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
  • E21B27/00—Containers for collecting or depositing substances in boreholes or wells, e.g. bailers, baskets or buckets for collecting mud or sand; Drill bits with means for collecting substances, e.g. valve drill bits
  • E21B27/02—Dump bailers, i.e. containers for depositing substances, e.g. cement or acids
• • 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
  • E21B29/00—Cutting or destroying pipes, packers, plugs or wire lines, located in boreholes or wells, e.g. cutting of damaged pipes, of windows; Deforming of pipes in boreholes or wells; Reconditioning of well casings while in the ground
  • E21B29/06—Cutting windows, e.g. directional window cutters for whipstock operations

Definitions

• the invention relates to a device for performing milling operations in an underground borehole.
• Such milling operations may include the underreaming of the borehole or the cutting of a window in a well tubular.
• US patent specification No. 5,551,509 and International patent application PCT/GB95/02267 , paragraphior number WO 96/09460 disclose the use of a rotary milling tool which is induced to cut a window in a well casing by pressing a rotating mill downwards along the slant surface of a whipstock which is fixed within the well casing at the location where the window is to be milled.
• UK patent application GB 2,306,985 discloses a mill which is pressed radially into the casing to be milled by means of hydraulic pistons which protrude in a radial direction from the bit motor housing and which are actuated by the elevated pressure of the fluid which simultaneously actuates the hydraulic bit motor.
• the fluid is injected via a coiled tubing which is also used to pull or push the mill in longitudinal direction through the casing during the window cutting operation.
• a further disadvantage of the known milling devices is that the rotating mill exerts a high and variable tangential torque to the device which induces the device to run a a ⁇ m tangential direction.
• the known devices tnerefore need to be guided by guide means, such as a whipstock, nich is fixed firmly inside the casing to avoid the device to run away during the milling operations . It is ar object of the present invention to alleviate the disadvantages of the known milling devices. Summary of tne Invention
• the device thereto comprises a stator housing, a toppling head which is pivotably secured to the housing and equipped with a number of rotatable mills, a drive mechanism for rotating each mill re_at ⁇ ve to the toppling head, and a pivot mechanism for pivoting the toppling head relative to the housing between a contracted position m which each mill is substantially aligned with the stator housing and an extended position in which each mill protrudes at an angle n a lateral direction away from the housing.
• the device is equipped with a pair of contra-rotatable mills that exert opposite tangential torques to tne device which neutralise each other.
• Such contra-rotating mills are able to cut in the casing or otner well tubular a well-defined window having well-polisnec rims which can be sealed off easily.
• the stator housing defines a longitudinal central plane of the device and the drive mechanism comprises a flexible drive shaft which is rotatable about an axis of rotation located in sa d central plane and which forms an input shaft of a gearwheel mechanism within the toppling head, which gearwheel mechanism comprises a pair of contra-rotating output shafts on which the mills are mounted.
• the pivot mechanism allows the toppling nead to pivot relative to the stator housing about a pivot axis which is substantially orthogonal to said central plane, that the output shafts are rotatable about axes of rotation which are parallel to each other and which are located at substantially equal distances from the central plane of the device and that the mills comprise substantially cylindrical bodies on which helical cutting teeth are mounted such that the helix angles of tne cutting teeth are identical but opposite to each other and the cutting teeth of adjacent mills face each other at or near said central plane.
• the drive mechanism comprises a hydraulic Moineau-type motor having a rotor which is rotatably mounted at the upper end of the stator housing and which is secured to the upper end of the flexible drive shaft and the pivot mechanism comprises a hydraulic piston which is slidably arranged within the stator housing between the outlet of the Momeau-motor and a slant upper surface of the toppling head such that m use the elevated pressure of the driving fluid discharged by the motor presses the piston against said slant upper surface of the toppling head thereby inducing the toppling head to pivot towards the extended position thereof.
• the hydraulic piston is slidably arranged around the flexible shaft and the flexible shaft is made of a resilient material and exerts a residual torque to the toppling head which torque induces the toppling head to pivot towards its contracted position m the absence of hydraulic pressure exerted to the piston.
• the device is used as a casing window milling device a cuttings collecting box is secured to the housing beneath the mills and in use the hydraulic driving fluid emerging from the motor flushes cuttings from the mills into the cuttings collecting box.
• Fig. 1 is a side view of the milling device according to the invention with a pair of mills in a retracted position;
• Fig. 2 is a schematic longitudinal sectional view of the milling device of claim 1;
• Fig. 3 snows the milling device of Fig. 2 wherein the mills are extended and are cutting a window in a well casing;
• Fig.4 shows an alternative embodiment of the device according to the invention where the device is used as a wellbore underreamer.
• a milling device having a stator housing 1, a toppling head 2 and a pair of contra-rotating twin mills 3 and 4.
• the twin mills 3 and 4 face each other at a central plane of symmetry of the device which is orthogonal to the plane of drawing of Fig. 1 and which intersects the plane of the drawing at central axis 5.
• the toppling head 2 is pivotably suspended within the stator nousing 1 by a pair of hinge pins 6 which permit the toppling head 2 to rotate about an axis of rotation 7 which is substantially orthogonal to the central axis 5 and the central plane of symmetry of the device.
• the toppling head 2 comprises a gear box (not shown) having a flexible input shaft 9 and a pair of parallel output snafts 8 which carry the mills 3 and 4 and which are rotated relative to the toppling head 2 at equal rotational speeds but m opposite directions, which are illustrated by arrows 10, m response to rotation illustrated oy arrow 12 of the flexible input shaft 7 relative to the stator housing 1 by means of a Moineau-type or other hydraulic or electric motor (not shown) .
• the m_ ⁇ s 3 and 4 comprise substantially cylindrical bodies on wnich helical cutting teeth 11 are mounted at similar DJt opposite pitch angles which teetn mtermesh at the central plane of symmetry of the device.
• a retracte ⁇ transportation mode m which the mills 3 and 4 are substantially parallel to the central axis 5 of the device and ao not protrude from the stator housing 1, as illustrated in Figs. 1 and 2.
• Fig. 2 shows that in the transportat_on mode the flexible shaft 9 obtains a curved shape and tnat the toppling head 2 has a slant upper surface 13 wnich has a top 14 that engages the lower end of a piston 15 which is slidably arranged inside the stator housing 1.
• Fig. 3 snows that liquid discharged by the hydraulic motor flows through an annular opening 16 between the upper end 1 " of the piston 15 and the flexible shaft 9 into the interior 18 of the piston 15, as illustrated by arrows 19.
• a nydraulic pressure difference is created between tne cavity 20 above the piston 15 and the piston interior 18 which induces the piston to slide downwards through tne stator housing 1 as illustrated by arrows 21.
• the downward motion of the piston also pushes the top 14 of the slant upper surface 13 of the toppling head 2 downwards wnich causes the toppling head 2 to pivot about pivot ax s ⁇ as illustrated by arrow 31.
• the mills 3 and 4 pivot together with the toppling head 2 aoout the pivot axis 7 towards their extended position and are simultaneously rotated by the shafts 8 and thereby mill a window 22 in a casing 23 surrounding the device.
• a guide plate 28 m the collecting box 26 serves to reduce the speed of the liquid so that the cuttings are allowed to be separated by gravity and/or magnetic forces from the liquid and are deposited at the bottom of the box, whereas the liquid is discharged via an opening 29 at the top of tne box 26 into the annulus surrounding the device .
• the mills 3 and 4 are cutting the window 22 in the well casing 23 the device is pulled upwards through the casing as illustrated by arrows 30 by means of a piston (not shown) above the device until the window 22 has the desired length.
• the device is suspended within the casing 23 from a coiled tubing or drill string (not shown) and that the coiled tubing or drill string is gradually pulled up during the milling operations whilst the piston above the device ensures that the device is moved up through the casing 23 at an accurately defined speed and over an accurately defined distance .
• the mills 3 and 4 The balanced forces exerted by the mills 3 and 4 to the stator housing allow the device to mill a straight and well defined window in the well casing 23 m a quick and accurate manner and without leaving cuttings in the casing interior.
• the mills may have a non-cylindrical shape, such as a frusto-conical shape. In such case it is preferred that the axes of rotation of the mills intersect each other at the central plane of the device.
• Fig. 4 shows an embodiment of the device according to the invention where the device is used for underreammg of an uncased underground borehole.
• the upper part of the device shown m Fig. 4 is similar to the upper part of the device shown in
• the device shown in Fig. 4 however contains no cuttings collection box and has a stator housing 1 which is rotated about the central axis 5 as is illustrated by arrow 40.
• the device of Fig. 4 is equipped with a single mill 4 which underreams the wellbore 41 as a result of the simultaneous rotation of the stator housing and of the mill 4 relative to the toppling head 2.
• the toppling head 2 is extended and retracted in the same way as described with reference to Figs. 1-3.
• the flexible shaft 9 is connected to the output shaft 8 via a gearbox in the toppling head 2, or may alternatively be integrated with the output shaft 8. If desired the underreamer device shown m Fig. 4 may be equipped with a pair of contra-rotatable twin mills 4 similar to those shown in Figs. 1-3.

Landscapes

• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (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)
• Earth Drilling (AREA)
• Milling Processes (AREA)
• Placing Or Removing Of Piles Or Sheet Piles, Or Accessories Thereof (AREA)

Priority Applications (1)

Applications Claiming Priority (4)

Publications (2)

Family

ID=8234868

Family Applications (1)

Country Status (12)

Cited By (2)

Families Citing this family (19)

Family Cites Families (16)

• 1999
  • 1999-06-09 ID IDW20002563A patent/ID27015A/id unknown
  • 1999-06-09 CA CA002334150A patent/CA2334150A1/en not_active Abandoned
  • 1999-06-09 DE DE69905364T patent/DE69905364D1/de not_active Expired - Lifetime
  • 1999-06-09 OA OA1200000337A patent/OA11626A/en unknown
  • 1999-06-09 EP EP99936456A patent/EP1088151B1/de not_active Expired - Lifetime
  • 1999-06-09 WO PCT/EP1999/004039 patent/WO1999064715A1/en active IP Right Grant
  • 1999-06-09 EA EA200100019A patent/EA002048B1/ru not_active IP Right Cessation
  • 1999-06-09 BR BR9911083-0A patent/BR9911083A/pt not_active IP Right Cessation
  • 1999-06-09 CN CN99807158A patent/CN1119499C/zh not_active Expired - Fee Related
  • 1999-06-09 AU AU51550/99A patent/AU741468B2/en not_active Ceased
  • 1999-06-09 NZ NZ508288A patent/NZ508288A/xx unknown
• 2000
  • 2000-12-08 NO NO20006247A patent/NO314855B1/no not_active IP Right Cessation

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events