US3324948A - Method and apparatus for moving tools and devices in pressured well bores on flexible supporting members - Google Patents

Description

June 13, 1967 METHOD AND APPARA PRESSURE!) Filed Sept. 23, 1964 POWERS ETAL FOR MOVING TOOLS AND DEVICES IN WELL BORES ON FLEXIBLE SUPPORTING MEMBERS 3 Sheets-Sheet 1 INVENTORS MAsro/v L, Powes,

(47'7" QUE-Y June 13, 1957 M. pom 5 T 3,324,948

/ METHOD AND APPARATUS FOR MOVING TOOLS AND DEVICES IN PRESSURED WELL BORES ON FLEXIBLE SUPPORTING MEMBERS Filed Sept. 25, 1964 3 Sheets-Sheet 2 F'LE.-EIA Fi Ear-SE1 INVENTORS MAsTO/v L0 POM/5E5, WILL/14M La MAer/M, BY (/OHM 0. ALEXA/V09 &

6 I W/LLH/TE A 7' EA/EY June 13, 1957 M PQWERS ETAL 3,324,943

METHOD AND APPARATUS FOR MOVING TOOLS AND DEVICES IN PRESSURED WELL BORES ON FLEXIBLE SUPPORTING MEMBERS Filed Sept. 23, 1964 3 Sheets-Sheet Z PiEl-ifil Il ='i.lE.-.ii IE" LELZ INVFNTORS MAST'OA/ Lo Paws-Es,

United States Patent Ofiice 3,324,948 Patented June 13, 1957 METHOD AND APPARATUS FOR MOVING TOOLS AND DEVICES lN PRESdURED WELL BORES N FLEXlBLE SUPPORTING MEMBERS Maston L. Powers, Ardmore, and William L. Martin, John D. Alexander, and Glen P. Willhite, Ponca City, Okla, assignors to Continental Oil Company, Ponca City, Okla, a corporation of Delaware Filed Sept. 23, 1964, Ser. No. 398,580 11 Claims. (Cl. 166-39) This invention relates to a method and apparatus for controlling the movement of wire line or cable suspended tools and devices in a well bore. More specifically, but not by way of limitation, the invention relates to a method and apparatus for controlling the movement of a device suspended upon a flexible supporting member into or out of an oil or gas well or the like so as to prevent the device from being detrimentally affected in its movement by the existence of a high pressure in the well bore. In a yet more specific, through non-limiting, aspect, the invention is directed to a method for running an electrical heater or ignitor into and out of an air injection well utilized in the secondary recovery of petroleum by a fireflooding operation.

In the technology of petroleum production, it is frequently desirable or necessary to lower certain types of tools or devices into the oil well upon flexible wire lines or cables. In some wells, the pressure in the well bore is quite high and is subject to large variations over short periods of time. Under such circumstances, the tool may be expelled from the well here by the force of gaseous pressure acting upwardly therein, and great difficulty is experienced in forcing the tool or device into the well bore in an even and uniform manner against the opposing force of such high pressure. It is also diflicult to control its movement when it is removed from the well bore.

The problem of controlled lowering of various treating tools and devices in a high pressure well bore is frequently experienced in secondary petroleum recovery operations using a fireflood or in-situ combustion technique in the secondary recovery. In this type of petroleum production, one or more injection wells are employed for injecting a combustion supporting gas, usually air, into the petroliferous formation in order to support the combustion therein, and to propagate the combustion front through the formation. In the course of the injection of air or other combustion supporting fluid into the formation, it is desirable to dispose a heater in the well bore at the level of the producing formation for the purpose of igniting the petroleum and heating the injected air. Electrical resistance heaters or igniters are frequently employed for the purpose of initial ignition of the petroleum and heating injected air, and in this technique, the heater is attached to the end of an electrical cable and lowered into the well bore to a position adjacent the formation.

Procedures which have thus far been developed for positioning the electrical heater in air injection wells are less than optimum. For example, the odds of losing an igniter in an injection well are approximately 5050. In high pressure well bores, the igniter may he suddenly expelled from the well bore by an increase in the pressure therein. In any event, a controlled and even descent and ascent of the heater to and from the desired vertical level in the Well bore is quite difficult to attain using existing techniques. The predominance of the difiiculty encountered in lowering the heater into the well bore occurs prior to the time that enough of cable has been lowered into the well bore to balance the force of the well pressure acting upwardly on the cross-sectional area of the cable which suspends the heater in the well bore. Normal injection pressures used in such air injection wells do not constitute a problem once the heater has been positioned in the Well at the level of the formation because the weight of cable and heater at the depth is usually sufficient to balance or exceed the upwardly acting pressure tending to squirt the cable out of the packing gland at the top of the oil well.

One of the most widely used methods of lowering of the heater in an air injection well now in use is to blow back the injection well, thus reducing the well pressure and allowing the heater to be lowered into the well by virtue of its own weight. The same technique is sometimes used for extraction or removal of the heater. Although the blowing back of injection wells is apparently not detrimental to the ignition and heating process it is time-consuming and, in some instances, may not be possible due to damage to a liner, sand production or when a tubingless completion has been made.

The present invention comprises a method, and an apparatus for the practicing thereof, by the use of which, an electrical heater or any other wire line or cable suspended device or oil well tool can be pumped into and retrieved from a high pressure well bore in an even and controlled manner while suspended on the wire line or cable.

Broadly described, the method of the present invention comprises positioning a motion control piston around the wire line, cable, or other flexible supporting member adjacent the device which is to be lowered into the well so that said motion control piston forms a seal with the walls of the well and with the flexible supporting member to completely obstruct the annulus between the flexible supporting member and the walls of the well; applying fluid pressure to the upper surface of the motion control piston sufficient to force the motion control piston, flexible supporting member and the device suspended thereon downwardly in the well; then, at a depth at which the weight of the device and the flexible supporting member exceeds the maximum fluid pressure acting upwardly in the well, forming a fluid passageway through the motion control piston to equalize the pressure on opposite sides thereof; and finally, continuing to lower the device in the well by paying out the flexible supporting member under controlled tension into the well until the device has descended to the depth desired under gravitational influence, Substantially the reverse of this procedure is used to remove the device from the well.

In one embodiment, the motion control piston which is utilized in the practice of the invention may be comprised of at least one swab cup which seats upon and seals against either the upper end of the device carried by the flexible supporting member, or upon an annular seat sealingly surrounding the flexible member at a point closely adjacent such device, with said swab cup being resiliently biased in either instance into sealing contact with the surrounding walls of the well bore.

Another embodiment of the motion control piston which can be employed comprises an elongated tubular means, such as a pipe, which is adapted to be connected to the upper end of the device suspended on the flexible member; an annular body or cylindrical shell surrounding the tubular means and forming an annulus with the tubular means for conducting fluid between the tubular means and cylindrical shell; means on the outer periphery of the cylindrical shell for resiliently engaging and sealing against the walls of the well tubing or well bore as the device and motion control piston are lowered into the well; and fluid pressure responsive, downwardly opening valve means in the fluid passageway constituted by said annulus between the tubular means and cylindrical shell and responsive to downwardly acting fluid pressure in said annulus to open downwardly and permit fluid to bypass said motion control piston when the pressure above the valve exceeds the pressure below the valve.

From the foregoing description of the invention, it will be apparent that the resent invention provides a novel and useful technique for lowering in a well bore in an even and controlled manner, a device connected to the lower end of a flexible supporting member such as a wire line or cable.

A more specific object of the present invention is to improve the ease with which electrical igniters or heaters may be lowered in air injection wells of the type used in fireflooding or in-situ combustion procedures of secondary recovery.

An additional object of the present invention is to provide a novel and efficiently functioning motion control piston for use in lowering a device into a well bore on the end of a wire line, cable or other flexible supporting member.

Additional objects and advantages of the present invention will become apparent as the following detailed description of the invention is read in conjunction with the accompanying drawings which illustrate the invention.

In the drawings:

FIGURE 1 is a schematic drawing illustrating the physical principles underlying and constituting the basis for the present invention.

FIGURE 2 is an elevational view of a novel motion control piston which can be used in the practice of the present invention showing the piston as it appears while being lowered in an oil well tubing.

FIGURES 3A and 3B are complementary longitudinal sectional views taken through the center of the motion control piston illustrated in FIGURE 2. FIGURE 38 should be considered as a continuous vertical extension of the structure shown in FIGURE 3A.

FIGURE 4 is a sectional view taken along line 44 of FIGURE 3B.

FIGURE 5 is a sectional view taken along line 5-5 of FIGURE 3B.

FIGURE 6 is an enlarged sectional view of the pressure differential valve seat with the valve member seated thereon.

FIGURES 7 through 12 are schematic diagrams illustrating one way in which the method of the present invention may be practiced.

Referring now to the drawings in detail, and particularly to FIGURE 1, the physical principles upon which the present invention is based will initially be discussed. The tubing string of a high pressure well is designated by reference character 10. An electric igniter or heater 12 is shown being lowered into the well on an electrical cable 14 which is passed through a rubber packer or blowout preventer 16 at the top of the well. The blowout preventer 16 prevents leakage of gas around the cable 14 at the top of the well. A movable packer or swab cup 18 seats upon an annular seat 20 which is fixed to, and seals against, the outer periphery of the cable 14. In the diagram of FIGURE 1, a pair of swab cups 18 are employed, and at the illustrated stage of the process, sealingly engage the seat 20 and the internal walls of the tubing 10. A radially inwardly extending protuberance or stop 22 is provided on the internal walls of the tubing 10, and is positioned to engage and arrest the downward movement of the swab cups 18 at a certain point in the descent of the heater 12, annular seat 20 and cable 14 as hereinafter described. It will be apparent in referring to FIG- URE 1 that the swab cups 18 seal against the flow of gas from the top of the Well downwardly toward the heater 12, unless the seal is purposefully broken, but do not seal against the flow of gas from the heater 12 upwardly in the tubing 10.

The forces acting on the cable 14 at the blowout preventer 16 are F and F and are equal and opposite at zero velocity of the cable. The upwardly acting force, F may be equated to other existing parameters by the equation F1:A1P1+T R1 where A =Cross sectional area of the cable, in.

P =Pressure below the blowout preventer, p.s.i. T=Tension applied to the cable at the surface, l'bs. R Friction of the cable on the blowout preventer, lbs.

The downwardly acting force, F may be defined by the equation 2= z( 1- 2)+ 2 where A =Cross sectional area of the tubing, in.

P =Pressure below the swab cups, p.s.i.

W=The weight of the cable and heater below the blowout preventer, lbs.

R =The friction of the swab cups, lbs.

When the cable is stationary, the forces, F and F are equal and the friction terms are zero. Thus,

Equation (3) indicates that the tension in the cable at the surface, T, is equal to the weight of the cable 14 and the heater 12, less the squirt force tending to eject these elements from the well, A P plus the force of any pressure difference acting on the swab cups 18 as where P; is equal to or less than P Since the weight of the cable 14 and heater 12 is proportional to the depth position of the heater, it is obvious that tension in the cable can go negative, and the cable and heater forced upwardly out of the tubing 10 as the depth goes to zero and P becomes approximately equal to P A and A are constants for a given wire line or cable diameter, and a given well bore or tubing diameter.

If, for example, the cross-sectional area of the cable 14 is equal ,4 of the cross-sectional area of the tubing 10 such that A equals A then Equation (4) states that the tension, T, in the cable 14 will be equal the weight of the cable 14 and the heater 12 when the difference across the swab cups is equal to the pressure above the swab cups. Obviously, the smaller the cable 14, the smaller the pressure difference which will be required to reach this condition; and the higher the well pressure, P the higher the difference in pressure which will be required, i.e., AP equals P 9. As the pressure difference is decreased, the tension on the cable is decreased.

The cable 14 will begin to squirt or be ejected from the tubing 10 when T is equal to, or less than, zero, or when Where k is the weight of the cable in pounds per foot, d is the depth to which the heater 12 has descended in the tubing 10 and C is the weight of the heater 12 and any other fixed load. By means of an equation of the type such as Equation (6), one can calculate the depth in the well below which the cable and igniter will fall freely for any given well pressure P and with the pressure equalized on both sides of the swab cups 18 so that AP equals zero. In other words, one can calculate the weight at which W will be at least equal to P A and at this depth, the pressure can be equalized on opposite sides of the swab cups 18 to permit free gravitational descent of the heater 12 and cable 14 in order to position the heater at the desired depth in the tubing 10. Equalization of pressure on opposite sides of the swab cups 18 can be accomplished by positioning a stop member 22 in the tubing at the depth where the pressure equalization is to be effected, that is, where P A is equal to or less than W, and the downward movement of the swab cups will then be arrested. Air can be circulated past the swab cups 18 downwardly to the location of the heater 12 in order to conduct the firefiooding operation according to known techniques. Of course, in other applications of the method of the invention, other fluids can be circulated downwardly in the well bore to the location of the wire line or cable suspended tool after the swab cups 18 or other motion control means of the general type hereinafter described have been arrested in their downward movement, or actuated to permit fluid to be circulated past these motion control devices.

As will have become apparent from the foregoing discussion, the equipment which is required to practice the method of the present invention is very simple and inexpensive, which facts contribute substantially to the utility of the method. The cable packoff or blowout preventer 16 can be any suitable device for confining or retaining the desired pressure above the motion control piston or swab cups 18, and may take the form of a hydraulically activated line wiper or manually operated blowout preventer, etc. The motion control piston can be any suitable swab cup, or can be a motion control piston containing a differential pressure bypass valve to permit fluid to be passed through the motion control piston when the depth of free fall is attained. Where swab cups are utilized as the motion control piston, these devices are strung on the cable or wire line facing upwardly and may be rested upon a sealing seat of the type illustrated in FIGURE 1, or alternatively, may be sealingly abutted against the top of the igniter, heater, logging sonde or other tool carried at the lower end of the wire line or cable.

In use, the system illustrated in FIGURE 1 is assembled and pressure is applied above the swab cups 18 as hereinabove described. When the heater 12 and cable 14 have reached a predetermined depth, the swab cups are arrested by the stop 22. At this location, the weight of the cable 14 and heater 12 is sufficient to cause continued down ward movement of these elements under gravitational influence. Air or other fluid can then be injected into the permeable formation.

On the return trip out of the well, the assembly is pulled uphole until a seat on the cable, or on the device suspended thereon engages the swab cups l8 resting on the stop 22. Pressure may then be applied above the swab cups 18 and the pull on the cable 14 is increased to effect recovery of the assembly under full control. The method and apparatus described have the advantage that P the pressure below the swab cups 18, can never exceed P the pressure above the swab cups, by any appreciable amount, since in this event, the swab cups would be raised olf their seat on the cable and the pressures, P and P would then be equalized.

An alternative method of disengaging the swab cups 18 from the seat 20 to facilitate air injection past the heater 12 or other device would be to install enlarged sections, or next-size pipe nipples, at the proper location in the well tubing or casing. With this arrangement, the swab cups 18 can be fixed to the power cable and air flow will occur around the outside of the cups when they are positioned in the enlarged sections. This arrangement has the disadvantage, however, of offering no protection against excess pressures below the cups.

In FIGURES 2, 3A, 3B, 4, 5 and 6, a novel motion control piston which may be secured to the wire line or cable and used in lieu of swab cups for controlling the downward motion of the assembly has been illustrated.

The power cable or wire line 30 extends downwardly in the tubing 32 and is connected above its lower end to a motion control piston and differential valve assembly designated generally by reference character 34. The control piston assembly 34 comprises tubular means, such as a pipe 36, which sealingly surrounds and engages the cable 30 and carries a fishing neck 38 at its upper end. The lower end of the pipe 36 is externally threaded and carries a tapered constricting nut 40 and a retainer nut 42.

An annular body, such as a cylindrical shell 44 concentrically surrounds the pipe 36 and defines therewith an annulus or fluid passageway 45. The cylindrical shell 44 in the illustrated embodiment comprises a plurality of threadedly interconnected portions including an apertured upper end cap portion 46 having ports 48 extending therethrough, a short coupling section 54) connecting the upper end cap portion 46 to the threaded upper end of an elongated central section 52, and a valve assembly containing lower section 54 which is threadedly connected to the lower end of the central section 52.

The lower section 54 of the cylindrical shell 44 is internally threaded for connection to the upper end of an electrical heater, logging sonde or other type of tool 56 which it may be desired to lower in the tubing 32. A retaining bushing 58 is used to interlock the cylindrical shell 44 to the pipe 36 through the cap portion 46.

At approximately its mid-portion, the central section 52 of the cylindrical shell 44 is provided with an annular sleeve 60 of rubber, or other suitable resilient material. The rubber sleeve 60 surrounds the central section 52 and rests upon a suitable retainer ring 62 which abuts a built-up, upwardly facing shoulder 64 formed on the outer periphery of the central section 52. The shoulder 64 may suitably be formed by building up the external surface of the central section 52 with weld metal. Immediately above the rubber sleeve 60, the central section 52 of the cylindrical shell 44 is externally threaded to receive an internally threaded compression nut 66 which bears against a ring 68 positioned in abutting contact with the upper end of the rubber sleeve 60. The outside diameter of the rubber sleeve 64} is such that when the sleeve is placed under compression by tightening the compression nut 66, the sleeve is expanded into sealing contact with the inner walls of the tubing 32.

A valve seat designated generally by reference character 7!? is positioned in the lower end of the central section 52 of the cylindrical shell 44. The valve seat 70 is annular in configuration, and includes an outer peripheral portion 72 and an inner peripheral portion 74 as best illustrated in FIGURES 4 and 6. The outer peripheral portion 72 of the valve seat 70 carries a radially extending circumferential flange 76 which bears against the lower end of the central section 52 of the cylindrical shell 44, and is held in abutting contact therewith by a tapered shoulder 78 formed on the lower section 54 of the cylindrical shell. A circumferential groove 80 is formed in the outer peripheral portion 72 of the valve seat 70 to receive an O-ring 82 which seals against the internal peripheral wall of the central section 52 of the cylindrical shell 44. The inner peripheral portion 74 of the valve seat 70 has an inwardly tapered surface 84 at its upper end which abuts a tapered retainer bushing 86 welded to the outer periphery of the pipe 36 when the valve seat 7t) is in its operative position. A pluraliy of circumferentially spaced, axially extending apertures 88 are formed through a central portion 90 of the valve seat 70 for permitting air to pass through the valve seat when the valve is open as hereinafter explained. A pair of inwardly tapered seating surfaces 92 are formed on the inner and outer peripheral portions 74 and 72, respectively, of the valve seat 70 and sealingly cooperate with mating tapered surfaces on a valve member 94.

The valve member 94 is annular in configuration and is biased upwardly in the cylindrical shell 44 toward the valve seat 70 by a helical spring 96 which is enclosed in a spring cup 98 which rests upon the retainer nut 42 and concentrically encircles the pipe 36. It will be noted that the retainer nut 42 can be axially adjusted to adjust the extent to which the valve member 94 will move off the valve seat 70 to a fully opened position. Also, as hereinafter explained, the resilience of the spring 96 can be adjusted to control the magnitude of the downwardly acting fluid pressure which is required to move the valve member 94 off the valve seat 70 to open the valve. A plurality of fluid discharge apertures or flutes 109 are formed in circumferentially spaced relation through the lower section 54 of the cylindrical shell 44 for permitting air to be discharged from the annulus 45 defined between the cylindrical shell 44 and the pipe 36.

To generally describe the operation of the novel motion control piston assembly 34 illustrated in FIGURES 2 through 6 before proceeding to a specific example of the use of the device, an electrical igniter, heater, logging tool or other device 56 is secured to the lower end of the lower section 54 of the cylindrical shell 44 in threaded engagement with the internal threads thereon. Suitable connections are made to the cable 30 for electrical conduction or mechanical support, as the case may be. The compression nut 66 is next adjusted axially on the central section 52 of the cylindrical shell 44 to compress the rubber sleeve 60 sufficiently to sealingly engage the internal walls of the tubing 32. The assembly 34 and device 56 carried at the lower end thereof are then forced downwardly in the tubing 32 by applying fluid pressure above the motion control piston assembly.

Using air as the pressure developing fluid, the air flows downwardly in the tubing 32, through the ports 48 and into the annulus 45 defined between the cylindrical shell 44 and the pipe 36. If the pressure in the well below the motion control assembly 34 is of suflicient magnitude to constitute a problem, the upwardly acting pressure will cause the valve member 94 to contact and seat on the valve seat 70. The air acting downwardly on the valve member 94 will oppose the upwardly acting pressure and will generally be greater than the upwardly acting pressure, but not greater than the combined forces exerted by the helical spring 96 and such upwardly acting pressure. The motion control piston assembly 34 is thus forced downwardly in the tubing 32 with the rate of descent being dually controlled by the applied downwardly acting fluid pressure, and the tension maintained in the cable 30. After the entire assembly reaches a depth at which its weight including the weight of the cable exceeds the upwardly acting force tending to move the assembly upwardly in the well, the assembly will then I continue to move downwardly under gravitational influence. At this point, or in fact, even prior to this time, if desired, the pressure above the differential valve as sembly can be increased so as to force the valve member 94 off its seat 70 and permit air to bypass the motion control piston assembly 34.

In order to afford a more complete understanding of the present invention, and particularly, of the method and apparatus of the invention as they may be employed for lowering an electrical heater into a well tubing during a fireflooding operation, the following example is presented in which an air injection well is to be ignited at a depth of 500 feet. The first step in igniting an air injection well during an in-situ combustion or fireflooding operation consists of injecting air into the well for a sufficient length of time to establish adequate air permeability in the vicinity of the well bore. Such preinjection of air may be carried out, for example, for a period of about four weeks.

When the initial injection of air is completed, and assuming a pressure in the well bore of 500 p.s.i., the electrical heater or igniter is attached to the motion control piston assembly 34 illustrated in FIGURES 2 through 6. The lowering of the assembly 34 and igniter 8 into the well is then accomplished in the manner schematically illustrated in FIGURES 7 through 12.

As illustrated in FIGURE 7, a suitable lubricator is attached to a conventional wellhead fitting 112 positioned at the upper end of a tubing string 114 and connected to the tubing string through a master gate valve 116. A source of pressurized fluid (not shown) is connected via a conduit 118 and valves 120 and 124 to the fitting 112. A throttling valve 126 is provided to release internal pressure, and a pressure equalizer line 128 is connected between the lubricator 110 and a fitting 130 and contains suitable control valves 132 and 134. A pressure gauge 136 is connected to the lubricator 110 for indicating the pressure therein, and a second pressure gauge 138 is connected through. a valve 140 to the wellhead fitting 112.

After the motion control piston assembly 34 has been made up as hereinbefore described, and the heater or igniter 142 secured to the lower end thereof, the assembly and heater are placed in the lubricator 110 with the rubber sleeve 60 of the assembly placed in compression by an amount sufiicient to permit it to sealingly engage the internal peripheral walls of the tubing 114. After the lubricator 110 has been connected as illustrated in FIG- URES 7 and 8, valves 126 and 120 are closed, and valves 124, 132 and 134 are opened. The master gate valve 116 is then slowly and carefully opened to allow the gas pressure in the tubing 114 to equalize into the lubricator 110 on both sides of the motion control piston assembly 34. The flow of fluid from the tubing 114 into the lubricator 110 to accomplish such pressure equalization is illustrated by the arrows in FIGURE 7.

With the pressure equalized on both sides of the motion control piston assembly 34 in the lubricator 110, the valve 124 is then closed and valves 120, 132 and 134 are opened to pump the motion control piston assembly 34 out of the lubricator 110 and into the tubing 114. During this time, an appropriate amount of tension is maintained on the cable 30 outside the well to provide additional control on the rate of movement of the assembly into the well.

After the motion control piston assembly 34 and the heater 142 attached thereto clear the lubricator 110 and enter the tubing 114, valve 132 is closed and valve 124 is partially opened to permit greater flow of the pressurized fluid from the conduit 118 into the tubing 114 behind the descending assembly 34 and heater 142. The fluid flow from the conduit 118 into the tubing 114 at this time is illustrated by the arrows in FIGURE 8. After the motion control piston assembly 34 and the heater 142 connected thereto have been pumped to the proper depth in the tubing 114 with approximately 60 p.s.i. differential pressure across the motion control piston, the differential pressure is increased to approximately 75 psi. to open the differential valve by forcing the valve element 94 ofl its seat 70. At this time, air injection into the oil sand is thus resumed as schematically illustrated by the fluid flow arrows in FIGURE 9 of the drawings. The differential valve is completely opened at approximately 112 p.s.i. pressure differential. With the heater 142 positioned adjacent the oil sand and air flow established in the manner described, power is then applied to the heater and the ignition process is accomplished.

After approximately twelve days, the heater 142 can be turned off and cooled by one additional day of air injection. The well is then shut in, the differential valve closed by reducing the pressure above the assembly 34 to permit the valve member 94 to return to its seat 70, and the assembly 34 and heater 142 pulled upwardly in the hole as appropriate amounts of air are bled out of the well above the motion control piston assembly. At this time, the valve 120' may be closed and the bleed ofl? of air from the well may be accomplished by cracking the valve 126. This stage of the process is illustrated in FIGURES 10 and 11 of the drawings.

As the motion control piston assembly 34 and the heater 142 reach a depth of approximately 240 feet in the tubing 114, the combined weight of the assembly, heater and cable will not equal or exceed the upwardly acting pressure acting on the cable at the top of the well. At this point, the motion control piston assembly 34 can be used as a brake by carefully adjusting the pressure in the tubing string 114 above the assembly 34 using the valve 126, or by means of a suitable back pressure controller. This procedure of bleeding the heater out of the well by the use of the valve 126 is illustrated in FIGURE 11 of the drawings. When the downwardly acting pressure exerted above the assembly 34 is at some appropriate level in excess of the pressure below the assembly, a net force tending to force the cable and assembly downwardly into the well is acting, and by applying an appropriate amount of tension to the cable 30 at the surface, or, by carefully venting the valve 126, the assembly 34 and heater 142 can be eased back into the lubricator 110. The master gate valve 116 can then be closed and the pressure on the lubricator 110 relieved by bleeding fluid through the valve 126 while maintaining the master gate valve 116 and the valve 120 closed. This period of the process is illustrated in FIGURE 12. When the motion control piston assembly 34 and the heater 42 have been removed from the lubricator 110, air injection can be resumed in the ignited well in accordance with techniques well understood in the field of secondary recovery of petroleum by fireflooding and in-situ combustion.

From the foregoing description, it will be apparent that the present invention provides a highly useful procedure and apparatus for positioning various tools and devices at any desired depth in an oil or gas well with the rate of descent of the tool or device being closely controlled at all times. The undesirable effects resulting from high pressures in the well bore are minimized, and the risk of loss of tools in the well bore as a result of parting of the cable or wire line used to lower them therein is greatly reduced. The apparatus which is employed in practicing the invention is relatively simple and inexpensive, and is generally reliable in operation and characterized by a long and trouble-free service life.

Although certain specific embodiments of the present invention have been described herein, and particular steps of the procedure and elements of the apparatus have been referred to by way of example, it will be readily understood that certain other steps and structures are equivalent to those which have been described and may be used in the practice of the present invention with equal facility. Such equivalent procedures are structures are therefore intended to be circumscribed by the spirit and scope of this invention except as the same may be necessarily limited by the appended claims or reasonable equivalents thereof.

We claim:

1. The method of controlling the movement of a device supported by a flexible member in a pressurized well, said method comprising:

positioning a motion control piston around said flexible member adjacent said device to form a seal with the walls of said well;

when said device is at depths in said well such that the maximum force due to fluid pressure acting upwardly in said well exceeds the combined weight of said device and the portion of the flexible member in the well, applying fluid pressure to the upper surface of said motion control piston and tension to said flexible member to control the direction and rate of movement of said device and flexible member in the well; when said device is at depths in said well such that the combined weight of said device and the portion of the flexible member in the well exceeds the maximum force due to fluid pressure acting upwardly in said well, forming a fluid passageway bypassing said motion control piston to equalize the pressure on opposite sides thereof; and then controlling the tension in said flexible member to control the direction and rate of movement of said device and flexible member in the well. 2. The method of lowering into a well a device suspended on an elongated flexible member comprising:

positioning a motion control piston around said flexible member adjacent said device to form a seal with the Walls of said well;

applying fluid pressure to the upper surface of said motion control piston suflicient to force said piston, flexible member and suspended device downwardly in the well;

after said device and flexible member have been lowered to the shallowest depth in the well at which the weight of said device and the portion of the flexible member in the well exceeds the maximum force due to fluid pressure acting upwardly in said well bore, forming a fluid passageway bypassing said motion control piston to equalize the pressure on opposite sides thereof; then continuing to lower said device in said well bore to the depth desired under gravitational influence.

3. The method claimed in claim 2 wherein said fluid passageway is formed by disengaging said motion control piston from said elongated flexible member and permitting fluid to pass between said motion control piston and said elongated flexible member.

4. The method claimed in claim 2 wherein fluid is circulated through said fluid passageway and downwardly in said well during said continued lowering of said device in said well under gravitational influence.

5. The method claimed in claim 2 wherein said device includes an upwardly facing annular seat thereon sealingly surrounding said elongated flexible member; and

said motion control piston is positioned on said seat and in sealing engagement therewith and with the walls of said well during the downward movement of said device and elongated flexible member prior to reaching the depth at which said fluid passageway is formed; and

said fluid passageway is formed by disengaging said motion control piston from contact with said seat.

6. The method of preventing blowout of a device suspended on an elongated flexible supporting member, such as a wire line or the like, from a well bore during lowering of the device into the well bore, said method comprising positioning a sealing member around said elongated flexible member adjacent and above said device for movement downwardly in said well bore with said flexible member and device, and for sealingly obstructing with said sealing member the annulus between said elongated flexible member and the walls of said well bore to prevent fluid flow downwardly in said well bore; then applying a fluid pressure, P above said sealing member sufficient to move the sealing member, flexible supporting member and device downwardly in said well bore at a controlled, predetermined rate while maintaining the tension, T, in said flexible member positive according to the equation where A is the cross-sectional area of the well bore; P is the pressure in the well bore below said sealing member; A is the cross-sectional area of said elongated flexible member; W is the Weight of the elongated flexible supporting member and heater device below the sealing member; and R is the frictional resistance offered to said downward movement by said sealing member in its sealing engagement with said well bore; then when W is at least equal to P A equalizing the pres sure on opposite sides of said sealing member by re- 1 l lieving the seal established thereby to permit fluid to flow by said sealing member in either direction; and

continuing to lower said device to the depth desired under gravitational influence. 7. The method claimed in claim 6 wherein said sealing member is positioned around said elongated flexible member by securing around said elongated flexible member in fluid tight relation thereto, an annular, upwardly facing seat of lesser diameter than said well bore; and

placing an annular sealing member of greater inside diameter than the thickness of said elongated flexible member and having a resilient, radially expandable outer peripheral portion engageable with the walls of said well bore around said elongated flexible member and in abutting sealing contact with said annular, upwardly facing seat.

8. The method claimed in claim 7 wherein said annulus is obstructed by applying fluid pressure to said resilient radially expandable outer peripheral portion of said annular sealing member to bias said outer peripheral portion into sealing engagement with the walls of said well bore while said annular sealing member is in abutting contact with said annular, upwardly facing seat.

9. The method claimed in claim 7 wherein the pressure is equalized on opposite sides of said sealing member by lifting said annular sealing member off said annular, upwardly facing seat to permit the fluid to pass between said annular sealing member and said elongated flexible member and around said annular, upwardly facing seat.

10. The method of igniting and propagating a combustion front through a petroliferous formation comprising:

drilling an injection well from the surface into the formation;

injecting air into said formation from said injection well to increase the air permeability of the formation in the vicinity of the well bore;

attaching an electrical heater to the end of a flexible power supply cable;

positioning a motion control piston around said flexible power supply cable adjacent said electrical heater to form a seal with said power supply cable and with the walls of said injection well;

applying downwardly acting fluid pressure to the upper surface of said motion control piston to force said piston, flexible power supply cable and electrical heater downwardly in the injection well;

after reaching the shallowest depth at which the combined weight of said electrical heater and the portion of said flexible power supply cable in said injection well exceeds the maximum fluid pressure acting upwardly in said injection well, forming a fluid passageway bypassing said motion control piston to equalize the pressure on opposite sides thereof;

continuing to lower said electrical heater in said injection well under gravitational influence to the depth of said petroliferous formation;

energizing said electrical heater to ignite the oil in said formation adjacent the bore of said injection well; continuing to circulate air into said injection well through said fluid passageway and into the formation while said heater is energized; then de-energizing said heater and retrieving said heater and motion control piston from the injection well by pulling said power cable upwardly until said heater is at a depth such that the weight of the heater and the portion of the flexible power supply cable in the injection well is less than the maximum fluid pressure acting upwardly in said injection well; then closing said fluid passageway and applying downwardly acting fluid pressure to the upper surface of said motion control piston to control the continued upward movement of said heater and power cable in the injection well.

11. Apparatus for lowering a device suspended on an elongated flexible supporting member into a well tubing, which apparatus comprises:

a motion control piston positioned adjacent and above said device and supported by said elongated flexible supporting member, said motion control piston comprising:

an elongated pipe around said elongated flexible supporting member;

an annular body around said pipe and having an outer peripheral sealing portion for sealingly engaging the walls of said tubing, said annular body comprising:

a cylindrical shell concentrically surrounding said pipe and defining with said pipe a fluid passageway;

a resilient expandable sleeve around the outer periphery of said cylindrical shell intermediate its length; and

axially adjustable compression means maintained on said cylindrical shell adjacent said resilient expandable sleeve for axial movement on said cylindrical shell to compress said resilient expandable sleeve in an axial direction and cause said resilient expandable sleeve to expand radially into sealing engagement with said tubing;

an annular valve seat positioned in said fluid passageway inside said cylindrical shell;

a spring biased valve member movably mounted on said pipe adjacent said valve seat and resiliently biased into sealing engagement with said seat in opposition to fluid flow in a downward direction through said fluid passageway; and

means for applying a downwardly acting fluid pressure to said motion control piston and said device downwardly in said well bore.

7/1961 Lewis l66l48 X 2/1962 McStravick et al. 166-4 CHARLES E. OCONNELL, Primary Examiner.

STEPHEN J. NOVOSAD, Examiner.

Claims (2)

1. 2. THE METHOD OF LOWERING INTO A WELL A DEVICE SUSPENDED ON AN ELONGATED FLEXIBLE MEMBER COMPRISING: POSITIONING A MOTION CONTROL PISTON AROUND SAID FLEXIBLE MEMBER ADJACENT SAID DEVICE TO FORM A SEAL WITH THE WALLS OF SAID WELL; APPLYING FLUID PRESSURE TO THE UPPER SURFACE OF SAID MOTION CONTROL PISTON SUFFICIENT TO FORCE SAID PISTON, FLEXIBLE MEMBER AND SUSPENDED DEVICE DOWNWARDLY IN THE WELL; AFTER SAID DEVICE AND FLEXIBLE MEMBER HAVE BEEN LOWERED TO THE SHALLOWEST DEPTH IN THE WELL AT WHICH THE WEIGHT OF SAID DEVICE AND THE PORTION OF THE FLEXIBLE MEMBER IN THE WELL EXCEEDS THE MAXIMUM FORCE DUE TO FLUID PRESSURE ACTING UPWARDLY IN SAID WELL BORE, FORMING A FLUID PASSAGEWAY BY PASSING SAID MOTION CONTROL PISTON TO EQUALIZE THE PRESSURE ON OPPOSITE SIDES THEREOF; THEN CONTINUING TO LOWER SAID DEVICE IN SAID WELL BORE TO THE DEPTH DESIRED UNDER GRAVITATIONAL INFLUENCE.
2. 11. APPARATUS FOR LOWERING A DEVICE SUSPENDED ON AN ELONGATED FLEXIBLE SUPPORTING MEMBER INTO A WELL TUBING WHICH APPARTUS COMPRISES: A MOTION CONTROL PISTON POSITIONED ADJACENT AND ABOVE SAID DEVICE AND SUPPORTED BY SAID ELONGATED FLEXIBLE SUPPORTING MEMBER, SAID MOTION CONTROL PISTON COMPRISING: AN ELONGATED PIPE AROUND SAID ELONGATED FLEXIBLE SUPPORTING MEMBER; AN ANNULAR BODY AROUND SAID PIPE AND HAVING AN OUTER PERIPHERAL SEALING PORTION FOR SEALINGLY ENGAGING THE WALLS OF SAID TUBING, SAID ANNULAR BODY COMPRISING: A CYLINDRICAL SHELL CONCENTRICALLY SURROUNDING SAID PIPE AND DEFINING WITH SAID PIPE A FLUID PASSAGEWAY; A RESILIENT EXPANDABLE SLEEVE AROUND THE OUTER PERIPHERY OF SAID CYLINDRICAL SHELL INTERMEDIATE ITS LENGTH; AND AXIALLY ADJUSTABLE COMPRESSION MEANS MAINTAINED ON SAID CYLINDRICAL SHELL ADJACENT SAID RESILIENT EXPANDABLE SLEEVE FOR AXIAL MOVEMENT ON SAID CYLINDRICAL SHELL TO COMPRESS SAID RESILIENT EXPANDABLE SLEEVE IN AN AXIAL DIRECTION AND CAUSE SAID RESILIENT EXPANDABLE SLEEVE TO EXPAND RADIALLY INTO SEALING ENGAGEMENT WITH SAID TUBING; AN ANNULAR VALVE SEAT POSITIONED IN SAID FLUID PASSAGEWAY INSIDE SAID CYLINDRICAL SHELL; A SPRING BIASED VALVE MEMBER MOVABLY MOUNTED ON SAID PIPE ADJACENT SAID VALVE SEAT AND RESILIENTLY BIASED INTO SEALING ENGAGEMENT WITH SAID SEAT IN OPPOSITION TO FLUID FLOW IN A DOWNWARD DIRECTION THROUGH SAID FLUID PASSAGEWAY; AND MEANS FOR APPLYING A DOWNWARDLY ACTING FLUID PRESSURE TO SAID MOTION CONTROL PISTON AND SAID DEVICE DOWNWARDLY IN SAID WELL BORE.

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