main bore, said main valve tip and said orifice means being so configured, and said main valve tip being adapted to be so positioned with respect to said orifice means, when said main valve means is open, that the flow of drilling fluid through said inlet to said main bore, around said main valve tip and through said orifice means produces a first fluid pressure in said main bore at said inlet to said first fluid passageway, which first fluid pressure is lower than the annulus fluid pressure at said inlets to said second and third fluid passageways, whereby, when said pilot valve is closed, said first fluid pressure will be communicated through said first fluid passageway to the said upper chamber of said cylinder while said higher annulus fluid pressure will be communicated through said third fluid passageway to said lower cylinder chamber, creating a pressure differential across the main valve piston which is sufficient to overcome the closing effect of said main valve spring, so as to retain said main valve open and, when said pilot valve is opened responsive to said signal, said annulus fluid pressure will be transmitted through said second fluid passageway to said upper cylinder chamber, reducing the pressure differential across said main valve piston sufficiently to permit said main valve spring to cause said main valve tip to move toward said main orifice, so as to reduce the flow of drilling fluid through said main bore and create a positive pressure pulse in said drilling fluid in said drill string above said assembly. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 11, 12, 13, 14, 15, 16)
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10. The apparatus according 1 wherein said orifice means comprises an orifice plate in said main bore defining a single orifice therethrough.
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17. A pulser apparatus responsive to a signal from a downhole sensor for creating a positive pressure pulse in a column of drilling fluid being circulated through a drill string to a drill bit, said apparatus comprising:
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a wire-line retrievable assembly adapted to be received within the bore of the drill string; seating means on said retrievable assembly for seating the assembly in the lower portion of the drill string in predetermined relationship to an orifice means carried by the drill string and defining a main orifice and in such a manner that a major portion of the drilling fluid which flows to said bit may flow through an annulus between said assembly and the wall of said drill string and through said orifice means in said drill string before being supplied to said drill bit; main valve means in said assembly for selectively restricting the flow of drilling fluid through said main orifice in said orifice means, said main valve means comprising, a valve tip carried by said assembly and adjustable toward and away from said main orifice to adjust the amount of drilling fluid flowing through said main orifice, a main valve spring on said assembly for urging said main valve tip towards said main orifice, a main valve piston connected to said main valve tip by a main valve stem, a cylinder in surrounding relationship to said main valve piston and comprising an upper chamber above said main valve piston and a lower chamber below said main valve piston; a first fluid passageway in said assembly having an inlet in communication with the lower portion of said main valve tip and an outlet in communication with said upper cylinder chamber, for supplying drilling fluid at a pressure substantially equal to that of the drilling fluid immediately below said main valve tip to said upper cylinder chamber; a second fluid passageway in said assembly having an inlet in communication with said annulus and an outlet in communication with said upper cylinder chamber, for supplying drilling fluid at substantially the pressure in said annulus to said upper cylinder chamber; pilot valve means in said assembly for selectively closing said second fluid passageway responsive to a signal from said sensor; and means for operating said pilot valve means, said operating means comprising, a DC electric motor adapted to operate responsive to said control signal, a threaded drive shaft adapted to be rotated through a plurality of revolutions about its longitudinal axis by said motor when said motor is operated, a threaded follower on said drive shaft and held against rotation, so that said follower will move up or down responsive to rotation of said drive shaft, and a valve stem interconnecting said follower and said pilot valve tip for transmitting the vertical movement of said follower to said valve tip to open said pilot valve; a third fluid passageway having an inlet in communication with said annulus and an outlet in communication with said lower cylinder chamber for supplying drilling fluid at a pressure substantially equal to the pressure in said annulus to said lower cylinder chamber; said orifice means and said main valve tip being so dimensioned and configured, and said main valve tip being adapted to be so positioned with respect to said orifice means, when said main valve means is open, that the flow of drilling fluid around said main valve tip and through said orifice means produces a first fluid pressure at the inlet to said first fluid passageway which first fluid pressure is lower than the annulus fluid pressure at said inlets to said second and third fluid passageways, whereby, when said pilot valve is closed, said first fluid pressure will be communicated through said first fluid passageway to said upper chamber of said cylinder, while said higher annulus fluid pressure will be communicated through said third fluid passageway to said lower cylinder chamber, creating a pressure differential across said main valve piston which is sufficient to overcome the closing effect of said main valve spring means, so as to retain said main valve open and, when said pilot valve is opened responsive to said signal, said annulus fluid pressure will be transmitted through said second fluid passageway to said upper cylinder chamber, reducing the pressure differential across said main valve piston sufficiently to permit said main valve spring means to cause said main valve tip to move towards said main orifice, so as to reduce the flow of drilling fluid through said main orifice and create a positive pressure pulse in said drilling fluid in said drill string above said assembly. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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31. An apparatus responsive to a signal from a downhole sensor for creating a positive pressure pulse in a column of drilling fluid being circulated through a drill string to a drill bit, said apparatus comprising:
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an orientation sub carried by the drill string and having a central bore longitudinally therethrough, an orientation key in said orientation sub and extending into said central bore, and an upwardly facing helical surface disposed around the inside diameter of said central bore; and a wire-line retrievable mud pulser assembly adapted to be received within the bore of the drill string and seated on said orientation sub, said retrievable mud pulser assembly comprising a main valve means adapted to at least partially restrict the flow of drilling mud through the central bore of said orientation sub responsive to said signal from said downhole sensor, to thereby create a positive pressure pulse in said column of drilling fluid, and a downwardly facing helical surface on said retrievable mud pulser assembly adapted to engage said orientation key in said orientation sub as said retrievable assembly is lowered into said drill string, to thereby orient said retrievable assembly in a predetermined angular relationship to said orientation sub and to engage said upwardly facing helical surface in said bore of said orientation sub as said retrievable assembly is lowered further into said drill string, for seating said retrievable assembly in a predetermined longitudinal relationship to said orientation sub. - View Dependent Claims (32, 33, 34)
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Specification