US2552901A - Method of controlling wells - Google Patents

Description

y 1951 I. A. MILLER 2,552,901

METHOD OF CONTROLLING WELLS Filed May 16, 1949 v fro A. M///er' [NI/[NTOR ayfl y w ATTORNEYS Patented May 15, 1951 METHOD OF CONTROLLING WELLS Ira A. Miller, Dallas, Tex., assignor to Otis Pressure Control, Inc., Dallas, Tex., a corporation of Texas Application May 16, 1949, Serial No. 93,509

8 Claims. 1

This invention relates to the method of controlling petroleum wells and refers more particularly to shutting off the flow of wells temporarily by closing off well conduits other than by the usual flow control equipment of the well. This is oftentimes required in order to close off a well to permit a modification of the control equipment as, for instance, for the purpose of repairing, replacing or installing diiferent flow equipment.

It has heretofore been proposed to close off or freeze off conduits extending substantially horizontally by injecting therein a slurry or slush of small ice particles and water and then externally refrigerating the conduit whereby the slush is turned into a plug of ice which effectively closes off the conduit. However, when it was attempted to close 01f the flow string or other pipe string of a petroleum well by this method, it was found that the ice slurry usually fell through the pipe string too quickly for it to freeze due to the pipes vertical position, render ing it impossible to form an ice plug within the pipe string.

An object of this invention is to provide a method fo controlling a petroleum well under pressure by closing off the string well conduit to be controlled other than by the usual control equipment of the well.

Another object is to provide a method of controlling a well producing substances which are not readily freezable at temperatures near the freezing point of water by injecting viscous cohesive material into the conduit to be controlled to form a static plug therein and freezing this material.

A further object is to provide a method for closing off a well conduit other than by the usual well control equipment where the conduit has a larger diameter than any connection communicating therewith.

Still another object is to provide a method of modifying the control equipment of a well by temporarily closing off the well conduit to be controlled below the lowest operable control therefor whereby the desired modification of the control equipment can be made.

Other and further objects of the invention will appear from its description.

In the accompanying drawings which form a part of the instant specification, are to be read in conjunction therewith, the single figure is an elevational view partially in section of well head and flow control equipment illustrating a. method of closing ofi one of the well conduits in accordance with an embodiment of this invention.

It is believed that the invention will be more readily understood by first referring to the structural parts of a typical well head installation. Referring to the figure, the ground surface is shown schematically at 5 having a bore hole 6 extending vertically therein. Within the bore hole is set the usual well string of easing 1, and

in the interest of simplicity, other surface strings of casing have been omitted from the drawings.

Supported on the casing string I i a Christmas tree designated generally by the numeral 8 equipped with the usual flow connections 9 communicating through the control equipment with the interior of the flow string of pipe or tubing [0.

This Christmas tree or control equipment includes the casing head I l, a ram type tubing head l2 and master valve I3. It is to be understood that this control equipment is shown by way of illustration and not in a limiting sense but that the invention may be employed regardless of the type or kind of control equipment with which the well is equipped.

The tubing head I2 serves a double purpose, providing a hanging means for suspending the tubing string I0 and also providing a means for sealing the annulus between the body of the tubing head and the peripheral wall of the tubing string. The means for accomplishing this includes opposing rams I3 carrying packing elements I4. The packing elements are made up of suitable seal material and with the two rams forced into engagement with the wall of the tubing by the rods [5, and with each other, provide a seal between the rams and the tubing. Seal elements I6, in the upper surface of the rams, provide the seal between the rams and the tubing head body. The rams are mounted for sliding movement in the cylindrical portions I2a of the tubing head and their position therein is controlled by the usual rods I5 which have a threaded connection within the bonnet I'I bolted to the tubing head body. Of course, the hanging function is provided by the engagement of the tubing collar Illa on the upper surface of the rams. The rams may be withdrawn from the tubing head for the purpose of repair or replacement of packing by removing the bolted bonnet II. These rams are all in accordance with well known commercial equipment, and it is believed that additional description thereof may be dispensed with.

The invention may be employed with utility under many varied conditions. By way of illustration, a few examples of. conditions which make it advisable to close off a well string of pipe to permitv modification oi the flow control equipment will be given. oftentimes upon occurrence of the first signs of blowing, well equipment will be installed which is not adapted to control the pressures which develop in the well but which is installed because of its ready availability at the time the well comes in. It then becomes necessary to close oif the well in order to modify the control equipment to install equipment which is heavy enough to control the pressures that develop in the well..

Oftentimes when working on producing wells, the bolts holding down the control equipment mounted on the tubing hanger are removed in order that the packing or other parts thereof may be repaired. Sometimes when this occurs, if the blowout preventers or rams of a ram type head are not sufiicient to hold the tubing string against the pressure within the well, the whole tubing string, including the well head equipment secured thereto, will be" forced upwardly, sometimes even looping over due to the weight of the Christmas tree. This, of course, is 'not a usual occurrence but is a problem with which the industry is occasionally presented. When this does occur, it is necessary to close off the tubing below the loop and adjacent the Well head so it maybe cut and threaded to receive a new tubing length and then equipped with suitable control equipment. This invention is well adapted for this use.

Other operations for which this invention is especially adaptable include the replacement of all or certain lengths of the Well tubing which may be corroded or eroded, the repair or replacement of certain portions of the well con trol equipment including packing and seal elements; and the removal of tools, pipe strings or the like that might have become jammed within one of'the'well conduits while it was being lowered into the conduit and wherein the jammedequipment, a lowering line, rod or the like, extending through the control equipment makes it impossible to operate the usual normal control equipment.

In accordance with this invention, when it is desired to shut off the flow through a well conduit and where the conduit to be closed is filled with a substance such as petroleum oil or gas, which is not readily freezable at such temperatures that may be easily obtained by available sources of refrigeration; a substance which is readily freezable at or near the freezing point of water is forced into the conduit at the zone it is to be closed off to form a static plug which may then be frozen by application of refrigeration exteriorly of the conduit. It has been found that this refrigeration may be adequately and suitably provided by placing a pack of Dry Ice about the exterior of the conduit at the level it is to be frozen on". It is usually desirable to .carry out this operation in one of the flow fittings which make up a part of the conduit for It has been found to be necessary for the plug to be substantially completely static during the actual freezin operation.

In some instances, water, has been successfully employed for this purpose, even in vertical conduits, where the pressures to be controlled are very high as, for instance, five thousand pounds per square inch and higher. It is notunclerstood what causes the water to remain in the upper portion of the conduit and resist gravity, but it is assumed that the very high pressures involved serve to hold the water in place at the upper portion of the conduit though the conduit is filled with a lighter substance, such as gas, below the water level. However, it has been found that when lower pressures are involved, the water rarely, if ever, will remain in place as a static plug so that the freezing may proceed, and that oftentimes, even in high pressure wells, the water will fiow to thebottom of the tubing.

Because of the uncertainty of the results to be obtained when it is attempted to use water as the substance to be injected into the conduit, it is not recommended that water be used for this purpose. This is especially true where the sitnation is one in which time is of the essence. In order to avoid a blowout, the use of water should not be risked because of the likelihood of failure of the water to remain as a static plug the reason that this portion of the conduit has .thereacross when the conduit, downstream from the plug, is opened while carrying out the modification operation. However, it has been found that a conduit having substantially cylindrical walls as, for instance, in a length of tubing, can 'be closed in accordance with this invention.

duit in'the refrigerated zone.

which may be frozen in the upper portion of the conduit.

It has been found that a plug of frozen ma- It has been found that mixtures of earthen 7 materials and water are entirely satisfactory for this purpose. These earthen materials may be naturally occurring dirt or clay in the vicinity of the well where these are not sandy, or may be clays which are commercially prepared and sold for use in drilling muds. It is preferable to use material having abrasive substances therein such as shell, rock particles .or the like because these abrasives frictionally engage the walls of the conduit to hold the plug of the substance more securely within the conduit both while the plug is being frozen and after it is frozen.

Where the material may be introduced into the frozen zone of the conduit to be closed through a flow passage which is no smaller than the diameter of the conduit of the refrigerated zone, it may enter the conduit axially thereof. However, where large diameter conduits such as well casings are to be closed off, it is usually necessary to introduce the material into the conduit through a relatively small opening as, for example, a two inch diameter flow fitting of a casing head. Obviously, a rod of cohesive material having a diameter of approximately two inches will fall downwardly within the large diameter conduit and therefore, the material is preferably extruded into the conduit at an angle to the longitudinal axis of the conduit. When this of the conduit and to adhere thereto. tional material is forced into the conduit, a plug drawings for this purpose.

is done, apparently the material as it .extrudes into the conduit is caused to engage the walls As addiis finallybuilt up which will close off the interior of the conduit. When the material is introduced directly into the refrigerated :zone of the conduit, engagement of the moist extruded ribbon with the refrigerated wall causes the material tofreeze to the wall andaid in the formation of a static plug of material. Therefore, it is usually preferable to refrigerate the conduit before the substance to be frozen is introduced into the conduit, but sometimes the refrigeration may be applied after the plug of freezable substance has been formed within the conduit.

It is believed that an understanding of the invention will be facilitated by referring to a specific example and attention is directed to the It will be assumed for purposes of this explanation that the packing element 14 of the ram type tubing head has become worn and must be replaced. The ram and packing element may be withdrawn from the tubing head by removing the bonnet ll, but before this can be done, it is necessary to close off the annulus between the conduit provided by the casing l, the casing head H, and the tubing head l2 and the conduit provided by the string of flow tubing Ill. Also, it is necessary to close off the interior of tubing Ill and to suspend the tubing for it will be recalled that the rams serve the dual function of suspendin the tubing and providing a seal between the tubin and the tubing head.

In accordance with this invention,the conduit, including the casing l, may be closed off by forcing a plug of viscous cohesive material into the space between the tubing and the casing head. Refrigeration is applied to the exterior of this conduit by means of a Dry Ice pack l8 supported exteriorly of casing head H by a retainer I9 secured to theupper end of casing 1.. When a static plug of viscous cohesive freezable material has been formed within the casing head closing off the annulus, the refrigeration provided by the Dry Ice pack willfreeze the plug to effectively seal off the annulus.

The flow fitting I la of the casing head is equipped with a valved fitting 20 and to this fitting is secured ,a cylindrical member 2! which may be, for instance, a length of five inch casing. This barrel or cylinder 21 is filled with cohesive earthen balls 22 which are a mixture of earthen material and'sufficient water to make them mold able and cohesive. Aplug 23,.substantial1y filling the interior of barrel 2|, backs up the balls 22 and will serve-as apiston for-forcing the cohesive substance of the balls 22 into the interiorof the conduit to 'beiclosed off.

A driving force for extruding the cohesive materialinto well head I I may be provided by securing a cap 24 onto the free end-ofbarrel 2 l. The cap has an aperture therethrough connected by line 25 with a source of fluid pressure which may be the discharge of a pump 26 or may be a connection to a high pressure gas or the like.

Around the usual well installation, there usually are numerous pumps which may be employed for actuating the piston 23. Examples of these are pumps for forcing cement into a well during cementing operations, slush pumps for circulating drillin mud, pumps for actuating blowout preventers and the like.

When the Dry Ice pack [8 has been secured of the casing head; Just what happens within the casing head, of course, isspeculative, and the theory advanced here is given byway of explanation and is not to be considered as binding or limiting the scope of the appended claims or of the invention.

It is believed that the ribbon of material 22d,

as it .extrudes from the opening Ila, enters the .annulusand due to itsstifi and cohesive character, will extend substantially laterally into the interior of the conduit until it engages a rigid surface such as the wall of tubing ill or the inner wall of the; well head. It will then commence to 100p over ina distorted manner in a fashion similar to toothpaste squeezed from a tube. The material 22 is forced by high pressure into the Well head and finally forms a static plug of material closing off the annulus between the tubing andthe well head. When sufficient material has been forced into the conduit to provide the static plug, valve 20 is closed and sufficient time is allowed for the Illllgto freeze solidly. Of course, during the freezing of the plug, the material expands so as to tightly fillthe annulus and effectively seal it off. It will be noted that the inner wall of the casing head is somewhat constricted adjacent the lateral openings Na and it will be appreciated that the plug of material frozen within the annulus-will be additionally secured in place due to this irregular contour and also due to portions of frozen material extending into the lateral openings I la.

It is contemplated that thestatic plug may be formed within the conduit :prior to refrigeration, but where large diameter conduits are involved, it is preferredto refrigerate during the formation of the'plug.

When the annulus has been sealed oil, the interior of the tubing l0 may be closed 01f in a conventional manner well known to those skilled in the art, by lowering, a plug into the interior of the tubing and'anchoring it in place adjacent the upper end. This is done'with the use of special equipment, now in commercial use in the oil industry, and not constituting in itself a part of the invention, and for this reason, further reference to such-equipment will be dispensed with in this instrument.

cially carried outin-theoil fields, and which spear is connected to the usual derrick or mast through a traveling blockor the like and serves to suspend the tubing string so that the ram I3 may be withdrawn from the tubing head in order that the packing element l4 may be-replaced.

As heretofore indicated, the bonnet I1 is removed to permit withdrawal of ram I3. When the packing element M has been replaced in the ram and any other necessary repairs made, the ram is reinserted into the tubing head, the balance secured in place and then the spear which suspended the tubing is removed as is the plug which was previously landed to close off the interior of the tubing. The upper flow control equipment above the tubing head 12 is placed in proper order and then the plug of frozen material is allowed to thaw and may be extruded, at least in part, from the interior of the casing head through outlets Ila by the pressure within the annulus.

In an operation such as this, it usually is not necessary to thoroughly clean out the substance 22a when the modification operation is completed,

but in instances where this is desirable, as where well products are produced through the annulus, the material may be washed from the conduit closed off in any suitable manner which will be well understood t those skilled in the art.

From the foregoing it will be seen that this invention is one well adapted to attain all of the ends and objects hereinabove set forth, together with other advantages which are obvious and which are inherent to the method.

It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims.

As many possible embodiments may be made -of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

The invention having been described, what is claimed is:

l. The method of temporarily closing off a vertically disposed well conduit other than by the usual flow control equipment where'the conduit contains substances not readily frozen at temperatures near the freezing point of water comprising the steps of applying refrigeration to the exterior of the conduit at the position or level thereof that it is desired to close it off, and while continuing the application of refrigeration to the conduit injecting into the conduit a viscous temperatures near the freezing point of water comprising the steps of applying a pack of Dry Ice about the exterior of the conduit at the level it is desired to close oif the conduit in a manner to refrigerate the interior thereof, and while continuing the application of refrigeration to the conduit' injecting into the conduit a viscous cohesive substance readily freezable at the temperature of refrigeration of the conduit to form a static plug of the cohesive substance in the refrigerated Zone, and continuing the refrigeration to freeze a plug of solid material within and clos-' ing off the conduit.

3. The method of temporarily closing 01f a vertically disposed well conduit other than by the usual flow control equipment where the conduit contains substances not readily frozen at temperatures near the freezing point of water comprising the steps of applying refrigeration to the exterior of the conduit at the position or level thereof that it is desired to close it off, and while continuing the application of refrigeration to the conduit injecting a viscous cohesive mixture of water and earthen material into the interior of the conduit at the refrigerated zone to form a static plug of the cohesive substance therein, said mixture having a consistency similar to that of molding clay, and continuing the refrigeration to freeze the cohesive substance to a plug of solid material within and closing ofi the well conduit.

4. The method of claim 3 wherein the earthen mixture contains abrasive material.

5. The method of claim 3 wherein the refrigeration is provided by securing a Dry Ice pack to the exterior of the conduit at the level it is to be closed off.

6. The method of temporarily closing off a vertically disposed large diameter well conduit other than by the usual flow control equipment of a well where the conduit is filled with a material not readily frozen at normally available refrigeration temperatures comprising the steps of refrigerating the well conduit at the level it is desired to close it off, extruding a viscous cohesive self-supporting substance laterally into the refrigerated zone through an opening of smaller diameter than the conduit to be closed to form a static plug of cohesive substance therein, said substance being readily frozen at the available refrigeration temperatures within the conduit and continuing the refrigeration to form a frozen plug of the cohesive substance to close oil? the well conduit. '7. The method of claim 6 wherein the material to be frozen is a water earthen material mixture of about the consistency of molding clay.

8. The method of modifying the control equipment of a high pressure petroleum produc ing well having a well conduit operatively connected to and controlled by the control equipment comprising the steps of forcing an earthen mixture containing sufficient water to render the mixture deformable and cohesive into the conduit at the level it is desired to close the conduit off to form a static plug of the mixture therein, applyingrefrigeration to the exterior of the conduit at the level of the plug to freeze the plug solidly closing oif the conduit, then modifying the control equipment located above the frozen plug as desired while maintaining the frozen plug, and then thawing the frozen plug.

IRA A. MILLER.

REFERENCES CITED The following references are of record in the file of this patent:

, UNITED STATES PATENTS Number 7 Name 7 Date 1,342,781 Vedder June 8, 1920 2,033,561 Wells Mar. 10, 1936 2,193,144 Rymal Mar. 12, 1940

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