US2309697A - Well cleaning - Google Patents

Description

Feb. 2, 1943. N. E.'GUNDERSON WELL CLEANING 3 Sheets-Sheet 2 Filed Dec. 26, 1940 v awwww 0 Patenied Feb. 2, 1943 WELL OLEANIN G Norris E. Gunderson, Mishawaka, Ind., assignor to Layne-Northern Company, Incorporated, Mishawaka, Ind., a corporation Indiana Application December 26, 1940, Serial No. 371,659

Claims. (01.166-20l This invention relates to well cleaning, including pressure vacuum means for clearing the well screen and adjacent surrounding structure, or interposed aggregate and surrounding structure, and may include means and methods for chemical treatment either hot or cold in connection therewith.

In certain types of well, a bore is dug from the surface of the ground into the water or oil bear-.-

ing sands and usually cased ofi to the sands. Below the lower end of this casing the bore forms a chamber in the sands for the reception of gravel or other strainer aggregate, this chamber often being dug or enlarged as by mechanical or hydraulic reaming. A well column, of smaller size than the well casing, with a depending screen ordinarily of the same diameter as the column, is lowered to bring the screen into the chamber, the casing in some cases being mainsand and silt, which should be removed before the well is ready for service.

Also after wells have been in use'for some time there is a tendency in some cases for the strainer structure to silt up and seriously impair flow, and in other situations a deposit of chemical, electrolytic or other nature forms on the scren, and/or the surrounding aggregate, it having been found in some instances that this deposit has substantially solidly filled a major part of the screen interstices and the well capacity has been reduced so much that the well is worthless.

The present invention contemplates means and methods for remedying such situations, improving well flow, and restoring wells to usefulness.

The objects of the present invention are to provide means and methods for;

Accomplishing segregated screen areas to localize treatment;

Establishing pressure and vacuum action respectively on said segregated screen areas;

Treating a segregated screen area with acid or other suitable chemical to efiect loosening on disintegration of adhering substances, and if desired, continuing such treatment into the surrounding aggregate, or structure;

Heating the treating chemical in such areas to accelerate the action, or heating such areas leading downward along the column 23, and,

alone should chemical treatment not" appear indicated; and for Combining the actions of heat, chemicals, pressure, and vacuum.

A'further object is to improve the detail of the devices employed.

The means bywhich the foregoing and other objects are accomplished and the method of their accomplishment will readily be understood from the following specification upon reference to the accompanying drawings, in which:

Figs. 1 and 2 are respectively sectional elevations of the upper and lower portions of a well, showing the preferred type of apparatus in use therein.

Figs. 3 and 4 are respectively similar sectional elevations showing modified forms of the apparatus.

Referring now to the drawings in which various parts are indicated by numerals:

II is the casing of a well bore extending from the surface of the ground into the liquid bearing strata I2 of a well, in which strata the well bore forms a chamber l3. I5 is an inner casing which has been cut of! above the level of the strata. l2 and sealed adjacent its upper end to the casing It as by a concrete collar 11. Secured to the lower end of this casing is a screen I9 which depends into and is ordinarily coextensive in length with the depth of the chamber [3, a portion only of the upper end of the screen being here, shown. The chainber l3 around the screen I9 is filled with gravel or the other aggregate 2| which serves to support the sand wall of the chamber and which with the screen completes the desired strainer.

Disposed above and within the well and extending into the screen I9 is pumping appara tus which preferably includes a motor 22, and a depending pump discharge column 23 carrying at its lower end a pump 24 from which an open end suction pipe 25 depends. 26 is a lateral continuation of the upper end of the column 23, and 21 a valve controlling discharge therefrom. 28 is a return flow line leading downward from the pipe 26 along the pump column, and 29 a control valve therefor. 30 is an auxiliary line for feeding in steam and/or chemicals, this line also preferably cross connected into the return flow pipe 23. 3| is a control valve.

32, as and as are heads which shiftably fit within the screen I! and are provided with flexible sealing means 31 as heavy discs of soft rubber projecting beyond the periphery of the heads into intimate contact with the inner surface of the screen, these discs serving to seal the heads against flow along the screen, the heads being spaced apart to form chambers 39 and 4|, separated by th head 33, and respectively subject to pressure and suction. The heads 32 and 33 are annular and lit around the pump suction pipe 25, to which they are securely attached and sealed, forming with the screen, the chamber 33 around the suction pipe. The suction pipe ex- 5 tends past the head 33 and opens into the chamber 4| between the heads 33 and 35. 7

43 are bolts, fastened as by nuts 45 to th three heads, to complete the fastening and spacing of whichparts having like function are designated by the numeral previously used with the addition of the letter "A; 23-A is}. short return flow line which leads laterally from the pump column 23-A adjacent the pumpfl-A, flow through this line being controlled by a valve.

29-A having a valve stem extending upward to the surface of the ground, there being no steam line corresponding, to the line 30 shown, but such line may obviously be installed as in the preceding showing. Otherwise the structure as shown is substantially identical with the showing of Figs. 1 and 2, except that cup leathers 3'I-A are substituted for the disc rubber 31.

Fig. 4 shows a further modified form of the device in which parts having like function are similarly designated by the numeral previously used with the added letter B. In this form, the suction pipe 25-B continues through heads 32-13, 33-3, and 35-3 to form supports and spacing means for all of them, the pipe being closed at its lower end as by a cap 43, and having lateral openings 50 to establish suction commu'nication with the chamber ll-B between the heads 33-B, and 35-3.

Each of the heads comprises a solid disc 5|, 'and a disc 53, which is perforated to prevent trapping liquid therebetween. The discs of each head carry an interposed sealing ring 55, preferably triangular in cross section and of soft rubber, which projects beyond their peripheral edges and is adapted to be moved into sealing contact with the screen by movement of one' disc toward the other, and a similar ring 51 to seal the head around the suction pipe.

Collars 59, rigidly secured to the suction pipe 21-B, limit separation of the discs and movement of the heads along the suction pipe. The

solid discs 53 are movable discs, the perforated 55 discs preferably being tight around the suction pipe. Either may be of metal or wood, preferably, however, the movable solid disc 5! of the central head 33-13 is of woodso that it will tend to float away from the perforated disc which is preferably metal, whereas the solid disc SI of the upper and lower heads 32-3, 33-3 are preferably of metal so that they will drop away from the perforated heads when pumping is shut down and thereby loosen the sealing rings 55 to permit easier shift of the pumping structure along the sleeves. The solid discs of heads 32-3 and 33-B are respectively on the under and upper sides of these heads so that they are moved apart by pumping pressure in the chamber 39-3 between these heads, and the solid disc of heads 35-B underlies that head so that it is drawn upward by suction in chamber "-3, to respectively effect sealing of the heads against the screen during pumping.

The return flow line 23-B from the pump column 23-B is slidable through the head 32-13 and is sealed to the head by a compressible asket 6|.

In using the device, as typically shown in Figs. 1 and 2,-for washing the screen I3 and aggregate therearound, the structure including pump column 23, pump 24, and suction pipe 23, is lowered as by a cable 33 and suitable hoisting devices, not shown, and the heads 32, 33, and 35 carried by and supported from the suction 25 are positioned within the screen l3, lowering being sometimes initially stopped when the upper head 32 is at the upper end of the screen, but usually being continued until the lower head 35 is at the lower end of the screen. In either position, the three heads divide of! two limited screen areas separated by the head 33 and limited at the top and bottom respectively by the heads 32, and 35, and establish two adjacent chambers 33 and II, each having a screen wall. Suction pipe 25 is connected into one of these chambers and discharge pipe 23 into the other thereof. As shown,

suction pipe 25 extends without communication or opening through chamber 33 and terminates with its open lower end in lower chamber II, and discharge pipe 28 terminates in upper chamber 39 segregated from chamber ll by the head 33. The motor 2| is started and the pump 24 put in operation drawing liquid continuously from chamber 4| through suction pipe 25 and establishing a vacuum action in such chamber, which vacuum action cooperates with such liquid pressure as may exist in the surrounding strata, to cause inward flow of liquid through that part only of screen 13 which is around the chamber 4|, the restriction in screen area greatly increasing flow velocity and violence. The liquid drawn in by suction and external pressure is discharged through the pump column 23, the continuation 26 thereof and, if the valve 21 be open, to overflow.

The present construction and operation, however, contemplates partial closure of the valve 21 so that back pressure is set up against such discharge, and a head is set up to cause return flow through the pipe 28, which terminates at the underside of the upper head 32, and discharges into the chamber 39. Closure of the valve 21 toward cut-off is continuedsufliciently to set up through pipe 23 a pressure head in chamber 39 which will cause discharge flow therefrom against the external pressure in the surrounding strata, the discharge flow being concurrent with the inflow to the suction chamber 4| adjacent and being diverted by the local reduction in external pressure set up by the suction in the adjacent chamber, and tending to become a circulatory flow through the immediately surrounding aggregate into such chamber. This action is substantially idential in all the forms of the device shown, and in this, and all the other forms, flow along the inside of the screen from one chamber to the other, or otherwise into or from either chamber is substantially sealed off by the heads.

The liquid forced outward from chamber 39 through the screen dislodges accretions from the screen and stirs up the sandand silt in the aggregate and with additional liquid from the surrounding strata is drawn into chamber ll through the adjacent screen section 'and discharged by the pumps to continue a cycle in which a major part of the silt and accretion laden water is discharged at the surface. This action is confined by the head structure to the localized section of the screen opposite the heads and is continued until the pump discharges at the surface runs clear. The apparatus is raised or lowered from time totime as the case may be by incremental distances each equal to the spacing of adjacent heads, as heads 32 and 33, in order that so far as possible the entire screen area will be acted on by both pressure and suction flows, and pumping repeated until the screen is cleared, sections of pipe being removed or added from time to time as necessity requires to permit the raising or lowering.

The operations just described are primarily for cleaning the aggregate and surrounding strata around the screen in well building, and in restoring a well in which the strata has silted up during use and capacity of the well has been thus impaired.

In a large number of cases,however, after a well has been in long use the screen, and often the adjacent material, has become so clogged with'hard deposits that the simple pumping operations just described are inadequate. In such cases the more complete apparatus, such as is shown in Figs. 1 and 2, is lowered into the well, connection is made to the auxiliary line 30 from a suitable source of supply, not shown, and acid or other chemical forced into the pressure chamber 39 through the line. This chemical is allowed to act on the deposits on the screen and if necessary steam is turned in through the same line 30, from a source also not shown, to accelerate the action of the chemical. The chemical thus put in is confined by the heads 32 and 33 to a limited area of screen and its action concentrated thereon. Such of the chemicals as passes outward through the screen drops downward along and in treating contact with the screen immediately below and surrounding the intake to the suction chamber 4|. Pumping action subsequent to acid treatment causes substantially all the acid charged liquid to be discharged from chamber 39 and drawn through the adjacent screenarea into chamber 4|, so that any unspent acid may act thereon, and is particularly advantageous in that the circulatory flow promotes the removal of substantially all the acid and confines discharged acid to the immediate vicinity of the screen areas, insuring, in later pumping, that infiowing liquid will entirely remove remaining acid, and prevent damage to such screen by acid otherwise disseminated and possibly changed into more corrosive form by liquid in the strata.

Operation may be commenced at the top or bottom of the screen, but ordinarily is most ef- In this treatment the chemical may be used cold or steam or other heating resorted to to increaseits efliciency. 'The chemical may be under steam -or other pressure to induce movement through the screen. Both the temperature and pressure set up are observable through the thermometer 48 and pressure gage 41, the pressure reading particularly being indicative of loosening of deposits and resulting cleaning effected by chemical action on the screen.

The screen may be chemically treated throughout its entire length by progressive shift, before pumping is begun, chemical treatment and pumping may be concurrently employed, or chemical and pumping may be alterbulent flow of the chemical used.

fective where started at the bottom and shift Inoil wells where clogging is due to parafiin or other; materials susceptible to heat, steam treatment alone may be used with the pumping to effect dislodgement of clogging materials.

I claim:

1. In means for cleaning a well screen, which includes pumping means and a pipe extending therefrom into said screen; heads carried by said pipe for segregating screen-surrounded chambers, each said head comprising a perforate disc secured to said pipe, an imperforate disc reciprocably mounted on said pipe for movement toward said perforate disc under pressure due to actuation of said pumping means, means limiting separation of said discs, and an elastic ring, as of soft rubber, disposed between said discs in immediate adjacency with the peripheries thereof; said discs extending into adjacency with said screen, one of said discs being peripherally beveled facing the other thereof to establish between said discs a peripherally open groove for said ring, said ring being of greater cross-sectional area than said'groove, whereby initial separation of said discs is promoted and relative approach of said discs under pumping, will effect sealing contact between said ringand said discs and outwardly displace said ring into sealing contact with said screen.

2. A ring in accordancewith claim 1, which has a beveled side complementary to said disc bevel.

3. A head in accordance with claim 1, in which the specific gravity of said movable disc relatively to the submerging liquid is such as to promote disc separation.

4. A head in accordance with which said movable disc is disposed above the secured disc and is of buoyant material.

5. A head in accordance with claim 1, in

which said movable disc is disposed below said secured disc and is heavier than the submerging liquid. 1

. NORRIS E. GUNDERSON.

claim 1, in p

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