US2858890A - Method for secondary oil recovery - Google Patents

Description

Nov. 4, 1958 w. F; McMAHoN 2,858,890

METHOD ROR SECONDARY OIL RECOVERY Filed March 1e. 1955 2 sheets-sheet 1 Nov. 4, 1958 w. F. McMAHoN METHOD FOR SECONDARY OIL RECOVERY 2 Sheets-Sheet 2 Filed March 16, 1955 '/lfrlllllf llllllllllllllllllllll Il United States Patent 2,858,890 l Patented N ov. 4, '1958:

ffice METHOD FOR SECONDARY OIL RECOVERY William Frederick McMahon, Riverside, Calif. Application March 16, 1955, Serial No. 494,681 s claims. (ci. 16a-s) This invention relates to a method for the production of natural oil from stagnant pools in subsurface formations, especially those formations inwhich the natural energy has been depleted.

I have in a series of patents, to wit: Patentv No. 1,642,121, patented Sept. 13, 1927; Patent No. 1,779,483, patented Oct. 28, 1930; Patent No. 1,801,520, patented Apr. 21, 1931; Patentv No. 1,992,436, patented Feb. 26, 1935; Patent No. 2,080,622, patented Mayl 18, 1937; Patent No. 2,080,623, patented May 18, 1937; Patent No. 2,080,624, patented May 18, 1937; Patent No. 2,114,905, patented Apr. 19, 1938; Patent No. 2,291,911, patented Aug. 4, 1942, disclosed means and devices for raising natural oil from oil wells by employing a uid as a lifting means (hereinafter referred to as the power fluid) under pressure introduced into a tubing located in the oil well, this fluid intermingled with incoming oil from the oil formation in a high velocity zone, under a pressure relatively lower than the formation pressureor less than the submergence head of the oil in the oil well above said zone, suchras a venturi-tube, and the intermingled oil and power fluid are circulated to the surface through a tubing passageway separate from the tubing employed for the incoming power iluid.

I have now found that if, as the motive uid which is employed in the lifting of the oil, I employ it simultaneously to move oil out of stagnantpools into the oil well, I obtain surprisingly high rates of production from subsurface oil formations in which the natural energy has been depleted. v Y

In order to accomplish these results, I circulate the immiscible power liquid, e. g., Water, from the surface under pressure of the order of fifteen hundred pounds per square inch, in oil wells of less than fteen hundred feet deep, throughV two Wells, e. g., an imput Well and an output well, simultaneously and continuously causing the commingling of the irnmiscible liquid and oillocated in a stagnant pool somewhere in the formation between the two said wells and causing the oil to be moved out of the said pool and into a throat of a venturi-tube submerged in the oil in the output well and returning the vcommingled oil and water to the surface. In the mentioned output well is located the pumping means described in the aforementioned patents.

I heat the said immiscible power liquid to about two hundred thirty degrees Fahrenheit and circulate about thirty-five gallons per minute through tubing connected with the venturi-tube located in the output well, and thirty-live gallons per minute into the formation through the imput well.

With these said rates of circulation of liquid I recover about twelve or more barrels of net oil per hour from the formation.

With the above mentioned temperatures used in the power liquid, the heat transferred to the oil-water stream in the output well containing the jet pump or venturitube is seven hundred fty thousand British thermal` units per hour and the heat loss to the formation, and which 2 serves to heat the formation and area surrounding the output well, is four hundred thousand British thermal units per hour.

In output wells of less than two thousand feet deep, I nd in heating the power liquid to a temperature of two hundred thirty degrees Fahrenheit and circulating this heated liquid down throughpthe jet pump located deep in the output well that, the temperature of the returning commingling oil and water at the 'surface is about two hundred degreesFahrenheit or a differential loss of thirty degrees Fahrenheit. p

This said loss of thirty degrees in temperature results in a net loss of three hundred fty thousand British thermal units per hour in the output well. p

When using this heated water ood repressuring drive to 4cause natural oil to be moved into the output well' from stagnated conditions or pools in the formation,

I have found that a considerable quantity of tine sand' is moved simultaneously with the natural oil into the said output well and I get a surprising increase in the rate-of ow of oil to the surface when I cause this fine sand to be simultaneously and continuously removed from the output well with the natural oil, as contrary to an intermittent action in the removal of said sand and oil. p

I base this increasein oil production on the fact that unless this tine sand, which has a neness similar to that of flour, is immediatelyfand continuously removed to the surface together with the oil just as soon as the sand reaches the output well, said sand 'will'build up lin the area surrounding the said output well and cause rthe oil production to be either shut olf or'considerably re-y duced. Thusfrom my discovery it is evidentthat many oil wells were heretofore abandoned prematurely because 'of the lack of removal and the accumulation of the said ne ilour like sand in the area surrounding the abandoned oil well and caused the oil well bore to be shut olf from the formation.

My invention will be yfurther described in connection with the drawings, in which: l f Y Fig. 1 lis a schematic elevation view of the recover system, showing the joint piping system and the union relationship of two oil wells ljoined together to provide anvintegral unit utilizing a subterranean channel.l Fig. 2 is a sectional elevation through the jet pump. Fig. 3 is a fragmentary sectional elevation at the well head of the output well in which is located the jet pump. Fig. 4 is a fragmentary sectional elevation at the well head of the input well through which water is fed into a subterranean channel. l Y f .i Fig. 2 illustrates 4the form of jet pump described inl detail in Patent No. 2,114,905, to which reference mayl be had for more and further particulars of the structure and mechanical operation of the jet pump. I may use the form of jet pump illustrated in any of the other of m patents referred to above. .f

I employ the form here illustrated as a convenient eX- ample of a mechanical structure in which-the process of my invention may be carried out, without any intention of limiting the method to said structure, since the method may be carried out in any of the structures disclosed in myv listed patents or in any other structure wherein the immiscible` liquid and oil may be comtional pumping means for reasons to be described below.` An outlet 3 is provided near `the bottom lthereof con-v trolled by a check valve 4 and connected by linev 5 to the suction side of pump 7. A main supplyline 8 will be connected to tank 1 to furnish a supply of water to the suction side of pump 7 from outside sources such as i f or example, water wells or rivers or oceans and in this line 8 would be incorporated a lter 9 to eliminate plant life and sea life and oxygen from the water thus used. A suitable chack valve 10 is provided in line 8, and

also ai booster pump 1,1 will-be incorporated in line 8 if needed-to raise water from a source well not shown to supply water to the suction side of pump 7.'

The discharge from pump 7 passes into a main disp charge pipe line 12 and then into discharge pipe line 13 leading into the oil formation 14 through input well 15 and said discharge also passes into discharge pipe line t 16 which is connected with the jet pump 17 located in the the output well 18. n .The line 16is jacketed by the tubing 19 which isl connected to the jet pump 17 and serves to"pr0yide an l annulus passageway 20 for fluids entrained from the formation 1'4` by theA jet pump 17. This tubing 19 is suspended in the output well 18` by conventional means 21 forming the casing head 22. From this annulus passageway 2 0 fluids circulatedl by the pump`7 plus all uids en- 1 trained from the formation 14 are discharged therefrom 'at the cross 23- into line 24.

t is recirculated tothe pump 7 through line 5 and oil is p withdrawn through line 28. A suitable valved 29 cleanout or drain line v30 is provided in the bottom of tank 1 to flush out the sand separated from the water and oil inlank V1'. The sand flushed out of tank 1 is conveyed l by line 30 to=a sump pit'not shown. An automatic bleeder line 3-1 maintains a constant water level 32 in tank i1. This bleeder 31 is connected to the bottom of tank 1 and also to the line 30l leading to the sump pit above mentioned.

A storagebr shipping tank 32 receives the oil conveyed thereto byline 28. i

By referring to'Fig. 1 it will be noted that Ij provideat the output well head 22 what is termed in the industry as a christmas. tree 33.l This so-called christmas tree 33 comprises a series of four plug valves 34, 35, 36 and' 37 arranged tofreverse'thefow of fluid'sinto 'the line 16 and tubing 19t andi permits, at the` operators will, fluid to be discharged into the formation 14throughthe jet pump 17 The regular direction of ilow of discharge from pump 7 intoline16 is made by closing plug valve 34 and opening valvel35 and' closing valve 36 and having valve 37 opened. Io reverse the-flow; of the discharge lfrom pump' 7 `so that the' flow is directed into the annulus passageway 20 IA arrange the said' four plug valves thusly, valve-734 opened, valve 35 closed, valve 36 openedandy valve `37 closed. Il use this latter valve manipulation when cleaning out the output well from sand and/or discharging water into -the formation 14 through output well 18. Shouldg the annulus 20 become plugged with sand at any time-I simply reverse the ow of fluid ffrom pump 7 as just described and clean out the-said annulus 20;

A'pressure gauge 38 lconnected in the christmas tree 33` serves-to show the pressure set up by thepumpy 7. n

.Referring now tothe jet pump 17 which is located in the= output well 18 and to Fig. 2 of the drawings.

Atthe end of tubing 16 and' 19 is positionedl a pumpbody 39; cored or boredvat'40- at one end to produce an linlet bore intoY which the tubingy 19 may be threaded or otherwise secured by ya fluid-tight connection. The opposite end of the body is likewise bored or coredlat 41. The bore41` is closed by a subjoint or'bull plug 42 whichl makes a fluid-tight seal in thejbore 41.k The inner face-of the plug 42 forms a' liemispherical surface 43; There is-thus formed a chamber 44 Coredpassages 48`r connect chamber 44 with upper chamber 45.` The pump body 39 is cored to produce a chamber 46 whichcommunicates with, the formation 14 through the Side wall of pump body `39'. The chamber 46 is separated from chamber 44 and chamber 45 by a wall.47.

Connected to tubing 16 is a split venturi-tube formed of two axially aligned venturi cones 49 and 50 whose nozzles 51 and 52 are spaced from each other by a small separation 53 which has direct communication with chamber 46 and formation 14.

Venturi- cones 49 and 50 each have threaded engagement with pump body 39 to make a duid-tight seal with the body 39.

The nozzles 51 and 52 are cast of tungsten-carbide material to resist abrasion set up by sand being entrained from the formation 14. These nozzles are secured in Venturi- cones 49 and 50 by lead seals 54 in a fluid-tight seal construction. These nozzles have direct communication with formation 14 through the medium of chamber 46. The discharge orice in nozzle 51 is smaller in diameter than the opposing orifice in nozzle 52.

The discharge outlet 55' from cone 50 and nozzle 52 is so positioned that the axis of the cone is coincident with the vertical radius of the semispherical cup 43.

The .tubing 19 is of such length that the inlet port 46 is atthe desired submergence below the uid level of the iluid in the bore hole forming the output well 18';

' The' operation of the un'it is as follows: The hot water is pumped'by pumpv 7 at the desired discharged pressure asreportedv by gage 38 and passes downwardly through? tubing 16, entersfn'ozzle 51 andy discharges therefrom lthrough' chamber 53v into the opposite nozzle 52. The fluids and sand entrained from the formation 14 intermingle with the hotwater in this nozzle 52 and are discharged at 55 into the chamber 44 of the pump body 39. From chamber' 44 the intermingled' fluids ow upward througlli` passage 48l into the chamber 45 thence upward through the annulus passage 20' to the surface of the earth.

AS1 is explained' in the aforementioned' listed patents, this zone at chamber 53 is the vena contracta of the venturi-tube system and the hot water being circulated by pump 7 is at its' highest linear velocity, at this point, of any in the entire system. At this point or chamber 53 the hydrostatic pressure is converted intovelocity and consequently, the pressure inv chamber 53 is low comparednto that at the inlet to the' nozzle 51fro'r at the outlet 55 from nozzle 52. This highest vel'ocity being a function of the dynamic head of the water owi'ng in line 1'6 in' relation to the pump 7 discharge pressure'. As the pump pressure is increased a velocity of hot Water isreached' in the venturi=tub`e whereA the static head of the-oil in the bore hole 1-8 is suilicient to permit the oil?, sand and gas to ow throughchamber 53 into nozzle 52 as also explained above.

It will be observed that the commingled fluids in the annulus passage 20 vflow in a closed system into' pipe 24 andV out of pipey 5 to andi fromtank 1.A A stung' box 59 is provided to seal off the tubing I6 in relation to tubing 19 to cap the annulus passage 20.

A conventional casing 56 is used in output well 18 and a conventional casingl 57 is likewise used in input well 15. BothV of these casings will be perforated' at the place where the casing contactsy the formation 14. One or more input wells 15 may be used to'supply the output well 18. The input well 15 and out'put well 18 will be spaced from one hundred feet to three hundred feet apart.

Pump 7 will be a triplexpump construction capable of discharging about seventy gallons per minute up to' twenty-five hundred pounds per square inchpressure and the average pressure used `will be about seventeen hundred4 lifty pounds per suare inch pressure. Therefore operating under seventy gallons per minute discharged into line 12v at seventeen hundred fty poundsper square inch pressure I will use a'ninety horsepower internal combustion engine'to drive the pump 7`.

, In theaverage oil well' there may be found enough gas to run this engine and if so I will use pipe line 58 having connections with the engine, not shown, and the casing's 56 and 57 and also with the tank 1 atV the uppermost portions thereof in each case. Otherwise I will use butane to run this prime mover, or an electric motor may be used in oil elds where electricity is available.

The said seventy gallons per minute of water discharged by pump 7 will be used to feed the input well pipe 13 to discharge about thirty ve gallons per minute into the formation 14 through this input well 15 and the remaining thirty-tive gallons per minute will be used as a power fluid or motivating medium in output Well 18 to operate the jet pump 17 located therein. I have above described the piping means or system to distribute this said seventy gallons per minute of water, heated in tank 1 to about two hundred degrees Fahrenheit, to input well 15 and output well 18.

One of the important discoveries I have made to increase the production of oil is to overcome the present conventional oil eld practice of providing means such as gravel pack or the like to hold out sand from entering into the output well in order that the conventional reciprocating rod pumps would not become sanded up. I overcome this erroneous practice by removing the sand as fast as it `comes into the oil well, and I let the sand come freely into the oil well rather than to hold the sand out from coming into the oil well. By so doing I prevent the fines or tine sand from building up in the area in the formation 14 surrounding the well 18 and shutting off the oil fromv entering the well 18. Thusly I welcome all the sand to now come into the output well 18 and by so doing I provide a free flow of oil and sand into the output well 18 and I cause the oil and sand to be removed to the surface simultaneously and continuously as fast as the sand comes into the output well 18, and by so doing I get a surpringly increase in oil production over that of the conventional methods.

But in order to efliciently remove this sand and oil, which is in a commingled state, I have discovered that I have to provide a certain specific velocity of fluid in the jet pump 17, or I should say in the venturi-tube located in the jet pump 17, or the jet pump will not work satisfactory. The velocities which must be used are as follows:

In a 500 well the velocity of the power iiuid is about 19,560 feet per minute; and in a 1,000 foot oil well, the velocity of the power fluid is about 27,350 feet per minute; and in a 2,000 foot oil well for example, the velocity of the power uid will be 33,900 feet per minute; and in a 3,000 foot oil well, for example, the velocity of the power fluid will be about 42,000 feet per minute.

I have used these said uid speeds in actual oil field tests and tind them practical as applied to raising oil, water, and sand from deep deposits in the earth.

An essential function in removing sand from deposits in the earth is to keep the sand moving continuously from the formation 14, as contrary to an intermittent action such as is found in a conventional reciprocating rod oil well pump.

This continuous sand entraining action serves to prevent quantities of fme sand from building up as a barrier surrounding the output well 18 and thusly shutting off the inward flow of oil thereto.

To lessen the abrasive action of the sand entrained into the jet pump 17 and upon nozzle 52 thereof, I circulate four to tive volumes of clear hot water as a motivating fluid to intermingle with one volume of fluid entrained from the formation 14 and containing a large percentage of tine sand.

For example, the area of the orifices of nozzles 51 and 52 will be made such so that when thirty-live gallons of iiuid 1s being circulated through the jet pump there will be seven to nine gallons per minute entrained from the formation 14 into the annulus passage 20 of the system.

The above mentioned thirtyiive gallons per minute of .6 iluid is the iiuid used in the jet jump 17 as my motivating fluid or water and it is heated so that in addition to its entraining function, it is also utilized for heating the formation 14 and augments the ow of oil and tine sand into the output well 18. The pressure set up by the ow of water out 0f the input well 15 onto the formation 14 causes oil to be moved in formation 14 toward and into output well 18 and it also causes loose sand to be moved together with the said oil. This heated water also augments the separation of the oil and water inV tank 1 in an efficient manner and by this action allows the water to be used over again as the motivating medium to entrain oil, sand and interstitial water from the formation 14 in a continuous and constant method of production, through means of a closed system arranged to automatically function as a whole, as contrary to an inter-v mittent functional method of recovery. An important function of this method is the provision for the continuous and constant removal of sand out of output well 18 on the basis of my findings that it is as equally important to provide for the above described removal of sand in the production of oil as it is to provide for the production of the natural oil. As'above stated the present conventional oil eld practice is to do everything possible to keep the sand out of the output well, whereas in my new result I provide every means to remove the sand out of the immediate'area surrounding the output well.

What I claim is:

l. A process for the secondary recovery of petroleum uids from a subterranean formation having therein an output well and an input well spaced therefrom comprising: providing a continuous iiow of heated liquid into and out of said output well thereby heating the formation adjacent the output well and the petroleum fluids therein, causing said flowing liquid during its passage from said output well to How at a linear velocity suflicient to entrain therein and convey therewith petroleum iiuids and entraining in said llowing uid and conveying thereby petroleum fluids from said output well, withdrawing liquid mixed with petroleum fluids from said flowing liquid during the passage of the latter from said output well, introducing additional heated liquid into said flowing liquid during passage of the latter into the output well, introducing into said input well heated liquid at a suiiicient rate, temperature and pressure to thereby heat said formation between said wells and the petroleum liuids therein and to drive a volume of said petroleum fluids into said output well, said steps of introducingheated liquid into said input and output wells being performed to jointly cause the flow of petroleum uids from the formation into said output well.

2. A process for the secondary recovery of petroleum uids from a subterranean formation having therein an output well and an input well spaced therefrom comprising: providing a continuous ow of heated liquid into and out of said output well thereby heating the formation adjacent the output well and the petroleum fluids therein, causing said flowing liquid during its passage from said output well to flow at a linear velocity sufficient to entrain therein and convey therewith petroleum fluids and sand particles and entraining in said iiowing liquid and conveying thereby petroleum fluids and sand particles from said output well, withdrawing liquid mixed with petroleum uids and sand particles from said flowing liquid during the passage of the latter from said output well, introducing additional heated liquid into said flowing liquid during passage of the latter into the output well, introducing into said input well heated liquid at a sutiicient rate, temperature and pressure to thereby heat said formation between said wells and the petroleum fluids therein and to drive a volume of said petroleum fluids into said output well, said steps of introducing heated liquid into said input and output wells being performed to jointly cause the flow of petroleum fluids from the formation into said output well.

3. The process of claim.4 "1 wherein the liquid introduced intothe inputl and output wells isY at a tempera-- ture lofl atleast-230 F. and' the flowing liquidl andfth'e, withdrawn liquid removedV from said output wellfis atl a temperature of about 200v F. i

4. The process of claim 1 wherein saidV linear velocity is at least 19,000 feet per minute.

5. The process of claim 1` wherein.` said linear velocity ranges between- 19,000 and 42,000 feet per minute.

6. The process of'claim 1 wherein thfheatedfliquid i's introduced'into said output well at a, pressure exceed ing the hydrostatic pressurein said output well by from 1500 to 2500 poundsper square inch.

7. The process of' claim l wherein saidfcontinuousow of liquid in said outputl well is effected by continuous-r circulation of liquid in a closed system.

8. A process for recovering` petroleum lluids from a subterranean formation havingspaced output and input wells therein comprising: introducing into said input well a heated liquid at a rate, temperature andy pressure sufcient to heat said formation between said wells and the petroleum iluids therein and to driver the latter into said output well, continuously circulating into. and out of the output well in a vclosed system heated liquid ata presf sure in excess of the hydrostatic head of the output well thereby heating the formation adjacent the output well and the petroleum fluids therein, producing in said output well with a portion of sa-id`excess pressure ow of said circulatingliquid'at au accelerated' linear velocity sufiicient to thereby entrain and convey therewith petroleum uid'sirr said' output well; removing. from -said accelerated How of liquids'aid entraineduid's, introducing additional' heated liquidi into said circulating liquid in sufficient quan-- tity andpressure to-ieplace said removed fluids and to maintain saidl quantity and pressure of fluid `circulating in said'closed' system.

neferencesfcited in the me of thisv patent UNITED. STATES PATENTS OTHER REFERENCES Uren: Petroleum ProductionA Engineering Exploitation, second edition, Pub. 1939 by McGraw-Hill, pp. 452 and 453'.

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