US1893487A - Bottom hole choke for oil wells - Google Patents

Description

Jan. 10, 1933. J. BLACK BOTTOM HOLE CHOKE FOR OIL WELLS 3 Sheets-Sheet 1 Filed Dec. 1. 1931 w m 3 MW m MW I 1 w :W 5 6 a. I w w m w w M M H Jan. 10, 1933. L. J. BLACK 1,893,487

BOTTOM HOLE CHOKE FOR OIL WELLS Filed Dec. 1. 1931 3 Sheets-Sheet 2 L. JfiZac/ Patented Jan. 10, 1933 PATENT OFFICE LEE J. BLACK, or BEAUMONT, TEXAS BOTTOM HOLE CHOKE FOR OIL WELLS Application filed December 1, 1931. Serial No. 578,353.

This invention relates to oil wells and particularly to whatrare known as chokes, that is, devices for reducing the flow from an oil well, these chokes being particularly used where oil wells are prorated.

The object of a bottom hole choke is to conserve the gas orginally in the oil sands. The cheapest way to lift oil is by the natural pressure of the gas in the sand and any method that will use the least number of cubic feet of gas per barrel of oil in lifting the oil out of the well is particularly to be desired as this prolongs the life of the field and secures the greatestultimate recovery of oil from the sands. At the present time, practically all flowing wells are choked at the top of the ground. This leaves a full column of fluid standing in thecasing which must be taken into consideration in figuring the lifting capacity located in the oil sands. Therefore, it has been held by engineers that if the well is choked near the top of the sands and only.

such oil allowed to pass as is desirable to produce from the well, then the bottom hole pressure will not only be greater but will last longer for causing the flowing of the well.

Some attempts have been made to provide bottom hole chokes but as yet very few, if any practical operating units, have been installed to my knowledge, one of the reasons being the difliculty of operating the choke at the great depth at which the choke is normally disposed, the depth of wells at which the wells are usually flowed through the tub ing being approximately four thousand feet at least.

The tubing used is usually 2 inches in interior diameter, the tubing weighing about 6% pounds per foot. Thus the string of tubing used would weigh some twenty-six thousand pounds. It has been proposed to secure a bottom hole choke by providing a valve adjacent the bottom of the well which is raised or lowered .by means of screw-threads, the valve being operated by rotating the string of tubing. This is open to a number of serious objections. As the weight increases, that is, as the depth of the well increases, the weight of the superincumbent pipe or tubing resting on such screw-threads increases the friction load on the screw-threads and when it is attempted to rotate the string of pipe from the top of the ground, the friction set up by the tubing tends to prevent any rotation on the threads. This is particularly true when it is considered that the tubing weight is normally above twenty thousand pounds and may go as high as fifty thousand pounds.

Furthermore, the weight of the superincumbent string of tubing increases the friction load on all the threads of the string so that when it is attempted to rotate the string of pipe through the top of the ground, the joints near-the top make up first until the joints have entirely closed and refused to creep together any further. Thus, with the ordinary made-up string of tubing and the superincumbent weight supported thereby, the threads in the joints of the tubing would 9 move first, because of the lesser diameter of the threads and the lesser "friction area, than the threads which operate the choke valve itself. Furthermore, this rotation of the pipe string tends to rotate the packer below 5 the choke valve and this packer will not have suflicient strength to stand the torsional strains which are necessary in order to cause the upper half of the choke to rotate onthe threads of the lower half. 9

The general object of my invention, therefore, is to provide a bottom hole choke which is entirely practical and in which the Wei ht of the superincumbent string of tubing through which the oil passes and which contains the choke valve is not supported on the threads of the pipe sections entirely and is'not supported by the threads which are supposed -to actuate the choke valve, but on the contrary'my object is to provide a structure wherein no weight is carried by the threads of the choke valve itself but wherein the string of inner tubing is divided into a plurality of sections, the lowermost section below the choke having anti-friction devices or balls supporting the weight of the string of tubing above the choke, thus permitting this upper section of the tubing to be rotated freely and easily to cause the operation of the choke. 10a

Figure 4;

A still further object is to provide a construction of this kind which, because the choke is not operated by the screw-threads on the inner string of pipe, will not elongate as the choke is closed or shorten as the choke is opened but in which the length of the string of pipe remains constant at all times and in all positions of the choke valve,

Another object is to permit a relatively free rotation between the upper string of pipe and the lower string of pipe which will thus not transmit any torsional strain to the packer.

Other objects will appear in the course of the following description.

My invention is illustrated in the accompanying drawings, wherein Figure 1 is an elevation of the casing head and the flow connections of a well;

Figure 2 is a longitudinal section of a well casing at its lower end and showing my choke valve structure in position therein;

Figure 3 1s an enlarged vertical section through the casing head and the upper part of the inner string of tubing showing how the tubing is supported upon the casing head; Figure 4 is a vertical section through the choke valve structure and the outer casing of the well;

Figure 5 is a section on the line 5-5 of Figure 4; I

Figure 6 is asection on the line 6-6 of Figure 7 is an elevation of the T which connects the inner strin of tubing to the flow pipes, the structure icing shown partly in vertical section.

Referring to these drawings, 10 designates the outer casing of the well and 11 the casing shoe, the upper end of the well casing 10 ing connected to the usual casing head 13 which is provided with the side outlets 14 and with the usual bowl 15. Extending downward through the casing head and through the casing 10 is the inner tubing 16.

This tubing is, of course, made up in lengths, the len hs having screw-threaded engagement with each other and carries the screen The tubing is reduced in diameter adjacent its lower end at the point where the choke is formed as at 17, this portion being exteriorly screw-threaded- Disposed upon this reduced portion is the. bearing sleeve 18 which extends inward beneath the lower end of the pipe section 16 and is provided with a relatively small bore 19.

Disposed within the bearing sleeve 18 and resting upon the shoulder 20 formed by this bearing sleeve is a sleeve nut 21 which extends upward above the shoulder 20 and which at its lower end is interiorly screwthreaded for engagement with a sleeve 22 which extends down below the lower end of the bearing sleeve 18 and is exteriorl screwthreaded at 23. for engagement with the lower connection 24 which in turn is operatively engaged with an ordinary rubber packer 25 such as is commonly used in oil wells. While I prefer to use a packer below the choke, I do not wish to be limited to this as a spring anchor such as is commonly used under the same circumstances might be used in place of a packer, or with a packer.

The upper face of the shoulder 20 carries a packing gasket 26 and the outer face of the sleeve 22 also carries a packing gasket 27 which engages the inner face of the bearing sleeve. The sleeve 22 is formed to provide a choke valve seat 28. The sleeve 21 at its upper end extends inward at 29 and is interiorly screw-threaded. This inward annular extension 29 is formed with a plurality of passages 30. Having screw-threaded engagement with the-threads on the inward extension or nut 29 for the sleeve 21 is the screwthreaded stem. 31 of a valve 32, this valve having screw-threaded engagement with the stem and being tapered to fit the face of the valve seat 28; Disposed upon the screwthreaded stem 31 is a guide nut 33 having a plurality of radially extending spacing arms.

The upper end of the stem 31 is provided with outwardly extending arms 34 held upon the stem by the nuts 35 and the interior of the pipe section 16 is formed with longitudinally extending grooves 36 with which the extremities of the arms engage. It will be obvious, therefore, that when the pipe section 16 is rotated, the stem and valve 32 will be caused to rotate within the nut 29 and thus by rotating the pipe 16, the choke valve 32 may be moved toward or from the seat 28, thus enlarging or reducing the space between the valve 32 and the seat 28 and thus controlling the flow of oil through the well.

Because of the very great length of the string of pipe designated generally 16, it is necessary to support the lower end of this string of pipe upon ball bearings. To that end, the connection 24 is formed to provide an upwardly extending annular shoulder 37 which supports upon it the anti-friction bearing rings 38 and the anti-friction elements 39 shown as anti-friction balls mounted within the cage. It must be seen that the pipe ing head 13 to the surface of the ground.

Within the bowl 15 there is disposed antifriction bearing ring 39, the outer face of which is tapered to have wedging engagement with the tapered inner face of the bowl 15. This bearing ring 39 carries upon it the ball bearing elements designated generally 40. The pipe section 16 at this portion of the well is formed with the outwardly projecting shoulder 41 which rests upon these anti-friction elements and rotates freely thereon.

Nuts 42 are engaged with the pipe section 16 just below the bearing ring 39 to prevent any upward movement of the inner string of pipe 16. Having screw-threaded engagement with the upper end of the bowl 15 of the casing head is a bonnet 43, the upper end of which is contracted in diameter andformed with the inwardly projecting shoulder 44. The upper end 45 of this inwardly contracted portion of the bonnet is exteriorly screwthreaded for a cap 46. Resting upon the shoulder 44 is the junk ring 47 and resting upon this junk ring are the packing rings 48 and resting upon these packing rings is a packing nut 49 engaged by the cap 46. This packing 48 is thus capable of being forced.

tightly against the inner tubing or pipe 16 to prevent the escape of oil or gas.

It will be seen that the inner string of pipe is thus supported in two places by antifriction bearings, in other words, just below the choke and adjacent the top of the well. Thus the inner string of pipe may be readily turned by suitable appliances and as this inner string of pipe is turned in one direction or the other, the choke valve will be shifted to close or open the bore of the choke to a greater or less extent as desired to secure a proper flow from the well. -In order to provide for carrying off the oil from the upper end of the inner tubing, I provide a swivel connect-ion to the flow outlets which is shown in Figure 7. This includes the T 50, the lower end of which fits closely around the pipe nipple 160: which constitutes the upper end of the inner pipe string. Flow pipes 51 leads from this T 50. The lower end of the T fits within a packing gland 52 engaged by a nut 53, there being acking rings 54 disposed between the packing gland 52 and the lower end of the T 50. Bolts and nuts 55 engage the packing gland with the T so that the packing gland may be adjusted from time to time to compress the packing 54.

The upper end of the T is formed with a shoulder 56 upon which a packing 57 rests, this packing bearing against the nipple 16a and this packing is compressed by means of an exteriorly screw-threaded cap 58 which engages within the upper end of the T. This provides a swivel connection between the T 50 and the upper end of the inner pipe or tubing. I do not wish to be limited to the swivel connection connecting the top of the tubing with the side flow outlets as obviously other means might be provided for this purpose which will permit the inner string of pipe 16 to be rotated. Any suitable means such as are well-known in oil well practice may be used for rotating this inner string of of the rubber packing25 below the choke as in some cases it is not desirable to use a packer and in that case any anchoring means ma be used, thus, for instance, I can use a rub er packer which is extended by the weight of the tubing above and connected to a perforated pipe extending to the bottom of the well which supports the weight and expands the packer or I can use a. packer provided with a spring anchor holding the packer from rotation so that no torsional strain will be placed upon the rubber packer. It will be understood that all that is required is that the parts belowthe antifriction bearing 38 shall be held from rotation, that is, that the connection 24 shall be held from rotation and, of course, that the packing shall be provided which will prevent any gas or liquid from passing up exteriorly of the inner string of tubing 16. It will be particularly noted that in my construction, I provide anti-friction bearings in the casing head and adjacent the choke and that by this means I can set suflicient weight of tubing upon the packer 25 to ensure its expansion without in any way impeding the rotation of the tubing.

Furthermore in my construction rotation of'the inner string of tubing does not longitudinally expand it or longitudinally contract it in opening or closing the choke valve but the length of the tubing ,remains constant at all times. This is a very important feature of my inventionwas by this means I disturb neither the upper holding device or the lower packing element. Where a choke valve is used which is shifted by threads on the tubing 16, then as the weight on the superencumbent pipe increases on the threads, it increases the frictional load on the threads and then when it is attempted to rotate the string of pipe from the top of the ground, the joints near the top make up first and eventually when all the joints have made up or tightened, the rubber on the packer is subjected to a very high torsional stress. By providing antifriction bearings, however, there is no danger of rotating the rubber packer. Therefore, if you set half of the weight'of the tubing on the packer, there would be no question but that the inner string of pipe would rotate upon the" anti-friction bearings without affecting the pipe, whereas where the Weight of the pipe rests entirely upon the screw-threads and the entire weight of the pipe must be raised or lowered upon these screw-threads, the operator would never know whether he rotated the packer or injured it or not except by the action of the well or by pulling the tubing because if the 1 rubber on the packer was under compression sufiicient to make a seal against the casing, and was rotated, then it would certainly break up the rubber or break up the seal between the rubberv and the casing.

I claim 1. In a bottom hole choke, a pipe string comprising an upper pipe section and a lowerpipe section, the lower pipe section having means whereby it may be anchored to the wall of a well casing, an anti-friction bearing disposed between the lower end of the upper pipe section and the upper end of the lower section, a sleeve engaged with the lower pipe section and extending up into the lower end of the upper section and formed to provide a tapered valve seat, a nut operatively carried upon said sleeve and within the upper section, the nut being held from rotation, a valve coacting with the seat and having a screwthreaded stem engaging the screw-threads of the nut, and an arm carried by the stem, the inner face of the upper pipe section being formed with a longitudinally extending groove into which the extremity of the arm extends whereby to cause a rotation of the stem upon a rotation of the upper pipe section.

2. A bottom hole choke comprising an u p-- per section and a lower section of pipe, the

, lower section being screw-threaded for engagement with an anchoring means, the upper section being screw-threaded for engagement with the lower end of a string of p1 pe, a sleeve engaged with the interior of the lower section and extending up beyond the lower end of the upper section and having a valve seat, anti-friction bearings disposed between the lower end of the upper section and the upper end of the lower section, a sleeve nut carried by the first named sleeve and extending upwardon the inside of the lower section, a tapered valve coacting with the seat and having a screw-threaded stem engaged by said nut, and means on the upper section whereby the valve stem may be rotated upon a rotation of the upper section, said means permitting the independent longitudinal movement of the valve stem and valve.

3. A bottom hole choke comprising an upper pipe section adapted to be connected at its upper end to a pipe string and exteriorly threaded at its lower end, a bearing ring engaging the screw-threads at the lower end of the pipe section, the lower end of the bearing ring extending inward, a lower pipe section disposed in spaced relation to the bearing ring, anti-friction bearings disposed between the bearing ring and the upper end of said sleeve, an inner sleeve attached to the lower I pipe section and extending upward past the bearing ring and formed at its upper end to rovide a valve seat, asleeve nut engaged wit the exterior of the last named sleeve and extending upward therefrom and screwthreaded at its upper end, the sleeve nut engaging against the bearing ring to prevent upward movement of the upper section with relation to the lower section, a valve having a screw-threaded stem engaging the threads of said nut, an arm on the valve, and means on the upper section engaging said arm for common rotary movement, but permitting the arm, stem and valve to move longitudinally of the upper section.

4. A bottom hole choke comprising an upper section and a lower section of pipe, the lower section being formed for engagement with an anchoring means, the upper section being formed for engagement with the lower end of a string of plpe, a sleeve enga ed with the lower section but extending up eyond the lower end of the upper section and having a valve seat, anti-friction bearings disposed between the lower end of the upper section and the upper end of the lower section, a nut carried by the first-named sleeve and extending upward on the inside of the lower section, a valve coacting with the seat and having a screw-threaded stem engaged by said nut, and means on the upper section whereby the valve stem may be rotated upon a rotation of the upper section, said means permitting independent longitudinal movement of the valve stem and valve.

In testimony whereof I alfix my signature.

' LEE J. BLACK.

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