CA1256095A - Combination shock tool and reamer/integral blade stabilizer - Google Patents
Combination shock tool and reamer/integral blade stabilizerInfo
- Publication number
- CA1256095A CA1256095A CA000535096A CA535096A CA1256095A CA 1256095 A CA1256095 A CA 1256095A CA 000535096 A CA000535096 A CA 000535096A CA 535096 A CA535096 A CA 535096A CA 1256095 A CA1256095 A CA 1256095A
- Authority
- CA
- Canada
- Prior art keywords
- mandrel
- housing
- reamer
- integral blade
- coupling means
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 230000035939 shock Effects 0.000 title claims abstract description 45
- 239000003381 stabilizer Substances 0.000 title claims abstract description 26
- 230000008878 coupling Effects 0.000 claims abstract description 18
- 238000010168 coupling process Methods 0.000 claims abstract description 18
- 238000005859 coupling reaction Methods 0.000 claims abstract description 18
- 238000005452 bending Methods 0.000 claims abstract description 14
- 238000011068 loading method Methods 0.000 claims abstract description 6
- 230000004044 response Effects 0.000 claims abstract description 4
- 239000012530 fluid Substances 0.000 claims description 3
- 238000005553 drilling Methods 0.000 description 7
- 230000008901 benefit Effects 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 4
- 238000005755 formation reaction Methods 0.000 description 4
- 238000010276 construction Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 230000000087 stabilizing effect Effects 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 239000000356 contaminant Substances 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 210000003414 extremity Anatomy 0.000 description 1
- 210000004124 hock Anatomy 0.000 description 1
- 238000007866 imination reaction Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 238000007790 scraping Methods 0.000 description 1
Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B17/00—Drilling rods or pipes; Flexible drill strings; Kellies; Drill collars; Sucker rods; Cables; Casings; Tubings
- E21B17/10—Wear protectors; Centralising devices, e.g. stabilisers
- E21B17/1078—Stabilisers or centralisers for casing, tubing or drill pipes
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B17/00—Drilling rods or pipes; Flexible drill strings; Kellies; Drill collars; Sucker rods; Cables; Casings; Tubings
- E21B17/02—Couplings; joints
- E21B17/04—Couplings; joints between rod or the like and bit or between rod and rod or the like
- E21B17/07—Telescoping joints for varying drill string lengths; Shock absorbers
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B7/00—Special methods or apparatus for drilling
- E21B7/04—Directional drilling
Landscapes
- Engineering & Computer Science (AREA)
- Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Mining & Mineral Resources (AREA)
- Physics & Mathematics (AREA)
- Environmental & Geological Engineering (AREA)
- Fluid Mechanics (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Mechanical Engineering (AREA)
- Earth Drilling (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A combination shock tool and integral blade stabilizer or reamer includes a housing defining a longitudinal axis and having a mandrel slidably disposed therein for movement along the longitudinal axis of the housing in response to shock loadings in the axial direction. The mandrel has a diameter less than that of the housing and a portion of the mandrel extends outwardly of one end of the housing. Coupling means is provided on an end portion of the outwardly extending mandrel portion for effecting a connection to a drill bit, and further coupling means on the housing is included for effecting a connection thereof to the lower end of a drill string. The housing and the end portion of the mandrel each also have an integral blade stabilizer or reamer thereon adapted to engage and be supported by the bore of a well being drilled whereby the outwardly extending mandrel portion is relatively close to the support point created by engagement of the integral blade stabilizer or reamer on the mandrel end portion with the well bore during use thus helping to avoid high bending moments and deflection in the mandrel during use.
A combination shock tool and integral blade stabilizer or reamer includes a housing defining a longitudinal axis and having a mandrel slidably disposed therein for movement along the longitudinal axis of the housing in response to shock loadings in the axial direction. The mandrel has a diameter less than that of the housing and a portion of the mandrel extends outwardly of one end of the housing. Coupling means is provided on an end portion of the outwardly extending mandrel portion for effecting a connection to a drill bit, and further coupling means on the housing is included for effecting a connection thereof to the lower end of a drill string. The housing and the end portion of the mandrel each also have an integral blade stabilizer or reamer thereon adapted to engage and be supported by the bore of a well being drilled whereby the outwardly extending mandrel portion is relatively close to the support point created by engagement of the integral blade stabilizer or reamer on the mandrel end portion with the well bore during use thus helping to avoid high bending moments and deflection in the mandrel during use.
Description
~256095 COMBINATION SHOCK TOOL A~D REAMER/I~TEGRAL
BLADE STABILIZER
BACKGROU~D OF THE I~VENTIO~
-When drilling for oil or gas, the most common drill string assembly at the bottom of the hole, commonly termed the bottom hole assembly (BHA), is (from the bottom up), drill bit, bit sub, shock tool, drill collars, and drill pipe.
It is well known in the art that the best performance of the shock tool is achieved when it is positioned as closely to the drill bit as is possible. As is well known, a shock tool typically comprises an elongated housing within which is slidably disposed an elongated mandrel. Suitable splines prevent relative rotation between the mandrel and the housing and resilient means disposed within the housing interact between the housing and the mandrel to take up shock and vibration thus helping to protect the drill bit from vibration damage and excessive wear.
When drilling very abrasive formations, the drill bit of course gradually wears down with the result being that the inside diameter of the hole being drilled gradually becomes smaller. If the inside diameter of the hole is allowed to become smaller, a problem is encountered when a new bit is lowered into the hole in that the new bit must be used to ream the hole with the result being that the new bit becomes partially worn before it even reaches the bottom of the hole. This situation is commonly corrected by the use of a down hole reamer. A reamer is a tool which typically has from three to six rollers spaced about its circumference and which roller~ are in contact with the formation. Its primary function is to ensure that the inside diameter of the hole 3~
is maintained at the desired value. The reamer however provides another function, namely that of a stabilizer.
Since the rollers are in contact with the wall of the well bore, the lateral stabilizing e~fect helps to ensure that the axis of the drill string is maintained in the center of the well bore.
Another tool which has a function very similar to that of a reamer is commonly termed an integral blade stabilizer (IBS). The IBS typically comprises a plurality of circumferentially spaced apart fixed blades which engage the wall of the well bore during drilling.thus tending to keep the well bore to the desired inside diameter while at the same time providing a lateral ~tabilizing effect similar to that described above in conjunction with the reamer.
When drilling formations that are unconsolidated, or when the formations are at an oblique angle to the well bore, there is a tendency for the drill string to gradually move off course and for an angle to develop resulting in the well bore moving off true vertical.
However, in most cases there i8 a requirement that the well bore be truly vertical and when angle "build up" is experienced, a special procedure is implemented to enable drilling to proceed vertically. To deal with this situation, a typical bottom hole assembly is comprised of the following (from the bottom up); drill bit, drill bit sub, IBS or reamer, drill collar, IBS or reamer, shock tool, drill collars, and drill pipe.
One disadvantage of the above arrangement is that the efficiency of the shock tool has been reduced because of the distance increase between such tool and the drill bit, it being kept in mind that for best performance the shock tool should be positioned as close to the drill bit as is possible. In view of this disadvantage, a prefçrred BHA assembly which serves to reduce somewhat the distance between the shock tool and the drill bit is as follows:
drill bit, drill bit sub, IBS/reamer, shock tool, IBS/reamer, drill collars, drill pipe.
The precise assembly can therefore be varied somewhat. However, the above-noted BHA is one of the most commonly used. The basic ob~ective is to stabilize the drill string between the two IBS or reamers and thus provide a relatively rigid assembly in order that the hole being drilled will be maintained truly vertical.
It will be appreciated that in order to prevent a "build up" of angle or deviation from the true vertical, it is necessary to stiffen the assembly to its maximum potential. However, a conflicting situation arises since (a) for best performance of the shock tool there i5 the above-noted requirement that it be positioned as close to the drill bit as possible;
(b) the shock tool however i6 the most flexible member of the BHA and it is prone to excessive deflection. This is due to the fact that its telescopically arranged mandrel or shaft is of smaller outside diameter than the rest of the bottom hole assembly thus giving it a lower stiffness factor;
(c) when this shock tool is placed between the two IBS with the two reamers, the two IBS or two reamers act as supports and the assembly between them acts as a long beam which is subject to bending or deflection. Since reamers and IBS are relatively long, the bending moment is significant and deflection occurs resulting in an undesirable angle "build up~ and deviation of the hole away from true vertical.
_ 4 _ ~256095 When a "build up" of "angle" is developing, the normal practice has been to reduce the weight on the bit (WOB). However, the rate of drill bit penetration (ROP) is directly proportional to the WOB. Hence, when WOB is reduced in an effort to eliminate the build up of "angle"
the ROP is reduced in proportion thus requiring a greater time to drill the well at a considerable increase in cost.
SUMMARY OF THE INVENTION
In accordance with the present invention, the I8S's or reamers are combined with the shock tool to provide a single combination tool. This new arrangement significantly shortens the whole assembly while at the same time the most critical point, i.e. the exposed telescoping mandrel or shaft of the shock tool is now located very close to the IBS/reamer support point (which in use is in contact with the well bore wall) thus significantly reducing the bending moment at the most critical cross section. A significantly more rigid assembly i6 the result and straighter holes can be drilled. Because of the increased stiffness of the assembly, there is no need to reduce the WOB (weight on bit) and hence overall drilling rates can be maintained at relatively high levels thus reducing costs.
A further advantage of this new tool arrangement i8 that by combining several tools into one, the shock tool is effectively positioned closer to the bit than was permitted when the several tools were used separately, thus resulting in better overall performance of the shock tool itself.
A 6till further advantage of the new tool is that since two connections (tool joints) have been eliminated, and since tool joints are critical components subject to occasional fai~ure, the e}imination of these joints makes the entire bottom hole assembly safer.
_ 5 _ ~256095 BRIEF DESCRIPTION OF THE VIEWS OF DRAWINGS
Further features and advantages of the invention will become apparent from the following description of the preferred embodiments of the invention wherein:
FIG. 1 is a view of a typical prior art bottom hole drill string assembly;
FIG. 2 is a view of a bottom hole assembly in accordance with the present invention;
FIG. 3 comprising parts 3A, 3B, 3C together comprise a longitudinal view, partly in s~ction, of a shock tool-IBS (integral blade stabilizer) combination in ~ accordance with the present invention;
FIG. 3D i6 a cross-section view along line 3D-3D
in Fig. 3;
FIG. 4 comprising parts 4A and 4B are views of the upper and lower ends of a shock tool-reamer combination, the shock tool component of the combination being as in Figure 3 but omitted from Figure 4 for purposes of avoiding duplication.
FIG. 5 is a composite section view showing sections A-A, B-B and C-C of Fig.4.
DETAILED DESCRIPTIO~ OF PREFERRED ~MBODIME~TS
Reference will be had firstly to Figure 1 which represents a prior art bottom hole assembly (BHA). This illustration shows a preferred prior art BHA assembly as noted previously and starting from the bottom up it comprises a drill bit and drill bit sub 10, an integral blade stabilizer or reamer 12, a ~hock tool 14 for absorbing shock and vibration passing along the drill string, a further integral blade stabilizer or reamer 16 connected to and positioned just above the shock tool 14, followed by the usual drill collars and drill pipe 18.
The two IBS/reamers 12 and 16 are shown as contacting the well bore wall at points Rl and R2 respectively and ~256095 deriving lateral support therefrom. The distance between Rl and R2 is given by Ll while the distance from Rl up to the critical reduced diameter mandrel portion of the shock tool (see Item 20) is given by dimension Al. If it is assumed, for purposes of illustration, that a bending force P is applied to the bottom hole assembly half way between points Rl and R2, then a bending moment diagram may be constructed as indicated in Fig. 1, the bending moment being at a maximum half way between points Rl and R2. The bending moment Ml appearing at the critical mandrel portion 20 of the shock tool will of course be dependent upon the relationship between Ll and Al.
With reference now to Fig. 2 there is shown an integral blade stabilizer (IBS) or reamer and shock tool combination 24 in accordance with the present invention.
This combination tool includes a housing 26 defining a longitudinal axis and having a mandrel 28 slidably disposed within the housing for movement along the longitudinal axis of the housing in response to shock loadings in the axial direction. Mandrel 28 has a diameter less than that of the housing 26. The mandrel is, of course, non-rotatable relative to the housing by virtue of spline means to be described hereinafter.
Suitable coupling means 30 are provided on that end of the mandrel 28 which extends outwardly of the lower end of housing 26 for effecting a connection to a drill bit 32.
Further coupling means 34 are provided on the opposite upper end of the housing for effecting connectiQn thereof to the lower end of a drill string 36.
As shown in Fig. 2, the coupling means on the mandrel is associated with an enlarged diameter portion and this enlarged diameter portion i6 provided with an integral blade stabilizer (IBS) or a reamer 38 adapted to engage and to be supported by the bore of a well being _ 7 _ ~2~095 drilled. Similarly, the upper end of housing 26, fairly closely adjacent the previously mentioned connection means 34, is provided with an integral blade stabilizer or reamer 40 which is also adapted to engage and be supported by the bore of a well being drilled. The lateral support points provided, i.e. where contact is made by the IBS or reamer a~semblies, is indicated by support points R3 and R4. It will thus be seen that by combining the IBS's or reamers and the shock tool into one combination tool, that the whole assembly is significantly shortened as compared with the prior art assembly shown in Figure 1, while the most critical point, i.e. the exposed reduced diameter mandrel portion 28, is now very close to the lower support point at R3 thuk reducing the bending moment at the critical cross section and resulting in a significantly more rigid assem~ly.
In the typical prior art embodiment illustrated in Figure 1, Ll, i.e. the distance between points Rl and R2, was typically in the order of 173 inches. The - 20 distance Al in the prior art arrangement from point Rl to the critical cross section was typically in the order of 50 inches. This compares most unfavourably with the novel arrangement of Figure 2 wherein dimension L2 between support points R3 and R4 is typically in the order of 90 inches while dimension A2 between support point R3 and the reduced diameter of mandrel 2~ is in the order of 12 inches. ~sing these dimensions, a few simple bending moment calculations can be performed which will show that for a given lateral force applied half way between the support points provided by the well bore wall, that the bending moment M2 at the critical cross section is only about 1/4 the ben~ing moment ~1 arising in the prior art configuration ~hown in Figure 1. This vast reduction in bendlng moment at the critical section arises because of - 8 - ~256095 the great reduction in overall length and also because of the fact that the distance between the lower support point and the lower end of the mandrel is greatly reduced.
With further reference to the drawings, the embodiments of the invention are illustrated in detail in Figures 3-5.
With reference to ~igure 3 there is shown a combination shock tool-integral blade stabilizer. The tool 24 includes an elongated cylindrical housing 26.
10 Housing 26 comprises a multiplicity of sections secured together by tapered screw-threaded joints. An elongated mandrel 28 is disposed within housing 26 for movement along the longitudinal axis of same. Suitable seals 50 are interposed between the lower end of housing 26 and the 15 outer sUrface of mandrel 28 to prevent ingress of grit and other contaminants. The lower end section of housing 26 is provided with internal splines 52 which cooperate with B correspo~ ing splines formed on the exterior of the mandrel ~ such that they are in cooperating interengaged 20 relationship as illustrated in Fig. 3D thereby to prevent relative rotation between mandrel 28 and housing 26. An axial passage 53 for drilling fluid extends completely through the tool 24.
A spring stack 54 comprising a series of annular 25 Belleville-type washers 56 is disposed in an annular space 58 defined between a reduced diameter portion of mandrel 28 and an enlarged inside diameter portion of housing 26.
The lower end of spring stack 54 rests against a shoulder 60 defined by annular sleeve 62 which is fixed relative to 30 the housing 26 while the upper end of the spring stack bears against a further shoulder 64 defined by annular end piece 66 which ~s threaded on to the upper end of the mandrel 28. Suitable annular seals 68 prevent ingress of abrasi~e materials into the region between the mandrel and 35 the housing at the upper end of same.
9 ~2S60gS
The annular members of the spring stack 54 are designed to provide the desired spring constant for the shock tool assembly whereby to allow shock and vibration forces to be taken up without "bottoming out" of the spring stack under the influence of the loadings applied by the heavy drill string.
The upper end of housing 26 is internally threaded and receives an upper body member 70, the extreme upper end portion 72 of which comprises a coupling means 72 in the form of an internally threaded section for providing a secure connection to the lower end of a drill string (not shown) by means of the usual tapered threaded connection. Immediately below the coupling means 72 is an integral blade stabilizer (IBS 74) which,in itself, may be of a conventional design. The I~S 74 includes a plurality of circumferentially spaced blades 76, such blades being inclined to the axis of the tool in somewhat helical or oblique fashion thereby to provide a cutting or scraping action to assist in maintaining the well bore at the required diameter. Since the outer extremities of these blades contact the well bore, a lateral stabilizing effect is also achieved.
The lowermost end of mandrel 28, i.e. that portion which projects outwardly of the lower end of housing 26, is provided with an enlarged portion 80 and the extreme lower end of this enlarged portion 80 includes an internally threaded coupler portion 82 whereby to allow for direct connection to a drill bit (not shown) by means of the usual tapered threaded connection. This enlarged portion 80 also includes a further integral blade stabilizer 84 having a multiplicity of blades 86 thereon and constructed and f~nctioning in essentially the same manner as the upper IBS 74.
- 10 - ~25~i~95 By virtue of the fact that the integral blade stabilizers 74 and 84 are combined with the shock tool to form effectively a single unit, the overall length of the assembly can be greatly reduced as compared with the prior art arrange~ents and, moreover, the lower IBS 84 is in close proximity to the lower end of the mandrel 28 which projects outwardly of housing 26 thus reducing very substantially the bending moments to which it iB subjected thereby providing the advantageous effects described 10 previously.
Fiqure 4 shows only the upper and lower end portions of an alternative tool arrangement in accordance with the invention. The intermediate portion comprising the shock tool has not been 6hown as it is essentially the same in construction as that described above in conjunction with Figure 3.
The combination tool illustrated in Figure 4 includes a mandrel 28 as before having an enlarged portion 80A formed at the lower end of same with a coupler portion 82A located at the extreme lower end of the assembly and being provided with internal threads for connection to a drill bit, as shown. The enlarged portion 80A, instead of being provided with an integral blade stabilizer as described above, is provided with a reamer assembly 90.
The reamer 90 comprises three equally spaced apart rollers 92 each located in a respective recess 94. Similarly, the upper end portion of the tool is provided with an internally threaded coupler portion 72A similar to that described above ~or connection to the lower end of a drill string. Ju~t below this coupler portion 72A there is provided a further rea~er assembly 96 such reamer assembly 96 being of id~tical construction to the reamer assembly 90 and co~prising reamer rollers 92 disposed in suitable recesses 94. Each reamer roller is rotatably journalled ,2S6095 on an elongated shaft 97, the opposing ends of shaft 97 being mounted in support blocks 98 with the shafts 97 being secured against rotation by pin means 100. The reamer rollers 92 are each provided with rows of spaced apart carbide inserts 102 which, in operation, successively engage the inner wall of the well bore in known fashion thereby to ensure that the well bore diameter is maintained at the correct value while at the same ti~e providing the required degree of lateral stability.
The basic function and operation of the embodiment illustrated in Figs. 4 and 5 and the advantages associated with same are essentially as described previously.
Preferred embodiments of the invention have been described for purposes of illustration. Various modifications within the spirit of the invention and the appended claims will be apparent to those skilled in this art from the above description e.g. those skilled in this art will realize that in many cases the (IBS) or reamer need only be provided on the lower end of the tool i.e. on the mandrel coupling portion.
,.
BLADE STABILIZER
BACKGROU~D OF THE I~VENTIO~
-When drilling for oil or gas, the most common drill string assembly at the bottom of the hole, commonly termed the bottom hole assembly (BHA), is (from the bottom up), drill bit, bit sub, shock tool, drill collars, and drill pipe.
It is well known in the art that the best performance of the shock tool is achieved when it is positioned as closely to the drill bit as is possible. As is well known, a shock tool typically comprises an elongated housing within which is slidably disposed an elongated mandrel. Suitable splines prevent relative rotation between the mandrel and the housing and resilient means disposed within the housing interact between the housing and the mandrel to take up shock and vibration thus helping to protect the drill bit from vibration damage and excessive wear.
When drilling very abrasive formations, the drill bit of course gradually wears down with the result being that the inside diameter of the hole being drilled gradually becomes smaller. If the inside diameter of the hole is allowed to become smaller, a problem is encountered when a new bit is lowered into the hole in that the new bit must be used to ream the hole with the result being that the new bit becomes partially worn before it even reaches the bottom of the hole. This situation is commonly corrected by the use of a down hole reamer. A reamer is a tool which typically has from three to six rollers spaced about its circumference and which roller~ are in contact with the formation. Its primary function is to ensure that the inside diameter of the hole 3~
is maintained at the desired value. The reamer however provides another function, namely that of a stabilizer.
Since the rollers are in contact with the wall of the well bore, the lateral stabilizing e~fect helps to ensure that the axis of the drill string is maintained in the center of the well bore.
Another tool which has a function very similar to that of a reamer is commonly termed an integral blade stabilizer (IBS). The IBS typically comprises a plurality of circumferentially spaced apart fixed blades which engage the wall of the well bore during drilling.thus tending to keep the well bore to the desired inside diameter while at the same time providing a lateral ~tabilizing effect similar to that described above in conjunction with the reamer.
When drilling formations that are unconsolidated, or when the formations are at an oblique angle to the well bore, there is a tendency for the drill string to gradually move off course and for an angle to develop resulting in the well bore moving off true vertical.
However, in most cases there i8 a requirement that the well bore be truly vertical and when angle "build up" is experienced, a special procedure is implemented to enable drilling to proceed vertically. To deal with this situation, a typical bottom hole assembly is comprised of the following (from the bottom up); drill bit, drill bit sub, IBS or reamer, drill collar, IBS or reamer, shock tool, drill collars, and drill pipe.
One disadvantage of the above arrangement is that the efficiency of the shock tool has been reduced because of the distance increase between such tool and the drill bit, it being kept in mind that for best performance the shock tool should be positioned as close to the drill bit as is possible. In view of this disadvantage, a prefçrred BHA assembly which serves to reduce somewhat the distance between the shock tool and the drill bit is as follows:
drill bit, drill bit sub, IBS/reamer, shock tool, IBS/reamer, drill collars, drill pipe.
The precise assembly can therefore be varied somewhat. However, the above-noted BHA is one of the most commonly used. The basic ob~ective is to stabilize the drill string between the two IBS or reamers and thus provide a relatively rigid assembly in order that the hole being drilled will be maintained truly vertical.
It will be appreciated that in order to prevent a "build up" of angle or deviation from the true vertical, it is necessary to stiffen the assembly to its maximum potential. However, a conflicting situation arises since (a) for best performance of the shock tool there i5 the above-noted requirement that it be positioned as close to the drill bit as possible;
(b) the shock tool however i6 the most flexible member of the BHA and it is prone to excessive deflection. This is due to the fact that its telescopically arranged mandrel or shaft is of smaller outside diameter than the rest of the bottom hole assembly thus giving it a lower stiffness factor;
(c) when this shock tool is placed between the two IBS with the two reamers, the two IBS or two reamers act as supports and the assembly between them acts as a long beam which is subject to bending or deflection. Since reamers and IBS are relatively long, the bending moment is significant and deflection occurs resulting in an undesirable angle "build up~ and deviation of the hole away from true vertical.
_ 4 _ ~256095 When a "build up" of "angle" is developing, the normal practice has been to reduce the weight on the bit (WOB). However, the rate of drill bit penetration (ROP) is directly proportional to the WOB. Hence, when WOB is reduced in an effort to eliminate the build up of "angle"
the ROP is reduced in proportion thus requiring a greater time to drill the well at a considerable increase in cost.
SUMMARY OF THE INVENTION
In accordance with the present invention, the I8S's or reamers are combined with the shock tool to provide a single combination tool. This new arrangement significantly shortens the whole assembly while at the same time the most critical point, i.e. the exposed telescoping mandrel or shaft of the shock tool is now located very close to the IBS/reamer support point (which in use is in contact with the well bore wall) thus significantly reducing the bending moment at the most critical cross section. A significantly more rigid assembly i6 the result and straighter holes can be drilled. Because of the increased stiffness of the assembly, there is no need to reduce the WOB (weight on bit) and hence overall drilling rates can be maintained at relatively high levels thus reducing costs.
A further advantage of this new tool arrangement i8 that by combining several tools into one, the shock tool is effectively positioned closer to the bit than was permitted when the several tools were used separately, thus resulting in better overall performance of the shock tool itself.
A 6till further advantage of the new tool is that since two connections (tool joints) have been eliminated, and since tool joints are critical components subject to occasional fai~ure, the e}imination of these joints makes the entire bottom hole assembly safer.
_ 5 _ ~256095 BRIEF DESCRIPTION OF THE VIEWS OF DRAWINGS
Further features and advantages of the invention will become apparent from the following description of the preferred embodiments of the invention wherein:
FIG. 1 is a view of a typical prior art bottom hole drill string assembly;
FIG. 2 is a view of a bottom hole assembly in accordance with the present invention;
FIG. 3 comprising parts 3A, 3B, 3C together comprise a longitudinal view, partly in s~ction, of a shock tool-IBS (integral blade stabilizer) combination in ~ accordance with the present invention;
FIG. 3D i6 a cross-section view along line 3D-3D
in Fig. 3;
FIG. 4 comprising parts 4A and 4B are views of the upper and lower ends of a shock tool-reamer combination, the shock tool component of the combination being as in Figure 3 but omitted from Figure 4 for purposes of avoiding duplication.
FIG. 5 is a composite section view showing sections A-A, B-B and C-C of Fig.4.
DETAILED DESCRIPTIO~ OF PREFERRED ~MBODIME~TS
Reference will be had firstly to Figure 1 which represents a prior art bottom hole assembly (BHA). This illustration shows a preferred prior art BHA assembly as noted previously and starting from the bottom up it comprises a drill bit and drill bit sub 10, an integral blade stabilizer or reamer 12, a ~hock tool 14 for absorbing shock and vibration passing along the drill string, a further integral blade stabilizer or reamer 16 connected to and positioned just above the shock tool 14, followed by the usual drill collars and drill pipe 18.
The two IBS/reamers 12 and 16 are shown as contacting the well bore wall at points Rl and R2 respectively and ~256095 deriving lateral support therefrom. The distance between Rl and R2 is given by Ll while the distance from Rl up to the critical reduced diameter mandrel portion of the shock tool (see Item 20) is given by dimension Al. If it is assumed, for purposes of illustration, that a bending force P is applied to the bottom hole assembly half way between points Rl and R2, then a bending moment diagram may be constructed as indicated in Fig. 1, the bending moment being at a maximum half way between points Rl and R2. The bending moment Ml appearing at the critical mandrel portion 20 of the shock tool will of course be dependent upon the relationship between Ll and Al.
With reference now to Fig. 2 there is shown an integral blade stabilizer (IBS) or reamer and shock tool combination 24 in accordance with the present invention.
This combination tool includes a housing 26 defining a longitudinal axis and having a mandrel 28 slidably disposed within the housing for movement along the longitudinal axis of the housing in response to shock loadings in the axial direction. Mandrel 28 has a diameter less than that of the housing 26. The mandrel is, of course, non-rotatable relative to the housing by virtue of spline means to be described hereinafter.
Suitable coupling means 30 are provided on that end of the mandrel 28 which extends outwardly of the lower end of housing 26 for effecting a connection to a drill bit 32.
Further coupling means 34 are provided on the opposite upper end of the housing for effecting connectiQn thereof to the lower end of a drill string 36.
As shown in Fig. 2, the coupling means on the mandrel is associated with an enlarged diameter portion and this enlarged diameter portion i6 provided with an integral blade stabilizer (IBS) or a reamer 38 adapted to engage and to be supported by the bore of a well being _ 7 _ ~2~095 drilled. Similarly, the upper end of housing 26, fairly closely adjacent the previously mentioned connection means 34, is provided with an integral blade stabilizer or reamer 40 which is also adapted to engage and be supported by the bore of a well being drilled. The lateral support points provided, i.e. where contact is made by the IBS or reamer a~semblies, is indicated by support points R3 and R4. It will thus be seen that by combining the IBS's or reamers and the shock tool into one combination tool, that the whole assembly is significantly shortened as compared with the prior art assembly shown in Figure 1, while the most critical point, i.e. the exposed reduced diameter mandrel portion 28, is now very close to the lower support point at R3 thuk reducing the bending moment at the critical cross section and resulting in a significantly more rigid assem~ly.
In the typical prior art embodiment illustrated in Figure 1, Ll, i.e. the distance between points Rl and R2, was typically in the order of 173 inches. The - 20 distance Al in the prior art arrangement from point Rl to the critical cross section was typically in the order of 50 inches. This compares most unfavourably with the novel arrangement of Figure 2 wherein dimension L2 between support points R3 and R4 is typically in the order of 90 inches while dimension A2 between support point R3 and the reduced diameter of mandrel 2~ is in the order of 12 inches. ~sing these dimensions, a few simple bending moment calculations can be performed which will show that for a given lateral force applied half way between the support points provided by the well bore wall, that the bending moment M2 at the critical cross section is only about 1/4 the ben~ing moment ~1 arising in the prior art configuration ~hown in Figure 1. This vast reduction in bendlng moment at the critical section arises because of - 8 - ~256095 the great reduction in overall length and also because of the fact that the distance between the lower support point and the lower end of the mandrel is greatly reduced.
With further reference to the drawings, the embodiments of the invention are illustrated in detail in Figures 3-5.
With reference to ~igure 3 there is shown a combination shock tool-integral blade stabilizer. The tool 24 includes an elongated cylindrical housing 26.
10 Housing 26 comprises a multiplicity of sections secured together by tapered screw-threaded joints. An elongated mandrel 28 is disposed within housing 26 for movement along the longitudinal axis of same. Suitable seals 50 are interposed between the lower end of housing 26 and the 15 outer sUrface of mandrel 28 to prevent ingress of grit and other contaminants. The lower end section of housing 26 is provided with internal splines 52 which cooperate with B correspo~ ing splines formed on the exterior of the mandrel ~ such that they are in cooperating interengaged 20 relationship as illustrated in Fig. 3D thereby to prevent relative rotation between mandrel 28 and housing 26. An axial passage 53 for drilling fluid extends completely through the tool 24.
A spring stack 54 comprising a series of annular 25 Belleville-type washers 56 is disposed in an annular space 58 defined between a reduced diameter portion of mandrel 28 and an enlarged inside diameter portion of housing 26.
The lower end of spring stack 54 rests against a shoulder 60 defined by annular sleeve 62 which is fixed relative to 30 the housing 26 while the upper end of the spring stack bears against a further shoulder 64 defined by annular end piece 66 which ~s threaded on to the upper end of the mandrel 28. Suitable annular seals 68 prevent ingress of abrasi~e materials into the region between the mandrel and 35 the housing at the upper end of same.
9 ~2S60gS
The annular members of the spring stack 54 are designed to provide the desired spring constant for the shock tool assembly whereby to allow shock and vibration forces to be taken up without "bottoming out" of the spring stack under the influence of the loadings applied by the heavy drill string.
The upper end of housing 26 is internally threaded and receives an upper body member 70, the extreme upper end portion 72 of which comprises a coupling means 72 in the form of an internally threaded section for providing a secure connection to the lower end of a drill string (not shown) by means of the usual tapered threaded connection. Immediately below the coupling means 72 is an integral blade stabilizer (IBS 74) which,in itself, may be of a conventional design. The I~S 74 includes a plurality of circumferentially spaced blades 76, such blades being inclined to the axis of the tool in somewhat helical or oblique fashion thereby to provide a cutting or scraping action to assist in maintaining the well bore at the required diameter. Since the outer extremities of these blades contact the well bore, a lateral stabilizing effect is also achieved.
The lowermost end of mandrel 28, i.e. that portion which projects outwardly of the lower end of housing 26, is provided with an enlarged portion 80 and the extreme lower end of this enlarged portion 80 includes an internally threaded coupler portion 82 whereby to allow for direct connection to a drill bit (not shown) by means of the usual tapered threaded connection. This enlarged portion 80 also includes a further integral blade stabilizer 84 having a multiplicity of blades 86 thereon and constructed and f~nctioning in essentially the same manner as the upper IBS 74.
- 10 - ~25~i~95 By virtue of the fact that the integral blade stabilizers 74 and 84 are combined with the shock tool to form effectively a single unit, the overall length of the assembly can be greatly reduced as compared with the prior art arrange~ents and, moreover, the lower IBS 84 is in close proximity to the lower end of the mandrel 28 which projects outwardly of housing 26 thus reducing very substantially the bending moments to which it iB subjected thereby providing the advantageous effects described 10 previously.
Fiqure 4 shows only the upper and lower end portions of an alternative tool arrangement in accordance with the invention. The intermediate portion comprising the shock tool has not been 6hown as it is essentially the same in construction as that described above in conjunction with Figure 3.
The combination tool illustrated in Figure 4 includes a mandrel 28 as before having an enlarged portion 80A formed at the lower end of same with a coupler portion 82A located at the extreme lower end of the assembly and being provided with internal threads for connection to a drill bit, as shown. The enlarged portion 80A, instead of being provided with an integral blade stabilizer as described above, is provided with a reamer assembly 90.
The reamer 90 comprises three equally spaced apart rollers 92 each located in a respective recess 94. Similarly, the upper end portion of the tool is provided with an internally threaded coupler portion 72A similar to that described above ~or connection to the lower end of a drill string. Ju~t below this coupler portion 72A there is provided a further rea~er assembly 96 such reamer assembly 96 being of id~tical construction to the reamer assembly 90 and co~prising reamer rollers 92 disposed in suitable recesses 94. Each reamer roller is rotatably journalled ,2S6095 on an elongated shaft 97, the opposing ends of shaft 97 being mounted in support blocks 98 with the shafts 97 being secured against rotation by pin means 100. The reamer rollers 92 are each provided with rows of spaced apart carbide inserts 102 which, in operation, successively engage the inner wall of the well bore in known fashion thereby to ensure that the well bore diameter is maintained at the correct value while at the same ti~e providing the required degree of lateral stability.
The basic function and operation of the embodiment illustrated in Figs. 4 and 5 and the advantages associated with same are essentially as described previously.
Preferred embodiments of the invention have been described for purposes of illustration. Various modifications within the spirit of the invention and the appended claims will be apparent to those skilled in this art from the above description e.g. those skilled in this art will realize that in many cases the (IBS) or reamer need only be provided on the lower end of the tool i.e. on the mandrel coupling portion.
,.
Claims (10)
1. A combination shock tool and integral blade stabilizer (IBS) or reamer, the combination including a housing defining a longitudinal axis and having a mandrel slidably disposed therein for movement along the longitudinal axis of the housing in response to shock loadings in the axial direction, the mandrel having a diameter less than that of the housing; a portion of the mandrel extending outwardly of one end of said housing, coupling means on an end portion of the outwardly extending mandrel portion for effecting a connection to a drill bit, and further coupling means on said housing for effecting a connection thereof to the lower end of a drill string, and wherein said end portion of said mandrel has an integral blade stabilizer or reamer thereon adapted to engage and be supported by the bore of a well being drilled whereby said outwardly extending mandrel portion is relatively close to a support point as created by engagement of the integral blade stabilizer or reamer on said mandrel end portion with the well bore during use thus helping to avoid high bending moments and deflection in said outwardly extending mandrel portion during use.
2. The combination of claim 1 wherein said coupling means on said mandrel end portion and said integral blade stabilizer or reamer on said mandrel end portion are closely adjacent one another.
3. The combination of claim 2 wherein said housing also carries an integral blade stabilizer or reamer adjacent an end thereof which is opposite said one end from which said mandrel projects outwardly.
4. A drill string bottom hole assembly comprising the integral blade stabilizer or reamer and shock tool combination defined in claim 1 or 2 or 3 in combination with and interposed between a drill bit and a drill string, said drill bit being connected directly to said coupling means on said mandrel and said drill string being connected to said coupling means on said housing.
5. For use in a drill string adjacent a drill bit, a shock tool including a housing defining a longitudinal axis, a mandrel telescopically received within said housing and extending outwardly from one end thereof for sliding movement relative thereto along said axis, said mandrel being of lesser diameter than said housing and being non-rotatable relative to said housing, coupling means on both said mandrel and said housing for interconnecting said shock tool between the drill bit and the drill string, and wherein said mandrel has means thereon adapted to engage the wall of a well bore during use whereby to laterally support said mandrel during use under the influence of loadings applied thereto.
6. The shock tool of claim 5 wherein said means on said mandrel which are adapted to engage the wall of the well bore during use comprise reamer and/or integral blade stabilizer means.
7. The shock tool of claim 5 wherein said coupling means on said mandrel is adapted for securing a drill bit thereto and said means on said mandrel for engaging the wall of the well bore being located immediately adjacent said coupling means such that in use said means for engaging is located closely adjacent a lowermost portion of the outwardly extending mandrel to assist in reducing the bending moments in the mandrel that might otherwise occur in response to said loadings.
8. The shock tool of claim 5, 6 or 7 further including reamer and/or integral blade stabilizer means on said housing for engaging the wall of the well bore during use to laterally support said housing, said last mentioned means being located at that end of said housing which is opposite said one end from which said mandrel projects outwardly.
9. A drill string bottom hole assembly comprising the shock tool as defined in claim 5, 6 or 7 in combination with a drill bit and a drill string, said drill bit being connected directly to said coupling means on said mandrel, and said drill string being connected directly to said coupling means on said housing.
10. Apparatus according to any one of claims 5-7 wherein a fluid passage extends axially through said shock tool to supply, in use, drill fluid to the drill bit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000535096A CA1256095A (en) | 1987-04-21 | 1987-04-21 | Combination shock tool and reamer/integral blade stabilizer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000535096A CA1256095A (en) | 1987-04-21 | 1987-04-21 | Combination shock tool and reamer/integral blade stabilizer |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1256095A true CA1256095A (en) | 1989-06-20 |
Family
ID=4135465
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000535096A Expired CA1256095A (en) | 1987-04-21 | 1987-04-21 | Combination shock tool and reamer/integral blade stabilizer |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1256095A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110700826A (en) * | 2019-10-29 | 2020-01-17 | 徐州盛阳工程机械有限公司 | Mining equipment mining pin |
-
1987
- 1987-04-21 CA CA000535096A patent/CA1256095A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110700826A (en) * | 2019-10-29 | 2020-01-17 | 徐州盛阳工程机械有限公司 | Mining equipment mining pin |
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