Vibratory rotary drilling tool

Claim 2

A vibratory rotary drilling tool comprising: a mass adapted for rectilinear oscillation in response to impulsive forces having a frequency; a housing in which is slidably mounted at least a portion of said mass; a spring for providing linear restoring forces to said mass; a sealed chamber containing said spring within said housing; said mass being adapted for co-movement with a drill bit, whereby said drill bit, said mass and said spring act as a spring-mass system having a fundamental frequency; said impulsive forces constituting vibrations of said drill bit as said drill bit is rotated during drilling; and wherein the ratio of the frequency of said impulsive forces of said drill bit to the fundamental frequency of said spring-mass system is substantially within the range of 0.25 to 1.5, and the ratio of actual damping to critical damping of said spring-mass system is substantially 0.5 or less, such that the oscillations of said mass and drill bit are reinforced and amplified thereby.

Claim 3

The tool of claim 1 wherein said mass includes a reciprocating mandrel attached to a drill bit.

Claim 4

The tool of claim 1 wherein said spring is a contained compressible fluid.

Claim 5

A vibratory rotary drilling tool comprising: a tubular housing adapted to be secured at its upper end to a drill collar of a drill string; a mandrel reciprocally mounted to said tubular housing for rotation therewith and having a lower end adapted to be secured to a drill bit; a spring interposed between said housing and said mandrel for providing linear restoring forces to said mandrel, said spring being contained within a sealed chamber defined by the surfaces of said housing and said mandrel, whereby said drill bit and said mandrel, in conjunction with said spring, act as a spring-mass system that reinforces and amplifies oscillations of said drill bit in response to impulsive forces having a frequency, said impulsive forces constituting vibrations of said drill bit as said drill bit is rotated during drilling; said spring-mass system having a fundamental frequency; and wherein the ratio of the frequency of said impulsive forces of said drill bit to the fundamental frequency of said spring-mass system is substantially within the range of 0.25 to 1.5, and the ratio of actual damping to critical damping of said spring-mass system is substantially 0.5 or less, such that the oscillations of said mandrel and drill bit are reinforced and amplified thereby.

Claim 6

A vibratory rotary drilling tool comprising: a tubular housing adapted to be secured at its upper end to a drill collar of a drill string; a mandrel reciprocally mounted to said tubular housing for rotation therewith and having a lower end adapted to be secured to a drill bit; a spring interposed between said housing and said mandrel for providing linear restoring forces to said mandrel, said spring being contained within a sealed chamber defined by the surfaces of said housing and said mandrel, whereby said drill bit and said mandrel, in conjunction with said spring, act as a spring-mass system that reinforces and amplifies oscillations of said drill bit in response to impulsive forces having a frequency, said impulsive forces constituting vibrations of said drill bit as said drill bit is rotated during drilling; said spring-mass system having a fundamental frequency; and wherein the ratio of the frequency of said impulsive forces of said drill bit to the fundamental frequency of said spring-mass system is substantially within the range of 0.25 to 1.5, and the ratio of actual damping to critical damping of said spring-mass system is substantially 0.5 or less, such that the oscillations of said mandrel and drill bit are reinforced and amplified thereby.

Claim 7

The tool of claim 4 wherein said spring is a compressible fluid contained by said chamber.

Claim 8

The tool of claim 5, wherein said mandrel is spaced from the upper end of said housing, said spring comprising a compressible fluid disposed within said housing between the upper end thereof and said mandrel.

Claim 9

The tool of claim 5, wherein a portion of said chamber is disposed immediately above the upper end of said mandrel and the remainder of said chamber surrounds a portion of said mandrel including the upper end thereof.

Claim 10

The tool of claim 5 further including a quantity of lubricant contained by said chamber.

Claim 11

A vibratory rotary drilling tool for use in a drill string having a drill bit comprising: a tubular housing; a tubular mandrel reciprocally mounted to said tubular housing for rotation and limited reciprocation therewith; a spring disposed between said housing and said mandrel for resiliently transferring axial forces between said housing and said mandrel; a surface within said mandrel defining a drilling fluid passageway; a sealed chamber containing said spring, said chamber being defined by the surfaces of said housing and said mandrel; said mandrel being adapted for co-movement with a drill bit such that said mandrel and said drill bit in conjunction with said spring form a spring-mass system that reinforces and amplifies oscillations of said drill bit in response to impulsive forces having a frequency, said impulsive forces constituting vibrations of said drill bit as said drill bit is rotated during drilling; said spring-mass system having a fundamental frequency; and wherein the ratio of the frequency of said impulsive forces of said drill bit to the fundamental frequency of said spring-mass system is substantially within the range of 0.25 to 1.5, and the ratio of actual damping to critical damping of said spring-mass system is substantially 0.5 or less, such that the oscillations of said mandrel and drill bit are reinforced and amplified thereby.

Claim 12

A vibratory rotary drilling tool for use in a drill string having a drill bit comprising: a tubular housing; a tubular mandrel reciprocally mounted to said tubular housing for rotation and limited reciprocation therewith; a spring disposed between said housing and said mandrel for resiliently transferring axial forces between said housing and said mandrel; a surface within said mandrel defining a drilling fluid passageway; a sealed chamber containing said spring, said chamber being defined by the surfaces of said housing and said mandrel; said mandrel being adapted for co-movement with a drill bit such that said mandrel and said drill bit in conjunction with said spring form a spring-mass system that reinforces and amplifies oscillations of said drill bit in response to impulsive forces having a frequency, said impulsive forces constituting vibrations of said drill bit as said drill bit is rotated during drilling; said spring-mass system having a fundamental frequency; and wherein the ratio of the frequency of said impulsive forces of said drill bit to the fundamental frequency of said spring-mass system is substantially within the range of 0.25 to 1.5, and the ratio of actual damping to critical damping of said spring-mass system is substantially 0.5 or less, such that the oscillations of said mandrel and drill bit are reinforced and amplified thereby.

Claim 13

The tool of claim 9 further comprising a channel means for directing drilling fluid into said drilling fluid passageway.

Claim 14

The tool of claim 10 wherein said spring is disposed within a chamber defined by the surfaces of said housing, said mandrel and said channel means.

Claim 15

The tool of claim 9 wherein said spring is disposed between the upper end of said mandrel and the upper end of said housing.

Claim 16

The tool of claim 9 wherein said spring comprises a compressible fluid and said damped fundamental frequency is variable for adapting said tool to differing drilling operations.

Claim 17

A vibratory rotary drilling tool for being interposed between a drill bit and a drill string comprising: a housing including an upper end for being threadably connected to the drill string and having inner and outer cylindrical walls; a mandrel having a lower end for being threadably connected to the drill bit and having inner and outer cylindrical walls, said inner wall of said mandrel defining a drilling fluid passageway between the drill string and the drill bit; upper and lower means for sealing interposed between said inner wall of said housing and said outer wall of said mandrel; a portion of said inner wall of said housing and a portion of said outer wall of said mandrel intermediate of said upper and lower means for sealingly defining a chamber; a spring fluid contained by said chamber; a plurality of sealable passageways between said outer wall of said housing and said chamber for filling and draining said spring fluid; longitudinal radial splines extending inwardly of said inner wall of said housing; longitudinal radial splines extending outwardly of said outer surface of said mandrel and engaging said inwardly extending splines of said housing, such that said housing and said mandrel rotate in unison but may axially reciprocate relative to one another under the influence of said spring fluid; said mandrel and said spring combining with the drill bit to form a spring-mass system having a fundamental frequency; wherein said mandrel and the drill bit of said spring-mass system oscillate rectilinearly in response to impulsive forces having a frequency, said impulsive forces constituting vibrations of said drill bit as said drill bit is rotated during drilling; and wherein the ratio of the frequency of said impulsive forces of said drill bit to the fundamental frequency of said spring-mass system is substantially within the range of 0.25 to 1.5, and the ratio of actual damping to critical damping of said spring-mass system is substantially 0.5 or less, such that the oscillations of said mass and drill bit are reinforced and amplified thereby.

Claim 18

A vibratory rotary drilling tool for being interposed between a drill bit and a drill string comprising: a housing including an upper end for being threadably connected to the drill string and having inner and outer cylindrical walls; a mandrel having a lower end for being threadably connected to the drill bit and having inner and outer cylindrical walls, said inner wall of said mandrel defining a drilling fluid passageway between the drill string and the drill bit; upper and lower means for sealing interposed between said inner wall of said housing and said outer wall of said mandrel; a portion of said inner wall of said housing and a portion of said outer wall of said mandrel intermediate of said upper and lower means for sealingly defining a chamber; a spring fluid contained by said chamber; a plurality of sealable passageways between said outer wall of said housing and said chamber for filling and draining said spring fluid; longitudinal radial splines extending inwardly of said inner wall of said housing; longitudinal radial splines extending outwardly of said outer surface of said mandrel and engaging said inwardly extending splines of said housing, such that said housing and said mandrel rotate in unison but may axially reciprocate relative to one another under the influence of said spring fluid; said mandrel and said spring combining with the drill bit to form a spring-mass system having a fundamental frequency; wherein said mandrel and the drill bit of said spring-mass system oscillate rectilinearly in response to impulsive forces having a frequency, said impulsive forces constituting vibrations of said drill bit as said drill bit is rotated during drilling; and wherein the ratio of the frequency of said impulsive forces of said drill bit to the fundamental frequency of said spring-mass system is substantially within the range of 0.25 to 1.5, and the ratio of actual damping to critical damping of said spring-mass system is substantially 0.5 or less, such that the oscillations of said mass and drill bit are reinforced and amplified thereby.

Claim 19

A vibratory rotary drilling tool for being interposed between a drill bit and a drill string comprising: a housing including an upper end for being threadably connected to the drill string and having inner and outer cylindrical walls; a mandrel having an upper end, a lower end for being threadably connected to said drill bit, and inner and outer cylindrical walls, said inner wall of said mandrel defining a drilling fluid passageway between said upper end of said mandrel and said drill bit, said upper end of said mandrel slidably disposed within said housing and spaced from said upper end of said housing; a conduit for conducting drilling fluid between said drill string and said drilling fluid passageway; a first sealing means interposed between said inner wall of said housing and said outer wall of said mandrel; a second sealing means interposed between said inner wall of said mandrel and the outer wall of said conduit; a third sealing means interposed between the upper end of said housing and said conduit; a chamber defined by said housing, said mandrel, said conduit and said first, second and third sealing means having a volume which is dependent on the axial position of said mandrel relative to said housing; a spring fluid contained by said chamber; longitudinal radial splines extending inwardly from said inner wall of said housing; and longitudinal radial splines extending outwardly of said outer surface of said mandrel and engaging said inwardly extending splines of said housing, such that said housing and said mandrel rotate in unison but may axially reciprocate relative to one another under the influence of said spring fluid.

Claim 20

A vibratory rotary drilling tool for being interposed between a drill bit and a drill string comprising: a housing including an upper end for being threadably connected to the drill string and having inner and outer cylindrical walls; a mandrel having an upper end, a lower end for being threadably connected to said drill bit, and inner and outer cylindrical walls, said inner wall of said mandrel defining a drilling fluid passageway between said upper end of said mandrel and said drill bit, said upper end of said mandrel slidably disposed within said housing and spaced from said upper end of said housing; a conduit for conducting drilling fluid between said drill string and said drilling fluid passageway; a first sealing means interposed between said inner wall of said housing and said outer wall of said mandrel; a second sealing means interposed between said inner wall of said mandrel and the outer wall of said conduit; a third sealing means interposed between the upper end of said housing and said conduit; a chamber defined by said housing, said mandrel, said conduit and said first, second and third sealing means having a volume which is dependent on the axial position of said mandrel relative to said housing; a spring fluid contained by said chamber; longitudinal radial splines extending inwardly from said inner wall of said housing; and longitudinal radial splines extending outwardly of said outer surface of said mandrel and engaging said inwardly extending splines of said housing, such that said housing and said mandrel rotate in unison but may axially reciprocate relative to one another under the influence of said spring fluid.

Claim 21

The vibratory rotary drilling tool according to claim 15 further comprising a quantity of lubricant contained by said chamber.

Claim 22

The vibratory rotary drilling tool according to claim 15, wherein said first sealing means is disposed adjacent the lower end of said housing and said second sealing means is disposed adjacent said upper end of said mandrel.

Claim 23

The vibratory rotary drilling tool according to claim 15, wherein said first and second sealing means are adjacent said upper end of said mandrel such that said chamber is disposed substantially between said upper end of said mandrel and said upper end of said housing.

Claim 24

The vibratory drilling tool according to claim 15, wherein said conduit is affixed to said mandrel for reciprocation therewith.

Claim 25

The vibratory drilling tool according to claim 15, wherein said conduit is affixed to said housing, such that said mandrel will reciprocate relative to said conduit and said housing during drilling operations.

Claim 26

The vibratory rotary drilling tool according to claim 15, wherein said mandrel is adapted for comovement with said drill bit such that said mandrel said drill bit, and said spring fluid cooperate to form a spring-mass system having a damped fundamental frequency, said drill bit oscillates at a known frequency, the ratio of said drill bit frequency to said fundamental frequency is within the range of 0.25 to 1.5, and the ratio of actual damping to critical damping of said spring-mass system is 0.5 or less, such that the oscillations of said drill bit are reinforced and amplified.

Claim 27

The vibratory rotary drilling tool according to claim 17, wherein said chamber contains a quantity of lubricant having a specified gravity greater than that of said spring fluid such that said lubricant provides lubrication between said mandrel and said housing during drilling operations.

Claim 28

The vibratory rotary drilling tool according to claim 18 further comprising lubricating means for providing lubrication between said housing and said mandrel during drilling operations.

Claim 29

The vibratory drilling tool according to claim 21, further comprising means for adjusting the percentage change in said volume of said chamber per unit of axial displacement of said mandrel, thereby allowing variation of said fundamental frequency to adapt said tool for differing drilling operations.

Claim 30

The vibratory drilling tool according to claim 21 further comprising means for adjusting the percentage change in volume of said spring fluid per unit of axial displacement of said mandrel, thereby allowing variation of said fundamental frequency to adapt said tool for differing drilling operations.

Claim 31

The vibratory rotary drilling tool according to claim 22 further comprising a plurality of sealable passageways between said outer wall of said housing and said chamber for adding and draining said spring fluid and said lubricant.

Claim 32

The vibratory rotary drilling tool according to claim 23 wherein said drilling tool further comprising a plurality of sealable passageways between said outer wall of said housing and said chamber for adding and draining said spring fluid, said lubricating means includes a third sealing means interposed between said inner wall of said housing and said outer wall of said mandrel, a lubricant contained between said second and third sealing means and a plurality of passageways through said housing for adding or draining said lubricant.