US 3294169 A
Description (OCR text may contain errors)
| J. OBRIEN 3,294,169
METHOD AND APPARATUS FOR CONTROLLING WELL FLUIDS Dec. 27, 1966 2 Sheets-Sheet 1 Filed Dec. 17, 1962 INVENTOR. LEO J. O'BRIEN BY 4mm4 ATTORNEY.
Dec. 27, 1966 1.. J. O'BRIEN 3,294,169
METHOD AND APPARATUS FOR CONTROLLING WELL FLUIDS Filed Dec. 17, 1962 2 Sheets-Sheet 2 F I G. 8 ATTORNLE United States Patent 3,294,169 METHOD AND APPARATUS FOR CONTROLLING WELL FLUIDS Leo J. OBrien, Crystal Lake, 1., assignor, by mesne assignments, to Union Oil Company of California, Los Angeles, Calif., a corporation of California Filed Dec. 17, 1962, Ser. No. 244,959 12 Claims. (Cl. 16646) This invention relates to a method and apparatus for controlling the flow of fluid in wells and the adjacent formation. One aspect of the invention relates to the control of flow of fluid between a well and an adjacent formation. Another aspect of the invention relates to the control of flow of fluid between vertically adjacent zones of a well bore.
The prior air recognizes the need for controlling the flow of fluid between a well and a surrounding permeable formation in both drilling and producing operations. Prior art techniques employed have included the plugging of formations, the casing of well bores, and the forming of mud filtrate sheaths. The prior art also recognizes the necessity for controlling the flow of fluid between adjacent zones of a well bore. For example, in fluid injection, acidizing, and fracturing operations, it is usually desired to pressurize only a selected section of the well. Numerous kinds of packers designed to meet this need have proved to be reasonably satisfactory for use in cased wells. In uncased wells, satisfactory packing is difficult to achieve.
It is an object of this invention to provide a method and apparatus for the control of fluid flow between a well bore and the encompassing formation. It is another object of this invention to provide an apparatus and method for controlling flow of fluids between adjacent zones of a well. Another object of this invention is to provide packing and casing means which are easily installed and removed for use in well bores. Other objects of the invention will become apparent from the following description, which is made with reference to the drawings, of which:
FIGURE 1 is a sectional view of a well bore in which is disposed a drill string and means for controlling flow of fluids from the well bore to the formation in accordance with this invention.
FIGURE 2 is a view of FIGURE 1 taken in the direction 2-2,
FIGURE 3 is a sectional view of an apparatus usefu in the method of this invention in drilling and packing operations,
FIGURE 4 is a view of valve means forming a part of the apparatus of FIGURE 3,
FIGURE 5 is a sectional view of a packer useful in accordance with this invention,
FIGURE 6 is a sectional view of an alternate packer structure,
FIGURE 7 is a sectional view of a double packer particularly adapted for use in formation fracturing operations, and
FIGURE 8 is a sectional view of a well bore provided with a temporary casing in accordance with this invention.
The method of this invention utilizes electric field-responsive fluids, commonly called electrofluids, which display a dramatic increase in apparent viscosity in the presence of an electric field. The fluids themselves form no part of this invention, but are well known in the art and described in patents and in the literature e.g., Winslow 2,417,850 and 3,047,507. Some such fluids are produced by incorporating finely divided particulate solids, such as finely powdered silica, in a dielectric fluid, which is usually a refined'hydrocarbon, such as white oil, or a lower viscosity lubricating oil fraction. Various additives may be incorporated in such fluids to serve different purposes.
For example, it is usual to incorporate a fluidizing agent which permits the use of greater quantities of particulate solids without raising the residual viscosity of the product to an undesirably high level. Where it is desired to employ a DC rather than an AC. field to activate the fluid, small amounts of basic nitrogen-containing compounds are usually added. In the practice of the instant invention, where large quantities of field-responsive fluids are required, and a rather high residual viscosity is desirable, it is preferred to keep the use of additives to a minimum. For this purpose, it is also preferred to use alternating potential to control the apparent viscosity of the electrofluid in the well bore. Where little or no fluidizer or basic nitrogen compounds have been added, the tendency of the fluid to emulsify upon contact with formation Water is reduced.
Referring to FIGURE 1, formation 10 is penetrated by well bore 12, in which is disposed drill string 14. The well bore has penetrated a formation zone 16 of high permeability, which result in considerable fluid loss to the formation and difliculty in maintaining drilling fluid circulation. To meet this problem, drill string 14 has been equipped with assembly 20 which comprises a section of drill pipe 22, a tubular, electrically conducting electrode 24 which encompasses pipe section 22, bearings 26, 28' and bearing retainer assemblies 26 and 28 which are disposed at opposite ends of electrode 24, and electrically insulating spacer 30 and 32 which serve to electrically insulate pipe section 22 from the remainder of the drill string. The electrode is supported from insulators 30 and 32 by means of frangible spokes such as spokes 34 and 36. A plurality of longitudinal spacers is provided externally of electrode 24. These spacers, which are shown best in FIGURE 2 and designated by numeral 38, are longitudinal stringers which are fabricated of an electrically insulating material. They function to retain the electrode 24 in electrically insulated relationship with respect to the well bore.
An electrical circuit, including a potential source comprising generator 43, variable resistance 45, switches 44 and 49, and ground stake 51, in cooperation with electrical conductors 53 and 55, provides means for applying an electric potential between electrode 24 and pipe section 22, or between electrode 24 and the wall of well bore 12. In the latter case, the electrical connection is maintained between the stake and the well bore by the natural conductivity of the earth. Conductors 53 and 55 may be a part of the drill string, as described in US. Patent No. 2,178,931.
In operation, the assembly is lowered to a position adjacent the formation zone of high permeability, as shown in FIGURE 1. An electric field-responsive fluid is then introduced through the annulus between the drill string and the wall of the well bore. Since the fluid tends to preferentially enter the larger space between electrode 24 and insulated pipe section 22, a high electric potential is applied between electrode 24 and pipe section 22 by closing switch 44 and operating switch 49 to connect potential source 43'to conductor 55. It will be understood that conductor 53 connects to electrode 24, while conductor 55 connects to pipe section 22. Fluid in the space between the electrode and pipe section is thereby rendered very viscous, or semi-solid, which prevents further flow of fluid upward between the electrode-and drill stem, and directs the fluid upward between the electrode and well-bore. Thus, an economy of fluid is achieved.
After the annular space between the electrode and well-bore has been filled with the electric field-responsive fluid, a high potential in the range of about 50,000 to 3 250,000 volts per inch of radial distance between the electrode and well bore is applied by connecting switch 49 to ground stake 51. The fluid in the annular space between the electrode and well bore is thereby rendered solid, or at least semi-solid, and the electrode secured firmly in place. Since the fluid between the electrode and pipe section 22 is no longer energized, the drill string may be rotated to shatter frangible spokes 34 and 36 and to break conductor 55 lose from pipe section 22. Drilling fluid may be pumped down the drill string and drilling may then proceed in the usual manner. The electrode 24, acting in conjunction with the annular column of electric field-responsive fluid, will retain an effective seal at the well interface with formation zone 16 so long as a high electric potential is maintained. Circulation of drilling fluid and cuttings upward through the space between the electrode and drill string can be maintained in the usual manner. Bearings 26' and 28' and bearing retainer assemblies 26 and 28 are provided to maintain the electrically insulated relationship between the electrode and drill string and to prevent binding of the drill string and electrode in the event the drill string does not remain central in the well bore. The interior member of the bearing assembly is, of course, fabricated of an electrically insulating material, such as polyfluoroethylene. When it is desired to remove the drill string from the well bore, the electric potential is disconnected and the electrode 24 is pulled upward with the drill bit.
An alternate apparatus for use in conjunction with a drilling string or a tubing string is depicted in FIGURES 3 and 4., Threaded tubing section 40 is adapted for connection in a drill string. Electrical conductors 41 and 42 extend downward through the well boreexternally of the drill string and make connection to the apparatus as will later appear. Pipe section 40 is surrounded by spoolshaped member 46, which is supported directly from pipe 40 and is fabricated of an electrically insulating material, such as plastic. Outside of and annular to member 46 is tubular electrode 48, which is fabricated of steel. Electrode 48 may be of any desired length, and is of a diameter such that it will conveniently fit within the well bore. Electrode 48 is retained in position and rotatably supported from pipe section 40 by means of flanges 50 and 56 of spool-shaped member 46, in cooperation with metal raceways 58 and 59 and the complementary raceways 60 and 61 which are formed in electrode 48. Ball bearings 62 and 64 complete the supporting assembly. Conduit 42 makes electrical connection to metal raceway 58, and then through ball bearing 62 to electrode 48.
Perforated ring 52 cooperates with flange 50 to form a valve for controlling flow of fluid through annulus 65 axially of the pipe section 40. Ring 52 is supported by element 46 and is readily rotatable via bearing 66 and raceway 67. Referring to FIGURE 4, flange 50 and ring 52 are seen to be perforated by a plurality of holes indicated generally by the numerals 70 and 74, '70 indicating perforations in flange 50 and 74 indicating perforations in disc 52. Flange 56 is similarly perforated. It is evident that when the holes 70 and 74 are rotatably displaced from each other, flow of fluid axially of the packer is prevented. On the other hand, when holes 70 and 74 are brought into registry, it is evident that fluids may flow through openings in flange 56, through annular space 65,
' and thence through the valve formed by ring 52 and flange 50. While the valve formed by ring 52 and flange 50 may be operated by mechanical or hydraulic means for rotating ring 52, electrical actuation is preferred. For example, a solenoid, not shown in the drawing, may be supported from member 46 and used to drive ring 52. The solenoid may be energized through conductor 41, which may carry two wires and thus provide power to the solenoid, or conductor 41 may carry only a single wire and 'the drill string used as a return lead. It will be evident that numerous other valve means may be employed. In practice, it is desirable that the openings 70 and 74 be of the greatest possible cross-sectional area so that the valve means, when opened, will provide minimum resistance to flow.
Referring to FIGURE 5, a packer useful in fracturing and oxidizing operations is shown. Formation 78 is penetrated by well bore 80, in which is inserted tubing string 82. The lower portion of the tubing string 82 supports electrically insulating blocks 86 and 88 which, in turn, support tubular electrode 90. Electrical conductor 91 is provided to energize electrode 510. In operation, the tubing string is lowered into a well bore adjacent the bottom thereof, or adjacent to a packer which seals off a lower portion of the well bore, and electric potential responsive fluid is pumped downward through the tubing string and upward in the annulus surrounding electrode 90. Electric potential is then applied between ground and electrode 00 by means of conductor 91. A potential source similar to that shown in FIGURE 1 may be employed. The annularly shaped column of electrofluid 94 is energized and rendered semi-solid by the applied potential. Electrofluid in the Well bore below electrode may be removed by baling. Fracturing fluid is then introduced into the space below electrode 90 through the tubing string, and pressure applied to fracture'the formation in the conventional manner. The potential source may then be disconnected and the apparatus withdrawn from the well bore. If desired, insulating rings 88 may be replaced with valve means as shown in FIGURES 3 and 4, whereby the electrofluid below electrode 90 may be dis placed upward through annular space 96 by the injection of fracturing liquid. In this case, the interior surface of tubular electrode 90 should be protected by a layer of electrically insulating material to prevent solidification of electrofluid within the annulus, in the event the tubing string is grounded.
Referring to FIGURE 6, a simple packer is shown to comprise tubing string 100, spool 102 which is fabricated of an insulating material, cylindrical screen 104, conductor 106, and frangible disc .108. To set this packer, the assembly is lowered into the well-bore and electrofluid is introduced under pressure down the tubing string and through openings 107 and 109 in the tubing string and spool, respectively. The electrofluid flows outward through screen 104, whereupon electric potential is applied by means of conductor 106 to freeze the packer in place by solidifying the electrofluid. The tubing string can then be rotated to bring holes 107 out of alignment with holes 109, and higher pressure applied to break frangible disc 108.
Referring to FIGURE.7, a double packer, useful in fracturing and acidizing formations at locations above the bottom of the well bore, is shown. It will be assumed that a decision is reached that well bore 110, which penetrates formation 112, should be fractured at position 114. A tubing string supporting the apparatus shown in FIG- URE 7 is lowered into well bore 110. Inner tubing section 116 is provided with apertures 117 and rupture discs 118 in the pipe at about the center of its length. An outer tube 120 which is fabricated of an electrically insulating material, preferably a suitable plastic, has perforations 122 at about the center of its length, and is spaced annularly to tube section 116 with perforations 1'22 adjacent to rupture discs 118. Outer tube 120 is spaced and insulated from inner tube section 116 by electrically insulating spacers 124, which are fabricated of a suitable plastic. Tubular electrodes 128 and 129 are supported externally of outer tube 120 above and below perforations 122. Electric potential can be applied to electrodes 128 and 129 by means of conductor 130, whereby electrofluid surrounding electrodes 128 and 129 may be energized. The lower extremity of tubing section 116 is closed by valve 131.
Means for centering the apparatus within the well bore may be provided, as shown in FIGURES 1 and 2. Alternatively, tubing string centering devices, well known in the art, may be provided on the tubing string above and below the apparatus of this invention, whereby proper centering is achieved. In operation, with valve 131 closed, electrofluid is pumped down the tubing string and sufficient pressure is applied to rupture the rupture discs 11 8. The electrofluid passes out through perforations 117 and 122 and into the annular space of the bore. At this time the electrodes are preferably energized by a small potential, say 50,000 volts per inch of radial space be tween the electrode and the surrounding well bore, whereupon the electrofluid in the space between the electrodes and well bore will become very viscous, but not immobile. Application of pressure is continued until the annular spaces 134 and 13 6 are filled with viscous electrofluid. Pressure is then relieved and the applied potential is increased to a value in the range of 50,000 to 250,000 volts per inch of radial annular distance between the electrodes and well bore wall. The valve 131 may then be opened to purge electrofluid from the tubing string by force of gravity, and fracturing fluid is then introduced through the tubing string and into the well bore zone 138 between electrodes 128 and 129. At this time valve 131 is, of course, closed. Fracturing of the formation is then carried out in the usual manner. It will be evident that since the electrofluid is not detrimental to the fracturing process, and since the fluid in any event is present in small amounts, the process may be carried out without ever opening valve 131, and indeed valve 131' can be replaced by means for closing the tubing section 116 below ports 117.
Referring to FIGURE 8, a well bore is provided with a temporary well casing in accordance with the teachings of this invention. Threaded casing sections 212, which form a portion of a well casing, are lowered irito well bore 210. Each section of the casing is novel in that it has an inner pipe 218 composed of an electrically nonconducting material, preferably a suitable plastic, and an outer metal pipe section 220 that is electrically conducting. Cement shoe 222 is threaded into the bottom of the casing. Cement shoe 222 features valve 224 that permits flow of cementing material downward through the shoe but checks upward flow. The casing string is lowered into the well bore. Next, cement plug 226, featuring rupture disc 228, is lowered to seat on cement shoe 222. A suitable amount of an electric field-responsive fluid is injected to just fill the annulus between the metal pipe sections which comprise the casing, and the well bore. Snugly fitting cement plug 230 is then lowered into the casing, and rests upon the measured volume of electric field-responsive fluid. Suitable pressure is exerted upon the plug 230 to rupture disc 228 and force electrofluid out through one-way valve 224 and into the annulus of the well surrounding the casing. When the annulus is filled, a high electric potential in the range of 50,000 to 250,000 volts per radial inch of distance between the casing and well bore is imposed upon the easing and ground, whereby the electrofluid is energized. The high potential freezes the electrofluid into a solid or semi-solid condition, effecting a temporary cementing. At a later date, if desired, the electric potential may be removed, which will again render the electric field-responsive fluid flowable, and make possible the salvage of the temporary casing, as well as most of the electrofluid.
In the practice of this invention, it is contemplated that any of the wide variety of art-recognized electric fieldresponsive fluids may be employed. A suitable non-limiting example of such a fluid is that disclosed in US. Patent 3,047,507 to Winslow as Example No. 15. Also, while the application of the electric field has been illustrated by applying a potential between an electrode and ground, using the natural conductivity of the earth, it will be evident that other means for applying an electric field to the electric field-responsive fluid may be employed.
For example, a plurality of electrodes may be disposed downhole in contact with the fluid, and electric potential applied to these electrodes.
The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
1. The method of controlling the flow of fluid between a well bore and a surrounding formation comprising disposing an elongated tubular electrode within said well bore in substantially coaxiaily aligned relation therewith, to form an annular space between said electrode and the walls of the well bore, disposing within said annular space a fluid that exhibits a change in apparent viscosity upon the application of an electric fluid, providing means by which an electric field may be applied across said fluid, and applying an electric field radially of said annular space.
2. The method in accordance with claim 1 in which said field is applied by connecting a potential source between said electrode and ground.
3. The method in accordance with claim 2 in which the magnitude of the applied potential is in the range of 50,000 to 250,000 volts per inch of radial distance between said electrode and the wall of said well-bore.
4. The method of isolating a well bore zone from an axially adjacent well bore zone comprising disposing a cylindrical member within said well bore between said zones, in spaced relationship with said well bore to form an annular space therebe tween, said cylindrical member being substantially impermeable to fluid flow in axial direction, disposing in the annular space a fluid that exhibits -a change in apparent viscosity upon the application of an electric field, providing means by which an electric field may be applied across said fluid, and applying an electric field transversely of said annular space.
5. The method in accordance with claim 4 in which the peripheral surface of said cylindrical member is conductive and said field is applied by connecting an electric potential between said surface and ground.
6. The method in accordance with claim 5 in which the magnitude of the applied potential is in the range of 50,000 to 250,000 volts per inch of radial distance between said peripheral surface and the wall of said well-bore.
7. The method of isolating a well bore zone from an axially adjacent well bore zone comprising supporting a cylindrical packing member in axially aligned, encompassing, fluid-tight relationship with respect to a tubing string, disposing said tubing string within said well bore to support the packing member between said well-bore zones and in spaced relationship with respect to the walls of said well-bore, disposing in the space between said member and the walls of said well bore a fluid that exhibits a change in apparent viscosity upon the application of an electric field, providing means by which an electric field may be applied across said fluid, and applying an electric field radially of said space.
8. The method in accordance with claim 7 in which the peripheral surface of said cylindrical member is conductive and said electric field is applied by connecting an electric potential between said surface and ground.
9. The method in accordance with claim 8 in which the magnitude of the applied potential is in the range of 50,000 to 250,000 volts per inch of radial distance between said electrode and the wall of said well bore.
10. A cased well comprising a well bore, a steel casing of diameter smaller than said well bore disposed therein concentrically therewith to provide an annular space between the walls of said well-bore and said casing, a column of a fluid that exhibits a change in apparent viscosity upon application of an electric field disposed within said annular space, and means for applying an electric potential between said casing and ground.
11. In a drilling apparatus for disposition in a well bore including a drilling string, a section of drill pipe connected in said string, means electrically insulating said section of pipe from the remainder of the drill string, a tubular electrode encompassing said section of pipe, to thereby form an annular space therebetween, said section of pipe and electrode being adapted to support in said annular space a fluid that exhibits a change in apparent viscosity upon the application of an electric field, means secured to said pipe for supporting said electrode in electrically insulating relationship and substantially concentrically With respect to said pipe, and means connected to said section of pipe and electrode for applying an electric potential between said electrode and said section of pipe.
12. An apparatus in aco'rdance with claim 11 including bearing means disposed internally of said electrode adja- References Cited by the Examiner UNITED STATES PATENTS 2,118,669 5/1938 Grebe 204- 180 2,217,857 10/1940 Byck 204-180 2,283,206 5/1942 Hayward 204 -180 2,625,374 1/1953 Neuman 20'4-180 2,799,641 7/1957 Bell 204-180 FOREIGN PATENTS 505,709 5/1939 Great Britain. 650,753 3/ 1951 Great Britain.
OTHER REFERENCES I Rogers, Composition and Properties of Oil Well Drillcent each end thereof, said bearing means being secured 15 ing Fluids, first edition, 1 4 Gulf Publishing Co Hons.
to said section of pipe and having a ring structure mounted thereon, said bearing means being rotatable with respect to said ring structure, said bearing means and said ring structure having flu-id passageways which upon registry permits communication of said annular space to said well bore.
ton, Texas, page 388. CHARLES E. OCONNELL, Primary Examiner.
2O JACOB L. NACKENOFF, Examiner.
T. A. ZALENSKI, D. H. BROWN, AssistantExaminers.