US2874780A - Oil well process and apparatus - Google Patents

Description

Feb. 24, 1959 R. J. GERTZEN on. WELL PRocEss AND APPARATUS Filed Nov. 5, 1956 1 m 2 .LF-

. 2,814,780 oupvvnLL Pnocnss AND APPARATUS.

Bignardi, Gertzen, 'Cut Bank, Mont., vassgnor to Union Dil vv Cmnpany of California, Los Angeles, Calif., a corporation 'ffCalifol-nia ppuliationNovfenlher 5, 1956, Serial No. .629,519 t clans.- toi ite-1015 lhis invention relates to improvements in. an oil-well process. and .apparanls ano particularly to improv-ed co bination of well tubing. eas anchor, .and bottoni hole pump. in which the process. of this invention. for in: iectins. fluids into and reino .ne lluids from an Under.- arouno. formation may be c... Ad out- ?anticularlv. the present invention is aprilieable in the liquid. treating of underground stratasnch as the acidizins of limestone iorniations, without the removal and :rerunnins of the production Ytubing- Although many oil. and gas producing formations are essentially sandstone or similar -pcrineahlc .strata containing littleif. any limestone and are thus relatively unaueeted .by mineral acids, some oil and sas .is found in limestone .or other calcareous .formations 1t .is Common to treat such limestone formations with strong mineral acidsin cruento enlarge the. bottom of the` `Woll 'bore and radisson/e part of; Athe borehole Walls as well 'as internal parts ofthe formation Ain order to increase .its permeability. and the, productivity vof the wel-l. Custorrrarilyv such acid treating inVQlzVS. lh? :icrlllillatiollwof PIU# ductionof oil. and gas from the we ll, the removal of sucker rods and bottom lnolc pump. the rernoval of the pumpior production tubingam .its Perforated SaS auch?? atnthe"`bottom `endfof the tubing, disconnection of the gasanehor, andf then the rerunnins of the production tubing hack, intothe hole. Theacid is therlrun into the well" bore; through the production tubing and discharged at. vthe bottom .or the well here. whereA it contacts and reacts with the limestone formation. y,Such acid Vis in@ hibted'against reaction with ferrous metals in any of the ,welllsnown manners, such` as the dissolution therein of. ,arsenious acid, soluble arsenate and arsenite salts, organic nitrogen bases, mercaptans, etc. After treatment the `production tubing is pulled from the hole, the gas anchor is reconneeted,` thetubingstring `is rerun into the hole, .theV sucker, rods `and bottom -hole pump are replaced in the production. tubing, Aexcess acid is 4then .pumped out of the. hole, and finally `crude petroleum is pumped from the thus treated formation.

4The `conventional, treatment as above detailed obviously requires three round trips in the hole; that for the re.- moval and reintroduction of the sucker rods and pump, for the production tubing, land for the acid line which usually comprises the production tubing. This `extensive handling. of theproduction tubing two times. is exceed.- ingly time` consuming landv therefore v ery expensive and may well run to over `$300 to $400 per well treatment. `Other liquid treating processes for permeable formations in general also frequently involve such extensive removal and'replacernent of well apparatus.

It is therefore a primary object of this invention to overcomeY thes'e objections and .provide for a more rapid process for liquid treating of permeable underground formations without the removal `of the pump orproducl tion tubing.

It is a spe'ei'c .object of` :this invention to provide a process for liquid treating permeable formations pene- United States Patent O "ice 2,874,780 Ps-teniet! lieb Q4., litttrated by a well bore such as acidizring a calcareous stratum, Awhich comprises removing the bottom hole pump and sucker rods, shutting off the open perf'orationsv in the gas anchor while it remains the bore, then opening speciallvprovided pefforations at the bottoin o the lgas anchor, then injecting the treating lfluidfo acid into-the formation ythrough the production tubing and through these lower perforations.

Another'specific object is to provide an improved production tubing string and'gas anchor apparatus which permits the acidizing or other liquid treating of subterranean `limestone formations merely by removing and r'erunning thesucker rods and the bottom hole pump.

Other objects and advantages of the presentinventon will becomeA more apparent to those skilledvin the art as the Vdescription and illustration thereof proceed.

Y Briefly the present invention comprises an improved well production apparatus irl which the production or pump tubing string is provided at its lower end with an improved gas `anchor` structuretprovided with the cusstomary perforations at its upper en d andin addition to `special perforations at its lower en d in conjunction with a longitudinally actuated valve Ainn'nediately above these perforations. In the process of this invention the specially designed pump and sucker rods are removed from the production tubing and gas anchor, an open` ended dummy pump cylinder and an imperforate tubular .extension vthereof provided at its lower .end with a cupV plunger on its exterior surface is landedrgin the primary pump seat `by means of either the sucker .rods Aalone or a sandline extending downwardly through the, pump tubing.r This closes the upper perforations of the gas anchor and permits lipid ilow downwalldly through, 'the production tubing, ldownwardly through the pump cylinder and tubular extension, through the longitudinallylaoting valve into .the bottoni Perforated VSection ofl the vgas anchor, andthrough these lower .perforations into contact with the formation- Tlile production tubing remains at all times in the boreholeL Following treat.- nnent .of the, formation with `the injected lluil, the dummy pump cylinder and its imperforat'e tubular extension arie removed vfrom the hole, `thensucker rodsand the `bottom hole Pnmnwith its perforated lower rhino intake portion are rerun into the hole, and the" longitudinally lactyins valve elernent above the lower perforations is closctl by means of `a longitudinally acting valve element suspenned from said como b v means of an hnpcrforatc Solid extension. Pumpingraction `is started, excess treating Huid such as acid is removed from the hole, and the production of the well begins. The fdouble round trip in the hole of the production tubing Previously required to remore and replace the gas anchor is eliminated. The improved design of the gas anchor and bottom hole pump comf b ination according to this invention permits these ad.- vantages. v

The present invention will be more readily understood Y by reference to the accompanying drawings in which:

Figure 1 is a vertical detailed view in partial cross section of the lower end of a borehole drilled into and through `a calcareous o r other formation to b e treated and in which the improved gas anchor and bottom hole pump of this invention is employed, and i Figure 2 shows the same well bore with the open-ended dnrninv porno cylinder landed at'the punir, Seat so that a fluid may be injected into the formation through 'the pump tubing.' The description of the drawings is specifically directed to the acidizing of calcareous' strata for purposes" of example. It should be understood ythat 'the 'invention may be applied to the `treating `ofnnderground formations f any kind with an injected uid. A 'l Referring now more particularly to Figure 1, a calcareous subterranean stratum containing oil and gas is penetrated by a well bore 12 whose walls are supported by well casing 14 and the bottom of which is provided with a cement seal 16. The calcareous formation 10 is underlain and overlain respectively by impermeable rock strata 18 and 20. Throughout the producing interval of the borehole penetrating permeable stratum 10, casing 14 is provided with a plurality of perforations 22 through which the oil and gas flows into the well bore and stands up in the annulus surrounding the gas anchor 28 forming liquid level 24. The oil and gas are separated in this annulus at level 24, the gas owing upwardly around pump tubing string 26 to the surface where it is removed from the casing head in the conventional way, and the oil iiows into the upper end of gas anchor 28 through the upper perforations 30 forming liquid level 31.

The gas anchor portion of the production tubing is that p ortion which lies below pump seat 32. Bottom hole pump 34 is suspended in the upper portion of gas anchor 28 by means of pump seat 32 and is provided with a lower cylindrical perforated oil intake extension 36 into which the oil below level 31 flows. It is picked up by pump 34 and pumped upwardly in the annulus between sucker rods 38 and pump tubing 26. It is removed from the top of the pump tubing and sent to production tanks in the conventional way.

The improved gas anchor according to this invention includes perforations 40 disposed at the lower extremity of the gas anchor, a seating nipple 42 concentrically disposed within the gas anchor immediately above lower perforations 40, a cup plunger 44 whose lower end is closed at 54 is suspended by means of solid rod 46 from the bottom of the pump so that plunger 44 forms a fluidtight seal in the seating nipple and closes off lower perforations 40 at the bottom of the gas anchor when the subterranean formation 10 is produced.

When a treating tluid is to be injected into the producing formation 10, as in the case of acidizing a calcareous or limestone oil-producing formation, sucker rods 30 are pulled upwardly unseating bottom hole pump 34 and the dependent structure from pump seat 32 and the whole mechanism is drawn to the surface through pump tubing 26. This opens seating nipple 42 and prepares the well for the introduction by means of the sucker rods or a sand line only of other equipment through the pump tubing preparatory to injection of treating uid.

Referring now more particularly to Figure 2, the same elements of the same formations 10, 18, and 20 are shown together with the casing, pump tubing, and gas anchor elements described in connection with Figure l. In this case a weighted dummy pump 34a, a hollow cylindrical element open at its upper end, is landed at pump seat 32 by means of either the sucker rods or in this case a sand line 50. A hollow imperforate tubular extension 52 extends from the bottom of dummy pump 34 downwardly through the gas anchor 28 and is provided at its lower extremity with a second cup plunger 45 whose lower end is open. The serially connected dummy pump 34a, tubular extension 52, and cup plunger 45 forms a conduit open from top to bottom for fluid flow. Cup plunger 45 seals against the internal surface of seating nipple 42 while the upper part of the gas Vanchor is sealed at pump seat 42. The treating liuid,

such as inhibited acid, ows downwardly through tubing string 26 around sand line 50, ows downwardly through dummy pump 34a in the direction of the arrow, through tubular extension 52 and cup plunger 45, and out through the lower perforations 40 at the bottom of gas anchor 28. The fluids then pass by displacement upwardly through the annulus surrounding the gas anchor and into the permeable oil producing formations through perforations 22 in the directions indicated by the arrows. The acid is thus displaced back into lthe formation where it partially dissolves the calcareous materials so as to increase the permeability to fluid flow.

After injection of the acid and completion of the treatment, dummy pump 34a, the tubular extension 52, the cup plunger 45 are pulled to the surface through the pump tubing by means of sand line 50. The bottom hole pump 34 and its solid extension rod 46 and cup plunger 44 are replaced as shown in Figure 1 at the bottom of the production tubing within the gas anchor. The bottom of cup plunger 44 in Figure 1 is closed by means of a plug 54 or otherwise so as to prevent fluid tiow through it thus shutting off lower perforations 40. Reciprocation of sucker rod 48 actuates bottom hole pump 34 and pumps liquid from the annulus within the casing and around the gas anchor in the manner described in connection with Figure l from the borehole to the surface.

A complete acidizing operation has been described above and it should be noted that at no time was the pump or production tubing disturbed in the hole. By means of the modified gas anchor described above, the modified bottom hole pump with its extension rodvand cup plunger operating in conjunction with the gas anchor, it is now possible to acidize or otherwise treat a subterranean formation with a fluid in the manner described without removing the production tubing, but merely by removing the bottom hole pump and replacing it with a hollow dummy pump cylinder and a hollow tubular extension which also operates in conjunction with the same gas anchor and seating nipple. The rig time required for acidization or other fluid injection for well bore treating has thus been materially reduced.

As an example of the utilization of the present invention, in well bores drilled in Montana for the production of oil and gas from the Madison lime from a depth of 4000 feet the gas anchor and pump tubing assembly in the particular well was about 40 feet long. The distance between the pump seat and the seating nipple was slightly over 23 feet. The seating nipple was 12 inches long fabricated from 1.50 inch diameter extra heavy pipe welded at' its upper end by means of a funnel-shaped fitting to the inner wall of the gas anchor about 17 feet from the bottom. A plurality of 0.5 inch holes were drilled below the seating nipple and uniformly spaced around the bottom of the gas anchor. A 1.50 inch cup plunger plugged at its lower end was connected by means of a 0.75 inch steel rod at the bottom of the pump body. The perforated tubular extension comprising the pump intake consisted of a 1 inch schedule 80 tube closed at its lower end at the point of attachment of the 0.75 inch rod and provided with a plurality of perforations through which the oil iiowed to the pump intake. The dummy pump cylinder was provided with a hollow 1.50 inch cup plunger with its lower plug removed connected to the bottom of the dummy pump by means of a 1 inch schedule 80 tube about 16 feet in length. The dummy pump cylinder comprises a 2 inch schedule pipe open at its upper end and provided with exterior means for engagement in the pump seat in the same tting at which the pump is landed. This equipment was employed in the acidizing of a well in the Cut Bank field in Montana in which 500 to 4000 gallons of inhibited acid were introduced into and the excess removed from an oil well drilled into the Madison lime. The entire acid treating operation required only four hours, whereas previous acidizing treatments'in this same area and using conventional practice required as much as 16 hours in which the production or pump tubing was removed and rerun twice.

It is apparent therefore that the present invention has effected a substantial improvement in they acid treating of wells drilled into calcareous oil-producing formation.

It is obvious also that the present invention may as well be applied to treating other formations with other fluids in the same manner as herein described and that the same :advantages in time and expense are realized.

adjacent the upper end thereof and at least one lower aperture extending laterally through the walls and adjacent the lower end thereof; a pump seat disposed within said body member above said upper aperture; a well pump supported within said body member on said pump seat; a perforate tubular member extending downwardly within said body member from the intake port of said pump; a valve seat disposed within said body member above said lower aperture and below said tubular member; a valve element in register with said valve seat and sealing the lower end of said body member above said lower aperture; and an imperforate connecting rod having its upper end affixed to said pump and its lower end allxed to said valve element, whereby when said pump is seated communication between the well fluid producing portion of the well bore and the interior of said body member is only via said upper aperture but when said pump is raised said communication is also via said lower aperture.

2. An apparatus according to claimv 1 wherein said actuated and whereby said pump, said tubularV member,

said connecting rod and said valve element may be pulled from said body member, thereby opening said lower aperture into llow communication with said tubing string.

4. An apparatus according to claim 1 in combination with a cylindrical dummy pump open at its upper end and adapted to be seated in said pump seat, a hollow. imperforate tubular extension open at its lower end depend ing from said dummy pump forming an open ended conduit extending from above said pump seat to below said valve seat, and a valve element at the lower end of said tubular extension adapted to register with said valve seat, whereby said dummy pump and tubular extension may be disposed in said body member thereby closing said upper aperture and opening said lower aperture to communication with said tubing string and permitting fluid introduction through said string and said body member into the surrounding permeable strata.

5. An improved gas anchor and fluid pump for producing valuable tluids from underground permeable strata penetrated by a borehole which comprises an elongated tubular body member attached at the bottom end of a tubing string extending through said borehole and provided at its upper end with at least one upper perforation and at least one lower perforation adjacent its lower end, a pump seat disposed on the inner surface of said body member above said upper perforation, a valve seat disposed on the inner surface of said body member above said lower perforation, a reciprocating bottom hole pump within said anchor attached to said pump seat with its fluid intake below and its outlet above said pump seat and reciprocated by means of a sucker rod string extending through said tubing string, and a longitudinally acting valve element suspended from the lower end of said pump by means of an imperforate connecting rod and in register with said valve seat to close said valve when said pump is seated in said pump seat.

6. An apparatus according to claim 5 'wherein said longitudinally acting valve element comprises a cup plunger at the lower end of said connecting rod and said valve seat comprises a seating nipple open at each end and connected at its upper end to the inner wall of said body member above said lower perforation by means of a funnel-shaped element.

References Cited in the file of this patent UNITED STATES PATENTS 2,186,349 Simmons Jan. 9, 1940 2,307,557 Woodmansee Ian. 5, 1943 2,440,506 Furse Apr. 27, 1948 2,749,989 Huber June l2, 1956 2,776,013 Tausch Jan. 1, 1957

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