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Publication numberUS3485051 A
Publication typeGrant
Publication dateDec 23, 1969
Filing dateMay 22, 1967
Priority dateNov 29, 1963
Publication numberUS 3485051 A, US 3485051A, US-A-3485051, US3485051 A, US3485051A
InventorsWatkins Bruce J
Original AssigneeRegan Forge & Eng Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Double tapered guidance method
US 3485051 A
Abstract  available in
Images(2)
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Claims  available in
Description  (OCR text may contain errors)

Dec. 23, 1969 B. J. WATKINS DOUBLE TA PERED GUIDANCE METHOD Original Filed Nov. 29, 1963 2 Sheets-Sheet 2 INVENTOR.

Bea/:5 J War-mus BY p%%% United States Patent 0 M 3,485,051 DOUBLE TAPERED GUIDANCE METHOD Bruce I. Watkins, Palos Verdes Estates, Califi, assignor to Regan Forge & Engineering Co., San Pedro, Calif., a corporation of California Original application Nov. 29, 1963, Ser. No. 326,738, now Patent No. 3,347,567, dated Oct. 17, 1967. Divided and this application May 22, 1967, Ser. No. 640,274

Int. Cl. E02d 25/00; E21b 41/00; B23q 11/02 US. Cl. 61-46.5 8 Claims ABSTRACT OF THE DISCLOSURE A method of guiding and prealigning coupling members in subsea locations remote from a floating vessel from which one of the coupling members is lowered including establishing at least two vertically spaced annular coaxial abutment surfaces of different diameters on a casing head, establishing at least two vertically spaced annular coaxial abutment surfaces of different diameters on a casing head, establishing at least two axially spaced coaxial annular guidance surfaces of different diameters within a casing coupling member, moving the coupling member into engagement with the casing head to bring the two axially spaced abutment surfaces into engagement with the two axially spaced guidance surfaces in axially spaced double surface engagement to loosely prealign the coupling member axially to the casing head and thereafter moving the coupling member from the prealigned position into a completely landed or tightly coupled position. Both large and small diameter concentric annular abutment and guidance surfaces, respectively, are axially spaced from each other substantially equal distances and the double surface engagement is established concurrently to loosely prealign a multi-diameter coupling member to a multi-diameter inner bored casing head.

Cross-references to related applications This application is a divisional application of my copending application Ser. No. 326,738, filed Nov. 29, 1963, now Patent No. 3,347,567, entitled Double Tapered Guidance Method and Apparatus.

Background of the invention This invention relates in general to a method for interconnecting a pair of conductors or conduits in a subsea environment remotely of a floating vessel or platform from which at least one of the conductors or conduits is run. More particularly, the invention in its preferred form relates to a method for guiding and aligning a subsea well landing tool or bonnet onto a subsea conductor pipe head or the like where the landing tool is suspended from a conductor run from the vessel or platform and may approach the conductor pipe head in a tilted or vertically misaligned manner.

In subsea oil well drilling, completion, re-entry and production operations, it is necessary repeatedly to engage, connect and seal two conductors or conduits together at a location beneath the sea remote from the floating platform or vessel from which the operations are conducted. In many such operations, it is necessary to connect both large and small diameter concentric tubular members simultaneously. Such connections are frequently required when landing a production or drilling bonnet on a well head where the well head includes a casing or tubing hanger suspended in and extending upwardly of the well head cemented into the well. Particularly in subsea oil well drilling, the connections of casings beneath the sea requires fluid-tight seals to maintain Well pressures,

3,485,051 Patented Dec. 23, 1969 retain well and hydraulic fluids and keep high pressure sea water out of the well and casings. The preservation and protection of sealing means between the casings on coupling and uncoupling beneath the sea beyond the working depth of divers is of prime consideration. Also, it is believed that whether such multi'diameter coupling members are assembled on board a rolling or pitching floating vessel or beneath the sea remote from the vessel, an improved means of guiding and aligning the couplings together prior to their complete connection is required.

It is the principal object of this invention, therefore, to disclose and provide a method and apparatus for use with casing couplings, landing tools or drilling or production bonnets for prealigning multi-diameter concentric casings and tubings prior to their complete connection to align internal sealing means and cooperating sealing surfaces prior to the sealing abutment thereto on complete connection of the couplings or the like.

It is another object of this invention to disclose and provide a landing tool or coupling particularly adapted for use in landing marine conductor pipes or casings run from a floating vessel onto a stationary subsea conductor pipe head including two concentrically mounted vertically spaced casing heads.

It is a further object of this invention to disclose and provide a method and apparatus for use in connecting a movable coupling member onto a stationary, remotely located casing member to effect an axial prealignment of said members prior to their complete coupling together.

It is still another object of this invention to disclose and provide a method and apparatus for remotely engaging, aligning and connecting a pair of easing means, each including both large and small concentric diameter members, together in a simple, easily accomplished manner "without the need for additional, auxiliary guides or prealignment means other than the coupling portions of the casing means themselves.

Summary of the invention Generally stated, the method of the present invention comprises the provision of at least two vertically spaced, concentric abutment surfaces on a first male coupling member, as on a stationary subsea oil well head. A pair of axially spaced, concentric and generally annular guidance surfaces are provided within a second female coupling member, as on an oil well drilling bonnet or well head landing tool. The second coupling is then moved into engagement with the first coupling, as by running a drilling bonnet on the lower end of a marine conductor to a well head. On engagement of the first and second coupling members, prior to a complete connection where internal sealing means are operative, the couplings are prealigned by at least a double or dual surface engagement between axially spaced abutment surfaces of the first coupling member and the two axially spaced, concentric generally annular guidance surfaces within the second coupling member. In accordance with the present method, such double axially spaced abutment or aligning engagement occurs concurrently to axially prealign said coupling members prior to their complete assembly or connection. On such prealignment, in which any sealing means between mating coupling surfaces are also aligned, the coupling members are thereafter moved axially relative to each other and stopped at a completely connected position by a pair of abutment or stop means intermediate of the aforementioned guidance surfaces.

A further understanding of the method and apparatus of the present invention may be obtained by a consideration of the following detailed description of an exemplary embodiment of the double tapered guidance apparatus employing the method of the present invention. Reference 3 will be made to the accompanying sheet of drawings in which:

FIG. 1 is a vertical section view of an exemplary well head latch mechanism and associated landing tool apparatus employing the method and apparatus of the present invention shown partly engaging but misaligned over a well head;

FIG. 2 is a vertical section view of the apparatus of FIG. 1 with the landing tool apparatus pivoted into generally aligned relation to and over the well head prior to complete connection;

FIG. 3 is a vertical section view of the apparatus of FIGS. 1 and 2 shown in axially prealigned relation prior to complete connection to the well head; and

FIG. 4 is a vertical section view of the apparatus of FIGS. 1, 2 and 3 completely connected to the well head.

Referring to the drawings, an exemplary embodiment of the double tapered guidance apparatus, in accordance with the present invention, is shown and will now be explained in detail. A marine conductor 10, having a flange 11, is shown bolted to a marine conductor adapter flange 12 by bolts 13. Adapter flange 12 is shown bolted by bolts 14 to an examplary form of well head latch indicated generally at 15.

The exemplary well head latch indicated generally at 15 includes a lower body portion 16 and an upper body portion 17. A plurality of vertically positioned preferably hydraulically operated latch mechanisms 18 are mounted on the upper body portion 17, each such mechanism being adapted to selectively operate a camming block 19 against a dog 20 through a push rod 21 as shown in FIG. 1.

Sealing means 22 are provided within the bore 23 of upper body portion 17 with a retaining ring 24 provided between the sealing means 22 and adapter flange 12. Additional sealing means 25 are provided between the seal retaining ring 24 and the adapter flange 25 as shown in FIG. 1.

An exemplary double tapered landing tool in accordance with the present invention is indicated generally at and, in the exemplary embodiment, comprises a cylindrical bonnet or coupling member 31.

A conductor pipe 40, may be cemented into a well, as the conductor pipe 17 in my co-pending application Ser. No. 326,917, filed Nov. 29, 1963, entitled Subsea Well Control Tube Methods and Apparatus. A second, smaller diameter casing extends concentrically and upwardly of the casing 40. In the exemplary embodiment a casing head or hanger 41 is mounted concentrically within the conductor 40 to suspend the casing or tubing 42 down within conductor 40 to the well. The casing head or hanger 41 shown is of the flow through type with a passage at 43 provided between the casing and conductor walls which communicates with the well.

It should be understood that the description of apparatus thus far is exemplary only of one of many instances wherein it is desired to land a marine conductor on a stationary subsea conductor pipe head from a remote floating vessel or platform where the conductor pipe head includes a first conductor pipe, as conductor pipe 40, with a second conductor pipe or casing, as casing 41, concentric to and extending upwardly above the first conductor pipe.

In accordance with the present invention, the landing tool, indicated generally at 30, is provided with a first and second conical guidance surface to engage, align and guide the landing tool and associated well head latch and conductor pipe apparatus down onto the exemplary conductor pipe including the conductors or casings 40 and 41. The landing tool in the exemplary embodiment includes a generally cylindrical body portion 31 which is provided with a two-stage inner bore including bore portion 32 adapted to slidably fit over the large diameter exterior surface 44 of conductor pipe 411 and a smaller bore portion 33 adapted to slidably fit over the reduced diameter or head portion 45 of the conductor pipe 40. An

annular landing means or surface 34 is provided on the interior of the generally cylindrical body portion between bore portions 32 and 33 and is adapted to seat upon the circular landing ledge 35 provided on the conductor pipe 40 between portions 44 and 45.

The lower bore portion 26 of the well head latch, indicated generally at 15, is adapted to slide over and fit upon the larger diameter area 46 of the inner conductor or casing 41 and the smaller bore portion 23 of the Well head latch is adapted to' slide upon and fit about the smaller diameterarea 47 of the upper or head portion of the casing or inner conductor 41. Also, an annular landing means or surface 27 'is provided in the interior of the well head latch indicated generally at 15 between the bore portions 23 and 26 to land upon the circular landing ledge or stop 48 on the inner conductor or casing 41 between the large diameter area 46 and the small diameter area 47. Therefore, to completely land the conductor 10 and its associated well head latch, indicated generally at 15, on the well head, including the conductor pipe 40 and inner conductor or casing 41 in the exemplary embodiment, the landing means or surfaces 27 and 34 must rest upon the ledge or stop surfaces 48 and 35 respectively, as shown in FIG. 3.

A first guidance surface 50 is provided on the lower end of the body portion 31. Surface 50 extends .downwardly and outwardly of the body portion 31 to provide a downwardlyfacing concave guidance surface to suecessively receive and guide the two conductor casings or concentric casings 40 and 41. A second tapered guidance surface 51 is provided at the upper end of body portion 31. Surface 51 extends upwardly and inwardly of the body portion 31 providing an inner downwardly facing concave guidance surface spaced vertically from and above the first guidance surface 50. In the exemplary embodiment surface 51 is provided by a threaded collar 52 mounted to the body 31 but may be made integral therewith as surface 50 is shown.

In accordance with the present invention, the first and second guidance surfaces 50 and 51 associated with the body portion of the landing tool, or female coupling member as indicated generally at 30, are vertically spaced from each other the same distance that the second or inner conductor pipe or casing 41 extends upwardly of the outer or first conductor pipe 40. This relationship of surfaces 50 and 51 to casings 40 and 41 is necessary to the practice of the method of the present invention. Prior to the complete landing of the landing tool, coupling or bonnet, as indicated generally at 30, on the well head including casings 40 and 41, the first guidance surface 50 may engage and guide the cylindrical abutment surface on the upper end of the inner casing or conductor pipe 41 and direct it within the bore portion 32 of the body 31. On further downward landing movement of the landing tool or female coupling member onto the male coupling members 40 and 41, the first abutment surface 60 may engage and be directed by the second or upper guidance surface 51 as shown in FIG. 1. On pivoting of the coupling member on the casing head, the second or lower cylindrical abutment surface 61 on the outer conductor pipe 40 may be pivoted into the lower or outer guidance surface 50 on further assembly movement thereof into an axially prealigned position as shown in FIG. 2.

In the exemplary embodiment described, the contact between the coupling or landing tool and the casing heads prior to pivoting of the coupling to the position of FIG. 2 occurs between the abutment surface 60 and guidance surface 51. It is also possible in landing the coupling or tool on the casing heads that such contact may occur between the abutment surface 61 and guidance surface 50 prior to the pivoting movement of the coupling to the aligned position of FIG. 2. In either instance, however, there is an initial contact between either the abutment 60 and surface 51 or between abutment 61 and surface 50 and a subsequent pivoting movement of the coupling to bring surfaces 50 and 51 into contact with abutments 61 and 60, respectively, concurrently, if but for only a very short duration. Because of the relatively loose fit between the coupling member and casing heads in the double guidance contact position of FIG. 2, the coupling may be easily moved into the loose fitting, generally axially aligned position to the casing heads 40 and 41, as shown in FIG. 3. i

It should be noted that the fit of each of the bore portions 23, 26, 33 and 32 over and about the casing head outer surface portions 47, 46, 45 and 44, respectively, are snug fits on complete assembly of the coupling member or landing tool, indicated generally at 30, on the casing head portions 40 and 41, at the axial prealignment position of FIG. 4. The fit between bore surfaces 26, 33 and 32 and casing head outer surface portions 47, 46 and 45 shown in FIG. 3, are loose fits allowing an easy prealignment or preassembly of the apparatus parts at a remote subsea location when operating from a floating and possibly rolling or pitching vessel. The axial alignment of the apparatus in accordance with the present invention is thereby effected prior to the mating of any close tolerance sealing surfaces.

The provision of the two vertically spaced guidance surfaces 50 and 51 thus allows the engagement and axial alignment of the two vertically spaced cylindrical abutment surfaces 60 and 61, causing the landing tool 30 and associated well head latch and conductor pipe of the exemplary embodiment to become vertically aligned over the well head, as shown in FIG. 3, prior to the complete landing of the landing surfaces 27 and 34 upon the ledges or stop surfaces 48 and 45, respectively, as shown in FIG. 4. Such prior alignment of the landing tool, bonnet or coupling over the multi-diameter well head, conductor pipe or casing heads in accordance with the present invention greatly facilitates the landing and connection of such conductors and/ or couplings without damaging or impairing internal sealing means, such as the seal means 22 and particularly the seal means 49 on the interior of the exemplary landing tool body 31.

Having thus described an exemplary embodiment of the double tapered guidance method and apparatus in accordance with the present invention, what I wish to claim as new and secure by Letters Patent is defined and limited only by the following claims.

I claim:

1. A coupling guidance method for use in landing coupling members on stationary subsea casing heads remote from a floating vessel from which the coupling mem ber is lowered comprising the steps of:

running a coupling member from a floating vessel on a conductor pipe to a remote stationary subsea casing head;

establishing a first contact between annular tapered guidance surface on said coupling member and a first abutment surface on said casing head;

pivoting said coupling member on said first contact and establishing a second contact between a second annular tapered guidance surface on said coupling and a second abutment surface on said casing head; and

moving said axially aligned coupling member and casing head relative to each other to effect coupling thereof.

2. The method of claim 1 wherein said first and second guidance surfaces are axially spaced on said coupling member generally the same distance said first and second abutment surfaces are axially spaced on said casing head and including the further step of establishing said first and second contacts concurrently to prealign said coupling member and casing head prior to coupling thereof.

3. A method of prealigning a casing coupling member on a stationary subsea casing head means remote from a floating vessel from which the coupling member is lowered including the steps of:

establishing at least two vertically spaced concentric abutment surfaces on a subsea casing head means;

providing at least two axially spaced concentric annular tapered guidance surfaces within a. casing coupling member;

running said coupling member on a casing from said vessel into engagement with said casing head means to bring said two abutment surfaces into abutment with said two guidance surfaces to axially prealign said coupling member on said casing head means; and

thereafter moving said coupling member from said prealigned position into a coupled position with said coupling seated on said casing head means.

4. A method of guiding, prealigning and landing a multi-diameter bore landing tool from a floating vessel down upon a remotely located multi-diameter subsea well casing head comprising the steps of:

forming a pair of vertically spaced and relatively axially immovable concentric annular abutment surfaces on the exterior of a multi-diameter casing head having a large diameter lower portion and a smaller diameter upper portion;

forming a pair of vertically spaced and relatively axially immovable concentric annular tapered guidance surfaces within a multi-diameter bore landing tool having a large inner diameter lower bore portion and a smaller inner diameter upper bore portion, said bore portions being formed to fit over said head portions;

mounting said casing head at a stationary subsea first well casing and mounting said landing tool on a second well casing to be lowered to and coupled to said first well casing;

lowering said landing tool by its associated second casing from a floating vessel toward said casing head and guiding said lower bore portion over said upper head portion by lowering said guidance surface over said upper abutment surface;

lowering said landing tool further down on said casing head and establishing a dual vertically spaced guidance engagement by the lower guidance surface engaging the lower abutment surface and the upper guidance surface engaging the upper abutment surface and guiding said tool large bore portion over said head large diameter portion and said tool smaller bore portion over said head smaller diameter portion concurrently by said dual guidance engagement; and

thereafter landing said tool down on said casing head by still further lowering of said tool down on said head after said large and smaller tool bore portions have been prealigned over said large and smaller diameter head portions, respectively, said abutment surfaces passing through and disengaging from said guidance surfaces prior to complete: landing of said tool on said head.

5. The method of claim 4 including the steps of:

loosely fitting said landing tool on said casing head by said abutment surfaces passing through and disengaging from said guidance surfaces; and

snugly fitting said landing tool bore portions over said casing head diameter portions by a further axially spaced dual guidance engagement between said tool and head prior to complete landing of said tool on said head.

6. The method of claim 4 including the steps of:

providing a landing surface in said bore between said large and smaller bore portions and. a landing ledge on the exterior of said casing head between said large and smaller diameter portions during said forming steps; and

seating said landing surface upon said landing ledge during said step of landing said tool down on said casing head.

7. A coupling guidance method for use in landing coupling members on subsea casing heads remote from a floating vessel from which the coupling member is lowered comprising the steps of:

running a multi-diameter inner bore coupling member from a floating vessel on a conductor pipe to a remote stationary subsea multi-diameter casing head;

establishing a first engagement between a first annular tapered guidance surface on said coupling member and a first abutment surface on said casing head;

establishing a second engagement between a second annular tapered guidance surface on said coupling axially spaced therein from said first guidance surface and a second abutment surface on said casing head axially spaced thereon from said first abutment surface a distance equal to the spacing of said guidance surfaces;

guiding said first coupling member into a loose fitting generally axially aligned position on said second coupling member by moving said first and second guidance surfaces over and past said first and second abutment surfaces;

References Cited UNITED STATES PATENTS 895,750 8/1908 Harms et al. 285l33 2,552,899 5/1951 Manes 6146.5 2,962,096 11/1960 Knox 285l8 X 3,023,012 2/1962 Wilde 285--18 X 3,241,864 3/1966 Shaffer 285I8 CHARLIE T. MOON, Primary Examiner US. or. X.R.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,485,051 December 23, 1969 Bruce J. Watkins It is certified that error appears in the above identified patent and that said Letters Patentare hereby corrected as shown below:

Column 5, line 55, before "annular" insert an Signed and sealed this 27th day of October 1970.

(SEAL) Attest:

Edward M. Fletcher, Jr.

Attesting Officer Commissioner of Patents WILLIAM E. SCHUYLER, JR.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US895750 *Dec 31, 1906Aug 11, 1908George HarmsHot-air pipe.
US2552899 *May 19, 1947May 15, 1951Shell DevFloating drilling rig
US2962096 *Oct 22, 1957Nov 29, 1960Hydril CoWell head connector
US3023012 *Jun 9, 1959Feb 27, 1962Shaffer Tool WorksSubmarine drilling head and blowout preventer
US3241864 *Oct 29, 1962Mar 22, 1966Shaffer Tool WorksAutomatic connector
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4200312 *Feb 6, 1978Apr 29, 1980Regan Offshore International, Inc.Subsea flowline connector
US4209891 *Jul 17, 1978Jul 1, 1980Nl Industries, Inc.Apparatus and method for positioning one part relative to another part
US4456070 *Jul 26, 1982Jun 26, 1984Hughes Tool CompanyTieback connection method and apparatus
US4465134 *Jul 26, 1982Aug 14, 1984Hughes Tool CompanyTie-back connection apparatus and method
US4469136 *Feb 22, 1982Sep 4, 1984Hughes Tool CompanySubsea flowline connector
US4930938 *Jun 2, 1989Jun 5, 1990Exxon Production Research CompanyOffshore platform deck/jacket mating system and method
US6138774 *Mar 2, 1998Oct 31, 2000Weatherford Holding U.S., Inc.Method and apparatus for drilling a borehole into a subsea abnormal pore pressure environment
US6139256 *Aug 6, 1997Oct 31, 2000Solar Turbines IncorporatedApparatus for controlling the concentricity of a member with a centering device
US6263982Mar 2, 1999Jul 24, 2001Weatherford Holding U.S., Inc.Method and system for return of drilling fluid from a sealed marine riser to a floating drilling rig while drilling
US6360418 *Jul 18, 2000Mar 26, 2002Solar Turbines IncorporatedMethod for controlling the concentricity of a member with a centering device
US6470975Mar 1, 2000Oct 29, 2002Weatherford/Lamb, Inc.Internal riser rotating control head
US6913092Jul 23, 2001Jul 5, 2005Weatherford/Lamb, Inc.Method and system for return of drilling fluid from a sealed marine riser to a floating drilling rig while drilling
US7159669Oct 28, 2002Jan 9, 2007Weatherford/Lamb, Inc.Internal riser rotating control head
US7237623Sep 19, 2003Jul 3, 2007Weatherford/Lamb, Inc.Method for pressurized mud cap and reverse circulation drilling from a floating drilling rig using a sealed marine riser
US7258171Nov 21, 2005Aug 21, 2007Weatherford/Lamb, Inc.Internal riser rotating control head
US7448454Mar 23, 2004Nov 11, 2008Weatherford/Lamb, Inc.Method and system for return of drilling fluid from a sealed marine riser to a floating drilling rig while drilling
US7487837Nov 23, 2004Feb 10, 2009Weatherford/Lamb, Inc.Riser rotating control device
US7836946Mar 2, 2006Nov 23, 2010Weatherford/Lamb, Inc.Rotating control head radial seal protection and leak detection systems
US7926593Apr 19, 2011Weatherford/Lamb, Inc.Rotating control device docking station
US7934545Oct 22, 2010May 3, 2011Weatherford/Lamb, Inc.Rotating control head leak detection systems
US8061419 *Nov 13, 2008Nov 22, 2011Stream-Flo Industries Ltd.Casing head slip lock connection for high temperature service
US8408297Mar 15, 2011Apr 2, 2013Weatherford/Lamb, Inc.Remote operation of an oilfield device
US8701796Mar 15, 2013Apr 22, 2014Weatherford/Lamb, Inc.System for drilling a borehole
US8939235Feb 24, 2014Jan 27, 2015Weatherford/Lamb, Inc.Rotating control device docking station
US9004181Sep 15, 2012Apr 14, 2015Weatherford/Lamb, Inc.Low profile rotating control device
US9068423Feb 3, 2012Jun 30, 2015National Oilwell Varco, L.P.Wellhead connector and method of using same
US9074450Feb 3, 2012Jul 7, 2015National Oilwell Varco, L.P.Blowout preventer and method of using same
CN102575504B *Aug 20, 2010May 13, 2015阿克海底公司垂直连接器
DE2818125A1 *Apr 25, 1978Nov 2, 1978Standard Oil CoLoesbare verbindung fuer eine steigleitung
DE2832517A1 *Jul 25, 1978Aug 9, 1979Regan Offshore IntKupplung fuer unterwasser-abflussleitungen
DE2834033A1 *Aug 3, 1978Feb 15, 1979Seal Participants HoldingsAutomatische rohranschlussvorrichtung
WO2011021945A1 *Aug 20, 2010Feb 24, 2011Aker Subsea AsVertical connector for use on the seabed
WO2013152195A2 *Apr 4, 2013Oct 10, 2013National Oilwell Varco, L.P.Wellsite connector with floating seal member and method of using same
Classifications
U.S. Classification405/204, 29/464, 29/451
International ClassificationE21B33/03, E21B33/038
Cooperative ClassificationE21B33/038
European ClassificationE21B33/038
Legal Events
DateCodeEventDescription
Mar 15, 1982ASAssignment
Owner name: HUGHES TOOL COMPANY
Free format text: CHANGE OF NAME;ASSIGNOR:REGAN OFFSHORE INTERNATIONAL,INC.;REEL/FRAME:003957/0735
Effective date: 19820211