APPARATUS FOR INDUCING VIBRATION IN A DRILL STRING
An insert having a plurality of ports creating angled passageways through the walls of the insert is positioned in a drill string for altering fluid flow in the drill string and inducing vibration sufficient to speed up directional drilling and to prevent differential sticking in wellbores. Boundary layer flow along the walls of the drill string is drawn into an upstream group of ports to commingle with fluid in the central bore of the drill string and the insert. The flow is separated at a downstream group of ports and angled passageways cause the flow to be directed radially outward inducing vibration into the drill string.
This application is a regular application claiming priority of U.S. Provisional Patent application Ser. No. 60/582,064 filed Jun. 24, 2004, the entirety of which is incorporated herein by reference.
FIELD OF THE INVENTIONEmbodiments of the invention relate to apparatus which acts to induce a vibration into a drill string during drilling operations and, more particularly, to aid in advancing the drill string and drill bit, particularly when drilling horizontal wellbores.
BACKGROUND OF THE INVENTIONIt is known in drilling wellbores, and particularly, horizontal wellbores that inducing vibration in the drill string during drilling aids in advancing the bit through the formation. In horizontal wellbores, the gravity influence on moving the drill string downhole decreases and the weight lying against the low side of the borehole increases as the inclination angle increases, creating large frictional forces as the drill string is mechanically forced into the wellbore. Vibration acts to reduce friction between the drill string and the borehole permitting the drill string to move more freely therein.
Further, cleaning of the wellbore becomes more difficult as the inclination angle increase. The cuttings tend to accumulate along the lower side of the wellbore, about the drill string and create a situation wherein the drill string is prone to sticking in the wellbore.
Further, differential sticking of drill pipe is a common problem found in both vertical and horizontal drilling. Differential sticking is defined as a drill pipe being stuck in a wellbore caused by a differential between the formation pressure and the hydrostatic pressure in the wellbore. Typically, this situation occurs during overbalanced drilling where a permeable zone exists over which a thick layer of filtercake is deposited and there is contact between the drill pipe or drill collars and the filtercake. Other factors which may contribute to differential sticking are prolonged periods where the drill pipe is stationary, the length of the permeable zone, the filtercake thickness, the drilling mud type and the drilling mud properties. Conventionally differential sticking is resolved by jarring or rotating the drill pipe to attempt to free the drill pipe from the filtercake bond, chemically altering the filtercake properties and introducing nitrogen into the well in an attempt to reduce the hydrostatic pressure.
Vibration may be induced into a drill string using mechanical means to provide pulses of mechanical energy to the drill string. U.S. Pat. No. 4,384,625 to Roper et al. teaches the use of mechanical vibrators, such as hydraulically driven vibrators, incorporated into a drill string to vibrate the drill string at a suitable frequency and amplitude to reduce friction.
U.S. Pat. No. 4,243,112 to Sartor teaches a fluid-,driven rotary orbit jet reaction-type vibrator which is driven by a compressible fluid. The vibrator fits closely between a cover plate and a bearing surface and orbits about in a race so as to exert an orbiting radial vibrator force sequentially in all radial directions.
U.S. Pat. No. 6,009,948 to Flanders et al. discloses a resonator hydraulically operated by a fluid circulated from surface or by an electromechanical device such as a motor or a solenoid which imparts pulses of mechanical energy to aid in drilling, to free stuck drill string and to aid in cementing operations.
One disadvantage of the prior art devices is their complexity and the lack of access to permit passage of a wireline therethrough.
Ideally, a vibration inducing device is simple, inexpensive and is readily incorporated into a drill string without impeding operations integral to drilling.
SUMMARY OF THE INVENTIONEmbodiments of the invention use shock turbulence interaction created by positioning a venturi insert in a flow of fluids in a drill string to create vibrations in the drill string which are sufficient to free a stuck drill pipe or reduce a high frictional coefficient between the drill string and the wellbore to assist in drilling operations.
In a preferred embodiment, a venturi insert having a plurality of angled passageways extending from ports in both an upstream and a downstream wall and a central bore, directs boundary fluid flow into the central flow at the upstream end and directs fluid at the drill string as it exits the downstream passageways which causes vibration therein. The venturi insert is preferably mounted in a bore of a pup tool which is threadedly engaged in the drill string. An inner sleeve and end rings are used to position the insert in the fluid flow. The insert is constrained from lateral movement however it is axially moveable within the pup tool in the sleeve and may be caused to spin therein. A snap ring retains the sleeve, insert and retainer rings in the pup tool. The sleeve is supported at a downstream end by a shoulder formed in the bore of the pup tool.
Therefore in a broad aspect, a vibration inducing apparatus for controlling fluid flow within a bore of a drill string for creating vibration within said drill string comprises: a venturi insert fit to the drill string's bore and being axially moveable therein, the venturi insert having a body fit to the bore and having a central tubular bore formed therethrough for forming an annular wall extending between the drill string and the tubular bore; and a tubular fluid inlet formed in the insert's tubular bore projecting upstream from the annular wall; a tubular fluid outlet formed in the insert's tubular bore projecting downstream from the annular wall; wherein the annular wall comprises: a first angled wall extending downstream between the tubular fluid inlet and the body and radially outwards therefrom; a second angled wall extending downstream between the body and the tubular fluid outlet and radially inwards therefrom; and a plurality of ports formed in the first and second angled walls, the ports forming angled passages being directed radially inwards and downstream and radially outwards and downstream; wherein at least a portion of the fluid flows through the insert's angled passages and at least a portion of the fluid flows through the bore, the turbulence and pattern of the flow created upon exiting the insert inducing vibration in the drill string.
BRIEF DESCRIPTION OF THE DRAWINGS
As known to those skilled in the art, flow through a conduit, including flow through a drill string, is typified by a faster flow in a center flow stream and slower flow along the conduit wall; the boundary layer flow. As described in Technical Monograph 41—Understanding IEC Aerodynamic Noise Prediction for Control Valves by Floyd D. Jury at www.iceweb.com.au/Technical/ValveNoise.htm, noise generated downstream of a valve can come from the dissipation of mechanical energy in the fluid stream at a vena contracta of the valve. The primary noise mechanism is due to turbulence downstream of the vena contracta and is called turbulent shear flow. As flow becomes more intense due to the higher pressure drop across the valve, the normal shock begins to move further downstream and breaks up into several small shock cells. From each of the shock cells, shock waves are formed which travel downstream at some angle from the centerline. The shock waves bounce off the walls of the pipe and are reflected across the pipe to reflect off the opposite wall. As the reflected shock waves “bounce” down the pipe, the waves pass through the area of turbulence creating noise energy and impart vibration into the pipe wall. This is called “shock-turbulence interaction”. While typically this knowledge is used to reduce noise and vibration caused by flow restrictions through valves, in contradistinction, in the case of the present invention, the knowledge is combined with the knowledge of fluid flow through a conduit to create a vibration in a drill string to aid in drilling a wellbore.
Having reference to
More particularly, as shown in
In use, wherein the drill string 11 may be stuck in a wellbore or resistant to movement therein due to a high frictional coefficient between the drill string 11 and the wellbore, the vibration induced in the drill string 11 acts to free the drill string 11 or reduce the frictional coefficient, thereby permitting the drill string 11 to advance more rapidly through a formation, particularly during horizontal wellbore drilling. Further, the vibration induced in the drill string 11 reduces the likelihood of differential sticking during all types of drilling. Applicant also believes that vibration induced in the drill string 11 above the drill bit may act to absorb undesirable vibrations at the drill bit caused by the impact of the bit in the formation which may cause the drill bit to bounce, reducing drilling efficiency.
Having reference to
As shown in
In one embodiment of the invention, where the lower retainer ring 42 is a solid ring, the upper and lower retainer rings 41, 42 are spaced sufficient to allow the venturi insert 10 to be lifted off the lower retainer ring 42 by the fluid flow F′ exiting the ports 12 and thus permit the fluid to flow from the venturi insert 10 with minimal interference in the pattern of fluid flow F′. As shown in
As shown In
In particular drilling situations, it may be advantageous to position a plurality of said vibration inducing apparatus 1 within the drill string 11 at intervals along a length of the drill string 11 for creating vibration, particularly during sliding operations when drilling horizontal wellbores. A plurality of vibration inducing apparatus 1, as previously described are most easily inserted into the drill string 11 in individual housings or pup joints 20, the pup joints 20 being inserted into the drill string 11 at intervals such as at tubular joints (not shown).
The dimensions of the vibration apparatus 1 are dependant upon the diameter of the drill pipe 11 in which it is to be connected. The following is illustrative of one example only.
In one embodiment of the invention sized for use in a 3½ inch drill pipe, as shown in
As shown in
An insert 10 suitable for the 3½ inch pup joint having the above-listed dimensions is about 6 inches in length and has an outer diameter of 2.87 inches and an inner diameter of 2.67 at the body portion 23. The inlet and outlet 26, 27 extend approximately 1 inch from the angled walls 28, 29 which are angled at 45 degrees and are approximately 0.25 inches in length. The body portion is approximately 3.43 inches in length. The inlet and outlet 26, 27 have an outer diameter of 2.5 inches and an inner diameter of 2.3 inches. Any number of ports 12 between eighteen to forty two ports 12, all having a diameter ranging from 0.1875 to 0.210 inches, are formed in each of the angled walls 28, 19.
EXAMPLESIn a horizontal wellbore to be drilled in northern British Columbia, Canada, surface pipe was first set with a directional shoe in place. A vibration apparatus 1 according to an embodiment of the invention was positioned in a conventional directional drilling drill string 11 approximately 250 metres (833 feet) away from a drill bit. Drilling was commenced to drill out the directional shoe which incorporates a rubber wiper plug and a steel shoe. Surprisingly, the operation which typically takes 2-3 hours was accomplished in about ½ hour. So unusual was the rapidity of the drilling time, an on-site consultant on site halted the drilling so that the actual length of drill pipe 11 could be re-tallied. Further, drilling cuttings were examined for evidence that the rubber plug and steel shoe were actually drilled through. Evidentiary bits of rubber and steel were found in the cuttings.
In another example, generally directional drilling is accomplished with an alternating combination of repeated orientation of the drill bit by rotation of the drill string and drilling using a mud motor to rotate the drill bit.
More specifically, during the orientation operation, the drill string 11 is slowly rotated to orient a bent housing in the bottom hole assembly in the desired direction. A mud motor is then energized so as to rotate the drill bit along a curved path in the oriented direction. The non-rotating drill string 11 slides along the borehole as the mud motor drills the curved path. Repeated orientation is necessary for adjusting or setting the direction of the borehole. Each time the borehole inclination must be adjusted, drilling is stopped, the drill string is rotated to reorient the drill bit and then drilling using the mud motor is recommenced.
Applied in this second example, typically a 1.5 metre slide in the formation being drilled, took 2-3 hours and possibly up to 5 hours to accomplish. Numerous slides were performed during drilling using the novel vibration apparatus, the result being a significant savings in time. A particular example was one 7 metre slide which took only 1 hour, 15 minutes to complete. Rig time was estimated to cost about $4000 CDN per hour. Thus, the savings realized using the novel vibration apparatus were significant. An approximate saving of $10,000 CDN was made in drilling out the directional shoe and an additional saving of about $19,000 CDN for the 7 metre slide alone.
Other advantages arose. Additionally, soap and nitrogen used to create foam to lift drilling cuttings, typically has a tendency to lose foam integrity, the soap and nitrogen separating from one another. Advantageously, the turbulence in the drilling fluids created by the vibration apparatus 1 acts to effectively remix the soap and nitrogen improving the integrity of the foam and thus providing better cleaning of cuttings from the wellbore.
The result of the improved cuttings removal has further advantages in the drilling process, particularly related to directional surveys performed to determine the direction of the drill bit after each connection is made to the drill string 11. As the wellbore is much cleaner than when conventional vibration apparatus are used, the directional survey is typically completed the fist time it is attempted. With conventional drilling techniques where much debris and cuttings may remain in the wellbore, it may take 2-3 times to successfully survey the bit orientation.
Claims
1. A vibration inducing apparatus for controlling fluid flow within a bore of a drill string for creating vibration within said drill string comprising:
- a venturi insert fit to the drill string's bore and being axially moveable therein, the venturi insert having a body fit to the bore and having a central tubular bore formed therethrough for forming an annular wall extending between the drill string and the tubular bore; and
- a tubular fluid inlet formed in the insert's tubular bore projecting upstream from the annular wall;
- a tubular fluid outlet formed in the insert's tubular bore projecting downstream from the annular wall; wherein
- the annular wall comprising:
- a first angled wall extending downstream between the tubular fluid inlet and the body and radially outwards therefrom;
- a second angled wall extending downstream between the body and the tubular fluid outlet and radially inwards therefrom; and
- a plurality of ports formed in the first and second angled walls, the ports forming angled passages being directed radially inwards and downstream and radially outwards and downstream;
- wherein at least a portion of the fluid flows through the insert's angled passages and at least a portion of the fluid flows through the bore, the turbulence and pattern of the flow created upon exiting the insert inducing vibration in the drill string.
2. The vibration inducing apparatus as described in claim 1 further comprising a housing for positioning the venturi insert within the at least a portion of the drill string, further comprising: means for securing the venturi insert within a bore of the housing for axial movement therein.
3. The vibration inducing apparatus as described in claim 2 wherein the means for securing the venturi insert in the housing further comprises:
- an internal sleeve fit within the bore of the housing for housing the venturi insert and receiving the fluid flow, the insert being axially moveable therein; and
- upper and lower retaining rings for retaining the internal sleeve in the housing's bore and for limiting the axial movement of the venturi insert therebetween.
4. The vibration inducing apparatus as described in claim 3 further comprising:
- a shoulder formed in the housing against which the lower retainer ring is supported;
- a snap ring against which the upper retainer ring is supported: and
- a snap ring groove formed in the housing for accepting the snap ring for retaining the internal sleeve and retaining rings in the housing bore.
5. The vibration inducing apparatus as described in claim 2 wherein the housing is a pup joint threaded at an upper and lower end for connection to the drill string.
6. The vibration inducing apparatus as described in claim 1 wherein the plurality of ports are angled from about 24° to about 28°.
7. The vibration inducing apparatus as described in claim 6 wherein the plurality of ports are angled 26°.
8. The vibration inducing apparatus as described in claim 1 wherein the insert's bore is sized sufficient to permit passage of a wireline therethrough.
9. The vibration inducing apparatus as described in claim 1 wherein a number of the ports varies depending upon a diameter of the venturi insert.
10. The vibration inducing apparatus as described in claim 5 wherein a plurality of pup joints are threadedly engaged within a drill string at selected intervals for inducing vibration therealong.
Type: Application
Filed: Jun 23, 2005
Publication Date: Dec 29, 2005
Applicant: VIBRATECH DRILLING SERVICES LTD. (Medicine Hat)
Inventors: Kelly LIBBY (Medicine Hat), Dave TROTTER (Medicine Hat)
Application Number: 11/160,438