US2828821A - Oil well apparatus - Google Patents

Description

April 1, 1958 R. R WATERMAN 2,828,821

on. WELL APPARATUS Filed Feb. 5, 1954 Sheets-Sheet 1 -/50 lb. Gaye Pressure 366E STEAM v 550 lb. er .40, z LINE I i fl z ass-n H v i A .24; -10 32 DEPTH O I WELL (ABOVE FL u/o LEVEL I 1 3;

a; z 19- 24 l -7}=-300'F. HEATING SECTION RUSSELL mwArmm/v, CONDE vs. I INVENTOR. cm m" HUEBNE'RsBEEHLL-R,

WORREL & HERZ/G, CLEARANCE By ATTORNEYS.

April 1, 1958 Filed Feb. 3, 1954 R. R- WATERMAN OIL WELL APPARATUS 3 Sheets-Sheet 3 R. WA 7' ERMAN;

RUSSELL IN VEN TOR.

HUEBNER,BEEHLER,

WORREL A r TORNE vs.

United States Patent OIL WELL APPARATUS Russell R. Waterman, Long Beach, Calif. Application February 3, 1954, Serial No. 497,860

' 4 Claims. (Cl. 166-57) The application has reference to a method and apparatus for the production of crude petroleum from wells. This application is a continuation-in-part of applicants copending application Serial No. 170,116, filed June 24, 1950, now Patent No. 2,705,535.

More particularly the application is one directed to increasing the flow of oil wells by sending steam under pressure into a heating jacket in the well at the portion of the well to be heated, and there utilizing the major portion of heat in the steam in order to raise the temperature of the crude petroleum before it is pumped, making it flow more readily through the pump line.

It has long been appreciated that wells for the production of crude petroleum can be made to flow faster when the wells are heated. For more than fifty years a great variety of types of apparatus have been devised with the intention of carrying heat deep into oil wells. Some of these apparatus involve a recirculating system so that condensate from the steam as it gives up its heat is returned through a separate pipe line to the surface, presumably to save condensate and also possibly to avoid injecting steam into the production. Such systems have been found to be considerably more expensive than the amount of increase in production has warranted. Furthermore, the recirculating system necessitates a special pump for the condensate lifting an ever increasing head of condensate as the system is lowered into deeper wells. Moreover, recirculating systems necessitate two pipes in a well in addition to the pump line and tend to fill the wells with piping to the extent that the system cannot be worked in casings of small diameter. An added and very material objection is that the major portion of the steam tends to heat the returning condensate and the production as it nears the surface to such an extent that in wells of any appreciable depth there is no steam at the lower levels where the heating is most desirable and the temperature of condensate at those levels is not sufiiciently high to materially increase the production of the petroleum.

Other attempts have been made to employ non-recirculating systems, and in such systems there have been included safety release valves or pop-oil valves to release steam pressure after a previous build-up in pressure, presumably in an effort to raise the temperature in the steam line. The last-identified systems have had the marked disadvantage of discharging live steam into the well, causing emulsification of the crude petroleum to such an extent that systems of this kind have never operated successfully and have never been employed on a commercial scale.

Among the objects of the invention is to provide a new and improved method and apparatus for heating oil wells and particularly for heating selected portions of the oil well where the production can be benefitted most by application of heat at a relatively high temperature. v

Another object of the invention is to provide a new and improved method and apparatus for heating oil wells so hat heat can be applied over the entire depth of producing sand or strata at a relatively uniform rate throughout the depth or thickness of the strata.

Another object of the invention is to provide a new and improved method and apparatus for heating oil wells wherein the quantity of steam supplied and the amount of heat generated can be carefully and accurately regulated so that a maximum amount of heat may be imparted to the crude petroleum while at the same time overheating can be avoided.

Another object still is to provide a new and improved method and apparatus for heating oil wells wherein the ap paratus is of such small diameter that it can be lowered into the well between the casing and the pump string without it being necessary to remove the pump string and thereby avoid stopping production for a length of time no greater than that necessary to lower the apparatus into the well. and to recap the casing.

Still further among the objects of the invention is to provide a new and improved method and apparatus for the practice of the method by means of which the apparatus can be adjusted and fitted to agreat variety of conditions as, for example, different depths below the surface, different production fluid levels, different heads of fluid at the bottom of wells and different heating requirements so that a substantially maximum amount of heat can be applied specifically to the area needing most to be heated. The objects include heating under conditions where substantially a precise control can be maintained at all times over the quantity of steam supplied at a selected advantageous pressure to the end that the method can be operated sufficiently economically to warrant employment of the method and apparatus under conditions where the increase in fiow of crude petroleum over the normal pumping rate is as low as one hundred percent and lower.

Further included among the objects of the invention is to provide a new and improved method and apparatus wherein steam under pressure can be introduced'into oil wells by use of an apparatus of substantially small exterior diameter uniform throughout its length so that it can be raised or lowered to ditterent levels as occasion may require and further wherein an accurate control is included in the heating section readily variable as different conditions are encountered and further wherein sufficient control is exercised over condensate emitted from the heating section so that no live steam is permitted to escape into the well. Y

With these and other objects in view, the invention consists in the construction, arrangement and combination of the various parts of the device whereby the objects contemplated are attained, as hereinafter set forth, pointed out in the appended claims and illustrated in the accompanying drawings.

In the drawings:

Figure 1 is a schematic representation ofan oil well with the apparatus installed therein.

Figure 2 is a longitudinally sectioned foreshortened view of an oil well showing the relative location of the heating apparatus to the casing, the liner, and a pump string.

Figure 2A is a fragmentary vertical sectional view of an oil well showing an insulated steam line.

Figure 3 is a longitudinal sectional foreshortened view of the heating and condensing sections of the apparatus- Figure 4 is a longitudinal sectional viewof the lower portion of the condensing section normally fitting at the lower end of Figure 3.

Figure 5 is a graph showing steam pressure variations encountered as the heating process is applied and the rate of steam supplied in accordance with a time scale.

In the schematic view of Figure 1 there is illustrated an oil well comprising a casing 10 and a liner 11. The ground surface is indicated at 12 and the bottom of the well at 13. A pump string 14 is represented as extending into the well to a location 15 adjacent the bottom 13 of the well but sufiiciently above the bottoin'to be certain of pumping relatively clean crude petroleum. The well is capped in a conventional manner by employment asaaeer 3. of the customary cap 16. As further indicated the nortrial 'free level of crude petroleum in the bottom of the well is at 17 whereas the production fluid level when the pump is in operation is at 18. Heat is supplied to the well by means of a steam supply line 19 which takes steam from a conventional boiler, not shown, from which a section 29 of the steam line connects to a pressure regulator21 having a gauge 22 on the supply side and a gauge 23 on the opposite side to which the supply/"line 19 is connected.

At the lower end of the steam supply line 19 is a heating section 24, at the lower end of which is a condensing section 25.v It will be'noted that the lower end of the condensing section 25 is "at a short distance above the bottom 13 of the well, thereby leaving a slight clearance. The top of' the heating section is normally about at the height of the production fluid level 18. In the well schematically illustrated the bottom of the well will have a somewhat shallow sump 26 ordinarily filled with sludge above which is a depth of production fiuid 27 which will be determined by the particular character of the well in question. It is a reservoir of crude'petroleum which is supplied by inflow of the petroleum from the surrounding strata to a depth determined by the particular level and character of the strata. Above the production fluid level when the pump is operating is a space 28 normally filled with a mixture of air and gas and perhaps some water vapor held within the casing by means of the cap 16.

' The heating apparatus is shown in somewhat greater detail in Figures 2, 3 and 4. The steam supply line 19, which in most instances may be a l-inch to l -inch pipe, is customarily put together in the usual 20-foot lengths by employment of exterior couplings 30. A packing gland 31 of the customary variety may be provided at the cap or well head 16. At the lower end of the steam supply line 19 the heating section 24 is connected by means of an adapter 32. For illustrative purposes in Figure 2 the heating section is shown as of larger exterior diameter than the steam supply line, this circumstance being more particularly prevalent when a 1-inch steam supply line is employed with a l -inch heating section. Circumstances, however, may arise wherein the steam supply line may also be a usual line.

As is more readily seenin Figure 3, the heating section 24 includes a number of sections 24 of the customary conventional length at the upper end of which is a flush tool joint 33. At the upper end of the flush tool joint are internal threads 34 adapted to engage external threads 35 of the adapter 32. At the lower end of each heating section pipe 24' is a male flush tool joint 36 having external threads 37 at the lower end adapted to engage the internal threads 34 on the next lower female flush tool joint 33.

The flush tool joints in each case are pressed into the end of the pipe and sealed therein'by welds 38. As many lengths 24' of the heating section pipe may be joined together as conditions warrant. The series of lengms 24, 24", etc., comprising the heating section provide an interior passage .or chamber 39.

.At the lowermost end of the heating section there is attached an orifice body 40. The orifice body is provided with interior threads 41 adapted 'to engage the exterior threads 45 of the immediately adjacent flush tool joint 36. Extending through the orifice body is a bore comprising a larger section at the threads 41 joining a smaller section 42, there being provided interior threads 44 at the upper end of the smaller section. An orifice block 45 slides into the smaller section to a position limited by a shoulder 46. A strainer 47 threadedly engages the threads 44 and serves as a means of holding the orifice blockin place. The exterior diameter of the strainer is smaller than a bore 48 through the adjacent flush tool joint so that the strainer may he slid easily thereinto.

An orifice passage 4 extends axially through the upper end of the orifice block and is of smaller diameter than an outflow passage 50 therein. Holes 51 of the strainer are smaller in diameter than the diameter of the orifice passage 49. At the bottom and forming part of the orifice block is a turbulator indicated generally by the reference character 52. Extending through the turbu lator is an axial turbulator passage 54 intersected at its lower end by a transverse turbulator passage 55 so that the turbulator passage abruptly changes direction from axial to transverse before communicating with a passage 56 in the tool joint 33.

The condensing section 25 is attached to the tool joint 33 and customarily need be but a single pipe length of the usual 20 feet. At the lower end of the condensing section is a pilot body 57 having a point 58 to facilitate guiding it into the casing. The pilot body has therein a valve chamber 59 housing a ball 60 urged by a spring 61 normally into seating engagement with a corner 62 serving as a valve seat. The valve chamber 59 communicates laterally by means of out-flow passages 63 with the interior of the liner 11. By this device a condensing passage 64 serves as a communication medium between the orifice and the interior of the well at the area of the liner. The ball check 6:? serves as a means of preventing inflow of any fluid in the well while the apparatus is being lowered into place.

In Figure 2A the steam line 19 is shown covered with a heat insulating coating 19' of some suitable material. This is especially desirable to reduce condensation of steam on the way down when wells of greater depth are to be heated.

It will be noted from the foregoing description that the steam line, the heating section, and the condensing section are in axial alignment and of such comparatively small diameter that they are readily contained within the casingand also the liner between the wall of the liner and the pump line 14. Steam passed to the steam supply line 19 travels downwardly through the steam line to the heating section which, in the example chosen, has a chamber of slightly greater interior diameter than the interior diameter of the supply line. At the lower end of the heating section the orifice passage 4% provides a definitely controlled restricting orifice from which condensed steam in the form of water is forced outwardly at a rate of flow scarcely more than sufficient to pass all of the water which has been changed into condensate as the heat of the steam is given up. The heating section therefore forms a heating jacket wherein the steam under pressure is carefully controlled by operation of the orifice so that a major amount of its heat is given up in the area desired.

' As the condensate emerges from the orifice passage, it enters the turbulator through the axial turbulator passage 54 and then changes direction as it emerges through the transverse turbulator passages 55. In the event there may be some slight amount of steam with the ejected condensate, the steam will be first also to change direction impinging upon the interior wall of the passage 56 and will condense within the condensing passage 64 before it finally passes the ball check valve 61'} on its way through the outflow passage 63 to the interior of the oil well.

Inasmuch as the orifice passage or orifice opening is an important element to the successful operation of, the method and apparatus, the size of the orifice passage must be determined in accordance with the several factors involved in-a particular installation. It is essential that s orifice opening and the pressure of steam from the supply line. Consequently, although as an ideal condition, all the condensate must be ejected and no steam ejected therewith, under practical conditions of operation there will be some steam behind the ejection of condensate to the extent that a slight amount of steam will be passed with the condensate. The quantity of steam, however, must be kept to a minimum, below the ability of the condensing section to condense in order that no live steam be ejected into the well.

Among the varying conditions which influence the size of the orifice are the depth of the well, the head of liquid in the heating section, the size of the steam supply line and size of the heating section, the temperature of the crude petroleum below the production fluid level, and also the temperature of the well above the fluid level. It is accordingly necessary to provide an orifice which will meet the conditions in a given installation but for practical reasons an orifice should be selected which will perform satisfactorily under an assortment of conditions which may vary to a small degree between one installation and another, it being keptin mind that the steam pressure may be varied under different conditions so that an orifice of the same size may be made to function properly in one of several diiferent types of installations within reasonable limits.

By way of example and with reference to the schematic diagram of Figure 1, a set of conditions may be assumed in order to illustrate the determination of the proper size restricting orifice passage in the orifice block. For example, let it be assumed that the depth of the Well between the surface 12 and the bottom 13 is 2000 feet. In the well under a given set of conditions the free fluid level is 112 feet and that when under pump the production fluid level is 100 feet.

Let it further be assumed that the lower end of the pump line is set above the very bottom of the well by a distance of feet in order to make certain that only clear crude petroleum is being pumped. It will be advisable under those same circumstances to have the pilot body 57 set at approximately the same clearance above the extreme bottom 13 of the well.

Under these conditions a steam plant may be set to deliver 550 pounds per hour of steam at 150 pounds gauge pressure and at a temperature of 366 F. The temperature and pressure figures given are temperature and pressure figures at the surface 12, namely, at the top of the well.

For the conditions mentioned the depth of the well above the production fluidlevel is 1,900 feet. Consequently, there will be a pressure drop in the steam supply line throughout this 1,900 feet of travel in a l-inch pipe where a 1-inch pipe has been selected for the steam supply line. From steam tables the pressure drop will be found to be 96 pounds for the 1-inch pipe for the distance selected in the example.

Let it be assumed futher that temperature T has been found to be 200 F. T is 360 F. From steam tables the ratio of heat transfer between a steam pressure line and a surrounding gaseous body may be taken as 2. With these figures as a basis the condensation in the 1,900 foot drop of steam from the surface to the production fluid level will be found to be 195 pounds per hour. This of course is an approximate figure but accurate to the extent that steam calculations are made. The condensation will also be found to be equal to or slightly greater than 6 /2 horsepower.

In addition to the amount of condensate accumulating in the steam supply line there will also be a greater proportion of condensate forming in the heating section. Since the heating section is in a liquid bath, the heat transfer ratio can be taken as 110. The temperature of the liquid bath, namely, the crude petroleum liquid at the bottom of the well, upon measurement is assumed to be 150 F.

- perature of the steam in the heating section, will be 300 F., there being a drop in temperature of 66 F.- between the surface and the production fluid level. Under the same set of conditions there will be a drop in gauge pressure to 54 pounds gauge at the production fluid level..

With a ratio of T to T at approximately 110, the condensation in the heating section will be found to be substantially 349 pounds per hour. When this is added to the 195 pounds per hour of condensation in the steam line above the production fluid level, the total condensate for these two sections of the apparatus will be found to equal 544 pounds per hour. This is the amount of liquid which must be passed by the orifice passage. Another factor which enters into the size of the orifice passage is the pressure behind the liquid condensate.

By further calculation in accordance with conventional thermo-dynamic tables, the pressure drop between the production fluid level and the location of the orifice passage for the conditions herein selected will be found to be 34 pounds. 34 pounds added to the 96 pound pressure drop in the steam line equals a total-pressure drop of 130 pounds. 130 pounds subtracted from the initial 150 pounds gauge pressure at the surface gives 20 pounds of steam pressure at the orifice opening.

In the event insulation is employed on the steam line, the condensation occurring in the steam line will need to be calculated, taking into consideration the different rate of transfer of heat laterally in the insulated line.

From restricted orifice tables an orifice size will therefore be selected as one capable of passing 349 pounds per hour of water at a pressure of 20 pounds. Since some slight variation in orifice size is permitted, it will be practical to select the orifice size corresponding to a conventional drill size. Under the conditions herein selected by way of example a number 28 drill size will be found to produce an orifice opening closest to the calculated orifice opening for the 349 pounds of water per hour at 20 pounds pressure. A number 28 drill is foundfrom tables to be a drill having a diameter of .1405 inches. Under those circumstances where, as previously indicated, a one inch pipe is used for the heating section, by calculation it will be found that the area of a flow restricting orifice made with a number 28 drill as described is about 1.8% of the cross sectional area of the interior of the one inch pipe. Should a 1% inch pipe be used for the heating section, the percentage would be proportionately less with the same size orifice. A change in the conditions with respect to temperature of crude petroleum, temperness of the producing strata.

ature of the well, depth of the producing strata below the surface, etc., as already made reference to might suggest some variation in the size of the orifice within the limits which have been found capable of producing satisfactory performance. Satisfactory performance is experienced when the area of the orifice is from 1% to 15% of the heating section. The specific percentage will depend on variations in the values given in the example.

When the apparatus is to be employed in accordance with, for example, the set of conditions given, the heating section is lowered into the well after the condensing section. A sufiicient number of pipe lengths are joined together forming the heating section so that the overall length of the heating section is equal to the depth of production fluid at the bottom of the well. For installations where the producing strata may be above the bottom of the well, the length of the entire heating section may be calculated so that it is long enough to span the entire thick- After .the'heating section has been lowered to the selected positiomthe steam supply line is fastened at that level and steam is passed into the steam supply line. As an aid in understanding the action of the apparatus in accordance with the practice of the method herein disclosed, reference is made to the' graph of Figure 5. As there shown the timein minutes issltown on the horizontal axis. Two vertical axes are employed, the one on the left showing steam in pounds per hour, andtlre vertical axis on the right showing presto in n nasper square inch gauge. Under the asd conditions the graph of supply of steam at 555 pounds 'per hour will be the straight horizontal line 70. The curve of pressure will be a curve indicating a varying pressure namely, the curved line 71.

A s steam is' supplied the pressure dilierential gauges 22am 23 will show a very rapid pressure drop for about the first two minutes 'of operation until the pressure on the low side fof the pressure differential gauges, namely, the pressure in the steam supply line in the Well builds ep c about lllllpounds gauge. Thereafter there will be a' continued build-up of pressure but at a diminishing rate until after about seven minutes the pressure in the well will reach about 140 to 1-45 pounds gauge at the time the sears under pressurehits the production fluid level. Aft'er reaching that level, there will be a greater absorption o'filie'at from the steam and the pressure in the, steam line will diminish slightly until the heat Supplied star to balance the heat absorbed, after an interval of about eleven minutes following the start of the operation. Thereafter pressure will again begin to build up gradually until after about sixteen to seventeen minutes of operation steam reaches the orifice. At that pointcthere will be a sharp change in the registrations of the pressure ditferential gauges showing that the steam pressure has reached 150 pounds per square inch gauge. Where the steam is being supplied at the rate of 550 pounds per hour, the pressure will balance at 150 Pounds and continue on a straight line thereafter provided that an orifice of the proper size has been selected.

If, for example, the orifice should be too small, the buildup in pressure will go above 150 pounds per square inch as indicated by the dotted curved line 72 of Figure 5. It will be appreciated from the foregoing explanation that the amount of heat supplied to an installation can be very carefully balanced at all times during its operation by supplying the proper amount of steam at the selected pressure, which correct supply can be constantly checked by inspection of the pressure differential gauges 22 and 23.

If it be found that the temperature of the crude petroleum being pumped runs too high, the amount of steam can be reduced. On the contrary, if it be found that the temperature of the crude petroleum being produced is lower than good pumping conditions will permit, the quantity of steam can be increased in order to raise the temperature and thereby increase the rate of production on the pump.

While the apparatus and method herein described has been found particularly advantageous in the production of 'low gravity crude petroleum at moderately great depths up to about 3,500 feet, it has also been found that the method and apparatus can also be used successfully for clearing wells wherein the paraifin content has been high by heating the areas impregnated with paraifin, thereby permitting wellsof relatively high gravity to how freely at agreatly increased production rate.

While I have herein'shown and described my invention in what I have conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope of my invention, which is not to be limited to the details disclosed herein but is to be accorded the full scope of the claims so as to embrace any and all equivalent methods and apparatus.

Having described my invention, what I claim as new and desire to secure by Letters Patent is:

1. In an oil well including an oil accumulating space at thebottom of the well and a pump line in the well between said space and the surface, the combination of a bottom hole heater comprising a steam line for steamunder pressure located between the pump line and the wall of the well, an elongated heating jacket having a chamber therein, said heating jacket being independent of the pump line and forming a downward continuation of the steam line and being located between the pump line and the wall of the well, said jacket having an upper connection attached to said steam line, means forming a constantly open fiow restricting hydraulic orifice passage of fixed diameter at the lower end of the chamber and extending downwardly therefrom, an outflow condensing line having a chamber therein and extending downwardly from the orifice passage at a location spaced from the pump line and between the pump line and the wall of the well, and an unrestricted outlet opening at the lower end of the condensing passage.

2. In an oil well having a casing and liner assembly therein including an oil accumulating space at the bottirn of the well and a pump line in the casing between said space and the surface of the ground, the combination of a bottom hole heater comprising a steam line, a heating jacket and a condensing line attached generally in axial alignment in one continuous string and of substantially the same diameter, said diameter being smaller than the diameter of said pump line, said heating jacket having a chamber therein and having a connection secured to the steam line and extending axially downward from the lower end of the steam line at a location separated from said pump line and between the well casing and liner assembly and the pump line, means forming a constantly openfiow-restricting hydraulic orifice passage opening axially downwardly from the lower end of the chamber into the condensing line, means forming a condensing passage below the jacket and extending axially downwardly from the orifice passage and means forming an unrestricted outlet opening from the lower end of the condensing passage extending in a direction different from the longitudinal axis of the condensing passage.

3. A'bottom hole heater for'an oil well having a pump line'therein and comprising a steam line for steam under pressure and an elongated heating jacket having a chamber of substantially the same diameter as the steam line extending axially downwardly from the lower end of the steam line, said jacket being independent of and spaced from the pump line and being located between the .pump line and the wall of said well, means forming a constantly open restricted orifice passage opening axially downwardly from the lower end or" the chamber, said orifice passage having a cross-sectional area equal to between about 2 /2 and 9 /2% of the cross-sectional area of the chamber, a s'trainer at the inlet side of the orifice passage and a discharge passage means of larger capacity than the orifice passage located below and extending axially downwardly therefrom, means forming a discharge port from the discharge passage means and means forming a condensing passage located below and extending axially downwardly from'the discharge passage means, said condensing passage being at a location spaced from the pump line and between the pump line and the Wall of the well.

4. The bottom hole heater as defined in claim 3 wherein'said condensing passage has an outlet opening from the lower end, an axially 'imperiorate pilot body at the lower end of the condensing passage, said outlet opening having a portion thereof in the pilot body and extending laterally therewithin, and an outwardly open check valve in said outlet opening.

References Cited in the file of this patent UNITED STATES PATENTS

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