RU2088740C1 - Device for hole casing in insecure rocks - Google Patents

Abstract

FIELD: mining industry. SUBSTANCE: device includes casing string and drill string. The latter is accommodated inside the casing string for combined rotation and disconnection. Casing string is made in form of concentric arrangement of internal and external strings. Internal string is made for extension towards hole bottom and fixing in lower position with respect to external string and with seat in hollow lower part. The device has check valves located in upper part of internal string and drills unit located on seat of internal string. Drilled unit is made in form of shoe with axial channel in which check valve and spring ring are installed. Spring ring fixes valve relative to shoe, and member for fixing the shoe in seat of internal string. Drilled unit is secured to drill string by means of shear member. EFFECT: higher efficiency. 1 dwg

Description

 The invention relates to drilling equipment and can be used for fastening intervals of wells with unstable rocks.

 A device for fastening wells in unstable rocks (ed. St. USSR 1143825, class E 21 B 7/20, published. 07.03.85), containing a drill string located inside the casing. The casing has an internal guide protrusion for radial displacement of the drill bit. The device is equipped with an angular contact sliding bearing with upper and lower end cages having conical working surfaces, and a shank connected to the lower part of the casing with the possibility of rotation around its axis, while the upper annular casing is fastened to the drill string and has grooves for the exit drill cuttings flow. The lower annular yoke is bonded to the casing and has grooves for the passage of the drill bit when transporting the drill string inside the casing.

 This method is weakly effective due to the impossibility of carrying out insulation work, i.e. cementing wells. In addition, the design is not reliable in operation, since it is possible to jam the casing during transportation of the casing, which leads to the lack of overlapping of the necessary interval of unstable rocks and increases the accident rate. The descent casing contributes to a significant loss in the diameter of the well, which complicates its further operation.

 There is also known a device for fastening wells (ed. St. USSR 1250637, class E 21 B 7/20, published 29.12.84), containing a drill string with a rock cutting tool fixed in its lower part and placed casing concentrically to it.

 The device is equipped with a glass placed concentrically on the outside of the casing, a carriage with expandable elements, and the casing is made with a slot along its generatrix.

 The main disadvantage of this design is its low reliability of operation due to possible jamming of the casing string, as well as poor mounting efficiency due to the impossibility of insulating work. In addition, this design also contributes to a significant loss of the inner diameter of the well.

 The closest technical solution to the claimed is a device for fastening wells in unstable rocks (ed. St. USSR 1461851, class E 21 B 7/00, published. 02.28.89), containing a casing string and a drill string placed inside it.

 A rock cutting tool is attached to the drill string below the casing shoe. The device is equipped with a sealing element located in the space between the casing and the drill string.

 The device allows for fixing intervals of wells in unstable rocks.

 However, the efficiency and reliability of operation, as well as the previous analogues, is small.

 Low reliability is due to possible jamming of the casing and, as a consequence, the lack of overlap of the necessary interval of unstable rocks, as well as the loss of the inner diameter of the well.

 The purpose of the invention is to increase the efficiency and reliability of fastening wells in unstable rocks while maintaining the maximum possible internal diameter.

 This goal is achieved by the fact that in the device for fastening wells in unstable rocks, including the casing and placed inside it with the possibility of joint rotation and disconnection of the drill string, the casing is made in the form of concentrically arranged inner and outer columns, while the inner string is made with the possibility extension towards the bottom of the well and fixing in the lower position relative to the outer column and with a seat in the lower part of the cavity, and the device is equipped with fraternal valves located in the wall of the upper part of the inner column and a drillable assembly located on the seat of the inner column and made in the form of a shoe with an axial channel in which a check valve and a spring ring are installed to fix the valve relative to the shoe and the shoe fixation element on the seat of the inner the column, while the drillable assembly is fixed to the drill string by means of a shear element.

 Typically, in the process of drilling a well to isolate complicated intervals and incompatible drilling conditions or unstable rocks in the stress-strain state of the array (especially plastic deposits), designs of additional intermediate casing strings with various mechanisms of their fixation are used, leading to the loss of the internal diameter of the well due to the need descent of casing strings to the roof of complicated intervals and descent of additional intermediate (countersunk, liner, etc.) casing stakes onna for their overlapping and fastening.

 The inventive device allows, after lowering the columns to the roof of unstable deposits, to overlap the interval of unstable rocks by extending the inner pipe string and conducting insulation work.

 At the same time, the use of the design of welded collarless pipe strings in the layout of the descent collar casing will ensure maximum preservation of the inner diameter of the well structure while fulfilling the necessary requirements for isolation (overlapping and fastening) of unstable deposits and expand the operational capabilities of the well.

 In addition, the fastening of the drilled unit on the inner pipe string allows to increase the efficiency of the fastening of the well in unstable rocks while maintaining a possible internal diameter.

 The above allows us to conclude that there is a "inventive step" in the claimed technical solution.

 The drawing shows a longitudinal section of the proposed device.

 The device consists of two concentrically arranged outer 1 and inner 2 pipe columns and a drill string 3 located inside them with the possibility of joint rotation and disconnection. The inner pipe string 2 is made to extend toward the bottom of the well and fix on the outer pipe string 1, for which the outer pipe 1 has pipes 4 and 5 with threaded joints in the lower and upper parts.

 The inner string 2 has a pipe 6 at the bottom with a seat for arranging the bottom of the drill string 3, and the upper one has check valves 7 for cement flow and a pipe with a fixed threaded connection 8, in which grooves are made for gripping the drill string 3. Cams of the gripping unit 10 connected by a non-facet connection to the drill string 3.

 The drillable assembly 9, located on the seat of the inner column, has a shoe 11 with an axial channel in which the check valve 16 and the spring wheel 15 are installed, for fixing the valve relative to the shoe, screws fixation elements 12 of the shoe on the seat of the inner column, while the drillable assembly fixed to the drill string by means of a middle element consisting of a shoe 13 with shear pins 14 and a thrust ring 17.

 The device operates as follows.

 Mounted elements of casing strings 1 and 2 are lowered into the well, then casing 1 is fastened.

 The lower threaded connections of the outer casing 1 are fixed by welding or pins, and in addition, the casing 1 is cemented.

 The threaded connections of the nozzles 5 and 8 are fixed with pins, which keeps the casing 2 from turning to lowering and starting the rotation of the drill string 3.

 The layout of the bottom of the drill string 3 is lowered after deepening the well to a length greater than the retractable inner string of pipes 2.

 The drill string 3 is fixed with the inner pipe string 2, while the grip assembly 10 of the cam mechanism of the drill string 3 is connected to the grooves of the pipe 8 of the inner string 2. After the cams of the grip assembly 10 are inserted into the grooves of the pipe 8 of the inner string 2, the drill string is fixed to the right 3 with inner column 2.

 By rotating the drill string 3, the inner string 2 is withdrawn from the threaded connection 5, after which the inner string of pipes 2 is lowered and flushed through check valves 7 to the junction of the pipe 8 pipe string 2 with the lower pipe 4 of the outer string 1.

 In the process of axial movement of the drill string downward with rotation, the string 2 is held on the layout of the bottom of the drill string 3 by the jaws of the grip assembly 10 inserted into the grooves of the nozzle 8. When connecting the nozzle 8 along the thread with the nozzle 4, the bend is up to the stop, and the length of the retractable inner pipe string 2 controlled by control measurements on the surface.

 By performing the overlap process in this way, the complicated rock interval is fastened. For this, insulating material (cement slurry, etc.) is pumped through the drill string 3 with the outlet of the annular drilling fluid through the check valves 7.

 After pumping the required volume of insulating material and landing the squeeze plug on the thrust ring 17, the pins 14 are cut off and the drillable assembly 9 is disconnected from the drill string 3. At the same time, the drillable assembly 9 is fixed by a spring ring 15 and fixing screws 12 in the seat of the pipe 6 and remains in the well on the inner column 2.

 After disconnecting the drillable assembly 9 from the drill string 3, the cams of the grip assembly 10 are removed from the grooves of the pipe 8 of the inner string 2 and the drill string 3 is lifted. Further deepening of the well is carried out after the insulation material has solidified by drilling the drill assembly 9.

 To prove the advantages of the claimed design, design and modified well designs with various solutions for overlapping intervals of unstable rock deposits are given, mm: design well design 508-340-245-178 / 168; modified with the use of additional intermediate casing strings 508-340 • 273-194-140 / 127 or 508-340-245 • 178-127 / 114; using the construction of welded sleeveless pipes 508-340 (377 • 324) -245-178 / 168 or 508-340-245 (273 • 219) -168/146.

 Thus, the inclusion in the layout of coupling 340 or 245 mm casing strings, respectively, of a design of welded sleeveless pipes with diameters of 377 • 324 and 273 • 219 mm, preserves the maximum possible internal diameter of the well.

Claims (1)

 A device for attaching wells in unstable rocks, including a casing and placed inside it with the possibility of joint rotation and disconnection of the drill string, characterized in that the casing is made in the form of concentrically arranged inner and outer columns, while the inner string is made to extend in the direction to the bottom of the well and fixing in the lower position relative to the outer column and with a seat in the lower part of the cavity, and the device is equipped with check valves placed in the upper part of the inner column and a drillable assembly located on the seat of the inner column and made in the form of a shoe with an axial channel in which a check valve and a spring ring are installed to fix the valve relative to the shoe, and shoe fixation elements on the seat of the inner column moreover, the drillable assembly is fixed to the drill string by means of a shear element.