US 3261398 A
Description (OCR text may contain errors)
July 19, 1966 3,261,398
J. A. HAEBER APPARATUS FOR PRODUCING UNDERWATER OIL FIELDS Filed Sept. 4 Sheets-Sheet 1 INVENTOR JOHN A. HAEBER HIS AGENT July 19, 1966 J. A. HAEBER 3,261,398
APPARATUS FOR PRODUCING UNDERWATER OIL FIELDS Filed Sept. 12, 1963 4 Sheets-Swat 2 25 ii 79 I P 11 75 \g 78 74 r 7s-% F I G. 9
INVENTOR JOHN A. HAEBER HIS AGENT July 19, 1966 HAEBER 3,261,398
APPARATUS FOR PRODUCING UNDERWATER OIL FIELDS Filed Sept. 12, 1963 4 Sheets-Sheet 5 INVENTOR:
JOHN A. HAEBER H|S AGENT FIG. 4
J. A. HAEBER 3,261,398 APPARATUS FOR PRODUCING UNDERWATER OIL FIELDS July 19, 1966 4 Sheets-Sheet 4 Filed Sept. 12, 1963 INVENTOR:
JOHN A. HAEBER BYi e United States Patent 3,261,398 APPARATUS FOR PRODUCING UNDER- WATER OIL FIELDS John A. Haeber, Houston, Tex., assignor to Shell Oil Company, New York, N.Y. a corporation of Delaware Filed Sept. 12, 1963, Ser. No. 368,531 16 Claims. (Cl. 166-.5)
This invention is directed to apparatus for producing underwater oil and gas fields wherein the wellhead assembly mounted on the top of each well is positioned at a substantial distance below the surface of a body of water and is preferably positioned on the ocean floor.
A recent development in the oil industry is the development of oil and/or gas fields which are located underwater and oftentimes at a substantial distance, say to 100 miles offshore. Since well structures which extend to a point about the surface of the water form navigation hazards for ships operating in the vicinity, a new development has been the placement of the wellhead assemblies on the ocean floor. Wells of this type are presently produced by running the production flow lines from the Well to shore or to a stationary production facility mounted on piles at an offshore location. The use of flow lines running to shore limits the production of wells located many miles from shore as the oil-producing formation which is traversed by the well must be under substantial pressure so as to provide suflicient pressure to produce the oil and other well fluid up the well and then to overcome the frictional resistance encountered in the many miles of flow line extending to shore. On the other hand, the use of stationary production platforms is limited to rather shallow water depths as it is very costly to install such platforms in deep water and the cost would be prohibitive to construct and install stationary platforms for oil field purposes in deep Water, say over 400 feet in depth.
It is therefore a primary object of the present invention to provide apparatus for producing underwater oil fields wherein the wellhead assemblies are positioned on the ocean floor in water of any depth.
A further object of the present invention is to provide apparatus for reducing, or minimizing, the wells tubing pressure (pressure in the production tubing at the Wellhead) and thereby (l) prolong the wells period of natural flow (if any), (2) increase the production rate of the well, and (3) reduce the amount of lift gas required to produce the well after natural flow has either "ceased or declined to where the use of lift gas is beneficial.
Another object of the present invention is to provide methods and apparatus for supporting flow lines and other field collecting and distribution lines extending from the ocean floor to a position near the surface of a body of water.
A still further object of the present invention is to provide apparatus for supporting vertically-extending well flow lines and other field collecting and distributing lines above the ocean floor while providing means for connecting the flow lines to a suitable vessel at the surface for receiving the production fluid from the wells.
Still another object of the present invention is to provide apparatus for handling a multiphase production fluid from an underwater oil field whereby the gaseous phase of the production fluid may be separated from the oil 3,261,398 Patented July 19, 1966 "ice phase before the oil phase is raised above the ocean floor.
Still another object of the present invention is to provide apparatus for separating a multiphase oil production fluid in a vessel at the surface of the ocean and returning the oil phase of the production fluid down to storage facilities positioned on the ocean floor.
These and other objects of this invention will be understood from the following description when taken with reference to the drawing, wherein:
FIGURE 1 is a synoptic view illustraitng an underwater oil field having a plurality of wells drilled therein and connected to a production facility on the ocean floor which in turn is connected in fluidtight communication wih a vertically-extending cylindrical strucure positioned in the ocean floor and extending upwardly to a point near the ocean surface where it is connected with a floating vessel or production facility on the surface, the production facility on the surface also being in communication with suitable storage tanks located on the ocean floor;
FIGURE 2 is a longitudinal view diagrammatically illustrating the vertically-extending elongated cylindrical structure which extends into the ocean floor and is anchored therein;
FIGURE 3 is an enlarged cross-sectional view taken along the line 33 of FIGURE 2;
FIGURE 4 is an enlarged longitudinal view, taken partially in cross-section, illustrating a pump mechanism carried within the vertical cylindrical structure of FIG- URE 2;
FIGURES 5 and 6 are fragmental views, taken partial ly in cross-section, illustrating one method of connecting underwater pipelines to the vertical cylindrical structure of FIGURE 2;
FIGURE 7 is a cross-sectional view taken along the line 7-7 of FIGURE 4;
FIGURE 8 is a cross-sectional view taken along the line 8-8 of FIGURE 7; and,
FIGURE 9 is a fragmental view taken in the longitudinal cross-section of one form of a means for connecting pumping apparatus to the top of the vertical cylindrical structure of FIGURE 2.
Referring to FIGURE 1 of the drawing, a plurality of underwater wells are illustrated with their Wellhead assemblies 11, 11a and 11b positioned on the ocean floor 12. Each production wellhead assembly, for example Wellhead assembly 11, is provided with at least one flow line 13 and preferably two flow lines 13 and 14 whereby the well production fluid may be taken away through one line, and, if necessary, gas may be pumped down through the other line during later well life in order to produce the well. The other wellhead assemblies 11a and 11b are also provided with dual flow lines 13a, 14a and 13b, 14b, respectively. I
The production flow lines from the various underwater wells preferably lead to a production facility, generally represented by numeral 15, which is located on the ocean floor and is normally centrally located among the wells which are connected to it. The production facility 15 may be of various types. For example, the production facility 15 may be merely a manifolding station Where the production fluids from the several wells are combined so that they can be delivered by a single flow line to a distant terminal. On the other hand, the production facility 15 may also-be provided with suitable metering devices for metering the individual flow from each of the Wells prior to combining the several flows and sending them to the distant terminal.
As most oil is combined with gas in many oil fields, the production facility is preferably provided with suitable separators 16 for separating the gas from the oil before flowing the oil to the distant terminal. While high pressure gas separators 16 may be employed early in the life of the well, the production facility 15 is also preferably provided with low pressure gas separators 17 for use during the latter part of the well life. The production facility 15 may have a base frame 18 secured to the ocean floor and equipped with guide columns 19 on which a central removable frame 26 is positioned. The various manifolding lines and separators 16 and 17 are secured to and are removable with the inner frame 20 which is also preferably provided with a track 21. The track is employed in order to facilitate ease of positioning an underwater manipulator device adapted to open and close valves or to connect or disconnect various flow lines one from the other. Each of the flow lines coming to the production facility 15 is provided with a remotely-actuatable pipe connector 22 of any type well known to the art so that the flow lines may be disconnected from the production facility 15 before the central removable frame 20 and its associated equipment are pulled back to the surface for maintenance or repairs.
The fiowlines coming from the production facility 15 may be bound together in the form of a single bundle of lines 24, as illustrated in FIGURE 1. If the production facility 15 is merely a manifolding station, only a single flowline 24 would be needed during the early life of the wells. However, if the wells were produced by gas lift during the latter part of their life, the bundle of lines 24 should at least consist of a production flowline leading away from the production facility 15 and a gas line extending to the production facility 15 and thence on the individual wells 11, 11a and 11b. In the event that the production facility 15 also includes gas separation apparatus, the bundle of lines 24 should preferably include separate gas lines for high and low pressures to and from the high and low pressure gas separators 16 and 17, respectively. Additional lines may connect the production facility 15 with a distant terminal so that various types of well maintenance tools or instruments can be pumped down to the production facility 15 or to any of the individual wells for carrying out certain selected operations. It is to be understood that in an oil field having a great number of wells a plurality of production facilities 15 would be strategically located among the many wells.
Positioned at some distance from the production facility 15 is a free-head pile in the form of a large-diameter elongated and vertically-positioned cylindrical structure having its lower end closed in a fluid-tight manner .and sunken and anchored to the ocean floor. The upper end of the elongated tubular or cylindrical structure is located below the surface 26 of the ocean so as to be relatively unaffected by wind and wave forces and so that it does not constitute a hazard to navigation of ships in the area. For example, in water 1,000 feet deep the vertical cylinder may have 900 feet extending above the ocean floor 12, while several hundred feet are sunk in the ocean floor to anchor it securely in a vertical position. The vertical cylindrical structure may be in the order of 6 feet in diameter in its preferred form and as much as 2 inches in wall thickness to give it substantial rigidity. The vertical cylinder 25 may be originally transported to its offshore location on a series of barges or the ends of the cylinder 25 may be closed so as to aid in floating the structure to its desired location. The lower end of the vertical cylinder 25 may be jetted into the ocean floor in a manner well known to the art or it may be provided with a large diameter bit or series of bits mounted on a rotatable housing of the type well known to the art for drilling large-diameter holes. After drilling or jetting the lower end of the vertical cylinder 25 into place in the ocean floor, the walls at the lower end of the vertical cylinder 25 and/or the bottom thereof would be perforated so that cement could be pumped down the vertical cylinder 25, out the perforations and up the annular space between the vertical cylinder and the ocean floor formations so as to cement the vertical cylinder or freehead pile 25 in place in a manner well known to the art.
Preferably, the vertical cylindrical structure 25 is provided with a buoyancy tank 26a near its upper end for maintaining a tension thereon. As shown in FIGURE 2, the vertical cylinder 25 is also provided at spaced intervals along its length with a plurality of radially-extending support plates 27, 27a and 27b for supporting and securing the many fiowlines, such as flowline 28 to the vertical cylindrical structure 25. Thus, it may be seen that the vertical cylindrical structure 25 serves as substantially rigid support means for the major length of the many fiowlines extending from the ocean floor 12 to the floating production facility generally represented by numeral 30 (FIG. 1) which floats on the surface of the ocean 26. By using the vertical cylindrical support structure 25 of the present invention, a smaller floating production facility or a floating production facility with less buoyancy can be employed as the floating production vessel 30 only supports the flowlines between the vessels 30 and the top of the vertical cylinder 25 rather than having to support the thousands of feet of steel flowline extending from such a production vessel 30 to the various wells or production facilities on the ocean floor when the production vessel 30 is positioned in, say, 1,000 feet of water. In the event that flexible fiowlines are used, a greater number of support plates 27 would be employed as needed to prevent the flexible flowline from pulling apart under its own weight.
It is apparent that with floating production units, some motion of the platform is certain to occur regardless of how sophisticated a mooring system is used. This motion will chafe and deteriorate the lines hanging from the facility, and the loss hazard will be particularly high during stormy periods. If the lines are hanging free from the production facility deck, the lines are likely to part at or near the sea floor when failure takes place. However, when the lines are supported throughout a large portion of the sea floor to production facility deck interval of the present invention, with flexible pipe being used only for the free hanging portion between the top of the free-head pile and the production facility, the locus of failure is concentrated near the sea surface. Replacement of parted and damaged lines in this interval can be accomplished with relative ease and speed and at much less cost than if the failure had occurred at or near the sea floor. Thus, although use of floating production platform probably necessitates accepting higher failure rates of flow lines and collecting and distribution lines, the economic consequences of these failures can be at least partially controlled by controlling the location of the failures by employing the apparatus of the present invention.
The floating production facility 30 may be a vessel of any suitable form which is maintained substantially di rectly over the elongated vertical cylinder 25 in any manner well known to the art. Thus, the production vessel 30 may be flexibly anchored in place by a series of anchors and anchor lines (not shown) or the vessel may be provided with a series of propulsion units adapted to move the vessel in any direction so as to maintain it substantially over the vertical cylinder 25. One form of a production vessel may be triangular, as shown, with the hull made up of buoyancy cylinders 31, 32, and 33 at the corners while the interconnecting cross bracing members 34 are preferably hollow and form storage tanks for the oil produced from the wells until such time the oil is delivered to a tanker or barge 35. In the event that gas is not separated from the production fluid at the ocean floor production facility (FIGURE 1), the floating production vessel 30 is provided with suitable separating apparatus for separating gas and/or water from the oil produced. In addition to separators, the floating production vessel may be provided with heater-treaters or other demulsifying apparatus, metering tanks, etc. Although only two flowlines 37 and 38 are shown in FIG- URE l as extending between the top of the vertical cylinder and the production vessel 30, it is to be understood that these may be bundles of flowlines or other flowlines may extend individually between the vessel and the vertical cylinder 25. In addition, power lines 39 extend from the production vessel to suitable pumping apparatus whose power units are located at the top of the vertical cylinder 25, as will be described hereinbelow.
As illustrated in FIGURE 1, the apparatus of .the present invention may also include a series of interconnected storage tanks 40 to 45 preferably positioned in a frame 46 which in turn is anchored to the ocean floor 12. A flowline 47 extends from the interconnected tanks 40 to 45 and includes an oil conduit extending up the vertical cylinder 25 and to the production vessel 30. Thus, the ocean floor storage tanks 40 to 45 may serve as auxiliary storage capacity for the production vessel 30 in the event that the tanker is delayed due to storms, etc. Any surplus oil that cannot be held in the storage tanks in the crossmembers '34 of the production vessel 30 may be pumped down fiowline 47 alongside the vertical cylinder 25 and into any of the tanks to 45. The oil could be returned to the vessel in any suitable manner as by means of seawater displacement. The lowest point on the tanks is left open to the sea water to bleed off b.s. and w. (basic solids and Water) and to equalize internal and external tank pressures to avoid bur-sting or collapsing the tanks. Therefore, it is necessary to pump crude oil into the tanks with a pressure equivalent to the difference between the sea water head and the crude oil head. For unloading the tanks, it is necessary only to open a valve on the crude line at the surface to permit the sea water head to displace crude from the tanks. If withdrawal rates higher than those obtainable by sea water displacement are required, the flow rate can be increased by pumping or gas-lifting the crude. For emergency purposes, it may be desirable in some cases to arrange the flowlines and manifold in a manner such that the well production fluid passing through the flowline bundle 24 can flow directly into the storage tanks 40 to in the event of power failures on the production vessel 30. This could be done rather than shut in the wells.
As shown in FIGURE 2, a pump motor housing 50 is illustrated as being positioned on the top of the vertical cylinder 25 and secured thereto as by means of any suitable connector 51. The pump housing is shown in greater detail in FIGURES 4 and 7 as enclosing one or more pump motors, in this case three pump motors 52, 53 and 54 with the discharge lines 55 and 56 from the smaller pumps 52 and 53 being connected to the main discharge line 57 from the large pump 54 so that only one production fluid line 57a extends between the pump housing 50 and the production vessel 30. The discharge lines 55, 56 and 57 may be provided with check valves 58, 59 and 60. A plate 61 closes the bottom of the pump housing 50 and maintains it separated in a fluidtight manner from the interior of the vertical cylinder 25. As shown in FIGURE 4 a discharge pipe 62 extends through the plate 61 and out through the wall of the pump housing 50 through a flexible line to the production vessel 30 so as to discharge any gases accumulating at the top of the vertical pile or cylinder 25 below the plate 61. The electrical leads 39 may enter the valve housing 50 through the same wall as the pipe 57a (FIGURE 7). The pump motors 52, 53 and 54 are arranged to drive shafts or rods 63, 64 and 65, respectively, of suitable centrifugal or deep well pumps 66, 67 and 68 respectively. Preferably, the capacitie of the pumps are selected so that the large pump will run all the time and one or more of the small pumps will be run in an on-and-oif manner so that the production fluid in the vertical cylinder 25 is maintained at the desired level. Preferably, the liquid level in the vertical cylinder 25 is maintained near the lower end thereof close to the inlet (see conduit 24a and inlet port 82 of FIG- URE 5) for the production fluid so that there is little hydrostatic head being applied to the low pres sure-gas-oil separators at the production facility 15 (FIGURE 1). Hence, with or without employing the ocean-floor production facility 15 between the wellhead 11 and vertical cylinder 25, by maintaining the level of production fluid low in the vertical cylinder 25 the wells would have less of a hydrostatic head against which to produce. Thus, it may be seen that by employing the vertical cylinder 25 of the present invention as a receiver having little or no hydrostatic head applied thereto, that low pressure wells could be produced, or old wells could be produced for a longer part of their life, before resorting to gas lift methods.
Any suitable type of liquid-level controller may be employed to control the liquid level within the vertical cylinder 25. In one commercial form of a liquid-level controller an open-ended pipe is immersed into the liquid body and air is pumped through. As the hydrostatic head builds up around the pipe and it is harder to discharge the air from the pipe, a sensing device on the vessel will indicate this change in liquid level and start one of the pumps which runs until the liquid level has been again reduced to the desired point. In FIGURE 4, the vertical cylinder 25 is shown as having a 2 inch line 69 extending down to a predetermined level above the uppermost pump 68. This pipe 69 would be in communication with the vessel through a flexible line 70 (FIGURE 2). The pumps 66, 67 and 68 are suspended from shaft housing 71, 72 and 73 which surround the shafts 63, 64 and 65, respectively.
The pump housing 50 is removably secured to the top of the vertical cylinder 25 so that maintenance work can be done on the pumps as required. Although bolts could be unbolted by a suitable underwater manipulator as will be described hereinbelow, the housing may be provided instead with a suitable hydraulic or mechanical connector. One form of a suitable connector is shown in FIGURE 9 wherein the inner surface of the vertical cylinder 25 is provided with annular grooves 74 therein adapted to receive outwardly-extendible latching dogs 75 carried by a downwardly-extending wall 76 of the pump housing 50. The wall 76 has formed therein an annular chamber in which an'annular piston 78 is slidably mounted for a limited vertical movement. Hydraulic pressure can be supplied through conduits 79 or 80 to the top or bottom of the piston 72 to either lock or unlock the latching dogs 75 item the groove 74. Thus, when it was desired to remove the pump housing and pumps from the vertical cylinder 25, the latching dogs 75 of the connector 51 would be retracted and the whole housing and pumps would be pulled back to the production vessel by any suitable hoistmg means.
Arranged near the bottom of the vertical cylinder 25 just above the ocean floor 12 (FIGURE 5) are one or more fluid inlet ports 82 through which production fluid is delivered to the vertical cylinder 25 from a production line 24a which is in turn connected to the ocean floor production facility 15 (FIGURE 1) or directly to one of the wells. The pipe 24a may be originally connected to the vertical cylinder 25 by lowering it by means of a line 83 into a V-grooved or U-shaped opening at the top of an aligning and support bracket 85 secured to the outer surface of the vertical cylinder 25. A coupling 86 having an outwardlyextendible telescoping sleeve 87 is provided at the fluid inlet 82 in order to connect to the free end of the production line 24a in a fluidatight manner. A coupling of this type is shown and described in detail in the applicants copending patent application Serial No. 308,530, filed September 12, 1963, which describes a coupling employing a track and pinion arrangement for connecting the coupling.
The sleeve 87 may be moved outwardly in any suitable manner as by means of turning the actuating nut 8%. For this purpose an underwater manipulator may be employed which is either suspended from a track 90 secured to the outside of the vertical cylinder 25, or may be of the type that rests on the ocean floor while carying out operations. An underwater manipulator of this type is described in US. Patent 3,099,316 and includes a body member 91 provided with wheels 92 for propelling it around the track 90, propulsion units 93 for moving it through the water, a support and/ or power cable 94, a unit g5 containing lights and a television camera, as well as an extendible arm 96 having a wrench head 97 at the end thereof for manipulating various elements such as actuating bolt 88 on the connector 86. As described in US. Patent 3,099,316, the arm 96 of the manipulator device may be telescoped in or out, raised up or down, or rotated as desired to carry out the necessary operations.
In FIGURE 6 the underwater manipulator device described with regard to FIGURE 5 is shown as being employed to connect another :form of coupling 98 by turning its actuating screw 99 so as to connect lines 28 and 24!) together in a fluidtight manner.
It may be seen from the above description that a method has been provided for producing deep water oil and gas field in which a plurality of wells have been drilled. The method includes the steps of installing a large-diameter vertical cylinder on the ocean floor with the upper end below the surface of the ocean, producing well fluids from the wells into the lower portion of the cylinder, providing a vessel on the surface of the ocean in the vicinity of the cylinder, connecting the interior of the cylinder in fluid communication with the ve sel, and subsequently pumping well fluid from the cylinder to the vessel, preferably maintaining the level of the fluid in the cylinder in the lower portion thereof so as to reduce any hydrostatic head in the cylinder which would reduce the ability of the wells to produce under their own pressure. In addition, when the well production fluid contains gas the present method is altered to include the operation of separating the gas from the well fluid before the fluid enters the vertical cylinder. Alternatively, the method of the present invention includes the operation of separating a multiphase production fluid into its various components at the vessel on the surface of the ocean, and in the event that the storage capacity of the vessel is not suflicient, production fluid in the form of oil may be pumped back down to storage facilities on the ocean floor.
I claim as my invention:
1. Apparatus for producing underwater wells having wellheads positioned below the surface of a body of water, said apparatus comprising:
a large-diameter elongated cylinder vertically positioned with its lower end closed in a fluid-tight manner and sunk in and anchored to the ocean floor and its upper end below the surface of the body of water, said cylinder having port means through the wall thereof at a point near but above the ocean floor,
an underwater production wellhead assembly positioned near the ocean floor and having a production flowline,
first fluid flow conduit means interconnecting said roduction flowline of said underwater wellhead assembly with the port means in said elongated cylinder into which production fluid can be delivered,
pump means operatively mounted on said cylinder for pumping production fluid therefrom, said pump means having discharge port means extending from said cylinder near the top thereof,
a floating vessel including tank means, said vessel being positioned on the surface of the body of Water in the vicinity of said vertical cylinder, and
second fluid flow conduit means internconnecting the discharge port means of said pump means with said tank means of said vessel.
2. The apparatus of claim 1 wherein said pump means comprises a pump housing secured to the top of said vertical cylinder, a pump power unit positioned for operation within said pump housing, .a pump suspended at a predetermined level within said vertical cylinder, and power transmission means interconnecting said pump and the pump power unit.
3. The apparatus of claim 2 including power leads extending from said vessel to said pump power unit on said ertical cylinder to actuate said power unit.
4-. The apparatus of claim 3 including connector means securing said pump housing to the upper end of said vertical cylinder.
5. The apparatus of claim 4*. wherein said pump power unit is secured to said pump housing and said pump and power transmission means depend therefrom and are emovable therewith.
6. The apparatus of claim ll including buoyancy tank means mounted on the outside of said vertical cylinder ear the upper end thereof.
7. The apparatus of claim 1 including third fluid flow conduit means between said vessel on the surface and said underwater wellhead assembly.
8. The apparatus of claim 1 including third conduit means in communication between the vessel and said wellhead assembly for supplying gas under pressure thereto.
9. The apparatus of claim 1 including a gas-separating facility on the ocean floor and interposed in said first conduit means between said wellhead and said vertical cylinder.
1 .3. The apparatus of claim 9 wherein said first conduit means includes at least one production fluid flowline between said wellhead assembly and said gas-separating facility, at least one liquid flowline between said gas-separating facility and said vertical cylinder, and at least one gas flowline between said gas-separating facility and said vessel.
11. The apparatus of claim 1 including separator means on said vessel in communication with said second fluid flow conduit means for separatnig a multiphase hydrocarbon production fluid.
12. The apparatus of claim 11 including oil storage tank means positioned on the ocean floor and third conduit means in communication between an oil discharge port of said separator means and said tank means on the ocean floor.
13. Apparatus for producing an underwater well having a wellhead assembly positioned adjacent the ocean floor, said apparatus comprising:
a large-diameter vertically-positioned elongated support cylinder having its lower end sunk in and anchored to the ocean floor and its upper end below the surface of the ocean,
pipe support means secured to the outside of said support cylinder for securing a plurality of conduits thereto,
a floating vessel including tank means, said vessel being positioned on the ocean surface in the vicinity of said support cylinder,
an underwater production wellhead assembly positioned near the ocean floor, and
a production fluid flowline connected to and in communication with said wellhead, said flowline extending from said wellhead, along the ocean floor to said support cylinder, up the support cylinder while being secured thereto and upward to said vessel, said flowline being secured to said cylinder by said pipe support means.
14. The apparatus of claim 13 including oil storage tank means positioned on the ocean floor in the vicinity of said support cylinder and an oil conduit extending from said vessel to said storage tank means.
15. The apparatus of claim 13 including a second flowline interconnecting said wellhead and said vessel.
References Cited by the Examiner UNITED STATES PATENTS 2,594,105 4/1952 Watts 137172 2,622,404 12/1952 Rice 1758X 10 Gillespie 137344 Knapp et a1 16645 McLean et a1 175--8 Cole et a1. 114-05 Timmennan et a1. 1140.5 Huitt et a1. 166-46 CHARLES E. OCONNELL, Primary Examiner.
R. E. FAVREAU, Assistant Examiner.