Turbine for down-hole drilling

Information

  • Patent Grant
  • 6527513
  • Patent Number
    6,527,513
  • Date Filed
    Wednesday, January 31, 2001
    23 years ago
  • Date Issued
    Tuesday, March 4, 2003
    21 years ago
Abstract
A turbine (4) suitable for use in down-hole drilling and the like, and comprising a tubular casing (11) enclosing a chamber (18) having rotatably mounted therein a rotor (19). The rotor (19) comprises at least one turbine wheel blade arrays (30a) with an annular array of angularly distributed blades (30), and a generally axially extending inner drive fluid passage (14) generally radially inwardly of said rotor (19). The casing (11) also has respective generally axially extending outer drive fluid passage (16) associated with said at least one turbine wheel blade array (30a), and one of the inner and the outer drive fluid passages (14, 16) constitute a drive fluid supply passage and is provided with outlet nozzles (17) formed and arranged for directing at least one jet of drive fluid onto the blade drive fluid receiving faces (31) for imparting rotary drive to said rotor (19). The other of the inner and the outer drive fluid passages (14, 16) constitutes a drive fluid exhaust passage and is provided with exhaust aperture (28) for exhausting drive fluid from the turbine (4).
Description




The present invention relates to turbines suitable for down-hole applications such as bore-hole drilling and driving various down-hole tools.




Conventional turbines for down-hole use generally comprise a longitudinally extending turbine stage array in which the drive fluid passes substantially axially through a multiplicity of turbine stages connected in series. Particular disadvantages of this type of arrangement include relatively low efficiency due to the rapid increase of efficiency losses with increasing number of turbine stages, and the considerable length required to achieve any useful torque levels. Typical commercially available turbines of this type having of the order of 100 to 200 turbine stages, have a length of around 20 m and longer. Such a length presents considerable restrictions on the use of such turbines in non-rectilinear drilling e.g. directional drilling situations, because of restrictions on minimum radius of curvature of kick-off which can be used, as well as in drilling operations using coiled tubing because of the large lubricators required to accommodate the turbine together with the drilling tools and other equipment required. This in turn gives rise to substantial practical problems in the positioning of the injector at a suitable height, above the lubricator.




It is an object of the present invention to avoid or minimise one or more of the above disadvantages and/or problems.




It has now been found that a compact, high power, turbine can be achieved by means of a combined redial impulse and drag turbine in which substantially increased turbine drive output is obtained within a given length of turbine.




The present invention provides a turbine suitable for use in down-hole drilling and the like, and comprising a tubular casing enclosing a chamber having rotatably mounted therein a rotor comprising at least one turbine wheel blade array with an annular array of angularly distributed blades orientated with drive fluid receiving faces thereof facing generally rearwardly of a forward direction of rotation of the rotor, and a generally axially extending inner drive fluid passage generally radially inwardly of said rotor, said casing having a generally axially extending outer drive fluid passage, one of said inner and outer drive fluid passages constituting a drive fluid supply passage and being provided with at least one outlet nozzle formed and arranged for directing at least one jet of drive fluid onto said blade drive fluid receiving faces of said at least one blade array as said blades traverse said nozzle for imparting rotary drive to said rotor, the other constituting a drive fluid exhaust passage and being provided with at least one exhaust aperture for exhausting drive fluid from said at least one turbine wheel blade array.




Preferably the turbine has a plurality, advantageously, a multiplicity, of said turbine wheel means disposed in an array of parallel turbine wheels extending longitudinally along the central rotational axis of the turbine with respective parallel drive fluid supply jets.




In a particularly preferred aspect the present invention provides a turbine suitable for use in down-hole drilling and the like, and comprising a tubular casing enclosing a chamber having rotatably mounted therein a rotor having at least two turbine wheel blade arrays each with an annular array of angularly distributed blades orientated with drive fluid receiving faces thereof facing generally rearwardly of a forward direction of rotation of the rotor, and a generally axially extending inner drive fluid passage generally radially inwardly of each said turbine wheel blade array, said casing having a respective generally axially extending outer drive fluid passage associated with each said turbine wheel blade array, one of said inner and outer drive fluid passages constituting a drive fluid supply passage and being provided with at least one outlet nozzle formed and arranged for directing at least one jet of drive fluid onto said blade drive fluid receiving faces as said blades traverse said at least one nozzle for imparting rotary drive to said rotor, the other constituting a drive fluid exhaust passage and being provided with at least one exhaust aperture for exhausting drive fluid from said turbine wheel blade arrays, neighbouring turbine wheel blade arrays being axially spaced apart from each other and provided with drive fluid return flow passages therebetween connecting the exhaust passage of an upstream turbine wheel blade array to the supply passage of a downstream turbine wheel blade array for serial interconnection of said turbine wheel blade arrays.




Instead of, or in addition to providing a said inner or outer drive fluid passage for exhausting of drive fluid from the chamber, there could be provided exhaust apertures in axial end wall means of chamber, though such an arrangement would generally be less preferred due to the difficulties in manufacture and sealing.




In yet another variant of the present invention, both the drive fluid supply and exhaust passage means could be provided in the casing (i.e. radially outwardly of the rotor) with drive fluid entering the chamber from the supply passage via nozzle means to impact the turbine blade means and drive them forward, and then exhausting from the chamber via outlet apertures angularly spaced from the nozzle means in a downstream direction, into the exhaust passages.




Thus essentially the turbine of the present invention is of a radial (as opposed to axial) flow nature with motive fluid moves between radially (as opposed to axially) spaced apart positions to drive the turbine blade means. This enables the performance, in terms of torque and power characteristics, of the turbines of the present invention to be readily varied by simply changing the nozzle size—without at the same time having to redesign and replace all the turbine blades as is generally the case with conventional axial flow turbines when any changes in fluid velocity and/or fluid density are made. Thus, for example, reducing the nozzle size will (assuming constant flow rate) increase the (fluid jet) flow velocity thereby increasing torque. This will also increase the operating speed of the turbine and thereby the power, as well as increasing back pressure. Similarly increasing flow rate while keeping nozzle size constant will also increase the (fluid jet) flow velocity thereby increasing torque as well as giving an increase in the operating speed of the turbine and thereby the power and increasing back pressure. Alternatively, increasing the nozzle size while keeping the (fluid jet) flow velocity constant—by increasing the flow rate, would increase torque and power without increasing the turbine speed or back pressure. If desired, torque can also be increased by increasing the density of the drive fluid (assuming constant fluid flow rate and velocity) which increases the flow mass.




It will be appreciated that individual nozzle size can be increased longitudinally and/or angularly of the turbine, and that the number of nozzles for the or each turbine wheel blade array can also be varied.




The turbine blades can also have their axial extent longitudinally of the turbine increased so as to increase the parallel mass flow of motive fluid through the or each turbine wheel array, without suffering the severe losses encountered with conventional multi-stage turbines comprising axially extending arrays of axially driven serially connected turbine blade arrays.




Another advantage of the turbines of the present invention that may be mentioned is the circumferential fluid velocity distribution over the turbine blades is, due to the generally radial disposition of the said blades, substantially constant and thus very efficient in comparison with an axial turbine where the velocity distribution varies over the length of the blade and thus losses are caused through hydrodynamic miss-match of fluid velocity and circumferential blade velocity.




The turbines of the present invention also have some significant advantages over positive displacement motors in that they can use relatively viscous and/or dense drive fluids such as more or less heavily weighted drilling muds e.g. high density drilling muds weighted with bentonite or barytes, which are required, for example, for high pressure wells.




Another important advantage over conventional turbines for down-hole use is that the motors of the present invention are substantially shorter for a given output power (even when taking into account any gear boxes which may be required for a given practical application). Typically a conventional turbine may have a length of the order of 15 to 20 meters, whilst a comparable turbine of the present invention would have a length of only 2 to 3 meters for a similar output power. This has very considerable benefits such as reduced manufacturing costs, easier handling, and smaller radius borehole deviation negotiation ability.




Yet another advantage that may be mentioned is that the relatively high overall efficiency of turbines of the present invention allows the use of smaller size (diameter) turbines than has previously been possible. With conventional down-hole turbines, the so called “slot losses” which occur due to drive fluid leakage between the tips of the turbine blades and the casing due to the need for a finite clearance therebetween, become proportionately greater with reduced turbine diameter. In practice this results in a minimum effective diameter for a conventional turbine of the order of around 10 cm. With the increased overall efficiency of the turbines of the present invention it becomes practical significantly to reduce the turbine diameter, possibly as low as 3 cm.




In one, preferred, form of the invention the outer passage means serves to supply the drive fluid to the turbine wheel means via nozzle means, preferably formed and arranged so as to project a drive fluid jet generally tangentially of the turbine wheel means, and the inner passage means serves to exhaust drive fluid from the chamber, with the inner passage means conveniently being formed in a central portion of the rotor. In another form of the invention the inner passage means is used to supply the drive fluid to blade means mounted on a generally annular turbine wheel means. In this case the nozzle means are generally formed and arranged to project a drive fluid jet more or less radially outwardly, and the blade means drive fluid receiving face will tend to be oriented obliquely of a radial direction so as to provide a forward driving force component as the jet impinges upon said face.




In principle there could be used just a single nozzle means. Generally though there is used a plurality of angularly distributed nozzle means e.g. 2, 3 or 4 at 180°, 120° or 90° intervals, respectively. In the preferred form of the invention, the nozzle means are preferably formed and arranged to direct drive fluid substantially tangentially relative to the blade means path, but may instead be inclined to a greater or lesser extent radially inwardly or outwardly of a tangential direction e.g. at an angle from +5° (outwardly) to −20° (inwardly), preferably 0° to −10°, relative to the tangential direction—corresponding to from 95 to 70°, preferably 90 to 80°, relative to a radially inward direction.




As noted above the power of the motor may be increased by increasing the motive fluid energy transfer capacity of the turbine, in parallel—e.g. by having larger cross-sectional area and/or more densely angularly distributed nozzles. The driven capacity of the turbine may be increased by inter alia increasing the angular extent of the nozzle means in terms of the size of individual nozzle means around the casing, and/or by increasing the longitudinal extent of the nozzle means in terms of longitudinally extended and/or increased numbers of longitudinally distributed nozzle means. In general though the outlet size of individual nozzle means should be restricted relative to that of the drive fluid supply passage, in generally known and calculable manner, so as to provide a relative high speed jet flow. The jet flow velocity is generally around twice the linear velocity of the turbine (at the fluid jet flow receiving blade portion) (see for example standard text books such as “Fundamentals of Fluid Mechanics” by Bruce R Munson et al published by John Wiley & Sons Inc). Typically, with a 3.125 inch (8 cm) diameter turbine of the invention there would be used a nozzle diameter of the order of from 0.1 to 0.35 inches (0.25 to 0.89 cm).




The size of the blade means including in particular the longitudinal extent of individual blade means and/or the number of longitudinally distributed blade means, will generally be matched to that of the nozzle means. Preferably the blade means and support therefor are formed and arranged so that the unsupported length of blade means between axially successive supports is minimised whereby the possibility of deformation of the blade means by the drive fluid jetting there onto is minimised, and in order that the thickness of the blade means walls may be minimised. The number of angularly distributed individual blade means may also be varied, though the main effect of an increased number is in relation to smoothing the driving force provided by the turbine. Preferably there is used a multiplicity of more or less closely spaced angularly distributed blade means, conveniently at least 6 or 8, advantageously at least 9 or 12 angularly distributed blade means, for example from 12 to 24, conveniently from 15 to 21, angularly distributed blade means.




It will also be appreciated that various forms of blade means may be used. Thus there may be used more or less planar blade means. Preferably though there is used a blade means having a concave drive fluid receiving face, such a blade means being conveniently referred to hereinafter as a bucket means. The bucket means may have various forms of profile, and may have open sides (at each longitudinal end thereof). Conveniently the buckets are of generally part cylindrical channel section profile (which may be formed from cylindrical tubing section). Optimally, however, the bucket should be aerodynamically/hydrodynamically shaped to prevent detachment of the boundary layer and to produce a less turbulent flow through the turbine blade array and thus reduce parasitic pressure drop across the blade array.




Various forms of blade support means may be used in accordance with the present invention. Thus, for example, the support means may be in the form of a generally annular structure with longitudinally spaced apart portions between which the blade means extend. Alternatively there may be used a central support member, conveniently in the form of a tube providing the inner drive fluid passage means, with exhaust apertures therein through which used drive fluid from the chamber is exhausted, the central support member having radially outwardly projecting and axially spaced apart flanges or fingers across which the blade means are supported. Alternatively the blade means may have root portions connected directly to the central support member.




The turbines of the present invention may typically have normal running speeds of the order of 3,000 to 10,000, for example, from 5,000 to 8,000, rpm. In order to increase torque they are preferably used with gear box means. In general there may be used gear box means providing at least 5:1, preferably at least 10:1, speed reduction. Conveniently there is used a serially interconnected array of epicyclic gear boxes each having a gearing ratio of the order of 3:1 to 4:1, for example 2 gear boxes each having a ratio of 3:1 would provide an overall ratio of 9:1. Preferably there is used an epicyclic gear box with typically 3 or 4 planet wheels mounted in a rotating cage support used to provide an output drive in the same sense as the input drive to the sun wheel, usually clockwise, so that the output drive is also clockwise. Preferably there is used a ruggedised gear box means with a substantially sealed boundary lubrication system, advantageously with a pressure equalisation system for minimizing ingress of drilling mud or other material from the borehole into the gear box interior.




In a further aspect the present invention provides a turbine drive system suitable for use in downhole drilling and the like comprising at least one turbine of the invention drivingly connected to at least one reducing gearbox.




In yet another aspect the present invention provides a bottom hole assembly comprising at least one turbine of the invention drivingly connected to a tool, preferably via at least one reducing gearbox.




In a still further aspect the present invention provides a drilling apparatus comprising a drill string, preferably comprising coiled tubing, and a bottom hole assembly of the invention wherein the tool comprises a drill bit.











Further preferred features and advantages of the invention will appear from the following detailed description given by way of example of some preferred embodiments illustrated with reference to the accompanying drawings in which:





FIG. 1

is schematic side elevation of the downhole components of a drilling apparatus with a turbine drive system of the present invention;





FIG. 2

is a longitudinal section of part of the downhole drive system of the apparatus of

FIG. 1

showing one of the turbine power units therein (including

FIG. 2A

which is a transverse section of the turbine unit) but with bearing and seal details omitted for greater clarity); and





FIG. 3

is a partly sectioned side elevation of the main part of the turbine rotor without the bucket means;





FIGS. 4 and 5

are transverse sections of the rotor of

FIG. 3

but with the bucket means in place;





FIG. 6

is a transverse section of an epicyclic gear system used in the apparatus of

FIG. 1

;





FIG. 7

is a detail view showing the connection between the upper and lower turbine units;





FIGS. 8-12

show another preferred embodiment in which:

FIG. 8

is a longitudinal section corresponding generally to that of

FIG. 2

;





FIGS. 9 and 10

are transverse sections in the planes


{overscore (IX)}





{overscore (IX)}


and


{overscore (X)}





{overscore (X)}


indicated in

FIG. 8

;





FIG. 11

is a perspective view showing the principal parts of the turbine of

FIGS. 8-10

with the outer casing removed; and





FIG. 12

is a corresponding view with part of the stator removed to reveal the rotor.












FIG. 1

shows the downhole end of a borehole drilling apparatus drill string comprising a bottom-hole assembly


1


connected to a coiled tubing drilling pipe


2


. The principal parts of the assembly


1


are, in order, a top sub


3


, an upper turbine


4


, a lower turbine


5


, an upper gear box


6


, a lower gear box


7


, a bearing pack


8


, a bottom sub


9


, and a drill bit


10


. As shown in more detail in

FIG. 2

, the upper turbine


4


comprises an outer casing


11


in which is fixedly mounted a stator


12


having a generally lozenge-section outer profile


13


defining with the outer casing


11


two diametrically opposed generally semi-annular drive fluid supply passages


14


therebetween. At the clockwise end


15


of each passage


14


is provided a conduit


16


providing a drive fluid supply nozzle


17


directed generally tangentially of a cylindrical profile chamber


18


defined by the stator


12


inside which is disposed a rotor


19


.




The rotor


19


is mounted rotatably via suitable bushings and bearings (not shown) at end portions


20


,


21


which project outwardly of each end


22


,


23


of the stator


12


. As shown in

FIGS. 3

to


5


, the rotor


19


comprises a tubular central member


24


which is closed at the upper end portion


20


and, between the end portions


20


,


21


, has a series of spaced apart radially inwardly slotted


25


flanges


26


in which are fixedly mounted cylindrical tubes


27


(see

FIGS. 4 & 5

) extending longitudinally of the rotor.

FIG. 4

is a transverse section through a flange


26


which supports the base and sides of the tubes


27


thereat.

FIG. 5

is a transverse section of the rotor


19


between successive flanges


26


and shows a series of angularly spaced exhaust apertures


28


extending radially inwardly through the tubular central member


24


to a central axial drive fluid exhaust passage


29


. Between the flanges


26


, the tubes


27


are cut-away to provide angularly spaced apart series of semi-circular channel section buckets


30


forming, in effect, a series of turbine wheels


30




a


interspersed by supporting flanges


26


. The buckets


30


are oriented so that their concave inner drive fluid receiving faces


31


face anti-clockwise and rearwardly of the normal clockwise direction of rotation of the turbine rotor


19


in use of the turbine. The buckets


30


are disposed substantially clear of the central tubular member


24


so that drive fluid received thereby can flow freely out of the buckets


30


and eventually out of the exhaust apertures


28


. With the rotor


19


being enclosed by the stator


12


it will be appreciated that in addition to the “impulse” driving force applied to a bucket


30


directly opposite a nozzle


17


by a jet of drive fluid emerging therefrom, other buckets will also receive a “drag” driving force from the rotating flow of drive fluid around the interior of the chamber


18


before it is exhausted via the exhaust apertures


28


and passage


29


.




The rotor


19


of the upper turbine


4


is drivingly connected via a hexagonal (or similar) coupling


32


to the rotor of the lower turbine


5


which is substantially similar to the upper turbine


4


and is in turn drivingly connected via the upper and lower gear boxes


6


,


7


and suitable couplings


33


,


34


,


35


to the bottom sub


9


which has mounted therein a drill bit


10


. As shown in

FIG. 6

the gear boxes


6


,


7


are of epicyclic type with a driven sun wheel


36


, a fixed annulus


37


, and


4


planet wheels


38


mounted in a cage


39


which provides an output drive in the same direction as the direction of rotation of the driven sun wheel


36


.




In use of the apparatus, the motive fluid enters the top sub


3


and passes down into the semi-annular supply passages


14


of the upper turbine


4


between the outer casing


11


and stator


12


thereof, whence it is jetted via the nozzles


17


into the chamber


18


in which the rotor


19


is mounted so as to impact in the buckets


30


thereof. The motive fluid is exhausted out of the chamber


18


via the exhaust apertures


28


down the central exhaust passage


29


inside the central rotor member


24


until it reaches the lower end


24




a


thereof engaged in the hexagonal coupling


32


, drivingly connecting it to the closed upper end


24




b


of the rotor


19


of the lower turbine


5


. The fluid then passes radially outwards out of apertures


32




a


provided in the hexagonal coupling


32


of the lower turbine and then passes along into the semi-annular supply passages


14


of the lower turbine


5


between the outer casing


11


and stator


12


thereof to drive the lower turbine


5


in the same way as the upper turbine


4


. It will be appreciated that the lower turbine is effectively driven in series with the upper turbine. This is though quite effective and efficient given the highly efficient “parallel” driving within each of the upper and lower turbines. The drilling mud motive fluid exhausted from the lower turbine then passes along central passages extending through the interior of the gear boxes


6


,


7


, and bottom sub


9


whose upper end extends through the interior of the bearing pack


8


, to emerge at the drill bit


10


in the usual way.




With a single turbine unit as shown in the drawings suitable for use in a 3.125 inch (8 cm) diameter bottom hole assembly and a drive fluid supply pressure of 70 kg/cm


2


there may be obtained an output torque of the order of 2.5 m.kg at 6000 rpm. With a 3:1 ratio gearing down there can then be obtained an output torque of the order of 8 m.kg at 2000 rpm. With a system as illustrated there can be obtained an output torque of the order of 25 m.kg at 600 rpm which is comparable with the performance of a similarly sized conventional Moineau motor or conventional downhole turbine having a diameter of 4 ¾″ (12 cm) and 50 ft (15.24 m) length.




It will be appreciated that various modifications may be made to the abovedescribed embodiments without departing from the scope of the present invention. Thus for example the profiles of the buckets


30


and their orientation, and the configuration and orientation of the nozzles


17


, may all be modified so as to improve the efficiency of the turbine.




The embodiment of

FIGS. 8-12

is generally similar to that of

FIGS. 2-5

, comprising an outer casing


41


in which is fixedly mounted a stator


42


having a generally lozenge-section outer profile


43


defining with the outer casing


41


four angularly distributed generally segment-shaped drive fluid supply passages


44


therebetween. At the clockwise end


45


of each passage


44


is provided a drive fluid supply conduit


46


providing a drive fluid supply nozzle


47


directed generally tangentially of a cylindrical profile chamber


48


defined by the stator


42


inside which is disposed a rotor


49


.




The rotor


49


is mounted rotatably via suitable bushings and bearings


50


,


51


at the end portions


52




a,




52




b


which project outwardly of each end


53




a,




53




b


of the stator


42


. As shown in

FIGS. 9

,


10


and


12


the rotor


49


comprises an elongate tubular central member


54


which has a series of axially spaced apart radially inwardly slotted


55


flanges


56


in which are fixedly mounted four axially spaced apart sets of cylindrical tube profile or aerodynamically/hydrodynamically shaped turbine blades


57


providing an array of four turbine wheel blade arrays


58


A-D extending longitudinally along the central rotational axis of the rotor


49


.

FIG. 9

is a transverse section through a turbine wheel blade array


58


A and shows four nozzles


47


for directing jets of drive fluid into the blades


57


and a series of six angularly spaced apart exhaust apertures


59


′ extending radially inwardly through the tubular central member


54


to an inner drive fluid exhaust passage


59


. Inside the tubular central member


54


is provided a spindle member


60


mounting a series of annular sealing members


61


A-C for isolating lengths of inner drive fluid exhaust passage


59


′ A-C, from each other. A further length of inner drive fluid exhaust passage


59


′D is isolated from the preceding length


59


′C by an integrally formed end wall


62


.




Between the opposed flanges


56


′,


56


″ of each pair of successive turbine wheel blade arrays


58


A-D, the stator


42


is provided with relatively large apertures


63


which together with apertures


64


in the tubular central member


54


provide drive fluid return flow passages


65


for conducting drive fluid exhausted from the exhaust apertures


59


of an upstream turbine wheel blade array


58


A into the respective inner drive fluid exhaust passage


59


′, to the drive fluid supply passage


44


of a turbine wheel blade array


58


B immediately downstream thereof for serial interconnection of said turbine wheel blade arrays


58


A,


58


B. As shown in

FIG. 10

, the apertures


64


in the tubular central member


54


are orientated generally tangentially in order to improve fluid flow efficiency.




As may be seen from the drawings, the drive fluid supply conduit


46


are in the form of relatively large slots having an axial extent almost equal to that of the turbine blades


57


so that the fluid flow capacity and power of each turbine wheel blade array


58


A etc is actually similar to that of each of the (serially interconnected—see

FIG. 2B

) turbine units


4


,


5


, with its series of


12


turbine wheel blade arrays connected in parallel (as illustrated in

FIG. 3

) of the first described embodiment.




In order to isolate the drive fluid supply passages


44


of successive turbine wheel blade arrays


58


A,


58


B etc from each other, the flanges


56


supporting the turbine blades


57


are provided with low-friction labyrinth seals


66


around their circumference.




As will be apparent from

FIG. 8

, the close and compact coupling and arrangement of the four turbine wheel blade arrays


58


A-D, requires a much smaller amount of bearings and seals thereby considerably reducing frictional losses as compared with the type of arrangement illustrated in

FIGS. 23

, as well as considerably reduced length, thereby providing a much higher torque and power output for a given length and size of turbine, as compared with previously known turbines.




In other respects the turbine of

FIGS. 8-12

is generally similar to that of

FIGS. 2-5

. Thus the turbine blades


57


form concave buckets


67


oriented so that their concave inner drive fluid receiving faces


68


face anti-clockwise and rearwardly of the normal clockwise direction of rotation of the turbine rotor


49


in use of the turbine drive and fluid received thereby can flow freely out of the buckets


67


and eventually out of the exhaust apertures


59


.




In use of the apparatus, the motive/drive fluid enters the top sub


3


and passes down into the supply passage


44


of the first turbine wheel blade array


58


A between the outer casing


41


and stator


42


thereof, whence it is jetted via the nozzles


47


into the chamber


48


in which the rotor


49


is mounted so as to impact in the buckets


67


thereof. The motive fluid is exhausted out of the chamber


48


via the exhaust apertures


59


into the central exhaust passage


59


′ inside the central tubular member


54


whereupon it is returned radially outwardly via the drive fluid return flow passage


65


to the drive fluid supply passage


44


of the next turbine wheel blade array


58


B, whereupon the process is repeated.




With a four stage integrated turbine unit as shown in

FIGS. 8

to


12


for use in a 3.125 inch (8 cm) diameter bottom hole assembly and a drive fluid mass flow of 110 US gallons per minute (416 litres per minute) and a supply pressure of 1000 psi (70 kg/cm


2


) there may be obtained an output of 8200 rpm and 17.4 ft-lbs (2.4 m.kg). With a 12:1 ratio gearing down there can be obtained an output torque of 208.4 ft-lbs (28.8 m.kg) at 683 rpm, which is comparable with the performance of a similarly diametrically sized conventional Moineau motor but of twice the length of a conventional downhole turbine of greater diameter and more than four times the length.



Claims
  • 1. A turbine suitable for use in down-hole drilling, and comprising a tubular casing enclosing a chamber having rotatably mounted therein a rotor comprising at least one turbine wheel blade array with an annular array of angularly distributed blades orientated with drive fluid receiving faces thereof facing generally rearwardly of a forward direction of rotation of the rotor, and a generally axially extending inner drive fluid passage generally radially inwardly of said rotor, said casing having a generally axially extending outer drive fluid passage, one of said inner and outer drive fluid passages constituting a drive fluid supply passage and being provided with at least one outlet nozzle formed and arranged for directing at least one jet of drive fluid onto said blade drive fluid receiving faces of said at least one blade array as said blades traverse said nozzle for imparting rotary drive to said rotor, the other constituting a drive fluid exhaust passage and being provided with at least one exhaust aperture for exhausting drive fluid from said at least one turbine wheel blade array.
  • 2. A turbine as claimed in claim 1 wherein said turbine has an array of at least two turbine wheel blade arrays, which array extends longitudinally along the central rotational axis of the turbine, and wherein each one of said turbine wheel blade arrays has associated therewith a respective said outlet nozzle for directing at least one jet of drive fluid onto said blade drive fluid receiving faces of said turbine wheel blade array.
  • 3. A turbine as claimed in claim 2 wherein neighbouring turbine wheel blade arrays are axially spaced apart from each other and provided with drive fluid return flow passages therebetween connecting the exhaust passage of an upstream turbine wheel blade array to the supply passage of a downstream turbine wheel blade array for serial interconnection of said turbine wheel blade arrays.
  • 4. A turbine as claimed in claim 3 wherein each said turbine wheel blade arrays has associated therewith a plurality of angularly distributed outlet nozzles for directing a plurality of jets of drive fluid onto said blade drive fluid receiving faces of said turbine wheel blade array.
  • 5. A turbine as claimed in claim 4 wherein said outlet nozzles are orientated at an angle of from 95 to 70° relative to a radially inward direction.
  • 6. A turbine as claimed in claim 5 wherein said outlet nozzles are orientated tangentially relative to said turbine wheel blade array.
  • 7. A turbine as claimed in claim 5 wherein said exhaust apertures are orientated at an angle of from 95 to 70° relative to radially inward direction.
  • 8. A turbine as claimed in claim 7 wherein said exhaust apertures are orientated tangentially relative to said turbine wheel blade array.
  • 9. A bottom hole assembly comprising at least one turbine according to claim 3, which turbine is drivingly connected to a tool.
  • 10. A bottom hole assembly according to claim 9, wherein said turbine is drivingly connected to said tool via at least one reducing gearbox.
  • 11. A drilling apparatus comprising a drill string, and a bottom hole assembly according to claim 9 wherein the tool comprises a drill bit.
  • 12. A drilling apparatus according to claim 11, wherein said drill string comprises coiled tubing.
  • 13. A turbine as claimed in claim 3 wherein each said turbine wheel blade array has at least 6 turbine blades.
  • 14. A turbine as claimed in claim 3 wherein said turbine blades have an accurate channel section profile.
  • 15. A turbine as claimed in claim 3 wherein each said turbine wheel blade array comprises axially spaced apart radially outwardly extending turbine blade supports for mounting of angularly distributed axially extending turbine blade members providing said turbine blades of each said turbine wheel blade array.
  • 16. A turbine as claimed in claim 3 wherein is provided at least one reducing gearbox and said turbine is drivingly connected to said at least one gearbox.
  • 17. A turbine as claimed in claim 16 wherein said at least one gearbox is an epicyclic gear box.
  • 18. A turbine as claimed in claim 17 wherein said at least one gearbox has a reduction ratio of at least 5:1.
  • 19. A turbine as claimed in claim 3 drivingly coupled with at least one further said turbine.
  • 20. A turbine as claimed in claim 2 wherein said outer drive fluid passage is provided with said outlet nozzles, and said inner drive fluid passage is provided with exhaust apertures.
  • 21. A turbine as claimed in claim 2 wherein said inner drive fluid passage is provided with said outlet nozzles, and said outer drive fluid passage is provided with exhaust apertures.
  • 22. A turbine suitable for use in down-hole drilling, and comprising a tubular casing enclosing a chamber having rotatably mounted therein a rotor comprising at least one turbine wheel blade array with an annular array of angularly distributed blades orientated with drive fluid receiving faces thereof facing generally rearwardly of a forward direction of rotation of the rotor, and a generally axially extending drive fluid supply passage disposed in a location selected from: radially inwardly of said rotor, and within said casing, and provided with at least one outlet nozzle formed and arranged for directing at least one jet of drive fluid onto said blade drive fluid receiving faces as said blades traverse said at least one nozzle for imparting rotary drive to said rotor, and said chamber having an axial end wall provided with an exhaust aperture for exhausting drive fluid from the turbine.
  • 23. A turbine suitable for use in down-hole drilling, and comprising a tubular casing enclosing a chamber having rotatably mounted therein a rotor comprising at least one turbine wheel blade array with an annular array of angularly distributed blades orientated with drive fluid receiving faces thereof facing generally rearwardly of a forward direction of rotation of the rotor, and a generally axially extending inner drive fluid passage generally radially inwardly of said rotor, said casing having generally axially extending, angularly spaced apart, drive fluid supply and exhaust passages, said drive fluid supply passage being provided with at least one outlet nozzle formed and arranged for directing at least one jet of drive fluid onto said blade drive fluid receiving faces as said blades traverse said nozzle for imparting rotary drive to said rotor, and the drive fluid exhaust passage being provided with an exhaust aperture for exhausting drive fluid from the turbine.
  • 24. A turbine suitable for use in down-hole drilling, and comprising a tubular casing enclosing a chamber having rotatably mounted therein a rotor having at least two turbine wheel blade arrays each with an annular array of angularly distributed blades orientated with drive fluid receiving faces thereof facing generally rearwardly of a forward direction of rotation of the rotor, and a generally axially extending inner drive fluid passage generally radially inwardly of each said turbine wheel blade array, said casing having a respective generally axially extending outer drive fluid passage associated with each said turbine wheel blade array, one of said inner and outer drive fluid passages constituting a drive fluid supply passage and being provided with at least one outlet nozzle formed and arranged for directing at least one jet of drive fluid onto said blade drive fluid receiving faces as said blades traverse said at least one nozzle for imparting rotary drive to said rotor, the other constituting a drive fluid exhaust passage and being provided with at least one exhaust aperture for exhausting drive fluid from said turbine wheel blade arrays, neighbouring turbine wheel blade arrays being axially spaced apart from each other and provided with drive fluid return flow passages therebetween connecting the exhaust passage of an upstream turbine wheel blade array to the supply passage of a ownstream turbine wheel blade array for serial interconnection of said turbine wheel blade arrays.
Priority Claims (1)
Number Date Country Kind
9816607 Jul 1998 GB
CROSS REFERENCES TO RELATED APPLICATIONS

This application is a continuation in part of copending application serial number PCT/GB99/02450 titled “Drilling Turbine” which designated the United States and had an international filing date of Jul. 27, 1999. Demand was timely filed. Application serial number PCT/GB99/02450 had an international publication number of WO 00/08293, an international publication date of Feb. 17, 2000, and a priority date of Jul. 31, 1998 from GB 9816607.7.

US Referenced Citations (4)
Number Name Date Kind
2371248 McNamara Mar 1945 A
2750154 Boice Jun 1956 A
3966369 Garrison Jun 1976 A
5098258 Barnetche-Gonzales Mar 1992 A
Continuation in Parts (1)
Number Date Country
Parent PCT/GB99/02450 Jul 1999 US
Child 09/773698 US