US2148327A - Oil well completion apparatus - Google Patents

Description

Feb. 21, 1939. MI ET AL 2,148,327

OIL WELL COMPLETION APPARATUS Filed Dec. 14, 1937 4 Sheets-Sheet l Arman/M30 Eager Swat/u @ofizrt 75C Mazda/1 GHQ/pump Feb 21', 1939.

R SMITH ET AL 2,148,327

OIL WELL COMPLETION APPARATUS Filed Dec. 14, 1957 4 Sheets-Sheet 2 Ill!!!" 0 23 ql l llll J6 gvwo'nm @qgz Smdflm fiobertfl Mazda/L Feb. 21, 1939. R. SMITH ET AL OIL WELL COMPLETION APPARATUS Filed Dec. 14, 1937 4 Sheets-Sheet 3 law.

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Q fi WM w m/ V aawaaiii QMJcm/Wio 1%gar Ema?! Feb. 21, 1939. 1 R. SMITH ET AL OIL WELL COMPLETION APPARATUS Filed Dec. 14, 1937 4 Sheets-Sheet 4 Patented Feb. 21, 1939 UNlTED STATES 2,148,327 OIL WELL COMPLETION APPARATUS Roger Smith and Robert A. Mueller, Houston, Tex, assignors to Gray Tool Company, Houston, Ten, a corporation of Texas Application December 14, 1937, Serial No. 179,780 16 Claims. (01. nae-15) The present invention relates to oil well completion apparatus and methods. The principal object of the invention is to provide such apparatus and methods which will permit the entire sequence of usual as well as unusual operations in completing a well while providing the maximum safety against flow of fluid under high pressure from the well.

The apparatus and methods of the invention o utilize casing head formation equipment which gives the operator a wide choice in the safe performance of operations which are necessary or desirable to be performed, at any time prior to, during, or after the completion of the well.

5 The apparatus utilized is such that it permits the use of substantially all of the well-known pieces of control equipment of the prior art, such as master valves, blowout preventers, and the like, when needed, and the relegation of 59 these pieces of equipment to the position of accessories when their function is no longer desired.

A particular object of the invention is to provide a method and apparatus which will permit the washing of the well through the tubing, and

g; the subsequent elevating of the tubing to flowing position and hanging and sealing the same by means of its hanger, without the necessity of at any time breaking the tubing between the washing and hanging operations, so that the no connection from the lower end of the tubing in the well to the mud pump adjacent the well is never broken until the well'is entirely sealed at completion.

In the recent development of apparatus of '5 this character, the trend has been to provide equipment which will insure the maintaining of a seal both within the tubing and between the tubing and the casing at all times during the completion operations, particularly during the dangerous transition period when the gap is bridged between the washing and the hanging and sealing operations.

Most recently, progress has been made in the art in maintaining seals both with n the tubing 45 and between the tubing and the casing with equipment arranged in such fashion, and on such a foundation, that the individual pieces of equipment used to maintain the seals at the various stages of completion can be relegated go to the position of accessories when no longer needed, rather than being tied up as a permanent part of the well structure after. the individual pieces of equipment have performed their functions.

5 While developments of this type are useful,

and have contributed greatly to the safety and efficiency of oil well completion operations, it is nevertheless true that the primary safety precaution in well completion is to have available at all times means which will permit the instantaneous discharge of mud into the bottom of the well to control the pressures therein. That is, most operators have long sought for equipment which could be employed in a sequence of completion operations permitting the connection between the mud pump and the bottom of the tubing to be maintained at all times, par--' ticularly during the transition period between washing the well and hanging the tubing, and it is Weil -known in the oil fields that the confidence of the crew would be increased, and their work thus made more effective, if equipment capable of maintaining this connection were provided.

The apparatus and methods disclosed herein not only provide for the performance of all of the usual operations desirable or necessary during completion, but also for the performance of unusual operations which may be necessary to meet a particular situation, as well as providing a foundation which will adapt itself to future operations which may have to be developed as deeper and higher pressure wells are drilled.

It will be understood that while the, particular application of this invention is to the completion of high pressure wells which are filled with mud fluid, the invention is also adapted for use with facility for wells which are drilled and completed under pressure:

Another important object of the invention is to provide apparatus which. will increase the speed with which the well may be finally closed up by hanging and sealing the tubing in the casing head after the washing operation is commenced, and particularly after the washing operation is completed and the equipment is being changed from its condition for washing, to its condition for flowing the well. It will be understood that speedis of the essence at this critical time when the well has been washed and is coming in and before the tubing is hung and sealed.

In the drawings, which are illustrative of a preferred form of the invention, but which may be modified to suit particular situations:

Figure l is a side elevational view partly in section of the equipment at the surface of a high pressure well during the drilling stage;

Figure 2 is a view similar to Figure 1, showing the equipment at the stage when the tubing is being lowered into the well; I l

Figure 3 is a similar view, showing the equipment in condition when the tubing has been lowered into the well for the performance of the washing operation, or for the setting of packers or the like;

Figure 4 is a similar view showing the equipment after the tubing has been raised from the well after the performance of the above operations, preparatory to hanging the same;

Figure 5 is an enlarged vertical sectional view of the casing head, after the tubing has been 3;

Figure 6 is a side elevational view partly in section of the equipment at the surface of the well, after the Christmas tree has been positioned on the casing head and showing the manner of removing the back pressure valve from the tubing;

Figure 7 is a view similar to Figure 6 showing the completed well after the tubing back pressure valve has been removed;

Figure 8 is an enlarged vertical sectional view through the hanger and hanger collar, showing the construction of the back pressure valve carried by the latter, and

Figure 9 is a view similar to Figure 8, showing the back pressure valve equipped with a strainer.

In Figure 1, the outside or upper string of cylindrical casing is shown at In, said string having attached to its upper end a casing head I 2 provided with the well-known side outlets which may be closed by a bull plug ll or provided with a flow line controlled by a valve l3 as is well-known in the art. Referring to Figure 5, the casing head i2 is provided with an inside downwardly and inwardly tapered seat i8 above its side outlets, said seat being adapted to receive and seal with the lower tapered portion l3 of a hanger 20, the hanger being secured to the upper end of an inner string of casing 22. Mounted upon the casing head l2 and secured thereto by flange and bolt connections of like size, is an upper casing head 23 called a tubing head. The tubing head has a tapered bore at its lower end adapted to closely embrace the tapered upper portion 24 of the hanger 20, and an upper tapered inside seat 25 which receives and seals with the tubing hanger hereinafter described. Both the upper and lower faces of the hanger 20 are equipped with packing rings. The above-described arrangement for supporting and forming a seal with the casing hanger 20 is disclosed in Patent No. 2,082,413, Mueller et al., June 1, 1937.

The tubing head 23 is also provided with appropriate side outlets 26 below its seating surface 25, any of which may be either closed by a bull plug 30 or controlled by a flow valve 32 positioned in a flow line from said outlets.

Mounted upon the tubing head as a foundation, and connected thereto by flange and bolt connections of like size, is a master drilling valve 33, said valve being provided with a lower flange 33 of the same size as the upper flange of the tubing head 23 (Fig. 5), said flanges being secured together by bolts as shown and provided therebetween with an annular packing II to insure a sealing connection.

Surmounting the master drilling valve are a pair of blowout preventers 44 and 46, connected with each other and to the master drilling valve with flange and bolt connections of like size.

Any kind of blowout preventer may be used, but the type employing semi-cylindrical shoes 43 either manually or steam operated which engage the inner pipe to form a seal therewith is preferred. It will be understood that the shoes used amass? in this type of preventer are interchangeable, in order to seal with either a drill pipe, or a flow tubing.

The internal bores of the casing hanger 20, the tubing head 23, the master drilling valve 33, and the blowout preventers 4| and 43 are at least as large as, and preferably slightly larger than, the internal diameter of the casing 22, in order to permit the insertion through this control equipment of a drill bit having a diameter substantially as large as the internal diameter of the upper string of casing 22. These control devices must be of full bore as described above not only to pass the drill, but also to permit the passage into the well of the screen liner or packer and other devices which must be inserted therein both prior and subsequent to the completion of the well.

In Figure 1, the drill stem is shown at having a bit '2 at its lower end. It will be understood that the drill string is hollow, and that the bit is provided with suitable outlet openings so that the heavy colloidal mud used during drilling may be forced down through the drill string and out through the openings in the bit to carry the cut tings from the well upwardly through the casing and through the appropriate side outlets in the casing head, and also to keep the well filled with mud so that the head thereof will resist any tendency of the well to blow out during drilling and subsequent operations. The upper end of the drill string connects with a swivel 54, which is of well-known construction and need not be described. In general, the swivel includes means 33 for engaging the hook on the traveling block and a connection with the drill pipe which will permit the latter to be rotated with respect to the swivel, as is well-known in the art. A hose 58 connects with the upper portion of the swivel, the other end of said hose being connected with the upper end of a pipe in the side of the derrick, so that mud or water may be supplied to the drill pipe through the swivel by pumping means P located adjacent the surface of the well, usually at the side of the derrick.

If it is necessary at any time to insert the drill pipe into the well when dangerous pressure ex ists therein, the same may be lowered past the blowout preventers with the master drilling valve 33 closed, after which the blowout preventers are engaged with the drill pipe to form a seal. The master drilling valve may then be opened, and the drill pipe lowered into the well, while the blowout preventers maintain a seal therewith, the blowout preventers being operated alternately to pass the collars of the drill string as is well-known. The blowout preventers may be maintained in sealing engagement with the drill pipe during drilling if necessary.

When the well is full of mud, as will usually be the case when the apparatus of the present invention is employed, it may be unnecessary to use the blowout preventers to form a seal between the casing and the tubing during the insertion of the drill string and during the drilling operation. However, the blowout preventers should be available during the drilling operation in case dangerous pressures are encountered, at which time they may be instantly closed around the drill string and the drilling continued with the blowout preventers forming a seal between the casing and the tubing.

The drill string should contain adjacent the lower end thereof as at 60, a back pressure valve of well-known type which will permit the downauaaav ward flow of the drilling fluid through the drill string, yet which will prevent any upward flow 1 of fluid therethrough' from the well. It is unnecessary to disclose the precise type of such back pressure valve, as the same are well-known in the art and may be illustrated by those shown in the patent Nos. 1,740,770, December 24, 1929, and 1,872,139, August 16, 1932 to Gray et al.

"When the drilling has been completed, the drill string is removed with the blowout preventers in open condition if the well is full of mud and in safe condition, or if dangerous pressures exist in the well, the master drilling valve and blowout preventers may be used in the reverse manner from .that described above in the removal of the drill string.

Many operations may have to be performed at this dangerous stage of completion, particularly operations to determine if the well is drilled to the proper depth for running the flow tubing. Such operations usually involve the removal of the drill string, application thereto of other tools, and relnsertion of the same into the well. It may be necessary at this time to remove and reinsert the drill string many times. The operations referred to may include: running formation logging devices, drilling the rat hole, running the drill stem testing tube, reaming out the rat hole, and setting a perforated liner or strainer and packer. The bore through the master drilling valve 36, blowout preventers M and 46, and tubing head 23 is large enough to permit passage of all devices necessary to perform the above operations, and such as the screen liner or packer, and the control equipment disclosed may be v manipulated to accomplish the perhaps usual operations above, as well as unusual operation without losing control of the well.

When operations of the above type have been completed, the time will have arrived when it is desired to lower the flow tubing into the well. Before the well is ready to flow through this tubing, it may be necessary to utilize the same in performing otheroperations involving manipulating the tubing, such as setting a packer and so forth.

If the well is mudded up and there is no danger of high pressure fluid beingreleased from the well, the tubing may be built up in sections, one

attached to another by means of the conventional collars as the tubing is lowered into the well. The tubing may be open at its lower end, and the blowout preventers need not be used other than to support the tubing while sections thereof are being assembled to that portion of the tubing already in the well.

From the measurements pre iously taken, it will be known what portion of the tubing is to be positioned at the point of hanging, and at this point a special hanger collar 62 is built into the tubing string instead of a conventional collar.

Referring to Figure 8, this collar comprises a sleeve interiorly threaded at its lower end at 64 for engagementwith the upper end of the tubing section 66, and also interiorly threaded at its upper end as at 68 for the reception of the lower end of the lowering tubing section 10. This special collar is also exteriorly threaded at its upper end at 12, whereby the tubing hanger 14, which has a lower cylindrical interiorly threaded sleeve 16, may be screwed to the upper end of said collar.

While it is preferred ,to employ a threaded connection between the hanger l4 and the special collar 62, any other appropriate connection which can be quickly yet rigidly and permanently effected will suffice.

The hanger ll has a central bore 18 therethrough, which with the interior of its screw threaded portion 16, is of sufficient diameter to freely move along the tubing section between the special collar 62 and the next adjacent collar of the tubing above said special collar.

When the special collar I2 is built into the tub ing string, the hanger is positioned above the same and around the upper tubing string 10, being left unconnected with the collar 62 as shown in Figure 2.

Before the tubing is built up during its insertion, any desired type of device is secured to the. lower end thereof, such as a packer or the like,

and in operating such devices at the bottom of the well, it will usually be necessary to lower the tubing into the well until the special collar 2 is below the control equipment and the casing head and an appreciable distance down in the well as shown in Figure 3. For instance, to set'a packer in order to isolate particular sands, it may be necessary to force the tubing downwardly a considerable distance and with great pressure in order to set the packer. It would be possible, of

course, to closely anticipate the amount of downward movement necessary to completely expand the packer, and build into the tubing a conventional hanger at such point that it would just seat in the bowl of the tubing head 23 at the completion of the downward movement of the tubing to expand the packer, after which the well could be flowed through the tubing.

However, such a method is subiect to the disadvantage-that when extreme pressure is put on the tubing to expand the packer, the former, being perhaps thousands of feetlong'will become bent in many places throughout its length, and it is desirable to remove these bends-before the tubing is finally hung. The oil and gas flows from the well through the tubing under considerable pressure, and this pressure flow causes vibrations which eventually result in leakage if the tubing connections are not tight, and it is evident that if the tubing is distorted, ultimate leakage of the same is inevitable. Some wells now being completed may flow under their own pressure for many years, so that the permanency of the tubing installation is quite important.

When the tubing is lowered for any operations such as the setting of a packer, the special collar 62 is positioned in the tubing string at the desired point of hanging, and the hanger 14 is only loosely mounted on the tubing 10 above said collar. The tubing is lowered into the well to set the packer,

or perform any other similar operation, but the hanger "is kept in position above the casing head and above the control equipment if the latter is used, so that the tubing may be forced down into the well as far as necessary to perform the desired operation, with the special collar 62 disposed at the point of hanging going on down into the well below the casing head as far as necessary as shown in Figure 3. A removable strap 19 of any appropriate type may be bolted around the tubing beneath the hanger ll to hold it in place above the control equipment. The tubing may be moved downwardly until the hanger passeswhich time the hanger I4 is quickly and rigidly threaded onto the tubing at the collar 02, and lowered to seating position in the tubing head 28 as shown in Figure 5.

Because of the apparatus and method which permits subsequent elevation of the tubing after the packer setting operation, all of the bends in the tubing resulting from the packer. setting or other operations may be removed before the tubing is finally hung for the flowing of the well.

While in most cases, the bore through the hanger 14 need only be sufilcient so that it can move from the special collar 82 to the next collar in the tubing string above the same, if desirable, the said bore may be large enough to pass over the collars in the tubing string above the special collar, in which case theithreaded portion 12 of the special collar 82 may be of increased diameter to fit the lower threaded portion of the hanger, said collar being yet of small enough diameter to pass freely down into the casing. However, if any operation is expected which will necessitate an unusually great movement of the tubing down into the well after the special collar r is built into the tubing, and it is desired to take up this movement before hanging the tubing, the string of tubing I0 above the hanger may be made of sufficient length to take care of this movement without using a hanger having a larger bore.

Referring to Figure 3, the upper end of the tubing may at all times be connected with the swivel, and the rubber hose 58 extending to the pumps may be at all times in communication with the lower end of the tubing during the above operations, and at no time during insertion of the tubing with or without appliances secured to the bottom thereof, during the setting or operation of these appliances, and during the elevation and hanging of the tubing, will it be necessary to break the tubing. Therefore, mud may be pumped into the bottom of the well through the tubing immediately in case a dangerous condition is encountered. In equipment of the prior art, the hangers used, while perhaps capable of being lowered through the control equipment, cannot be built into the tubing without breaking the latter, thus leaving the well without the safe guard of being able to instantly pump mud to the bottom of the same during the time the hanger is being built in.

If the well is full of mud and in safe condition,

the blowout preventers need not be used, but if a dangerous pressure condition in the well is apparent, they may be used during insertion of the tubing, during setting or operating of any appliances at the bottom of the tubing, and during the raising of the tubing to the position of Figure 4, and while rigidly securing the hanger thereto and the subsequently seating the hanger.

With the well full of mud, it is necessary to wash the same and replace the column of mud in the casing with a column of other lighter liquid so that the well will flow. It may be desirable to provide a flow of water or other liquid upwardly outside the screen or strainer at the bottom of the casing, if such devices are used, in order to clear the perforations thereof so that the oil can pass into the casing. This washing of the well is an operation at the bottom thereof similar to the other perhaps necessary operations described above.

Referring to Figure 8, the special collar 82 is provided on its interior with a central series of reversely arranged threads 80 into which is threaded a valve housing 92 having a valve seat amass? 84 secured within the lower end thereof. A valve cage 98 has a threaded extension 88 which is threaded onto the lower end of said housing, holding the valve seat in place. Arranged within the valve cage is a ball valve member I normally forced against its seat by a valve spring iOi carried within the cage ll. The tension of the spring llll is sufficient to keep the valve normally closed, but is such that the valve may be moved from its seat under the pump pressure to permit a downward flow of washing water or mud into the well through the tubing.

With the well full of mud, the tubing is lowered into the well as previously described with the back pressure valve therein until the special collar is an appreciable distance down in the well and below the casing head, and with the hanger ll held above the control equipment, if possible, or at least, above the tubing head. When the tubing has been lowered, to washing position. the blowout preventers are engaged therewith and clear water or otherfluid is pumped downwardly through the tubing past the back pressure valve and out through the lower end of the tubing to wash the well. The hose 58 is connected with a two way valve I02 located adjacent the well, (shown diagrammatically in Fig. 3), so that either mud or water may be pumped into the well through the tubing from the lines M or W respectively. If the well is being washed with water, a quick shift of the valve I02 when dangerous pressures are encountered will permit the relatively heavy mud to be instantaneously pumped to the bottom of the well to quench the high pressure therein. Both outside and/0r inside washing may be performed as desired. Usually the lower end of the casing is provided with a strainer or screen, and it is conventional to equip the lower end of the tubing and the lower end of the strainer or screen with cooperating means to enable the former to seal with the latter, so that when the washing fluid is pumped downwardly through the tubing, it will pass out through the lower end of the screen, upwardly around the outside thereof, and up through the casing to discharge through the appropriate side outlets inthe casing head.

The lower end of the strainer or screen may also be equipped with a back pressure valve as is conventional, which may be opened mechanically by the tubing or in response to the pressure of the fluid flowing downwardly therethrough, which valve will close at thetermination of the washing operation so that all of the oil will enter the casing through the perforations in the screen or strainer.

During inside washing of the well, the tubing is raised to a point within or above the screen or strainer and fluid is forced downwardly through thetubing and into the casing through the lower end of the tubing, the fluid rising in the casing and discharging through the appropriate side outlets, in this instance through the side outlets 26 in the tubing head 23.

During either inside or outside washing through the tubing, the blowout preventers are engaged therewith so that various movements of the tubing may be effected as desired with safety; that is, the tubing may be manipulated up or down or rotated, and the blowout preventers maintain a seal therewith at all times.

During the washing operations, and during movements of the tubing incident thereto, not only will the blowout preventers provide control of the well between the casing and tubing, but

, 9,148,897 also the back pressure valve I00, while permitting downward flow of the washing fluid, will prevent upward flow of high pressure fluid from the well.

At the termination of the washing operation, either outside or inside or both, the tubing is elevated to'the position of Figuregi, with its special collar 82 positioned above the control equipment, it being evident that this collar may be safely moved through the control equipment without losing control of the well by alternate operation .of the blowout preventers 44 and 48 as previously described. When the tubing has reached this position, the hanger I4 is quickly and rigidly secured to the tubing by screwing the same onto the special collar 62 at the threads I2, after which the tubing is then lowered to hanging position as shown in Figure 5. During this lowering of the tubing with the hanger in place, control of the well may be maintained by keeping the lower blowout preventer 44 engaged with the tubing until the hanger is moved below the upper blowout preventer '46, after which the latter may be engaged with the tubing section 10 above the hanger, followed by the opening of the lower blowout preventer 44 and the lowering of the hanger to its seat.

Asshown in "Figure 5, the tubing head 23 is provided with looking screws IIO extending laterally through the flange 40 thereof, said screws being surrounded by a suitable packing III, the

latter being held in place by glands I I2 threaded into openings in flange 40 surrounding the looking screws.

When the hanger is seated as shown in Figure 5, the locking screws IIO are moved inwardly until their ends engage the upper beveled sur-, face H2 of the hanger, thus locking the hanger in its seat and compressing the packing rings H4 which extend completely around the hanger into sealing engagement with the bowl of the hanger seat in the tubing head 23.

At this time, the sealing engagement of the hanger with itsseat provides a permanent seal between the casing and the tubing, and the back pressure valve I provides a closure within the tubing against upward flow of fluid therethrough from the well.

It will be apparent from the above-described operations that a connection for instantaneous flow of mud from the pumps through the lower end of the tubing in the well is permanently maintained from the time the washing of the well is commenced, until the time when the tubing hanger is permanently hung, sealed, and locked in the casing head, withthe well completely closed.

If the tubing is to be lowered into the well under pressure, as. distinguished from a situation in whlchthe well is full of mud, the lower end of the tubing may be equipped with a frangible disc closure of well-known type, and the back pressure valve pensed with. In this situation, the tubing is lowered through the control equipment while the same maintains a seal therewith. As previously described, the hanger is rigidly attached to the tubing by the collar located at the point of hanging of the tubing, and the tubing is hung, sealed, and looked as described above, without opening up the well for flow of high pressure fluid either through the tubing or through the casing at any time.

If necessary, when inserting the tubing under pressure, any necessary operations at the bottom of the well may be effected prior to the in the tubing may be 'dis- I permanent hanging of the tubing, by attaching these devices, such as packers, to the lower end of the tubing and lowering them by means of the tubing into the well, while control ismaintained by the control equipment as above-described. During such lowering, the point of hanging of the tubing may be lowered into the wellto a point below the casing head 23, while the hanger, though mounted on the tubing, is retained above the casing head or the control equipment. When operations are completed, the tubing is elevated until its point of hanging is above the control equipment, the hanger quickly and rigidly attached thereto, and is then lowered and locked in its seat. By reason of the construction of the hanger and its manner of application to the tubing, after any necessary operations are performed with the tubing at the bot- I tom of the well, the' same may be elevated and the hanger attached thereto and hung without any loss of time. It is well understood that in oil well completion operations, the quicker the hanger can be attached, hung, and sealed, the better. I i

When the hanging and sealing operations have been completed, the upper string of tubing I0 is unscrewed from engagement with the threads 68 of the collar 62 and removed from the casing head equipment. Furthermore, the master drilling valve 35 and the blowout prewenters and 46, having now performed their function, may be safely removed from the casing head equipment and relegated to the position of accessories. This control equipment is quite heavy and expensive, and its removal to the position of accessories permits its immediate use on other wells in the field, or it may be kept available at the same well if its function is again desired.

After the removal of the control devices as described above, the Christmas tree equipment be of any appropriate type, and is shown com- I prising a master manifold valve I mounted directly on the tubing head 23, said valve being surmounted by a cross ,I 22 which may have positioned above the same a further Christmas tree control valve I24, and also another control valve I26 secured to a side outlet from said cross. The

other outlet from the cross opposite valve I26 may be similarly equipped with a control valve, ormay be closed with a bull plug I28, as desired.

The Christmas tree may be assembled and stabbed onto the casing head as a unit.

The master manifold valve I20 is much smaller and offers a much less pressure area to the fluid in the well than did the master drilling valve 36 which formerly occupied its position on the tubing head.

The master manifold valve I20 is connected in sealing engagement with the upper flange 40 of the tubing head by bolts, as shown, and the connecting flanges are of like size. Furthermore, the cross I22 is connected with the valvev I20, and with the auxiliary control valves I24 and I26 with flange and bolt connections of like size. I I

After the Christmas tree is mounted on the casing head as described above, the well is ready to flow after the tubing is opened. If a back pressure valve 02 was used to close off the tubing, it is removed as hereinafter described. A stufilng box I40 is provided above the valve I24, being carried by a flanged adapter I42 bolted to the upper flange of the valve I24. This stuffing box is built up around a solid rod I44 provided at its lower end with a tool shown in the form of screw threads I46 adapted to engage threads I 40 in the upper interior of the valve assembly 02, these threads being reversely arranged with respect to the threads 80 between the valve housing 92 and the hanger 14. The solid rod I44 .is lowered down through the valves I24 and I20 and the threaded tool I46 is screwed into the threads I48 of the valve housing. and after said tool is completely threaded into the valve housing, further rotation of rod I44 removes the valve housing and valve from the collar 62, after which the tool may be elevated to lift the valve assembly to position above the master manifold valve I20 as shown in the dotted lines in Figure 6, when said valve may be closed.

The well is under control during the removal of the valve assembly, as the stufflng box I40 forms a seal around the solid rod I44. When the valve assembly has been elevated above the valve I20 and the latter ,is closed, the stufling box I40 and the solid rod carrying the valve assembly are removed, and the conduit extending from the upper end of the valve I24 may be closed by a bull plug or a pressure gage fitting as desired, or a further flow line and choke as shown leading from valve I26 may be connected to the upper opening from the valve I24.

If the tubing has been closed by a frangible disc near its lower end, as previously described, it can be opened up when the well is ready to flow by opening the valve I24 while the valve I20 is closed, dropping a weight into the cross, closing the valve I24, opening the valves I20 and I26, thus permitting the weight to drop through ,the tubing, destroying the frangible disc to permit the well to flow through the Christmas tree side outlet controlled by the valve I26.

After opening up the tubing, the well is in condition for flowing through any of the outlets from the cross I22 as shown in Figure '7.

The present invention provides a marked flexibility of Cltl'Ol, and not only gives the operator a wide choice of what operations can be safely performed, but also a wide choice of the manner in which these operations may be safely carried out. For instance, when the completion of the well has arrived at the stage of Figure 6, with the Christmas. tree mounted on the casing head and the back pressure valve still in place within the collar 62, washing of the well may be performed through the Christmas tree. At this time, the solid rod I 44 and stuffing box I40 would not be present in the apparatus. When in this condition, a connection could be made to either of the valves I24 and I26 or through a valve positioned in place of the bull plug I20, and washing fluid is pumped downwardly through the tubing past the back pressure valve, and out through the bottom of the tubing, passing upwardly through the casing and discharging from the side outlets in the tubing head 23. That is, the well might be washed with the Christmas tree in place, rather than washing the well with the control equipment of Figure 3 in place.

Some operators may prefer to only perform the outside washing of the well with the control equipment mounted as shown at Figure 3, leaving inside washing of the well until the rod similar to the rod I44.

Christmas tree is in position and the well completely buttoned up. The flexibility of operation described above is obviously of pronounced advantage.

After the well has been completed as above described, it may be necessary to perform other operations subsequent to completion, perhaps after the well has flowed for a considerable time. With the well still under high pressure, the tubing may be plugged at any point by any wellknown type of tubing spear, said spear being set by a tool carried on the lower end of a solid The spear is inserted without opening the well to flow of high pressure fluid by reversing the operations described in connection with the removal of the valve housing and valve illustrated in Figure 6.

With the tubing closed, the Christmas tree is removed and replaced with the control equipment of Figure 4, after which the upper string of tubing 10 is lowered and engaged with the hanger, the blowout preventers engaged with the lowering tubing 10, after which the locking screws IIO are retracted to permit elevation of the tubing and hanger, control being maintained by the blowout preventers. The tubing may be com- ,pletely removed, if the spear plug is disposed at the lower end of the tubing, to permit the attachment to the lower end thereof of such devices as a packer, for instance, to isolate particular sands.

The tubing may be lengthened or shortened, to obtain a better oil-gas ratio, while control is maintained both through the tubing and casing by following the sequence of operations described above in manipulating the control equipment. Such lengthening or shortening of the tubing will involve raising the hanger 14 through the control equipment, loosening it from its collar, and then again rigidly securing it to a new collar built into the tubing at the proper point of hanging after the changes are effected. The hanger is then lowered to its seat and locked, the Christmas tree returned to position on the tubing head 23, and the spear plug removed as will be obvious from the preceding description.

In Figure 9 the back pressure valve housing 62' has formed integral therewith an upwardly extending strainer S, the latter being a cylindrical sleeve with a plurality of openings therein. It will be noted that this strainer is centrally disposed with respect to the housing, so that the lowering tubing 10 may pass down over the same when said tubing is secured to the collar 62. Instead of the threads I 46 on the interior of the valve housing in the embodiment disclosed in Figure 8, the upper end of the strainer carries an interiorly threaded socket I46 which is adapted to receive the threads on the lower end of the removing rod I44.

The strainer serves to protect the back pressure valve from any material passing downwardly through the tubing which might foul said valve. The threads I48 are reversely arranged with respect to the threads 00' between the valve housing and the collar 62, so that when the removing rod is threaded into the upper end of x the strainer in the same manner as previously described, the back pressure valve will be removed from the collar 62. The back pressure valve and strainer may be removed with safety in the same manner as described in connection with Figure 6.

Important features of the present invention are the ability to maintain circulation through the tubing during-the performance of operations at the bottom of the well, such as the setting of packers, and during subsequent elevation and hanging of the tubing, as well as the ability to maintain circulation from the pumps to the bottom of the tubing during the washing of the well, and subsequent elevation and hanging of the tubing. The above operations may be performed without breaking the tubing between the swivel and the bottom of the hole at any time, whereby circulation may be maintained during the entire procedures involved.

Notwithstanding that devices are available for the handling of wells under pressure without the help of heavier fluid, such as mud, and even though in most instances the procedure is planned to avoid the use of mud, it is generally accepted in practical oil well completion that whenever a question arises concerning the ability of the control mechanism to hold the pressure in the well, the use 01' ahead of mud should be resorted to as quickly as possible. With the tubing unbroken between the swivel and the bottom of the well at all times during the dangerous operations, the injection of mud to the bottom of the well can be performed by merely switching a valve at the pump manifold, thereby changing the fluid being inserted from oil or water as the case may be to water or mud in proportion to the weight desired. The ability to quickly inject mud into the hole remains the most effective safety feature in guarding wells against blowouts.

It will be apparent that this inventionmay be used in performing through the sequence of control operations in association with a wide choice of drilling methods, such as cable tool and rotary methods under pressure, rotary systems using both mud and pressure control operations. The invention herein described aifords a choice of settings at the bottom of the well, including completions with a liner, screen, and packer, and with perforated liner and the setting of production packers either during or after completion.

The invention of this application is an improvement in the method and apparatus for completing wells described and claimed in the application of Roger Smith, Serial No. 736,635, filed July 24, 1934, and application Serial No. 58,821, Robert A. Mueller and Roger Smith, filed January 13, 1936.

It will be obvious that various changes may be made in the method and apparatus described herein without departing from the invention.

We claim:

' 1. In well completion equipment, a tubing comprising upper and lower sections, a tubing collar for connecting saidsections, said collar having a bore threaded interiorly at its lower end for securing said lower section of tubing, and interiorly at its upper end for securing with said upper section of tubing, a removable valve housing secured within said collar between the upper and lower threads thereof, a tubing hanger having aibore surrounding the upper section of tubing and mounted for longitudinal movement thereon above said collar, said hanger bore having threads therein, and cooperating exterior threads on the upper end of said collar, whereby said hanger may be rigidly secured to said collar, and said upper section of tubing detached therefrom after hanging said lower section of tubing in the well with said hanger, said valve housing having means for receiving a-tool to remove the same from said collar after the lower section of tubing is hung.

2. In well completion equipment, a tubing collar for connecting upper tubing, said collar being of size and shape adapting it for lowering through the casing head and easing of a well, saidcollarhavingmeans arranged torrigidconnectionwith a lower section oftubing, and means whereby it may be detachably connected with an upper section of tubing, a unitary valve housing detachably secured within said collar, said housing having a valve therein providing for passage offluid downwardly therethrough but providing against passage of fluid upwardly therethrough, and means on said collar arranged for rigid connection with a tubing and lower sections of.

hanger preparatory to hanging said lower section of tubing in the well with said hanger, said valve housing having means for receiving a tool to remove the same as a unit from said collar after the lower section of tubing is hung.

3. In well completion equipment, a tubing col- 1 lar for connecting upper and lower sections of tubing, said collar being of size and shape adapting it for lowering through the casing head and casing of a well, said collar having means at its lower end arranged for rigid connection with a lower section of tubing, and means at its upper "end whereby it may be detachably connected with an upper section of tubing, a unitary valve housing detachably secured within said collar between said means, said housing having a valve therein providing for passage of fluid downwardly therethrough but providing against passage of fluid upwardly therethrough, and means on the upper end of said collar arranged for rigid connection with a tubing hanger preparatory to hanging said lower section of tubing in the well with said hanger and removing said upper section of tubing, said valve housing having means for receiving a tool to remove the same as a unit from said collar after the lower section of tubing is hung and the upper section of tubing is removed from said collar.

4. In well completion equipment, a tubing collar for connecting upper and lower sections of tubing, said collar being of size and shape adapting it for lowering through the casing head and casing of a well, said collar having means at its lower end arranged for rigid connection with a lower section of tubing, and means on the interior of its upper end whereby it may be detachably connected with an upper section of tubing, a unitary valve housing detachably secured within said collar between the upper and lower ends thereof, said housing having a valve therein providing for passage of fluid downwardly therethrough but providing against passage of fluid upwardly therethrough, and a hanger rigidly secured to the exterior of said collar at the upper end thereof for hanging the lower section of tubing in the well, said valve housing having means for receiving a tool t9 remove the same as a unit from said collar after the lower section of tubing is hung, and packing means on the exterior of said hanger for forming a seal with the interior of the casing head of the well.

5.A tubing collar for use in completing an oil well, said collarbeing of size and shape adapting it for lowering through the casing head and casing of a well, said collar having a bore therethrough and having means at its upper end arranged for rigid connection with a tubing hanger, and means at its lower and arranged for rigid connection with a lower section of tubing, said collar having means on its interior for detachably connecting an upper section of tubing therewith, and means below said last-named means for detachably securing a back pressure valve in said collar, the bore oi said collar above said lastnamed means being large enough to permit removal of the back pressure valve as a unit there-* from when the tubing is hung and the upper section of tubing is detached from said'collar.

6. A tubing collar for use in completing an oil well, said collar having a bore therethrough and being of size and shape adapting it for lowering through the casing head and casing of a well, said collar having means onits exterior arranged for rigid connection with a tubing hanger and means at its lower end arranged for rigid connection with a lower section of tubing, said collar having means at its upper end for detachably connecting an upper section oi tubing therewith, and means in said bore for detachably securing a back pressure valve therein, the bore of said collar above said last-named means being large enough to permit removal of the back pressure valve as a unit therefrom when the tubing is hung and the upper section of tubing is detached from said collar.

7. In well completion equipment, a tubing collar for connecting upper and lower sections of tubing, said collar being of size and shape adapting it for lowering through the casing head and casing of a well, said collar having means arranged ior rigid connection with a lower section oi tubing, and means whereby it may be detachably connected with an upper section of tubing, a unitary valve housing detachably' secured within said collar, said housing having a valve therein providing for passage of fluid downwardly therethrough but providing against passage of fluid upwardly therethrough, and having a strainer positioned above said valve to protect the sameI and means on said collar arranged for rigid connection with a tubing hanger preparatory to hanging said lower section of tubing in the well with said hanger, said valve housing having means for receiving a tool to remove the same as a unit from said collar after the lower section of tubing is hung.

8. In completion apparatus for use on an oil well which is produced through flow tubing lowered into a casing, a casing head having an inside supporting seat, a tubing hanger supported in said seat, a tubing collar rigidly secured to said hanger, said collar being or size and shape adapting it for lowering through said casing head and the casing of the well, said collar being rigidly connected with the upper end of the tubing to suspend the same from said hanger and having a bore therethrough, and a unitary valve housing detachably secured within said bore, said housing having a valve therein providing for passage of fluid downwardly therethrough but providing against passage of fluid upwardly therethrough, said valvehousing having means for receiving a tool to remove the 'same as a unit from said collar after the tubing is suspended in the well from said hanger.

9. In completion apparatus for use on an oil well which is produced through flow tubing lowered into a casing, a casing head having an inside supporting seat, a tubing hanger supported in said seat, a tubing collar rigidly secured to said hanger and extending below the same down into said casing head, said collar being of size and shape adapting it for lowering through the casing head and casing of the well, said collar being rigidly connected with the upper end of the tubing to suspend the same from said hanger and having a bore therethrough, and a back pressure valve removably secured within said bore, said valve providing for passage 01' fluid downwardly therethrough but providing against passage of fluid upwardly therethrough.

10. In completion apparatus for use on an oil well which is produced through flow tubing lowered into a casing, a casing head having an inside supporting seat, a tubing hanger supported in said seat,vpacking means between the outer wall 01' said hanger and the wall of said seat to form a seal for closing oil. the upper end of the casing, a tubing collar rigidly secured to said hanger and extending below the same down into said casing head, said collar being of size and shape adapting it for lowering through the casing head and casing 01' a well, said collar being rigidly connected with the upper end of a lower Section of tubing to suspend the same from said hanger, and having means whereby it may be detachably connected with an upper section of tubing, said collar having a bore therethrough, and a back pressure valve removably secured within said bore, said valve providing for passage of fluid downwardly therethrough but providing against passage of fluid upwardly therethrough.

11. In completion apparatus for use on an oil well which is produced through flow tubing lowered into a casing, a casing head having an inside supporting seat, a tubing hanger supported in said seat, a tubing collar rigidly secured to said hanger and extending below the same down into said casing head, said collar being of size and shape adapting it for lowering through the casing head and casing of a well, said collar being rigidly connected with the upper end of a lower section of tubing to suspend the same from said hanger. and having means whereby it may be detachably connected with an upper section of tub: ing, said collar having a bore therethrough and a back pressure valve with a strainer above the same removably secured within said bore, said valve providing for passage of fluid downwardly therethrough but providing against passage of fluid upwardly therethrough, said strainer serving to protect said valve.

12. In well completion equipment, a casing, a casing head having a hanger seat, a tubing in said casing, said tubing being made up of sections of pipe attached together by collars, one of said collars being located at the point of hanging of said tubing, and being rigidly connected with the upper end of a lower section 01' tubing and detachably connected with the lower end of an upper section of tubing, whereby it divides said tubing into a lower flow section and an upper removable section, means in said one of said collars for preventing upward flow oi fluid through said tubing from the well while providing for downward flow oi fluid therethrough, a hanger mounted for longitudinal movement on said upper removable section of tubing, means on said hanger arranged for rigid connection with said one of said collars to thereby rigidly secure said hanger to said lower flow section of tubing, whereby said hanger may be lowered into said seat to suspend said lower flow section of tubing in said casing, and said upper section of tubing detached from said one of said collars and removed from the equipment.

13. In .well completion equipment, a casing, a casing head having a hanger seat, a tubing in said casing, said tubing being made up of sections of pipe attached together by collars, one of said collars being located at the point of hanging of said tubing, and being rigidly connected with the upper end or a lower section oi tubing and detachof hanging of the latter ably connected with the lower end oi! an upper section of tubing, whereby it divides said tubing into a lower flow section and an upper removable section, a unitary valve housing detachably connected within said one of said collars, said housing having a valve therein providing for passage of fluid downwardly therethrough but providing against passage of fluid upwardly therethrough, said valve housing having means for receiving a tool to remove the same as a unit from said one of said collars, a hanger mounted for longitudinal movement on said upper removable section of tubing, means on said hanger arranged for rigid connection with said one of said collars to thereby rigidly secure said hanger to said lower flow sectionof tubing, whereby said hanger may be lowered into said seat to suspend said lower flow section of tubing in said casing, and said upper section of tubing and valve housing may be removed from said one of'said collars to flow the well.

14. In well completion apparatus, a casing, a tubing in said casing, a casing head having a hanger seat, a tubing hanger mounted for iongitudinal movement on said-tubing above the point of hanging of the latter for disposition above said casing head when said tubing is lowered into said casing with its point of hanging below said casing head, a collar for securing the sections of tubing together disposed at the point of hanging of said tubing, and being rigidly connected with the upper end or a lower section of tubing and detachably'connected with the lower end of an upper section of tubing, said collar dividing said tubing into a lower flow section and an upper removable section, means carried within said collar for preventing upward flow of fluid through said tubing from the well while providing for downward flow oi fluid therethrough, and means on said hanger arranged for rigid connection with said collarto thereby rigidly secure said hanger to said lower flow section of tubing, whereby said hanger may be lowered into said seat to suspend said lower flow section of tubing in said casing, and said upper section of tubing may be detached from said collar and removed from the equipment.

15. In well completion apparatus, a casing, a tubing in said casing, a casing head having a hanger seat, a tubing hanger mounted for longitudinal movement on said tubing above the point for disposition above said casing head when said tubing is lowered into said casing with its point of hanging below said casing head, a collar for securing the sections oi! said tubing together disposed at the point of hanging of said tubing, and being rigidly connected with the upper end of a lower section of tubing and detachably connected with the lower end of an upper section of tubing, said collar dividing said tubing into a lower flow section and an upper removable section, a unitary valve housing detachably secured within said collar, said housing having a valve therein providing for passage of fluid downwardly therethroughbut providing against passage of fluid upwardly therethrough, said valve housing having means for receiving a tool to remove the same as a unit from said collar, and means on said collar arranged for rigid connection with said hanger to'thereby rigidly secure said hanger to said lower flow section of tubing, whereby said rigidly secured hanger may be lowered into said seat to suspend said lower flow section of tubing in said casing, and said upper section of tubing and valve housing may be removed from said collar to flow the well.

16. In well completion equipment, a casing, a casing head having a hanger-seat, a tubing in said casing, a collar disposed at the point of hanging of said tubing connected rigidly with the tubing below and detachably with the tubing above, said collar dividing said tubing into a lower'flow section and an upper removable section, control equipment for forming a seal between said casing and said tubing mounted above said casing head, said tubing extending through said control equipment with said collar disposed below said casing head while performing operations with said tubing at the bottom of the well, a hanger mounted for longitudinal movement'on said upper section of said tubing, said hanger being of size and shape adapting it for lowering through said control equipment and being disposed above said casing head during the performance oi. said operations, whereby said control equipment may be actuated to form a seal with said tubing when desired with said hanger either above or below said control equipment, a removable back pressure valve in said collar, means on said hanger arranged for rigid connection with said collar to thereby rigidly secure said hanger to said lower flow section of tubing, whereby said tubing maybe elevated after the performance of said operations to position said collar above said control equipment, said hanger rigidly secured to said lower flow section of tubing and thereafter lowered to said seat to suspend said lower flow section of tubing in said casing without at any time opening the well for new through said tubing or between said tubing and said casing.

\ ROBERT A. MUmLER.

ROGER SMITH.

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