GB2112048A - Positioning of well pipe jack in a rig - Google Patents

Abstract

A well pipe jacking mechanism includes two generally vertical structures 29, 30 beneath a rig floor which function as power operated actuating units and which are offset circularly about the well axis from a tubular mousehole element 86, and with a blowout preventer 105 beneath the rig floor projecting away from the well axis at a location circularly between one of the generally vertical structures 29 and the mousehole 86. <IMAGE>

Description

SPECIFICATION Positioning of well pipe jack in a rig This invention relates to jacking mechanism of a general type especially adapted for lowering a lengthy and heavy string of casing into a well after drilling of the well. The mechanism preferably includes generally vertical structures beneath the rig floor having portions serving as fluid operated actuating units for moving one of two pipe supporting devices upwardly and downwardly relative to another such device to lower the casing.

The present invention is especially concerned with a unique manner of positioning such a jack mechanism and other parts of a drill rig together in a relatively confined space beneath a rig floor.

In accordance with the invention, the mentioned generally vertical structures are positioned at locations offset circularly about the well axis from a tubular mousehole member of the rig, with at least one blowout preventer being located at approximately the well axis and projecting outwardly circularly between one of the generally vertical structures and the mousehole.

In the drawings: Fig. 1 shows a well drilling rig embodying the invention; Fig. 2 is an enlargement of a portion of Fig. 1; Fig. 3 shows a portion of the apparatus of Figs. 1 and 2 in casing lowering condition; Fig. 4 is a view on line 4-4 of Fig. 2; Fig. 5 is an enlarged vertical section on line 55 of Fig. 3; Fig. 6 is a fragmentary horizontal section on line 66 of Fig. 2; Fig. 7 is a horizontal section on line 7-7 of Fig. 2; Fig. 8 is a view similar to Fig. 7 showing a variational arrangement; and Figs. 9 and 10 show two additional variations.

The rig 10 of Fig. 1 includes the usual rig framework structure having a rig floor 11 and an upwardly projecting derrick or mast 12 supported by a substructure 13 on the surface of the earth 14. A tubular drill string 15 having an upper non-circular kelly section 16 is rotated by a standard rotary table 17 about a vertical axis 18 to drill a well 19, and is suspended by a traveling block 20 through a line 21 connected to crown block 22 attached to the upper end of the derrick, with the line being actuated by drawworks 23 to progressively lower the drill string so that a bit connected to its lower end drills the well. Rotary table 17 includes an outer non-rotating rigid body 117 supporting an inner essentially annular part 25 through bearings 24 for rotation about axis 18.A master bushing and kelly bushing assembly 26 within vertical opening 27 in rotary part 25 engages and drives kelly 16. Part 25 and bushing assembly 26 are driven by the engine of drawworks 23 through a chain and sprocket drive 28.

During drilling, rotary table 17 is supported by two piston and cylinder mechanisms 29 and 30, and a beam 31 extending therebetween. Units 29 and 30 extend along two vertical axes 33 and 34 parallel to and equidistant from axis 18 at diametrically opposite locations, and each include a vertical cylinder body 35 and a piston 36 therein relatively actuable upwardly and downwardly by pressurized hydraulic fluid introduced above or beneath the piston head through lines 37 and 38 from a pressure fluid source 39 under the control of a valve 40.

Bottom walls 41 of the cylinders are supported by two essentially parallel rigid base members 42 and 43 connected at their opposite ends 44, 45, 46 and 47 to rigid members 48, 49, 50 and 51 of the rig substructure. The lower ends of the cylinders are located by reception between lugs 52 projecting upwardly from members 42 and 43. Beam 31 is supported by cylinders 35 and retained against horizontal movement by connection at locations 131 (Fig. 6) to the rig substructure, and may be formed of several parts but is typically illustrated as a unitary one-piece member containing a central opening 54 for passing drill string 15 or a casing string 55 (Fig. 3) downwardly along axis 18.Near its ends, beam 31 contains two vertical cylindrical passages 56 and 57 centered about axes 33 and 34 and closely receiving the upper ends of cylinders 35 in locating relation. Two rings 58 extending about and welded to cylinders 35 engage the horizontal undersurface 59 of beam 31 to support the beam. At each cylinder, beam 31 has an annular shoulder 60 overlying the cylinder wall and containing a circular opening 61 of a reduced diameter corresponding to the internal diameter of cylinder 35 and slightly greater than the external diameter of piston rod 62 of the associated piston 36 to allow movement of the piston rod upwardly through opening 61 and to a location above the beam when rotary table 17 is not in position on the beam. The externally cylindrical rod 62 is sealed with respect to cylinder 35 by an annular seal ring or gasket 63.In the drilling condition of Fig. 2, the upper annular end surface 64 of each piston rod 62 is at least as low as the plane of upper surface 53 of beam 31 and preferably slightly lower than that surface and flush with the upper ends of cylinders 35 in a horizontal plane 65.

When lowering casing (Fig. 3), rotary table is 17 removed, and an extension unit 66 is connected to the piston rods. Thus unit includes two vertical members 67 and 68 having reduced ends 69 projecting downwardly into cylindrical recesses 70 in piston rods 62, with annular shoulders 71 on elements 68 engaging the upper horizontal surfaces 64 of the piston rods to actuate unit 66 upwardly and downwardly with the pistons. A rigid beam 73 is connected to elements 67 and 68, as by welding and by braces 74 welded to elements 67, 68 and 73, and contains an opening 75 through which casing 55 extends. Two units 76 and 77 are supported on beams 31 and 73 and are adapted to releasably engage and support a casing.These units may be of a known type illustrated in Fig. 5, including an outer generally annular body 78 having tapering slip bowl surfaces 79 centred about axis 18 and engageable by circularly spaced wedge slips 80 having tapering outer surfaces 81 engaging surfaces 79 to cam the slips inwardly in response to downward movement.

Inner gripping faces 82 of the slips have teeth for gripping and supporting a casing 55. A ring 83 suspends the slips through links 84 pivotally connected at opposite ends to the slips and ring, and is power actuable vertically to raise and lower the slips between pipe gripping positions (full lines in Fig. 5) and released positions (broken lines) not engaging the casing. Piston and cylinder mechanisms 85, having their cylinders connected to body 78 and their pistons connected to ring 83, move the ring and slips vertically.

The rig includes a mousehole pipe 86 (Fig. 4), extending along an axis 87 which is generally parallel to axis 18 and lies in a vertical plane 88 (Fig.

6) extending toward and away from drawworks 23 and is inclined slightly to extend at a small downward and outward angle a with respect to the true vertical and axis 18. The mousehole may be mounted in this position by reception within an opening 89 in beam 31 (Fig. 6) and by connection of its lower end to the rig substructure. The mousehole receives pipe sections which are to be added to or have been removed from drill string 15. At an early stage during drilling, surface casing 91 (Fig. 2) is lowered into the well, with its upper end forming a wellhead 92 having a flange 93 to which there is connected a blowout preventer assembly 94 whose various elements are connected together by flanges 95 secured together in sealed relation by circularly spaced bolts 96.Assembly 94 may include an upper annular blowout preventer 97 containing an essentially annular sealing element constrictable against a drill pipe or casing to form a seal therewith. Beneath preventer 97, assembly 94 may include a number of ram type blowout preventers, 98,99 and 100, with an intermediate tubular fitting 101 connected between two of these ram type preventers and providing connections to the usual kill line 102 and choke line 103 extending in opposite directions away from axis 18. All of the blowout preventers and fitting 101 contain aligned vertical passages defining together a continuous vertical passage 104 through which a drill string or casing can extend downwardly from above assembly 94 into the well.

Each of the ram type preventers 98,99 and 100 includes a housing 105 defining part of the vertical passage 104 and forming also two projections 106 and 107 projecting in diametrically opposite directions from axis 18 and carrying outer housing elements 108 terminating at outer extremities 109.

The radial distance rbetween axis 18 and the extremity 109 of each of the projections 106 and 107 is greater than the radial distance R between axis 18 and mousehole tube 86 (Fig. 7), and is also greater than the radial distance R2 between axis 18 and each of the cylinders 35. Projections 106 and 107 of each of the blowout preventers 98, 99 and 100 contain two rams 110 which are diametrically opposite one another and are movable toward and away from one another and act in their radially innermost positions to form seals preventing upward flow of well fluid.Two of the ram type blowout preventers (typically units 98 and 100) may have rams shaped to engage the outer surface of a drill string or casing string to form a seal thereabout, while the third preventer 99 may have rams shaped to form a closure entirely across passage 104 and thus close off upward flow of fluid from the well if no well pipe is present in that passage, with these rams being designed also as cutters capable of shearing a drill string or casing string if necessary. Kill line 102 allows ejection of pressure fluid into the well if desired, and choke line 103 permits controlled discharge of fluid from the well.

In Fig. 7, cylinders 35 of units 29 and 30 are at diametrically opposite locations with respect to axis 18 and are both offset circularly about that axis from mousehole 86. Preferably, the axis of unit 29 is offset circularly from the axis of mousehole 86 an angular distance b which is greater than the angular distance c between the axis of mousehole 86 and the axis of unit 30. Also, the angle b is desirably greater than 90 , and the angle c is desirably less than 90 . One of the projections 106 of each of the ram type blowout preventers 98,99 and 100 projects radially outwardly circularly between unit 29 and mousehole 86, with the relatively great angular spacing b between those elements serving to provide ample space for reception of that projection and for access to the blowout preventers, cylinders, and other elements for servicing.The kill line 102 also preferably extends radially outwardly at a location circularly between unit 29 and mousehole 86, with the choke line 103 projecting in a diametrically opposite direction circularly between units 29 and 30. The kill and choke lines 102 and 103 preferably extend essentially perpendicular to the previously mentioned vertical plane 88.

All of the blowout preventers 98,99 and 100 may extend in the direction illustrated in Fig. 7. All of these preventers may be located higher than the lower ends of cylinders 35, or alternatively one or more of these preventers may be at a level beneath the lower extremities of the cylinders. In Fig. 2, the upper two ram type blowout preventers 98 and 99 are higher than the lower ends of cylinders 35, as are kill line 102 and choke line 103, while preventer 100 is beneath the level of the lower extremities of the cylinders, and is received between the two previously mentioned support or base members 42 and 43. Beams 42 and 43 desirably extend generally parallel to the length dimension of blowout preventer 100, at opposite sides thereof.Passages 56 and 57 in beam 31 are offset circularly different distances from vertical plane 88 in correspondence with the angles b and c of Fig. 7 to receive and locate the upper ends of the cylinders.

To summarize use of the rig of Figs. 1 through 7, rotary table 17 is first positioned on beam 31 supported by piston and cylinder units 29 and 30 as shown in Fig. 2 and the well is drilled utilizing the rotary table to turn the drill string as it is lowered into the well. Surface casing 91 is located in the well after a first portion of the well has been drilled, and blowout preventer assembly 94 is mounted to the wellhead as shown in Figs. 2,6 and 7. After the drilling is completed, rotary table 17 is removed and extension unit 66 and gripping units 76 and 77 are connected to the piston and cylinder units as in Fig.

3. The main string of casing 55 (smaller in diameter than casing 91) is then lowered through blowout preventer assembly 94 into the well, and when the weight of the casing becomes great enough to approach the capacity of the derrick, drawworks, traveling block, crown block, etc., the jacking mechanism is brought into action to lower the casing 55 further into the well. Pistons 36 are actuated to move unit 77 upwardly and downwardly, with unit 77 being actuated to its gripping condition during lowering movement to jack the casing downwardly, and with unit 76 being actuated to its gripping condition during upward movement of unit 77.

The variation of Fig. 8 may be identical with that of Figs. 1 through 7 except as discussed below. In Fig.

8, the axis of mousehole tube 86a is offset circularly through angle dfrom plane 88a (corresponding to plane 88 of Fig. 6), while the longitudinal axis 111 of each of the ram type blowout preventers corresponding to preventers 98,99 and 100 of Fig. 2 (one of which is represented at 98a in Fig. 8) may lie in plane 88a. The axes 33a and 34a of piston and cylinder units 29a and 30a (corresponding to units 29 and 30 of the first form of the invention) may lie in a vertical plane 112 perpendicular to plane 88a.

Thus, the axis of one of the piston and cylinder mechanisms is offset circularly from the axis of the mousehole an angular distance e which is greater than the circular offset between the axis of the mousehole and the axis of the other piston and cylinder unit, with one end of each of the ram type blowout preventers projecting radially outwardly from axis 18a at a location circularly between mousehole 86a and unit 29a, and with the kill line 102 also being received circularly between the mousehole and unit 29a, while choke line 103a projects in a diametrically opposite direction circularly between the two units 29a and 30a.As in the first form of the invention, one of the ram type blowout preventers may be located beneath the level of the lower extremities of the cylinders of units 29a and 30a, and project generally parallel to and between two support beams 42a and 43a corresponding to beams 42 and 43 of the first form of the invention. Thus, in Fig. 8 beams 42a and 43a may extend essentially parallel to plane 88a rather than at an angle thereto as in the first form of the invention. The angles band c of Fig. 7 or the angles e and fof Fig. may in some instances each be 90 , with the longitudinal axes of the those blowout preventers then typically extending at angles of approximately 450 with respect to plane 88 or 88a to be essentially midway between the mousehole and unit 29 or 29a.

In the variation of Fig. 9, the rotary table (not shown) may be supported in conventional manner during the drilling operation on the usual rotary table support beams 113, with jacking mechanism 114 being entirely removed from the rig during drilling and moved into position only for lowering casing 115 into the well. Piston and cylinder mechanisms 29b and 30b may have the bottom end walls 41 b of their cylinders 35b supported on two rigid vertical columns 116 which rest on a base structure 117 supported by the ground.Columns 116 and cylinders 35b thus form together two subfloor structures extending along two parallel vertical axes 33b and 34b to and above the level of rig floor 11 b. The upper ends of cylinders 35b project upwardly through openings in the opposite ends of the beam 31 b and to upper extremities 118 of the cylinders, with beam 31b being supported by the cylinders through rings 58b welded to the cylinders. Upper beam 73 is detachably connectible to the upper ends of the piston rods of units 29b and 30b, with gripping units 76b and 77b being supported on beams 31b and 73b.Ram type blowout preventers 98b, 99b and 1 00b may be located below the level of the lower extremities 41 b of cylinders 35b, and at the level of the lower support columns 116. The mousehole may be positioned either as shown in Fig. 7 or as shown in Fig. 8, and column 116 may be located with their vertical axes 33b and 34b either at the locations of axes 33 and 34 in Fig. 7 or at the locations of axes 33a and 34a in Fig. 8, with one end of each of the ram type blowout preventers 98b and 1 00b being located circularly between the mousehole and the support column 116 which supports and is vertically aligned with piston and cylinder unit 29b.

The variation of Fig. 10 may be the same as that of Figs. 1 through 7 or that of Fig. 8, except that the lower ends of piston and cylinder units 29c and 30c are supported on opposite ends of a generally horizontal beam 119 connected to and supported by wellhead 92c. Beam 119 may have a central tubular portion 120 connected into the blowout preventer assembly 94c, with portions of the beam projecting in diametrically opposite directions from that central portion 120 to support the two piston and cylinder units and the remainder of the jacking mechanism, and to also support the rotary table in the manner illustrated in Figs. 1 and 2 if desired. One or more of the ram type blowout preventers 98c, 99c and 100c (typically all of them as illustrated in Fig. 10) are located at a level above that of the lower extremities of the cylinders 29c and 30c, with one end of each of these preventers extending radially outwardly circularly between the mousehole and unit 29c.

Claims (11)

1. In a rig for drilling a well along a predetermined axis, the combination comprising a tubular mousehole extending generally parallel to said axis at a side thereof, jacking mechanism including first and second pipe supporting devices and a plurality of structures which extend beneath the level of said devices at different sides of said axis and which include power operated actuating units for moving one of said pipe supporting devices upwardly and downwardly relative to the other to jack a well pipe along said axis; characterized by at least one blowout preventer having a portion which projects laterally at a location circularly between said mousehole and one of said structures.

2. The combination as claimed in claim 1, in which said actuating units are piston and cylinder units extending essentially vertically and essentially parallel to one another at different sides of said axis.

3. The combination as claimed in claim 2, in which said blowout preventer is art a level above that of the lower extremities of said piston and cylinder units.

4. The combination as claimed in claim 1, in which said actuating units include piston and cylinder mechanisms and support columns beneath and supporting said piston and cylinder mechanisms, said blowout preventer being lower than said piston and cylinder mechanisms and at the level of said support columns.

5. The combination as claimed in claim 4, including two generally horizontal and generally parallel beams supporting said two structures, and a second blowout preventer approximately parallel to and beneath said one blowout preventer and laterally between and generally parallel to said beams.

6. The combination as claimed in any of the preceding claims, in which said one structure of the jacking mechanism is offset circularly more than 90" from said mousehole.

7. The combination as claimed in any of the preceding claims, in which said one structure is offset circularly from the mousehole farther than is the other structure.

8. The combination as claimed in any of the preceding claims, in which said one structure is offset circularly from the mousehole more than 90 , and the other structure is offset circularly from the mousehole less than 90 .

9. The combination as claimed in any of the preceding claims, including extension means detachably connectible to said structures for supporting one of said pipe supporting units.

10. The combination as claimed in any of the preceding claims, including choke and kill lines extending laterally away from said axis and one of which is received circularly between said mousehole and one of said structures.

11. Well drilling apparatus substantially as hereinbefore particularly described and as illustrated in the accompanying drawings.