US3543850A - Apparatus for injecting steam into oil wells - Google Patents

Description

United States Patent [72] Inventor George W. Stout Los Angeles California 211 App]. No. 794,320 [22] Filed Jan. 27, 1969 [45] Patented Dec. 1, 1970 [73] Assignee Walhamlin, Inc.

Lo s Angeles ,California a corporation of California [54] APPARATUS FOR INJECTING STEAM INTO OIL WELLS 9 Claims, 6 Drawing Figs.

[52] U.S. Cl... 166/62 [51] Int. Cl .E2lb 43/24 [50] Field of Search 166/302, 303, 57, 61, 62

[56] References Cited UNITED STATES PATENTS 895,612 8/1908 Baker 166/57 1,780,428 11/1930 Larsen 166/62 2,828,821 4/1958 Waterman 166/57 2,911,047 11/1959 Henderson 166/61 3,012,607 12/1961 DePriester et a1. l66/57X 3,207,219 9/1965 Mitchell .t 166/57 3,380,530 4/1968 166/57X 3,438,442 4/1969 l66/57X 3,456,735 7/1969 McDougall et a1. 166/57UX Primary Examiner-Stephen J. Novosad Attorney-Georges A. Maxwell ABSTRACT: The method and apparatus for inducing and maintaining the flow of oil in an oil producing formation into an oil well structure having a cased bore, a string of production tubing in the casing and a pump and sucker rod string in the casing including steam generating means at the top of the well and a string of insulated tubing sections connected with the steam generating means and extending downwardly through the chamber between the casing and the production tubing and opening in the bore in the formation, each tubing section having an elongate jacket about its exterior, an insulating filler between the section and the jacket, means securing and sealing one end of the jacket to the section and axially shiftable sealing means coupling the other end of the jacket to the section.

Patented Dec. 1,1910 7 3,543,850

.Iwuen for i 21,. KM

George 1." Szoua APPARATUS FOR INJECTING STEAM INTO OIL WELLS This invention relates to a novel apparatus for injecting steam into an oil well for the purpose of inducing and thence maintaining an increased rate of production from the well.

It has become common practice to inject steam into oil bearing formations to heat the formations and the oil therein whereby the oil flows more readily. This practice of injecting steam and heating well structures is employed in those wells wherein production has dropped and lowered to an extent where the wells are unprofitable to operate and m a result of depletion of the wells and/or due to the high viscosity of the oil and its reluctance to flow through the formation.

In carrying out steam injecting for heating well structures, it is common practice to inject steam into the formation for a period of time so that it permeates and heats the formation and oil therein, and to thereafter terminate injecting steam and to allow the oil to flow in and through the formation to the well structure. When production slows or subsides, steam is again injected, as before. This is the so-called huff and puff" method of steam injection.

The above-noted huff and puff method is wanting in that the well must be taken out of and put back into production service each time itbecomes necessary to inject steam.

Since it is necessary to conserve as much heat as is possible when injecting steam into a well, it has been found to be practically imperative that the steam be introduced through suitable insulated strings of tubing. Accordingly, in carrying out the above-noted huff and puff method of steam injection, if the production tubing is used to inject steam, it must be insulated and the pump and sucker rod string must be pulled therefrom when steam is injected and reenergized therein when production is to be commenced again. If the production tubing is not insulated, each time steam is to be injected, the production tubing and the pump and sucker rod string related thereto must be pulled from the well and a special string of insulated tubing for injecting the steam must be lowered into the well, which special string of tubing must be pulled from the well, upon completion of each steam injecting cycle to facilitate reengagement of the production tubing, pump and sucker rod strings. Such structures and procedures are both costly and time consuming.

In a less frequently practiced method of steam injection, a single well, about which a number of other wells are closely related, is employed as a steam injection well and the other surrounding wells are employed as production wells. Steam is constantly injected into the formation through the injection well to heat the production formation and to cause the oil to flow more readily to the production wells.

This method has proven satisfactory in a very limited number of oil fields where the production formation is very loose and open, so as to permit the steam to flow radially outward into the formation and where the production wells are in such close proximity to the injection well that it can be said that the several wells are substantially adjacent to each other.

The above is significant since it clearly points to the fact that in carrying out steam injecting the steam does not travel outwardly from the well, in the production formation, to any great extent, but quite apparently serves only to heat the formation in close proximity about the well, to cause the oil in that portion of the formation to flow more readily.

In the ordinary oil well, the liner or screen at the lower end thereof and/or the gravel pack in the well bore and about the liner or screen provide a limited predetermined open surface area in the formation and to and through which oil in the formation and under the pressure created by the earth above and action on the production formation, will flow.

It is my understanding and belief that when the production formation is heated by steam injection, the beneficial results obtained are the result of, in effect, opening up the formation surrounding the liner screen and/or gravel pack a substantial distance whereby the effective surface area within the well structure and formation and into and through which the oil can freely enter and flow is materially increased.

It is my theory and belief, therefore, that the effect of steam injection is not unlike the method of fracturing a formation to increase the open area in the formation through which oil can flow, but is much more effective in sandy formations and the like in which fracturing would have little or no beneficial effeet.

In light of the foregoing, an object of my invention is to heat and to maintain a portion of production formation about a well heated by continuous injection of steam into the lower portion of the well while the well is in production, that is, while oil is being pumped from the well.

A major principle upon which the method that I provide is based is that once a mass, such as an oil producing formation, is heated to a predetermined increased temperature, it takes a materially less amount of heat to maintain it at said increased temperature than was required to raise or increase its temperature to said increased temperature.

For example, it takes many BTUs to raise the temperature of water from, say F. to 212 F. or boiling, but once it is raised to 212 F. it takes or requires very little BTUs to maintain it at that temperature.

In order to carry out my new method, means and apparatus must be provided to effectively and efficiently inject steam into the well at the same time that oil is being pumped therefrom. Accordingly, the apparatus must be such that steam can be effectively injected into a well in which the production tubing, with pump and sucker rod string related to it, is in the well and functioning.

It is an object of my invention to provide heat insulated pipe sections of smaller outside diametric extent than the annulus between a well casing and a string of production tubing within the well casing.

Another object of my invention is to provide insulated pipe sections including an inner fluid conducting pipe with a tool joint box at one end, a tool joint pin at its other end, a tubular jacket about the pipe and between the box and pin and defining an annulus between the pipe and jacket, means fixing one end of the jacket to the pipe in sealed relationship therewith, axially shiftable sealing means between the other end of the jacket and the pipe hermetically sealing the adjacent end of the annulus and a filler of insulating material in the annulus.

Yet another object of my invention is to provide an insulated pipe section of the character referred to wherein the insulating filler is a material which is such that it can be advantageously compressed in the annulus to provide structural support and stability to the section, without adversely affecting its insulating characteristics.

Still further, it is an object of this invention to provide a pipe section of the character referred to wherein the hermetically sealed insulation filled annulus is evacuated of air, that is, the annulus is under a vacuum whereby the insulating characteristics of the section are materially enhanced.

It is an object of my invention to provide an insulated pipe section of the character referred to wherein atmosphere in the annulus is an inert gas having low heat conducting characteristics and under such pressure as to prevent collapsing of the jacket when the pipe section is subjected to high external pressures whereby the jacket can be established of relatively thin lightweight tube stock.

it is yet another object of my invention to provide a string of insulated pipe sections of the character referred to engaged in and extending longitudinally of the annulus between a well casing and a string of production tubing, connected at its upper end with a suitable. source of steam and open at its lower end to communicate with the well bore in a related oil bearing formation.

The foregoing and other objects and features of my invention will be fully understood from the following detailed description of a typical preferred form and carrying out of my invention, throughout which description reference is made to the accompanying drawings, in which:

FIG. 1 is a longitudinal sectional view of a typical well structure with my apparatus related to it;

FIG. 2 is a sectional view taken as indicated by line 2-2 on FIG. 1;

FIG. 3 is a longitudinal elevational view of an insulated pipe section; I

FIG. 4is an enlarged detailed sectional view taken as indicated by line 4-4 on FIG. 3; a

FIG. 5 is an enlarged detailed sectional view taken as indicated by line 5-5 on FIG. 3; and

FIG. 6 is an enlarged sectional view taken as indicated by line 6-6 on FIG. 3;

In FIG. 1 of the drawings, 1 show a typical, producing well structure W including a substantially vertical bore B entering the earths surface 10 and extending downwardly into an oil producing formation F. The bore 13 is provided with a suitable longitudinally extending upwardly and downwardly opening casing C. The lower end of the casing terminates at the upper portion of the formation F and carries a suitable elongate screen or perforated liner L which is secured to the casing by a hanger H and depends into the bore B, below the casing. The annulus between the bore and the liner is packed with gravel The top of the casing is closed by a suitable head H. Fixed to and depending from the head H is an elongate string of production tubing T, which tubing is smaller in outside diameter than the inside diameter of the casing C and liner L and cooperates therewith to define an annulus A.

The production tubing T extends upwardly through the head H and is closed by a tubing head H with a central vertical polish rod or sucker rod bushing and gland 1 1 and a lateral production discharge port (not shown) with which a production delivery line 12 is connected.

The lower end of the production tubing T opens downwardly and terminates within the liner L. The lower end of the tubing T is provided with a pump shoe 14.

A pump is seated in the shoe 14 to occur in the lower end of the tubing T and an elongate string of sucker rod R is fixed to the pump to extend upwardly through the tubing and the bushing and gland 11 of the heat 1-! and to connect with a suitable pump jack (not shown). The upper most section of the string of sucker rod is a polish rod, in accordance with common practice.

The well structure W is illustrated and described above is only intended to set forth a typical well structure with which the instant invention can be advantageously related. It is to be understood that the instant invention, to be described in the following, can be related to other and varied types of weil structures.

The apparatus that I provide, as shown in FIGS. 1 and 2 of the drawings, includes a suitable vertically extending hanger structure in the casing head l-I communicating with the upper end of the annulus A, and an elongate steam injection pipe string S of heat insulated steam conducting tubing sections engaged through the hanger structure 20 and held thereby and extending longitudinally and downwardly in the annulus A to terminate and open in the annulus, within the liner L and the area or zone of the formation F.

The upper end of the string S terminates above the head H and is connected with a steam supply line 21 extending from a steam generator or other suitable steam supply (not shown).

The sections of the steam injection pipe string S are like sections and, as shown in FIGS. 3, 4, 5 and 6 of the: drawings, include elongate vertical lengths or stands of steam conducting pipe 25, and exterior tubular jacket J surrounding the pipe 25 with clearance, and defining an annulus 26, a filler I of heat insulating material in the annulus 26, mounting means 28 securing one end of the jacket J to the pipe 25 and sealing the adjacent end of the annulus 26 and axially shiftable sealing means M at the other end of the jacket and hermetically sealing the other end of the annulus.

The upper end of the pipe 25 of each section of the string S is provided with interior threads defining the box 30 of a tool joint and the lower end of each section is provided with exterior threads defining the pin 31 of a tool joint. Accordingly, ad-

jacent sections can be coupled or connected to establish a string of sections in accordance with common or conventional practice.

The jacket I is a simple, straight length of tubing, somewhat shorter than the pipe 25 and is such that its upper and lower ends terminate below and above the box 30 and pin 31 at their related ends of the pipe 25.

The mounting means 28 is shown at the upper end of the section and includes a simple cylindrical block 40 with a central'bore 41 in which the pipe 25 is slidably engaged. The block 40 corresponds in outside diameter with the jacket .1 and is provided with a reduced lower end portion 42 corresponding in inside diameter with the jacket and slidably engaged therein. The block is welded in fixed and sealed relationship with the pipe 25 as by welding 43 and the jacket is fixed and sealed with the block as be welding 44.

In practice, the block 40 is located as close to the box 30 on the upper end of the pipe as is possible and can, as illustrated, be provided with tool-engaging flats 45 about its upper exterior, whereby the block provides means to facilitate making up the tool joints when the string S is being established.

In practice, the block can, in fact, surround a major portion of the box, lending support and strength thereto.

The insulating filler I can be of any suitable form and/or type of heat insulating material and is preferably of a type and/or nature that can be compressed and compacted to a considerable extent without adverse effects to its insulating characteristics and so that the insulation does not tend to break down and settle, serves to maintain the pipe and jacket concentric and also serves to lend support to the jacket whereby said jacket can be established of relatively thin walled tubing without adverse effect.

One commercially available insulating material which meets the above requirements is that material produced by Johns Mansville and sold under the trade name Cerafelt". This product is a felted asbestos fiber product and is such that its heat insulating characteristics are extremely effective and efficient and such that it can be compacted and compressed to a great and substantial extent without adversely affecting its insulating characteristics and, in fact, improving the same.

The filler I is engaged and suitably compressed and compacted in the annulus A, to substantially fill said annulus, to centralize the pipe in the jacket, and to support the jacket from within.

The axially shiftable sealing means Mat and between the other or lower end of the jacket .l and the pipe 25 is a sealing means which is such that it establishes a hermetic seal between the jacket and the pipe and at the same time allows or permits relative axial shifting of the lower end of the jacket relative to the adjacent portion of the pipe thereby compensating for such relative axial shifting as a result of expansion and contraction of the pipe and the jacket when the structure is in use.

There are a number of types of seals that could be advantageously employed to form or establish the means M.

In the preferred carrying out of the invention and as illustrated in the drawings the means M is a bellows type sealing means, including an elongate, tubular bellows 50 engaged freely about the pipe 25, a first securing means at one of its ends to secure and seal that end with an adjacent end of the I jacket and a second securing means at its other end to secure and seal that with an adjacent portion of the pipe 25.

The bellows 50 is established of thin, strong metal, such as beryllium brass and has straight, tubular upper and lower end portions 51 and 52 and a central portion 53 defining a plurality of radially outwardly disposed valleys and ridges and corresponding radially inwardly disposed ridges and valleys.

The first securing means securing and sealing the lower end of the jacket! with and to the bellows 50 could, if suitable or desired, include welding or a deposit of solder or cement, such as an epoxy cement between the lower portion of the jacket and upper end portion 51 of the bellows, which upper portion could be slidably engaged in or about the jacket.

In a similar manner, the second securing means securing and sealing the bellows to the pipe 25 could include welding, soldering or cementing the lower end portion 52 of the bellows to the pipe.

In the form of the invention illustrated the first or upper securing means includes an annular body 60 slidably engaged in the lower end of the jacket J. The body 60 has a central opening 61 in and through which the pipe freely projects, an annular, downwardly opening channel 62 in which the upper end portion 51 of the bellows is slidably engaged and fixed by means of silver soldering or epoxy cement and an elongate, tubular shield or skirt 63 corresponding in outside diameter with the jacket formed integrally with and about the lower portion of the body 60 and depending therefrom to occur in spaced relationship about the exterior of the bellows and substantially coextensive with the longitudinal extent of said bellows. The body 60 and/or upper end of the skirt 63 is fixed to the lower end of the jacket by welding 64.

The second or lower securing means in the form of the invention illustrated includes a cylindrical body or block 70 corresponding in outside diameter with the jacket and having a central opening 71 slidably receiving the pipe 25, an upwardly opening, annular channel 72 in'which the lower end portion 52 of the bellows is engaged and fixed by silver solder or epoxy cement and a reduced outside upper portion 73 slidably engaged in the lower end of the skirt 63. The body 70 is fixed to and sealed with the pipe 25 as by welding 74.

In the preferred carrying out of the invention, the body 70 is located immediately above the pin 31 on the pipe and its lower exterior portion is provided with tool-engaging Hats 75 to facilitate making up the tool joints when making up the string S.

The skirt 63 protects the bellows and its lower free end is supported and protected by the body 70.

In practice, the skirt 63 can be provided with a port 80 to facilitate packing the annulus between the skirt and the bellows with a suitable, fiberous, high temperature-resistant protective grease of packing compound or to allow free expulsion of foreign matter from within said annulus.

With the upper and lower securing means set forth above, it will be apparent that the annulus 26 is hennetically sealed so that foreign matter that might otherwise enter the annulus 26 and adversely affect the insulating filler I can not enter into said annulus.

Further, it will be apparent that relative longitudinal expansion and contraction of the pipe 25 and jacket J can take place without biasing and distorting either the jacket or pipe and without breaking or otherwise adversely affecting the seal.

In practice, the block 40 can be provided with a port 81 with a suitable sealing plug 82 therein and/or the jacket .I can inch and such that it can be compensated for by bellows 50 of limited longitudinal extent.

In operation, and when the string S is engaged in the well structure W and when the pump P is in operation to pump production from within the liner L, steam at approximately 300 F., at the bottom of the string S, is injected or discharged into the liner and the oil or production therein to heat and maintain said production heated and flowing.

The heat introduced into the production in the liner moves outwardly through the liner and gravel and into the producing formation F by conduction, heating said formation and the oil therein, causing said heated oil in the formation to flow more readily towards the well structure and, in effect, opening up the formation about the well structure for the free flow of production fluid therethrough.

As the heat moves or conducts outwardly in and opens the formation, the effect is like or similar to expansion of and increasing the surface area of the liner L and gravel pack G and such that the area surrounding the well structure and into which the production in the formation F, under normal well pressures and the like, can flow is materially increased, thereby increasing the rate of flow of the well.

In practice, the rate and pressure at which the steam is injected and the rate at which the oil is pumped from the well is be provided with one or more longitudinally spaced ports 83 v sealed as by soldering 84 or a screw type sealing plug 85, which ports facilitate drawing a vacuum or subatmospheric pressure in the annulus 26 and the insulating filler I or filling the annulus and said filler with an atmosphere of inert gas with low heat conductive characteristics at a subatmospheric pressure for insulating purposes or at greater than atmospheric pressure to provide interior pressure support for the jacket, as desired and as circumstances require.

In a typical embodiment of my invention, the pipe 25 is 1.05 OD and the jacket J is 1.875 OD and 1.805 ID, with the result that the major ID of the string S is 1.875 and the annulus 26 and the insulating filler I are .800" or slightly greater than three-fourths of an inch thick.

The annulus A in the well structure W need only be slightly greater than 1.875" wide to accommodate the string S. In

controlled and balanced so that the steam does not tend to blow the oil out through the pump and production tubing and/or escape unused and wasted, upwardly through the annulus A. Accordingly, little steam is required, making use of the noted small diameter, relatively low volumetric capacity steam injecting string both possible and practical.

As the apparatus is used and under proper control, the heated area of the formation F, the boundaries of which are indicated by the phantom line X in FIG. 1 of the drawings can be made to grow and expand at a slow, but steady rate. As the area grows, the rate of production is and can be increased and will continue to so increase until the maximum rate at which the formation can produce is reached.

It is to be noted that it is desirable that the liner not be pumped dry of oil so that a body of heated oil remains therein at all times to act as a heat sink and a source of heat for conduction of heat outwardly and into the formation.

I-Iaving described only a typical preferred form and application of my invention, I do not wish to be limited or restricted to the specific details herein set forth, but wish to reserve to myself any modifications and/or variations which may appear to those skilled in the art.

I claim:

1. In combination, a well structure including a vertical bore entering the earth's surface and extending into an oil bearing formation, a casing in said bore, a producing tubing string extending freely through the casing and defining an annulus,

fluid pumping means in said production tubing string, steam injecting apparatus related to the well structure and including steam generating means at the earth's surface, a string of steam injecting pipe sections connected with the steam generating means and extending longitudinally through said annulus and opening in said bore in said formation, each pipe section having upper and lower ends and having heat insulating means between its ends and about its exterior, said heat insulating means including a tubular jacket in spaced relationship about the pipe section and a filler of insulating material between the pipe section and the jacket.

2. A well structure as set forth in claim 1 including means at the ends of the jacket connecting and sealing the ends of the jacket to the pipe section whereby said pipe section, jacket and the means at the ends of the jacket define a hermetically sealed annulus chamber in which the filler occurs.

3. A well structure as set forth in claim 2 including means at one end of the jacket including an annular block slidably engaged about the pipe section and within the jacket and welded to said pipe section and said jacket, said means at the other end of the jacket including a first part fixed to and sealed with the jacket, a second part fixed to and sealed with the pipe secbellows and slidably engaging the other of said parts.

6. A structure as set forth in claim wherein said chamber is evacuated of air.

7. A structure as set forth in claim 6 wherein said insulating filler is compacted in said chamber between the pipe section and the jacket.

8. A structure as set forth in claim 7 wherein one end of the 5 pipe section has an internally threaded box and the other end of said section has an externally threaded pin.

9. A structure as set forth in claim 8 wherein the block fixed to one end of the pipe section and said part fixed to the pipe section at the other end thereof have circumferentially l0 spaced, radially outwardly disposed tool engaging flats.

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