US 3830304 A
Apparatus for isolating a production tubing string in an oilwell from the control head whereby pressures higher than the rated pressure of the control head may be applied to the producing formation, utilizes an outer housing with a telescoping inner mandrel and seals therebetween, with said outer housing being adapted for connection to the control head and the inner mandrel being capable of moving into the control head to make a fluidically sealed connection with the production tubing thereby isolating the control head from the higher pressures being applied through the tubing into the formation.
Description (OCR text may contain errors)
United States Patent [191 Cummins [451 Aug. 20, 1974 WELLHEAD ISOLATION TOOL AND METHOD OF USE THEREOF  Inventor:
 Assignee: Halliburton Company, Duncan,
 Filed: June 4, 1973  Appl. No.: 366,895
Alonzo E. Cummins, Duncan, Okla.
 US. Cl. 166/305 R, 166/77, 166/80, 166/85, 166/315  Int. Cl E2lb 43/00, E2lb43/25  Field of Search 166/70, 72, 77, 80, 84,
 References Cited UNITED STATES PATENTS 1,811,422 6/1931 Brown 166/80 2,927,642 3/1960 Meredith, Jr. et a1. 166/315 X 3,100,015 8/1963 Regan 166/77 X Haeber 166/84 X Newsome 166/77 X Primary ExaminerStephen .1. Novosad Attorney, Agent, or Firm-John H. Tregoning [5 7 ABSTRACT Apparatus for isolating a production tubing string in an oilwell from the control head whereby pressures higher than the rated pressure of the control head may be applied to the producing formation, utilizes an outer housing with a telescoping inner mandrel and seals therebetween, with said outer housing being adapted for connection to the control head and the inner mandrel being capable of moving into the control head to make a fluidically sealed connection with the production tubing thereby isolating the control head from the higher pressures being applied through the tubing into the formation.
11 Claims, 7 Drawing Figures PATENTl-Znmazmml 3. 30.30 SHEEI REF 3 FIG; 20
WELLHEAD ISOLATION TOOL AND METHOD OF USE THEREOF BACKGROUND OF THE INVENTION During the life of most producing oilwells, it often becomes desirable to further treat the well to enhance and increase production. Usually this involves applying an acidic solution to the producing formation under pressure or applying an hydraulic solution to the formation under extremely high pressure in order to fracture the formation and increase the flow of hydrocarbons therefrom. In order to take a well off of production and achieve the required acidizing or fracturing treatment or any other treatment, it is necessary to remove the wellhead from the well and tie into the production tubing. In order to remove the wellhead or tie into the production tubing, it becomes necessary to kill the well. This involves a process of pumping fluid, such as mud or water, into the well until a sufficient amount of hydrostatic pressure, or head, is obtained from the fluid to overcome the pressure of the formation and prevent the blowing-out of well fluids or formation fluids from the well. The killing process is one involving great amounts of expense, time and labor and, therefore, creates a highly undesirable situation. There are prior art devices available for treating or fracturing producing wells which allow the control head to be by-passed, thereby obviating the need to remove the control head from the well. The disadvantage of these prior art devices is that the well still must be killed before installation of the devices can be achieved. Once the well has been killed and the fracturing or treating equipment is attached to the production tubing, the treatment can begin. After the treatment of the well, it becomes necessary in many instances before the well can be placed on production to swab the killing fluid from the well. This further involves more expense, time and labor. The apparatus of the present invention provides means for communicating with production tubing directly without need of removing the wellhead from the well nor for killing the well or swabbing out afterwards. This is achieved by apparatus having an inner high pressure mandrel and an outer high pressure casing, with said casing being adapted for sealing contact with the wellhead, and said inner mandrel being adapted for sealing contact with the production tubing. The inner mandrel is arranged to be inserted through the wellhead without need for removing the wellhead.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates a schematic diagram showing the wellhead positioned upon the well and the underground formation.
FIG. 2a is a partial cross-sectional view illustrating the upper end of the apparatus of the present invention.
FIG. 2b is a continuation of FIG. 2a and is a partial cross-sectional view illustrating the upper medial portion of the apparatus of the present invention.
FIG. 20 is a continuation of FIG. 2b and is a partial cross-sectional view illustrating the lower medial portion of the apparatus of the present invention installed upon the wellhead.
FIG. 2d is a continuation of FIG. 2c and is a partial cross-sectional view illustrating the lower end of the apparatus of the present invention.
FIG. 3 illustrates a schematic drawing of the apparatus after it has been actuated and placed in communication with the production tubing.
FIG. 4 illustrates an alternate method of attaching the various flanged sections together.
DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIGS. 1 through 4 in which the preferred embodiments of the disclosed invention are incorporated, a normal producing well 1 is illustrated wherein the well comprises casing 2 passing into the ground, ground casing 3 located concentrically around casing 2, and production tubing 4 passing concentrically within casing 3 and 2, and communication with the producing formation 5. Located above ground and connected to ground casing 3, is the wellhead 6 having lower valve 7, intermediate valve 8, tee valve 9, and upper valve 10.
Referring to FIGS. 20, 2b, 2c and 2d, the wellhead isolation tool 100 is shown in the initial orientation. The apparatus consists of a tubular cylindrical outer housing 12 made out of substantially strong material rated to withstand pressures in excess of 20,000 psi. Located concentrically and slidably within housing 12 is a high pressure innermandrel 11 which is a tubular cylindrical member extending completely through housing 12 above and below the housing. Mandrel 11 has at its lower elongated end a seal collar 13 containing thereon a sealing cup 14 attached to seal collar 13 by ring 15. Located above seal cup 14 is secondary sealing means 16 located concentrically over collar 13. Above seal 16 is mandrel ring 17 also slidably concentrically located on collar 13. Collar 13 is a cylindrical tubular piece having an enlarged section 18 and a narrowed section 19, which combination of sections 18 and 19 jointly forms shoulder 20 thereon. Seal cup 14 contains inner enlarged shoulder 21 to mate with shoulder 20 of collar 13 and provide retaining means of cup 14 on collar 13. Ring 15 further contains circular sealing means 22 and an annular recess 23 therein, said sealing means 22 arranged to provide sealing contact between ring 15 and the restricted section 19 of collar 13. Collar 13 contains threaded end 24 which is threadedly connected into the lower end 25 of mandrel 11, which also contains threads 26 for mating with the threads of section 24. Circular seal 27 is located in recess 28 of section 25 to provide seal means contacting collar 13 in a sealing engagement. Section 24 of collar 13 is threadedly engaged into section 25 of the mandrel 11 so that the lower end of mandrel l1 abuts ring 17 thereby fixedly holding ring 17, seal 16, and cup 14 on the lower end of mandrel 11 in collar 13. Housing 12 further consists of lower adapter 30 which is attached to threaded-upper adapter 31 threadedly attached at threads 32 to housing 12. Lower adapter 30 comprises a cylindrical tubular piece having attachment flange inside adapter 30 and 31 provide sealing engagement between the adapters and the innermandrel 11. Flange 33 is provided for attaching the device to the wellhead. Flange 33 may be of the clamp type as those shown at 34 and 35, or may be of the bolt-through type FIG. 4. A further alternative of attachment means at flange 33 would be a threaded type attachment with mating threads on the wellhead control tee. The purpose of adapter 30 is to allow the different type of flanging means to be utilized with the tool without having to change the entire housing of the tool. Thus if the bolt type flange is available on the wellhead, section 30 having the clamp type flange may be removed and a different lower adapter having the bolt type flange may be replaced on the device in place of the clamp type adapter 30. Clamp 36 comprises a hinged multi-piece clamp having a circumferential body 39 with clamping wings or arms 40 and 41. These clamping arms actually comprise annular radially inwardly formed shoulders along the front and rear ends of circumferential band 39. The clamping force which is provided by wings 40 and 41 arises from the beveled or cam surfaces 42 and 43, acting upon the mating cam or beveled surfaces 44 and 45 of the upper flanges 34 and 35 of the housing pieces or upper adapters 30 and 31. The cam surfaces 42 and 43 are drawn down upon cam surfaces 44 and 45, thereby forcing flanges 34 and 35 into abutting relationship by the tightening of two bolts 46 and 47, which tightening pulls the multi-piece clamp unit into abutment with the flanges 34 and 35. This clamping arrangement is well known in the art, and the clamping devices may be readily obtained through any commercial outlet.
Housing 12, consisting of lower adapter 30, upper adapter 31, central housing section 50 and top adapter 51, serves as a housing unit for innermandrel 11, as well as providing an annular piston space 52 between housing 12 and mandrel 11. lnnermandrel 11 comprises a lower tubular section 53 and an upper tubular section 54. While these may be integrally formed as one section, it is obvious that for convenience and ease of manufacturing it would be desirable to form these in two sections as illustrated. Upper mandrel section 54 has at its upper end a locked-down clamping flange 55, threaded valve connection end 56, and an open bore passage 57 therethrough. Bore passage 57 extends through the entire length of innermandrel 11 in an unhindered, unrestricted tubular passage therethrough. Upper adapter 51 of housing 12 comprises a lower internally threaded skirt section 58, an intermediate ported section 19 and an upper clamping section 60 having clamping ridge 61 integrally formed thereon. Clamping ridge 61 is identical in structure to clamping ridges 34 and 35 on the lower end of housing 12, and also is identical to clamping ridge 55 located at the upper end of innermandrel 11. Clamping ridge 61 and clamping ridge 55 are arranged so that upon downward movement of inner mandrel 11 through housing 12 to its lowermost point of travel, ridge 55 will come into abutment with ridge 61 whereupon a clamp similar to clamp 36 may be applied to ridges 61 and 55, thereby locking the innermandrel 11 in the lowermost position within housing 12; this locking arrangement of the clamp on ridges 61 and 55 is illustrated in phantom in FIG. 212.
A hydraulic actuated piston system is illustrated in FIG. 2b wherein mandrel 11 carries upon its outer surface an annular piston shoulder 62 which moves vertically within annular piston space 52 between mandrel 11 and housing 12. Piston shoulder 62 passes circumferentially around mandrel 11 and has sealing elements 63 thereon providing sealing contact with the inner surface of outer housing 12. Annular shoulder 62 thereby provides a fluidic barrier between mandrel 11 and housing 12. Operation of this hydraulic piston arrangement will be more particularly described later in conjunction with description of the operation of the entire tool. Communication of fluids with annular space 52 and piston 62 is provided through upper port 64 and lower port 65. Communication is provided from these ports to annular space 52 through a narrower annular space 66 and a narrower annular space 67, respectively, communicating from ports 64 and 65 to annular space 52. These ports 64 and 65 further have internal threads 68 and 69, respectively, for receiving either a threaded plug member (not shown) or else a threaded adapter member 70 as shown. Threaded adapter member 70 has external threads 71, seal means 72 for providing a fluidic connection in port 64 or 65, and further has an enlarged tubular section 73 having internal threads 74 adapted for receiving standard threaded tubing connectors (not shown). Thus, adapter 70 provides a means of connecting a standard section of tubing into ports 64 or 65 of the apparatus.
Referring now to FIGS. 2a, 2b, 2c, 2d, and 3, operation of the apparatus will be described in more particular detail. In FIGS. 2a, 2b, 2c and 2d the apparatus is shown in its initial unextended position as it will be when placed upon the wellhead 6 (as shown in the Figures). When it becomes desirable to treat a well without having to kill it, the lower valve 7 may be closed off thereby closing-in the well. The upper valve 10 is then removed and the apparatus 100 fixedly attached thereto. This may be done as previously described by placing a clamping member 75 on flange 33 and the uppermost flange 76 of the wellhead 6; this applies a clamping sealing force similar to that of clamp 36 on flanges 34 and 35. Furthermore, a flat sealing ring with a beveled end may be placed between flange 33 and the uppermost flange of the control head, thus providing further sealing engagement between tool 100 and the control cross 9. After the apparatus is fixedly clamped to the wellhead and sealed off, the well is further closed in by means of the apparatus 100. At this time, the lowermost valve 7 may be opened and the well will still remain closed in due to the sealing arrangement previsouly described. It should be noted at this point that prior to opening the lower valve 7, a manually of automatically operable high pressure valve 80 (FIG. 3) should be attached to the upper end 56 of inner mandrel 11 at the threads thereon, and this valve 80 closed. This closes off and seals bore 57 passing through mandrel l1, and allows the operator to communicate fluidically at will with bore 57 through the valve located thereon. After the valve is placed on mandrel 11, and apparatus is sealingly attached to the upper end of the wellhead control cross 9, the lower valve 7 may be opened thereby providing a straightthrough open bore for inner mandrel 11 to pass through. At this time fluidic pressure may be applied through adapter 70, through port 64 and against the upper space of annular piston 62. Lower port 65 should be preferably opened to atmospheric pressure, thereby communicating atmospheric pressure to that section of annular piston space 52 located below piston 62. The application of pressure through port 64 results in a pressure differential across piston 62 thereby driving mandrel ll downward, penetrating through the control cross 9 and into production string of tubing, as shown in the FIG. 3. The injection of the sealing cup assembly on the lower mandrel 11 into production string provides a fluidically sealed arrangement between bore 57 and the inner bore of the production string; thus, fluidic pressure, which may be applied within bore 57 and within the production string, is isolated from any of the apparatus on the control head and the housing 12. At this point, the operator may attach high pressure fluid supply lines to the valve attached at the upper end of the innermandrel ll, whereupon he may open the valve on mandrel 11 and supply high pressure fluids through bore 57 and directly into the production string, thereby by-passing contact of the high pressure fluid with any of the control equipment located exteriorly to the production string in innermandrel 1 1. Thus it can be seen from this description of the operation of this tool that the well can be placed on high pressure fluids without need for pumping fluid or mud into the well in a killing operation, and high pressures can be obtained within the production tubing without applying said high pressures to any of the control equipment. Thus, in treating or fracturing a well having a control cross thereon which is rated at 10,000 psi, an operator can fracture or treat a well at 20,000 psi, or higher, without damaging the control equipment and without need for killing the well to replace the control equipment or by-pass it. In the oilfield it is common practice to utilize control heads and control equipment rated at 10,000 psi or less, because the need for any higher pressures so very infrequently arises that to utilize control equipment rated at higher than 10,000 psi would be economically unfeasible. Thus, by the use of this equipment and the apparatus disclosed herein, the well can utilize low pressure control head equipment satisfactorily while still allowing the operator to economically and efficiently apply high pressures to the formation to treat and fracture the well in the formation.
Although a specific preferred embodiment of the present invention has been described in the detailed description above, the description is not intended to limit the invention to the particular forms or embodiments disclosed herein since they are to be recognized as illustrative rather than restrictive, and it would be obvious to those skilled in the art that the invention is not so limited. For example, it would be obvious from this disclosure to form the lower adapter of the housing as an integral part of the housing, and also it would be obvious to form the innermandrel in one piece rather than in two pieces as illustrated. It would also be obvious to alter the sealing means at the lower end of the innermandrel to provide other type seals, or to provide threaded lower end of innermandrel 11 for threaded engagement with the production tubing. Thus, the invention is declared to cover all-changes and modifications of the specific example of the invention herein disclosed for purposes of illustration, which do not constitute departures from the spirit and scope of the invention.
What is claimed is: v
1. Apparatus for fluidically communicating the pro-- ply means at the surface while isolating fluid control equipment in the wellhead from high pressure fluids supplied through said apparatus from the high pressure fluids supply means, said apparatus comprising:
a. elongated tubular housing means arranged to be fluidically connected to said wellhead and further arranged to define an inner bore therethrough;
b. elongated tubular inner mandrel means concentrically and slidably located within said housing means in fluidic sealing engagement therewith; said innermandrel means further adapted to extend out of said housing means, both above'and below said housing means;
0. means for moving said innermandrel means within said housing means, said moving means being capable of extending said innermandrel means downward through said housing means, said moving means further adapted for extending said innermandrel means upward out of said housing means;
d. seal means for providing sealing engagement between said mandrel means and the production tubing string within said well; said sealing means adapted for providing fluidic sealing engagement between said innermandrel means and said production tubing string; and
e. means on said innermandrel means for allowing the bore through said innermandrel means to be alternately opened and closed.
2. The apparatus of claim 1 wherein said means for moving said innermandrel means within said housing means comprises hydraulic piston means between said innermandrel means and said housing means, said piston means arranged to receive hydraulic pressure applied thereto and convert said hydraulic pressure application into telescopic movement of said innermandrel with respect to said outermandrel.
3. The apparatus of claim 2 wherein said piston means further comprises an annular exterior shoulder on said innermandrel means and an annular interior recess in said housing means, said annular shoulder adapted to sealingly engage in said recess to form an annular piston therein, and said housing means having first and second port means through the wall thereof, said first port means communicating with one end of said annular interior recess and said second port means communicating with the opposite end of said annular interior recess.
4. The apparatus of claim 1 wherein said seal means comprises elastomeric sealing cup means located around the lower end of said innermandrel means, said cup means adapted to snugly and sealingly engage the inner bore of production tubing in an oil well.
5. The apparatus of claim 1 wherein said innermandrel means bore closing means comprises connection means at the upper end of said innermandrel means for receiving in sealing attachment valve means to alternatively close and open said bore of said innermandrel means. v
6. The apparatus of claim 5 wherein said tubular housing means further comprises a tubular upper major housing and a lower tubular adapter, said adapter having first connection means adapted to connect fluidically with said major housing and said adapter further having second connection means adapted to be sealingly engaged with the control cross on a wellhead.
means in the lowermost position of said innermandrel means within said housing means.
8. A method of applying fluidic pressure to an underground formation penetrated by an oil well bore hole wherein said well borehole contains a production conduit string and has control equipment including one or more valves and a control cross at the surface, said method obviating the need for killing the well while simultaneously bypassing high pressure fluids through the surface control equipment; said method comprismg:
a. closing the lowermost valve in the control equipment at the surface;
b. removing the uppermost portion of said control equipment;
c. sealingly attaching to the top of said remaining control equipment a tubular housing having an elongated inner bore aligned with the bore of said control equipment; said tubular housing having sealingly and slidably located therein an elongated tubular innermandrel extending above and capable of extending below said tubular housing, said innermandrel having sealing means at the lower end thereof capable of sealingly engaging the production tubing in said well borehole and means at the top for attaching opening and closing means to said innermandrel bore;
d. closing the bore through said innermandrel;
e. opening the lowermost valve and all valves in line with the bore of said innermandrel and said housing thereby providing an unobstructed straightthrough vertical bore through said control equipment;
f. moving said innermandrel through said housing and into said control equipment bore until said innermandrel has passed entirely through said control equipment;
g. sealingly engaging said innermandrel with said production conduit; and
h. supplying the desired high pressure fluids through said innermandrel bore from the top portion thereof into the production conduit, thereby bypassing said control equipment.
9. The method of claim 8 whereby said step of moving said innermandrel through said housing further comprises applying an activating fluid under pressure to the upper side of an annular piston located on said innermandrel, said annular piston being sealingly and slidably engaged in an annular piston recess in said housing, said pressure application being sufficient to overcome sliding friction between said innermandrel and said housing and capable of moving said mandrel into sealing engagement with said production conduit, said pressure applying step continuing until said mandrel engages said production conduit string.
10. The method of claim 8 further comprising prior to said step of supplying high pressure fluid through said innermandrel, the step of locking said innermandrel to said housing in the lowermost position of said innermandrel thereby maintaining said mandrel securely engaged in said production conduit.
11. A method of obtaining fluidic communication with a formation through an oil well production conduit string wherein said communication allows applying fluid pressure exceeding the maximum rated pressure of surface control equipment on said well, without need for killing the well or removing said surface control equipment, said method of communicating with said formation comprising:
a. closing-in said well by closing a valve in the vertical bore of said surface control equipment;
b. removing an upper portion of said surface control equipment thereby exposing the portion of said bore above said closed valve;
0. closing in said upper bore portion by attaching to said surface control equipment means containing extendible conduit therein;
d. opening said valve thereby reestablishing communication of closed-in lower bore portion with said closed-in upper bore portion;
e. extending said extendible conduit through the bore of said surface control equipment;
f. sealingly engaging said extendible conduit with the production conduit in said well thereby allowing fluidic communication through said extendible conduit from the surface to the production conduit while bypassing said surface control equipment.