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.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to telemetry apparatus and methods, and more particularly to a method utilizing telemetry data for the optimization of the performance of air hammer type drilling systems for the well drilling and production (e.g., oil and gas) industry.

2. Description of the Related Art

Acoustic telemetry is a method of communication used, for example, in the well drilling and production industry. In a typical drilling environment, acoustic extensional carrier waves from an acoustic telemetry device are modulated in order to carry information via the drillpipe as the transmission medium to the surface. Upon arrival at the surface, the waves are detected, decoded and displayed in order that drillers, geologists and others helping steer or control the well are provided with drilling and formation data.

It is well known that acoustic extensional waves can propagate through drill pipe if they contain frequencies that correspond with the passbands formed by the regular mechanical dimensions of drill pipe. Use of this communications channel enables real-time drilling telemetry to be the means by which drilling parameters (such as directional and formation) measured relatively close to the drill bit are sent to the surface. At the surface, the signals can be detected by a sensitive accelerometer whereby, after filtering and amplifying the signal, well information may be made available to the driller. An example of such a system is an Electronic Acoustic Receiver (EAR), which is detection and amplifying means to connect to a processor module and an RF system, thereby enabling two-way communication between the driller and the EAR.

Many practical mechanical means are utilized when drilling for oil and gas. A modern and popular approach is to ‘hammer’ at rock formations rather than using traditional rotary drills, which are limited to moving forward. Hammer drilling requires that the drilling fluid be a gas rather than a liquid, whereas rotary drilling requires the drilling fluid to be a liquid. Traditional rotary drill liquid motors used to rotate the drill bit are replaced by an air hammer in modern hammer drilling machines. This air hammer pounds the rock into small pieces by a rapid axial reciprocating motion.

Air hammers require a number of parameters to be in balance in order to achieve efficient forward progress. The main issues are to balance the air flow to the hammer with an appropriate weight on the hammer bit. If there is too much weight on the bit the hammer stroke is reduced, resulting in reduced penetration of the rock. Similarly, if there is too little weight on the bit then the work done by the hammer is reduced, again resulting in reduced rock penetration. If the air flow powering the hammer is too small, rock fragments may not clear the device and may jam the mechanism, whereas too much airflow can result in hammer bit damage. A balance of these parameters results in an ideal frequency and optimized rate of rock penetration.

BRIEF SUMMARY OF THE INVENTION

It is an object of the present invention to immediately provide feedback to drill operators utilizing air hammer drill systems. This invention provides the driller a direct visual indication of this event, and immediately shows effects due to changing any of the parameters under his or her control (e.g., air flow and hammer weight).

The signals are provided to the driller by the EAR's output being visually presented to the driller, along with current settings. This allows the driller to dial in the parameters of his or her choice until the optimal frequency is regained.

The visual output on screen displays the amplitude response of acoustic waves being detected and decoded at the surface by the EAR. It is then possible to process these amplitudes so that they show the Fourier transform of the amplitude response.

The advantage to such a system is that the transform shows the frequency response in real time of the air hammer working. As the hammer changes the rate at which it strikes the rock, the frequency display will faithfully follow by means of the acoustic channel from the hammer to the EAR at the surface.

It is this information that the drill operator can observe and use to determine the changes necessary in the system parameters to return the hammer to optimal frequency, and thus optimal performance. Any deviations from this necessitated by changing rock conditions can be accommodated by surface control, and the effect of these changes become immediately apparent, thereby enabling to just timely feedback to the driller but also the means to automate the changes necessary for optimal performance.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings, which illustrate the principles of the present invention and an exemplary embodiment thereof:

FIG. 1 is a diagram of the normal passbands of Range 2 drilling pipe; and

FIG. 2 is an example of an EAR's output being visually presented on a computer screen.

FIG. 3 is a diagram of a typical drilling rig, including an air hammer optimization system embodying an aspect of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following description, reference is made to “up” and “down” waves, but this is merely for convenience and clarity. It is to be understood that the present invention is not to be limited in this manner to conceptually simple applications in acoustic communication from the downhole end of the drillstring to the surface. It will be readily apparent to one skilled in the art that the present invention applies equally, for example, of subsurface stations, such as would be found in telemetry repeaters.

Referring to the drawings in more detail, FIG. 1 displays the normal passbands of Range 2 pipe. This is one example of what information may be provided during drilling operations, and the present invention is in no way limited to only Range 2 pipe.

FIG. 2 shows an example of a visual display a drill operator may see while operating the air hammer drill with the present invention. The display would appear on a computer screen, accessible by the driller, and directly connected to the air hammer drill system as well as the EAR. Results displayed on the screen are to be in real time, with the amplitude response of acoustic waves being detected and decoded at the surface displayed on the screen. Other information relevant to the operation of the air hammer drill system is individually selectable and viewable on screen.

The reference numeral 2 generally designates an air hammer optimization system. Without limitation on the generality of useful applications of the system 2, an exemplary application is in a drilling rig 4 as shown in a very simplified form in FIG. 3. For example, the rig 4 can include a derrick 6 suspending an air hammer actuator 8, which receives gas via a compressor hose 20 for pumping downhole into a drillstring 22. The drillstring 22 and the air hammer actuator 8 are connected to the system 2 which includes an EAR/detector 16, an amplifier 14, a filter 12, and a controller 10. The drillstring 22 connects to multiple drill pipe sections 24, which are interconnected by tool joints 18, thus forming a drillstring of considerable length, e.g. several kilometers, which can be guided downwardly and/or laterally using well-known techniques. The drillstring 22 terminates at an air hammer apparatus 32. In FIG. 3 we have shown acoustic modules (isolator 30 and transmitter 28) as separate from the conventional air hammer simply for clarity. Other rig configurations can likewise employ the air hammer optimization system of the present invention, including top-drive, coiled tubing, etc. The controller 10 includes a manually selectable input 34 for selecting a number of parameters undergone by the drill during operation. These parameters generally include bit weight, air flow, and hammer rate.

Information such as that contained in FIG. 1 will pass up a drillstring or up the drill pipe and be read by an EAR. This information will then be decoded, and relevant information will be displayed on screen. Relevant information includes, but is not limited to, bit weight, air flow, hammer rate, and relevant frequencies. This information can be used by the drill operator or by a system designed to automatically return the drill operation to optimal rock penetration by recalibrating bit weight, air flow, and other parameters.

Claims

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; andsaid 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; anda 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; andsaid 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; andadjusting 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; andacoustically 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.