US2054353A - Method and apparatus for shutting off water intrusion through perforated casings - Google Patents

Description

SePt- 15, l936 o. P. YoWELl.

METHOD AND APPARATUS FOR SHUTTING-OFF WATER INTRUSION THROUGH PERFORATED CASINGS Filed April 20, 1956 2 Sheets-Sheet l MMIII..

H H..........l

2 Sheets-Sheet 2 P. YOWELL Filed April 20, 1956 METHOD AND APPARATUS FOR SHUTTING-OFF WATER INTRUSION THROUGH PERFORATED CASINGS Sept. 15, 1936.

Patented Sept. 15, 1936 METHOD AND APPARATUS Foa sHUTTrNG oFF WATER INTnUsroN THROUGH PEB.- FoaATED cAsmcs olney P.Yowe11,wmmer,cauf.,assignor to o. P. i

Yowell Service Company, a corporation of California Application April 20, 1936, Serial No. 75,351

13 Claims. (Cl. 16B-21) This invention has to do in a general waywith oil well operations and is primarily concerned with an improved methodA and apparatus for shutting off water intrusion through the perforated casing in an oil well.

As is well known to those familiar with the art, it frequently happens in oil well practice that the perforated casing which is situated in the oil zone or oil sand and through which the oil is received for removal from the well, may be located in a zone which in addition to the oil sand contains a stratum of water sand from which Water enters the perforated casing to contaminate the oil.

Various types of electrical, chemical and photoelectric apparatus have been devised for locating the regions of water intrusion and after locating such region of water intrusion it is the usual practice to attempt to fill the perforations in the region of the formation surrounding this zone of intrusion with cement. It frequently happens that after this is done it is found that the contamination of the oil with the water continues and the reason for this, I have discovered, is that the small strainer perforations in the casing in the region where they are exposed to Water soon become corroded, forcing the water to migrate from the Water stratum up into the oil stratum so that it actually enters the perforated casin'g at a point spaced remotely from the actual water zone. It therefore becomes a primary object of this invention to devise a method of the class described which may incorporate as an initial step a procedure whereby the actual water stratum which is the sourcev of the contamination, may be accurately located.

In view of the fact that the perforations or vstrainer openings in the perforated casing are comparatively small, and further in view of the necessity of obtaining the maximum penetration l of cement into the formation in order to obtain a positive shut-off of water, my invention contemplates as an additional step under circumstances Where the perforations are small, the formation of new large perforations in the wall of the casingbefore the placement of cement therein.

In order to obtain the maximum penetration of cement into the formation, my invention con templates as a further step the discharge of such cement in the region or zone to be cemented under a substantial pressure and t safeguard against the migration of appreciable amounts of cement slurry beyond the objective zone of cementation due to pressure differences inherent in the formation or due to the pressure under which the cement is actually applied, my invention contemplates the initial placement of cement bridges at the two extremities of the water zone, such bridges extending out into the formation so as to provide a positive seal between the outer surface of the perforated casing and the surroundlng formation at the two extremities of the lwater zone.

The bridge referred to above becomes particularly important in connection with the upper end of the zone to be cemented since it is important that the return of cement into the perforated casing around the cement discharging apparatus be prevented.

Further, to prevent the possibility of cement slurry returning to the perforated casing in the region of the water zone above the point of delivery and thereafter rising in the perforated casing into the region above the water zone, it becomes a further object of this invention to provide a cement discharging apparatus which is equipped with sealing or packing means surrounding the cement discharge conduit and positioned so as to always maintain a seal between the cement discharge conduit and the interior of the perforated casing in the region of the upper bridge.

My invention also contemplates a novel form of cement discharging apparatus equipped with packing means for the purpose referred to above and also equipped with a valve whereby the fluid in the casing may be by-passed up through the cement delivery tubing during the installation of the tool in the well.' This valve is equipped with means for positively closing the same after the pressure discharge of cement has been made whereby the pressure may be held on the cement so applied and back circulation may be set up through that portion of the casing above the tool in order to insure the removal of any cement slurry which may have leaked past the tool into the region thereabove. In this connection my invention contemplates a tool which is equipped with an inwardly opening check valve in the cement delivery pipe through which such back circulation may be maintained.

The details in the procedure contemplated by this invention as well as certain details in the construction of a preferred form of apparatus for use in connection therewith will be best understood from the following description of the accompanying ldrawings which are chosen for illustrative purposes only and in which,

Fig. 1 is a sectional elevation of more or less diagrammatic character, illustrating a perforated casing in an oil well and further showing the manner in which corrosion is set up in the perforations of that portion of the casing which occupies the water zone or stratum;

Fig. 2 is a sectional elevation similar to Fig. 1 illustrating the step of cleaning the corroded perforations;

Fig. 3 is a sectional elevation illustrating the step of forming enlarged perforations in the casing for the discharge of cement from the casing into the formation;

Fig. 4 is a sectional elevation illustrating a casing which has been cleaned and perforated and further illustrating the results '0f the initial operation followed in a preferred procedure of placing bridges at` the two extremities of the water zone;

Fig. 5 is a sectional elevation which shows the cement plug contained within the casing at the region of the upper bridge as having been removed whlch is the condition present in the casing just prior to the final cementing operation; Fig. 6 is a sectional elevation illustrating the final cementing operation and a preferred form of apparatus which may be employed in effecting this operation;

Fig. 7 is a sectional elevation illustrating the final result of my process, the cement contained within the casing having been drilledtherefrom to leave an impervious wall in the region of the casing which occupies the water sand or zone; and

Fig. 8 is a sectional elevation illustrating a 'modified form of cement discharging apparatus.

More particularly describing the invention as herein illustrated and referring ilrst to Fig. 1 which, as pointed out above, illustrates a portion of a perforated oil well casing contained in a water sand or water zone, reference numeral li indicates a bore hole or well which contains a casing vI2 provided with the ordinary slots or screen perforations indicated at I3. Reference numeral I4 indicates a water sand or water zone which is shown as being between two oil sands indicated at l5 and I5.

It will be observed that the perforations in the casing which aresituated in the region of the water zone have accumulated corrosive matter so that they are plugged as indicated by reference numeral I6. These perforations being plugged, cause the water in the zone Ily to migrate in opposite directions along the walls of the bore hole as indicated at I1 and I1' so that the water may enter the perforated casing at a substantial distance from the zone or region in which it has its source. It will thus be seen that if an attempt is made to locate the Aposition of the water sand with any of the conventional water locating means which are lowered within the casing, with a casing such as is shown in Fig. 1,`

of the' formations surrounding the casing at the.

point of iluid'entry.

Various types of apparatus may be employed further movement. y ment of the tubing 20 with its packers 23 and 35 closed off with enlarged perforationsjthrough acuesta for effecting Athis washing operation. In other words, any of the conventional pressure or suction perforation washers may be used. For the purpose of illustrating this step in the process of my invention I have shown in Fig. 2 a washing 5 apparatus which simultaneously combines pressure and suction in two adjacent zones ofthe formation. Since the detailsin the construction and operation of this washer form nopart of the present invention, I 'will make no. attempt 10 to describe its structural details. However, for purposes of clarity the washer may be described as consisting in a general way of a hollow man'- drel or tubing 20 suspended through the medium of a tubing 2| from the surface of the ground. 15` The lower end of the tubing 20 is .shown as be-` ingl provided with a guide shoe 22 and such tubing is provided at extreme end portions with packing members 23 and 24 which are rigidly mounted thereon. The intermediate portion of 20 the tubing slidably extends through a sleeve section 25 which is equipped with a. slip assembly 26 associated with an anchor member 21 adapted to guide the slips thereon, the sleeve 25 also carrying a packer or a plurality of packers indi- 25 cated generally by reference numeral 2l. When this assembly is lowered into the desired position within the perforated casing the slip assembly is released through the medium of a bayonet lock 28 so that the further application of weight 30 causes'the slips to expand into engagement with the inner surface of the casing thereby locking the sleeve 25 and its associated packer against Continued downward move-- where thev tool is located.

In actualcoperation this cleaning procedure is carried out through the entire length of the perforated casing and after such cleaning operation has lbeen completed thewater locating apparatus of any conventional type such as iaf chemical, electrical or photoelectric Watei/ Witch is lowered into the perforated casing and the zone or zones of water intrusion are located.v 55

Assuming conditions such as are ill trated fin g Figs. 1 and 2, this water locating ap ratus will establish the limits of the water zo e as being/ between the points A and B of Fig. 2. g' y As is well known to lthose famil ar with the/60 art, most of the conventional nerforated/"cr strainer casings are provided with' perforations in the form of small Islots or open gs equipped. with buttons, such buttons being i rovidedI `with small slots and in lthe' event this is the' type of casing with which the process is being carried out, it is desirable in order to secure the most positive results. to provide the region of the casing wall in which the water intrusion isto be 70 which a cement slurry can be readily forced into the formation from the interior of theaslng.

For the purpose of providing these enlarged perforations any conventional casing perforator may be employed. Fig. 3 illustrates the Derfo- 75 vper end. The blade is adapted to be swung outwardly into perforating engagement with the casing through the medium of a tongue member 34 which is slidably and pivotally mounted in v, the lower end portion of the groove, such tongue member being actuated during downward movement of the body by means of a releasable anchor member generally indicated by reference numeral 35. This anchor member carries a tail piece 36 slidably mounted on a mandrel 31 and adapted to be latched against movement with respect thereto. 'I'he upper end of the mandrel 31 carries a wedge block or shoe 38 positioned behind the tongue 34 and adapted to wedge the same against the wall of the casing when the tail piece is latched to the mandrel and `the'fbody is moved downwardly relative to the tail piece. The tongue is provided with a casing gripping member in the form of a serrated Wheel indicated at 39; As was pointed out above the particular perforating tool forms no part of the present invention and for a more complete description of its construction and operation, reference is made to the co-pending application of Robert S. Smith, Serial No. 76,567, filed April 2'?, 1936, now matured into Patent No. 2,046,752,

. dated July 7, 1936, which is assigned to the assignee of the present application.

In the perforating step, which, as will be understood by those familiar with the art may be eliminated in the event the perforated pipe or casing is of a character such that cement slurry will readily flow through the openings therein, it is preferable that the perforations be started at a point slightly below the lower extremity B of the zone of water intrusion and that they be carried to a point slightly above the upper extremity A of such zone, these enlarged perforations being indicated generally by reference numeral-40 in Fig. 3.

As was pointed out above, it is a principal object of this invention to provide a process in which the water sand or zone of water intrusion can be positively isolated from the oil sand in the region outside-of the perforated casing prior to the closing off of the perforations Within the casing in the actual Water zone. In other words, my invention contemplates as one of its primary objects the placement or provision of what I may term bridges which surround the perforated casing and are sealed or locked in the formation at the two extremities of the water zone. The placement of these bridges is accomplished preferably by first installing a plug member 50 within the casing at a point below the lower extremity of the water zone and then supplying cement in any conventional way into the casing above this plug, such cement being supplied in a manner such that it is discharged through the perforations of the casing and is forced out into the formation forming a cement plug I within the casing and a cement bridge 52 which surrounds the casing in the oil shale adjacent the water sand. After this plug has been installed, a second plug 53 is placed within the casing at the upper extremity of the water sand which is followed by the installation of a cement plug 54 and an encasing cement bridge 55 which surrounds the perforated casing in the oil shale.

After the cement plugs and bridges 54 and 55 have had an opportunity to set, the cement plug 54 and its supporting plug 53 are drilled from the interior of the casing by means of any suitable drilling apparatus Which leaves the casing open down to the plug 5I and leaves the portion of the perforated casing at the upper extremity of the water zone encased in a cement bridge 55 preferably of substantial length, which positively seals that portion of thebore hole which extends through the oil shale above the bridge from the water sand. The oil shale below the water sand is correspondingly` sealed by the bridge 52. 'Ihe result of this operation is illustrated in Fig. 5, and the next step in the operation entails the placement of cement within that portion of the casing which occupies the water sand under sufficient pressure to completely encase the casing with cement thereby preventing water intrusion. The bridge 55 serves a purpose additional to that pointed out above in that it may be used to prevent the migration of cement slurry back into the perforated casing at a point above the Water zone where it might cause the cementing apparatus to be frozen in the casing or where it might serve to plug the perforations in the region of the oil zone which must be kept clear in order to obtain the maximum oil p'roduction.

In Fig. 6 I show a preferred form of apparatus which may be employed for performing the nal cementing operation, such apparatus being designed to maintain at a minimum the migration of cement back into the casing from the water zone. This apparatus consists of a cement dis-l charge conduit 60 having discharge openings 6|v at its lower end, such conduit being provided with a plurality of spaced packers 62 starting from a point immediately above the discharge end 6| and extending at predetermined spaced intervals throughout the full length of the discharge conduit 60. The discharge conduit 60 is formed of a lengthslightly greater than the distance between the two bridges 55 and 52 and the distance between the successive packers 62 is slightly less than the length of the bridge 55 as observed by the operator when it was installed.

The upper end of the discharge conduit 60 is connected with a fitting 64 which in turn is connected to a cement delivery pipe 65. The fitting 64 is provided with a valve seat 66 which is associated with a valve 61 mounted on the lower end of a Valve stem 68 which is slidably supported in a spider 69 and is biased'toward a closed position by means of a compression spring 10. The upper end of this valve stem is adapted to be engaged by a valve opening stem 1I which is mounted on a spider 12 in the bottom of the tubing 65. With this arrangement it will be seen that the valve may be opened and closed by rotating the tubing 65 in its threads 13 whereby it is attached to the box in theupper'endof the fitting 64. Reference numeral 15 indicates an inwardly opening check valve whichv is positioned in the bottom portion of the tubing 65, the purpose of which will appear from the description of the operation of this cementing tool.v

' discharge end rests on the bottom bridge 5l.

wardly through a tubing 65. 'Ihe cement discharging assembly is lowered down within the casing to the position shown in Fig. 6 at which its A cement slurry of suitable consistency and under a substantial pressure'is then delivered into the these packing members is always contained in the region of the casing surrounded by the bridge 55, thereby maintaining a positive pressure seal between the zone surrounding the region of the casing in which the cement is being applied and the region of the perforated casing above the bridge 55. Since the bridge 55 prevents the migration of cement slurry upwardly along the bore hole into the oil shale it will be seen-that the packing members 62 sealing the interior of the casing in the manner just described, co-operate with the bridge to prevent the migration of cement into the region above the bridge 55 through the interior of the casing.

This cement dischargingy operation is carriedl on until the delivery conduit has been raised a distance corresponding to the distance between the two bridges. When this has been accomplished the conduit 55 is rotated to unscrew the threads 13 a suflicient amount to permit the closure ofthe valve 61 whereby the cement plug so installed is held under pressure.

In order to insure the removal of any cement slurry which may possibly have leaked into the perforated casing above the uppermost packer,

I consider it preferable to next circulate a washing fluid, such as mud or the like, downwardly through the casingfrom the surface of the ground.'such fluid being returned with any cement slurry which may` have accumulated therein through the bypass valve 65. After this has been done and the desired time has elapsed, the cementing tool is vthen withdrawn from the well, leaving the region of the perforated casing which occupies the water sand completely filled with a cement plug and vcompletely surrounded with a wall or. encasement of cement which has been forced out into the formation under a substantial pressure.

The next operation in the event the water zone is situated between two portions of oil producing Ashale or sand, is to drill the cement from the interior of the casing thereby leaving an open pipe provided with perforations in the oil zone to be encased with a water impervious wall of cement 18 in the region of the water zone.

Fig. 8 shows a modified form of cementing apparatus which is preferably designed/ for use where the water intrusion is taking place at the bottom of the hole, since this apparatus ls one in which no particular precautions are taken to prevent the return of cement slurry into the casing around the cement discharge conduit. 'I'his apparatus is shown as comprising a cement discharge conduit 80 having a guide shoe 8| at its lower end and provided with a packing member frozen in the casing 'at theV end of the cementing operation. In the event the zone or region of Water intrusion is at the bottom of the hole, it will be the practice to merely unscrew the conduit 81 from the fitting 86 and leave the remainde v of the tool in the well. In the event this type of apparatus is used for shutting oi intermediate water intrusion.'l it will in the event it becomes frozen in the hole, be necessary to remove it from the casing by a milling operation. Bearing this point in mind, it will be seen that other types of apparatus may be employed for delivering the cement into the casing but to facilitate the removal of the tool and the delivery of cement into the desired zone under a substantial pressure, I consider :it preferable to use an apparatus of the type shown and described in connection with Fig. 6 which emb odies features of novelty that are claimed as a part of this invention.

It will be understood that while I have herein described and illustrated one preferred procedure contemplated by this invention, that various steps of the procedure may be eliminated depending upon the type of casing used and the well conditions encountered, also that while I have herein described and illustrated certain preferred forms of apparatus to be used in the practice ofthis process, that other types of apparatus may be used without departing from the scope of the invention asy expressed in the appended claims.

I claim as my invention:

1. A method for shutting oi intrusion from a water zone through the perforated casing of an oil well which includes: placing a cement plug and bridge in and around said casing at the lower extremityl of said water zone; surrounding saidcasing with a cement bridge at the upper extremity of said water zone; discharging cement under pressure within said perforated casing'near said bottom plug and bridge; and gradually raising the point of discharge of said cement at the same time maintaining a seal within said casing in the region of said upper bridge.

2. A method for shutting off intrusion from a. l l

' the point of discharge of said cement at the same time maintaining a seal within said casing in the region of said upper bridge-thereby lling and surrounding the casing with cement in the region of said water zone; and drilling the cement from lthe interior of said casing after it has set.

3. A method of shutting off intrusion from a water zone through the perforated casing of an oil well which includes: locating vthe upper and lower limits of said water zone; forming a plurality of open perforations in said casing in the region of said water zone; forming cement bridges in the formation surrounding said casing atl the two extremities of said water zone; and forcing cement under pressure into said casing and the formation surrounding same between said bridges.A

"4. A method of shutting oif intrusion from a water zone through the perforated casing of an oil well which includes: locating the upper and lower limits of saidv water zone; forming a plurality of open perforations in said casing in the region of said water zone; forming cement bridges in the formation surrounding said casing; forcing cement under pressure into said casing and the formation surrounding same between said.

bridges and drilling thev cement from the interior of said casing after it has set.

5. A method of shutting off intrusion from a water zone through the perforated casing of an oil well which includes: locating the upper and lower limits of said water zone; forming a plurality of open perforations in said casing in the region of said water zone; forming cement bridges in the formation surrounding said casing at the two extremities of said water zone; forcing cement under pressure into said casing and the formation surrounding same between said bridges; maintaining a seal within said casing in the ref gion of said upper bridge during said last men- 6. A method of shutting off water intrusion through the perforated casing of an oil well which includes the steps of: cleaning the perforations in said casing; locating the upper and lower extremities of the region of water intrusion through said perforations, forming cement bridges in the formation surrounding said casing at the two extremities of said region of water intrusion; and forcing cement under pressure into said casing and the formation surrounding same between said bridges.

7. A method of shutting off water intrusion through the perforated casing of an oil well which includes the steps of cleaning the perforations in said casing-locating the upper and lower extremities of the region of water intrusion through said perforations, forming cement bridges in the formation surrounding said casing at the two extremities of said region of water intrusion; forcing cement under pressure into said casing and the formation surrounding same between said bridges; maintaining a seal in said casing in the region of the upper bridge during said last mentioned cementing operation; and drilling the cement from the interior of said casing after it has set.

8. A method of shutting olf Water intrusion through the perforated casing of an oil well which includes the steps of cleaning the perforations in said casing; locating the upper and lower extremities of the region of water intruf sion through said perforations; forming a plurality of large perforations in the Wall of said casing in said region of water intrusion; forming cement bridges in the formation surrounding said casing at the two extremities of said region of water intrusion; forcing cement underpressure into the casing and the formation surrounding same between said bridges; maintainig a seal within said casing in the lregion of the upper bridge during said last mentioned cementing operation; and drilling the cement from the interior of said casing after it has set.

9. A method of shutting oif water intrusion through the perforated casing of an oil well which includes the steps of cleaning the perforations in said casing; locating the upper and lower extremities of the region of water intrusionthrough said perforations, forming cement bridges in the formation surrounding said casing at the two extremities of said region of water intrusion; forcing cement 'under pressure into said casing and the formation between said bridges; thereby illling such region of the casing and the surrounding formation with cement; maintaining a packing seal in said casing above the point of cement discharge during said last mentioned cementing operation; and then back circulating a washing fluid down through said casing and up through an internal conduit after said cement has been installed.

10. A method of shutting off intrusion from a water zone through the perforated casing of an oil well which includes: locating the upper and lower limits of said water zone; foiminga plurality of open perforations in said casing in the region of said water zone; forming cement bridges in the formation surrounding said'casing at the two extremities of said water zone; forcing cement under pressure into said casin'g and the formation surrounding same between saidbridges through a cement delivery tubingl extending from the surface of the ground; and

maintaining a packing seal between said delivery tubing and said casing in the region of said upper bridge during said last mentioned cementing operation.

11. A method of shutting off intrusion from a water zone through the perforated casing of an oil well which includes; locating the upper and lower limits of said water zone; forming a plurality of open perforations in said casing in the region of said water zone; forming cement bridges in the formation surrounding said casing at the two extremities of said water zone; forcing cement under pressure into said casing and thel formation surrounding same between said bridges through a cement delivery tubing extending from the surface of the ground; maintaining a packing seal between said delivery tubing and said casing in the region of said upper bridge during saidlast mentioned cementing operation and circulating a washing uid down through said casing and up through said delivery tubin'gin the region above said seal after vsaid last mentioned cementing operation.

12. For use in supplying cement under pressure to the interior of a perforated casing for the purposes described: an elongated tubing having a cement outlet at its lower end; a plurality y of packing members mounted on said tube above said outlet in predetermined spaced relation with each other; conduit means for delivering cement into the upper end of said tube; a valve in the upper end of said tube; and means operable by relative rotation between said delivery conduit and said tube for actuating said valve.

13. For use in supplying cement under pressure to the interior of a perforated casing for the purposes described: an elongated tubing having a cement outlet at its lower end; a plurality of packing members mounted on said tbe above said outlet in predetermined spaced relation with each other; conduit means for delivering cement into the upper end of said tube; a valve in the upper end of said tube; means operable by relative rotation between said delivery conduity and said tube for actuating said valve;

. and an inwardly opening check valve mounted OLNEY P. YOWEML.

Images