Description:
BACKGROUND OF THE INVENTION
In wells which require the use of well pumps, the well fluids in the producing formation consist primarily of oil and water with possibly some gas. Since it is desirable that the pump lift as much oil as possible on each stroke without pumping large amounts of water, the relative position of the oil-water interface in the formation with respect to the inlet to the well is important. If the well inlet is located improperly, then the pump may be pumping mostly water and very little oil. The problem of maintaining the proper relationship between the well inlet and the oil-water interface is complicated by the fact that the interface changes as pumping continues. To adjust the well inlet it has heretofore been necessary to remove the tubing string from the well bore which is a time-consuming and expensive operation.
Another factor affecting the efficiency of a well pump is the heat of the well fluids. If such fluids are of a relatively high temperature, pumping efficiency is reduced and possible damage to the pump seals or other components may result.
SUMMARY OF THE INVENTION
This invention relates to an improved well pumping method and apparatus for pumping oil from a sub-surface formation.
The invention eliminates the problem of the pump having to handle an excessive volume of water by adjusting the elevation of the well fluids inlet into the well relative to the oil-water interface within the formation to control the oil-water mixture drawn from said formation. This controls the volume of water flowing to the pump inlet and increases the volume of oil being pumped. Further, if the well has a high bottom hole temperature by reason of hot well fluids, proper adjustment of the inlet to control the water results in a control of such bottom hole temperature and this, in turn, reduces the problems and cost of treating both the oil and water at the surface.
The invention also provides for cooling the well fluids before such well fluids pass through the pump, whereby the major portion of the fluids handled by the pump are relatively cool liquids. Such cooling and condensing is accomplished by a heat exchanger disposed in the well below the pump inlet.
A primary object of the invention is to provide a well pumping method and apparatus, wherein the elevation of the well fluids inlet at the bottom of the producing well relative to the oil-water interface is adjusted to control the oil-water mixture entering the well to thereby control, as above noted, bottom hole temperature and water production; by controlling the water, the pump is not required to handle excessive volumes of water. The adjustment is made without the necessity of removing the tubing and is accomplished through the tubing after the well pump is removed or alternatively, is made by manipulating said production tubing without the necessity of removing the well pump.
Another object of this invention is to provide an improved well pumping method and apparatus which includes cooling the oil and other well liquids by means of a heat exchanger before such liquids are passed through the well pump to thereby assure that substantially all of the fluids handled by the pump means are relatively cool liquids which greatly increases pumping efficiency.
A further object is to provide an improved apparatus, of the character described, which includes an improved friction means anchor device for frictionally supporting within the well casing a well liner assembly having the well fluids inlet, whereby the inlet is maintained at the desired elevation but may be readily adjusted to and firmly supported in different positions as well conditions dictate.
Still another object is to provide an apparatus of the character described, having an improved heat exchanger located below the well pump and which has a coolant medium circulated to it by lines extending from the surface so that the coolant medium does not mix with the well fluids. If desired, the lines through which the coolant medium flows may be insulated to increase the efficiency of the heat exchanger.
Other objects will be apparent from the drawings, the specification and the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings, wherein like reference numerals indicate like parts, and wherein illustrative embodiments of this invention are shown:
FIG. 1 is a schematic view of a producing well having the improved apparatus comprising this invention disposed therein;
FIG. 2 is a schematic view of the lower portion of the producing well and illustrating the manner in which the inlet conductor of said well may be adjusted;
FIG. 3 is a view partly in elevation and partly in section of the upper portion of the liner assembly which is adapted to be set within the well casing and also showing the setting tool which locates said assembly within the well;
FIG. 3A is a continuation of FIG. 3 illustrating the lower portion of said liner assembly;
FIG. 4 is an enlarged view partly in elevation and partly in section of the anchor device which supports the inlet conductor assembly, said anchor device being shown in an unset position;
FIG. 5 is a view similar to FIG. 4, showing the anchor device in its set position;
FIG. 6 is a horizontal cross-sectional view taken along line 6--6 in FIG. 4;
FIG. 7 is a horizontal cross-sectional view taken along line 7--7 in FIG. 4;
FIG. 8 is a schematic view, similar to FIG. 1, illustrating the tubing acting as the means for adjusting the liner assembly within the well;
FIG. 9 is a view partly in section and partly in elevation of the mechanical heat exchanger which is disposed below the well pump inlet;
FIG. 10 is a horizontal cross-sectional view taken on the line 10--10 of FIG. 9; and
FIG. 11 is a horizontal cross-sectional view taken on the line 11--11 of FIG. 9.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the drawings, the letter A (FIG. 1) illustrates a production well which includes the usual well casing 10 and well tubing or production string 11; the standard well head equipment 12 and 12a seals off between the tubing and casing and between the tubing and pump rods 13 which extend downwardly within the well to a well pump 14. The pump lifts the well fluids to the surface through the tubing and said fluids are discharged through an outlet line 11b. A heat exchanger H which will be hereinafter described in detail, is connected in the tubing string below the pump 14 and serves to cool hot well fluids prior to their passage to the pump. Such cooling increases pump efficiency.
The lower end of the well is in communication with the producing formation F, and a liner assembly generally indicated by the letter B is mounted within the lower end of the casing. The assembly includes a liner 15 having a well fluids inlet or screen portion including inlet openings 16 through which well fluids are introduced into the well and is frictionally suspended in the casing by means of a frictional type anchor device 17. A packer 18 seals of the annulus between the liner assembly and the well casing.
Well fluids may flow into the lower portion of the well through the well fluids inlet provided by openings 16 in the liner assembly and then upwardly into the lower end of the tubing; when the pump 14 is operated, the well fluids will be pumped to the surface in the usual manner. Although a well pump is preferable, other means of artificially lifting the well fluids may be used.
As is well known, each formation normally contains an oil and water interface which is indicated by the heavy horizontal line I. In order to assure that the pump 14 is not required to handle an excessive volume of water, the inlet portion of the liner 15 is primarily maintained in a desired position relative to the oil-water interface by the frictional anchor device 17; the maintenance of proper position will be assisted by the frictional engagement of the packer 18 as well as by the sand accumulation about the lower portion of the liner. If the interface should rise, which would increase water production (FIG. 1), it is only necessary to slide the liner assembly B upwardly within the well casing to a higher position, whereby a lesser number of the inlet openings 16 will communicate with the water; such adjustment of the liner assembly changes the oil-water mixture which is writhdrawn from the well.
The adjustment of the assembly is carried out without removing the tubing 11 from the well. As schematically shown in FIG. 2, the adjustment is effected by first removing the well pump 14 and its rods 13 from the tubing, after which a conventional spear or gripping tool 19 is lowered by means of suitable rods 20 downwardly into the upper portion of the anchor device 17. Through manipulation of the rods 20, the spear is actuated to grip the bore of the anchor device and the liner assembly B is moved to the desired elevation.
The details of the spear or gripping tool 19 are not shown since there are many well-known tools available; one example of such tool is the rotary releasing spear manufactured by the Baash-Ross Division of Joy Manufacturing Co. and shown at page 433 of the 1969-70 Composite Catalog. The important feature is to make the adjustment of the liner assembly without having to remove the entire tubing string 11, which is a time-consuming and expensive opera-tion.
After the inlet portion of the liner 15 is properly adjusted, the spear 19 is released and is removed from the well. The pump 14 and its rods are then run back into the tubing and the well production proceeds with the inlet portion of the liner raised with respect to the water-oil interface I to assure that the pump is not pumping excessive water volume.
The particular apparatus which includes the liner assembly B and its associated packer and anchor device is subject to variation but one preferred form of apparatus is illustrated in FIGS. 3, 3A, 4 and 5. The liner 15 has its upper end coupled by means of a tubular section 21 with the lower end of the packer 18. This packer may be a well known pin type packer which is set by applying weight to its upper end. When the lower end of the liner 15 engages the bottom of the production well, weight is applied to shear a pin (not shown) in the packer 18 thereby allowing its packer element to be expanded into sealing position with the casing wall. After being set, a pin type packer is locked in set position to maintain its packing element in contact with the casing. One type of pin type packer, manufactured by Brown Oil Tools, Inc. and shown at page 922 of the 1969-70 Composite Catalog, has been found satisfactory.
The upper end of packer 18 is connected to the frictional anchor device 17 which is in turn connected through left-hand threads 22 with a setting tool 23. The setting tool includes an outer setting sleeve 24 which is secured to a lowering pipe 25. The usual bumper jar 26 which includes telescoping sections is also secured to the lowering pipe and is disposed within the sleeve 24. The lower end of the jar is connected by the left-hand threads 22 to the upper end of the anchor device 17.
In lowering the apparatus shown in FIGS. 3 and 3A into the well, the parts are in the position shown and a plurality of bowed friction spring S of the anchor device 17 are in a retracted position. The apparatus is lowered until the lower end of the liner 15 engages the bottom of the well, after which a sufficient downward force is applied through the anchor device to the packer 18 to move it into its set position. Thereafter, as will be explained in detail, the setting tool 23 is utilized to move the friction springs S into engagement with the casing wall whereby the inlet conductor assembly is supported within said casing. Since the packer 18 is in set position, its frictional engagement with the casing wall will assist in supporting the assembly. After the anchor device is set, the setting tool 23 is removed from the well by releasing the left-hand thread 22, thereby leaving the liner assembly in the well, as shown schematically in FIG. 1. Although the left-hand threads have been found satisfactory, other types of a releasable connection, such as a J-slot, may be employed.
Various types of anchor devices may be employed for frictionally supporting the liner assembly, but a preferable type is illustrated in FIGS. 4 and 5. The anchor device 17 includes a central mandrel 27 which has the left-hand connecting threads 22 in the upper end of its bore. On the lower portion of the exterior of the mandrel is mounted a pair of spaced annular expanders 28 and 29. The upper end of the mandrel is connected with an outer body or cage 30 through a plurality of slots 31 formed in the cage and pins 32 which project radially from the mandrel. The pins 32 are normally maintained at the lower end of the slots 31 by shear pins 33.
Each friction spring S has its upper end connected to the lower portion of the cage or body 30 and each spring has a double bow formed therein. An inward bow S-1 is formed intermediate of each spring S while a second inward bow portion S-2 is formed at the lower end of each spring; above the portion S-1 is an outwardly bowed portion S-3 and above portion S-2 is a second outwardly bowed portion S-4. The inwardly bowed portions of the spring are adapted to coact with the spaced expanders 28 and 29 which are secured to the central mandrel. When shear pins 33 are maintaining the parts in the position shown in FIG. 4, the inwardly bowed portions S-1 and S-2 of each spring S are at a different elevation than the expanders 28 and 29 and outwardly bowed portions S-3 and S-4 of the springs are retracted. With the parts in this position, the anchor device may be lowered within the well casing without said springs dragging on the casing wall.
For latching the outer body in a downward position relative to the inner mandrel, the cage or body is formed with a recess 34 within which is mounted a locking ring 35. When the pins 33 are sheared and the body or cage moves downwardly on the mandrel, the locking ring 35 is adapted to move into a locking recess 35a formed in the exterior of the mandrel. In order to properly locate the locking ring 35 relative to the recess, a stop ring 36 secured on the exterior of the mandrel is adapted to be engaged by the lower end of the body or cage 30 to limit the downward movement of the body with respect to the mandrel (FIG. 5).
After the apparatus is positioned within the well, and the packer 18 below the anchor device 17 has been set, the weight is applied to the body 30 through the setting sleeve 23. The lower end of the sleeve 23 may engage the upper end of the body by reason of the telescoping sections of the bumper jar 26. This fractures the shear pins 33 and permits the body to move downwardly relative to the inner mandrel 27 to the position of FIG. 5. In this position the inwardly directed bowed portions S-1 and S-2 of the springs S have moved upwardly on the expanders 28 and 29 to urge the outwardly bowed portions S-3 and S-4 of the springs into tight frictional contact with the wall of the casing 10. By the time the springs have reached this position relative to the expanders, the latch ring 35 has engaged within the groove 35a while the stop ring 36 has been engaged by the lower end of the cage or body 30. The anchor device is thus locked in its position frictionally engaging the well casing.
Since the liner assembly is maintained in its position within the well casing by the frictional contact of the springs S assisted by the frictional engagement of the packer element with the wall of the casing and the sand surrounding the screen, said conductor is capable of being moved relative to the casing by means of a tool such as the spear 19. It is merely a matter of gripping the inlet conductor assembly and overcoming the frictional engaging forces, after which the assembly may be slid along the wall of the casing to any desired position relative to the formation.
As above described, the use of the sprear 19 for shifting the liner assembly B does not require removal of the tubing string 11, although the well pump 14 and its rods must be removed. It may be desirable in many instances to arrange the apparatus so that this adjustment may be made without having to remove the well pump from the tubing. As is well known, the pump is connected to the surface through pump rods and the removal and replacement of the same involves time and labor.
In FIG. 8, a form of the invention is shown in which a tubular extension 37 projects downwardly from the tubing 11 below the pump. The lower portion of said extension includes a suitable means capable of being operated by the tubing string 11 for connecting the same to the anchor device 17. As shown, this connecting means comprises radially extending connecting pins 38 adapted to be received within J-slots 39 in the upper end of anchor device 17. Thus, whenever it is desired to adjust the liner assembly, it is only necessary to manipulate the tubing to connect the extension of the tubing string with the liner assembly B and move the latter to a different elevation with respect to the oil-water interface within the formation F. It is understood that other detachable type means can be employed in lieu of the pin and J-slot connection.
As previously noted, a heat exchanger H may be connected in the tubing string below the inlet to the well pump 14 for the purpose of cooling the well fluids prior to their passage to said pump. The heat exchanger conducts a coolant medium, such as water, into heat exchange relationship with hot well fluids entering the well before they are passed through the pump 14 without mixing the coolant medium with said well fluids. Because the heat exchanger is connected in the lower portion of the tubing string, it is desirable that said heat exchanger be designed to provide maximum heat exchange surface in a minimum length or vertical area within the bore. The use of the heat exchanger H assures that any hot well fluids are cooled so that the pump handles only relatively cool liquids, with the result that the pump efficiency is increased and the components of the pump, such as seals and the like, are protected against possible damage by reason of excessive heat.
A preferred construction of heat exchanger is shown in FIGS. 9 and 10. Such heat exchanger includes a central mandrel 40 which has its upper end adapted to be attached to the lower end of the well tubing string 11, thereby locating the heat exchanger below the well pump 14. An outer shell or housing 41 of larger diameter than the mandrel surrounds said mandrel to form an annular space between the parts. The upper end of the annular space is closed by an annular header or ring 42 which is welded to the exterior of the mandrel 40 and to the upper end of the shell 41. The lower end of the shell is closed by a similar header or ring 43.
An upper annular chamber 44 is formed between the top header 42 and a ring 45 spaced downwardly therefrom, the latter also being welded or otherwise attached to the mandrel and housing. A lower annular chamber 44a is formed at the lower end of the space between the shell and mandrel by a ring 45a located in spaced relationship above the lower header 43. A vertical conductor 46 projects downwardly in the space between the shell and mandrel extending through the top header 42, upper annular chamber 44, rings 45 and 45a and into the lower chamber 44a. The upper end of the conductor 46 has an extension 46a to which a coolant medium return line 47 may be connected and the latter extends upwardly to the surface of the well, whereby a coolant medium, such as water, is conducted upwardly from the lower chamber 44a of the heat exchanger.
A plurality of heat exchange tubes 48 extended between the upper chamber 44 and the lower chamber 44a to establish communication therebetween and to locate the tubes in the annular area or space between the mandrel and shell. The coolant medium is conducted from the surface through a pipe 49 into the upper chamber 44 so that a constant circulation of said medium through the tubes occurs.
The mandrel 40 has a plurality of perforations or openings 40a formed therein so that as the well fluids flow upwardly within the bore mandrel 40 enroute to the pump inlet, said fluids may circulate into and out of the annular space within the area between the shell and mandrel and within the area between the upper and lower chambers 44 and 44a. In this way, the well fluids are brought into direct heat exchange contact with the plurality of tubes through which the coolant medium is conducted so that maximum heat exchange occurs between the well fluids and coolant in said tubes.
After being cooled, the well fluids flow upwardly through the mandrel 40 and into the lower end of the tubing string 11 and then to the inlet of the well pump.
Although the inlet line 49 and the return pipe 47 may be permanently connected to their respective conductors, in which case said line and pipe are run simultaneously with the tubing string and heat exchanger, it may be desirable to removably connect said line and conductor to the heat exchanger so that each may be run and removed independently of the tubing and heat exchanger. If the line and conductor are to be handled separately, the upper end of the mandrel carries an inclined guide head 50 having an inclined guide surface 50a. At the lower end of said guide surface, two openings 51 and 52 are provided for receiving and landing the lower ends of the line 49 and the return pipe 47.
After the heat exchanger is run with the tubing string and said string is in the well, the inlet line 49 is lowered within the annulus between the tubing and the casing and the inclined guide surface 50a of the guide 50 guides said line into a landed and sealed position in the opening 52 to establish communication with the upper chamber 44. Thereafter, the return pipe 47 is run separately and is guided and landed into a sealed position in the opening 51 which communicates with the lower chamber 44a. Whether the inlet line 49 and the return pipe 47 are run with or separately from the heat exchanger, the manner of positioning the same does not affect the function of the heat exchanger. In each case a coolant medium is circulated downwardly from the surface to the mechanical heat exchanger, is passed in heat exchange relationship with the well fluids and the heated coolant medium is returned to the surface. This assures that the well fluids being handled by the pump means 14 are sufficiently cooled to increase pumping efficiency and to obviate possible damage to the components of the pump.
From the foregoing, it will be seen that an improved method and apparatus which greatly increases well pumping efficiency is provided. The inlet from the producing formation into the well is readily adjustable without removing the well tubing from the well. As has been explained, the adjustment may be accomplished by merely removing the well pump and rods and lowering a spear through the well tubing; or, if desired, the adjustment may be made with the tubing string itself. The adjustment assures that the well pump is not handling excessive volumes of water and, therefore, the primary purpose of the pump in pumping oil from the production formation is accomplished.
The provision of a heat exchanger below the pump inlet assures that in any "hot" well which is encountered, the heated well fluids will be sufficiently cooled to insure pumping efficiency and to prevent any damage to the various seals or other components of the well pump.
The foregoing disclosure and description of the invention are illustrative and explanatory thereof, and various changes in the size, shape and materials, as well as in the details of the illustrated construction, may be made within the scope of the appended claims without departing from the spirit of the invention.