Air hammer optimization using acoustic telemetry

Abstract

A system and method of optimizing air hammer performance in a well drilling rig whereby an electronic acoustic receiver (EAR) is used to monitor the effects of changing any of the operating parameters under his or her control. The signals are visually presented to the drill operator based on an EAR's output, along with current settings, allowing the drill operator to dial in the parameters of his or her choice until the optimal frequency of the air hammer is regained. The visual output displays the amplitude response of acoustic waves being detected and decoded at the surface by the EAR. The drill operator can observe and use this information to determine the changes necessary in the operating parameters to return the hammer to optimal frequency, and thus optimal performance.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is: 
     
         1 . A system for optimizing air hammer performance in a well drilling rig including a drillstring, which comprises:
 an air compressor connected to the drillstring;   a bit connected to the drillstring;   a controller connected to the compressor and the drillstring;   an air hammer attached to a downhole end of the drillstring, said air hammer having performance parameters including a percussive rate corresponding to an air flow from said compressor and bit weight, a penetration rate, and a frequency response;   an acoustic telemetry subsystem associated with the air hammer and adapted for transmitting said frequency response via acoustic waves along the drillstring;   said controller adapted for operating said actuator;   said controller including a manually selectable input for selecting parameters selected from the list comprising bit weight, air flow, and hammer rate;   a feedback input, the feedback input being responsive to said frequency response;   said controller programmed to automatically adjust for optimal settings an operating parameter of said air hammer in response to said frequency response, said operating parameters including air flow from said compressor and said bit weight; and   said controller being adapted to adjust said bit weight on said air hammer, said bit weight comprising an operating parameter of said air hammer.   
     
     
         2 . The system according to  claim 1 , further comprising:
 an electronic acoustic receiver (EAR) connected to the drillstring and the controller, said EAR being adapted for receiving acoustic waves therefrom and detecting the air hammer frequency response.   
     
     
         3 . The system according to  claim 1 , further comprising:
 a display device connected to said controller and adapted for displaying a real-time graphic display of the frequency response of said air hammer.   
     
     
         4 . The system according to  claim 1 , further comprising:
 said controller being adapted to adjust said air flow to said air hammer, said air flow comprising an operating parameter of said air hammer.   
     
     
         5 . A system for optimizing air hammer performance in a well drilling rig including a drillstring, which comprises:
 an air compressor connected to the drillstring;   a bit connected to the drillstring;   a controller connected to the compressor and the drillstring;   an air hammer attached to a downhole end of the drillstring, said air hammer having performance parameters including a percussive rate corresponding to an air flow from said compressor and bit weight, a penetration rate, and a frequency response;   an acoustic telemetry subsystem associated with the air hammer and adapted for transmitting said frequency response via acoustic waves along the drillstring;   said controller programmed to automatically adjust for optimal settings an operating parameter of said air hammer in response to said frequency response, said operating parameters including air flow from said compressor and said bit weight;   an electronic acoustic receiver (EAR) connected to the drillstring and the controller, said EAR being adapted for receiving acoustic waves therefrom and detecting the air hammer frequency response;   a display device connected to said controller and adapted for displaying a real-time graphic display of the frequency response of said air hammer;   said controller adapted to adjust said air flow to said air hammer, said air flow comprising an operating parameter of said air hammer;   said controller adapted to adjust said bit weight on said air hammer, said bit weight comprising an operating parameter of said air hammer;   an actuator, connected to said compressor;   said controller adapted for operating said actuator;   said controller including a manually selectable input for selecting parameters selected from the list comprising bit weight, air flow, and hammer rate; and   a feedback input, the feedback input being responsive to said frequency response.   
     
     
         6 . The system according to  claim 5 , which includes an acoustic isolator for use with tubular assemblies including an acoustic wave transmitter, which acoustic isolator comprises:
 a first coaxial tubular member with a first member length including a proximal end and a distal end, a first acoustic impedance and a first acoustic transit time;   a second coaxial tubular member with a second member length including a proximal end and a distal end, a second acoustic impedance and a second acoustic transit time;   the first and second tubular members being aligned so as not to be in physical contact;   a first coupling located at the proximal end of the first and second members, said first coupling restricting the motions of said members and said coupling whereby said motions are approximately equalized at their common points of contact thereby allowing exchange of acoustic energy between the tubular assemblies above said first coupling and said tubular members below said first coupling;   a second coupling placed at the distal end of the first and second members, said second coupling restricting the motions of said members to be equal at their common points of contact thereby allowing exchange of acoustic energy between the tubular assemblies below said second coupling and said tubular members above said second coupling;   the lengths, acoustic impedances, and transit times of said tubular members aligned so that by means of constructive and destructive wave interference the acoustic energy transmitted through the upper coupling results in reduced motion and reduced force in the second coupling, and acoustic energy transmitted through the lower coupling results in reduced motion and force in the first coupling whereby downward traveling acoustic energy is selectively reflected upward and upward traveling acoustic energy is selectively reflected downward;   the first and second coaxial tubular members comprised of dissimilar materials, such that acoustic waves originating at the distal end travelling along said coaxial tubular members travel at substantially different wave speeds;   said dissimilar materials of equal impedance value; and   said differing wave speeds inducing a phase difference between said coaxial tubular members, said phase difference depending on the length of the members.   
     
     
         7 . A method of optimizing air hammer performance in a drilling rig including a wellhead and a drillstring, which method includes the steps of:
 providing a compressor at the wellhead;   providing an air hammer;   providing a bit connected to said drillstring;   mounting said air hammer on a downhole end of said drillstring;   pumping compressed air from said compressor to said air hammer via said drillstring;   producing a frequency response with said air hammer in operation;   transmitting said frequency response with acoustic telemetry to the wellhead via said drillstring;   providing a controller at said wellhead;   connecting the controller to the compressor;   programming said controller to automatically adjust for optimal settings an operating parameter of said air hammer in response to said frequency response, said operating parameters including air flow from said compressor and said bit weight;   providing a feedback signal from said air hammer via said drillstring to said controller;   providing an electronic acoustic receiver (EAR) at the wellhead;   connecting the EAR to the drillstring and the controller;   detecting with the EAR an air hammer frequency response in the form of acoustic waves;   displaying as visual output on said display device an amplitude response of said acoustic waves being detected and decoded;   processing said amplitude to show a Fourier transform of said amplitude response;   selecting other information relevant to the operation of the air hammer drill system on said display device; and   adjusting the operating parameters with said controller for optimizing performance of said air hammer, said operating parameters including air flow from said compressor and said bit weight.   
     
     
         8 . The method according to  claim 7 , which includes the additional steps of:
 providing a first coaxial tubular member of a first length and including a first diameter, a proximal end and a distal end;   providing a second coaxial tubular member of a second length and including a second diameter, a proximal end and a distal end;   placing said first tubular member inside said second tubular member, wherein the members are not in physical contact, forming an acoustic isolator;   providing a pair of couplers located at the proximal and distal ends of said members, the couplers being adapted for connection to other like collars attached to said drillstring assembly sections;   generating acoustic transmitter signals with the BHA;   transmitting acoustic wave signals from the BHA upwardly through said drillstring assembly sections; and   acoustically filtering said signals with said acoustic isolator by either or both of these steps of filtering or reflecting said acoustic wave signals along said drillstring.