US3499486A - Method of and apparatus for treating wells - Google Patents

Description

March l0, 1970 L. B.-SCOTT APPARATUS FOR TREATING WELLS 4 Sheets-Sheetl 1 Filed Feb. 8. 1968 INVENTOR. y/5 66077' BY fg@ March 10, 970 L. B. SCOTT 3,499,486

APPARATUS FOR TREATING WELLS Filed Feb. 8, 1968 4 Sheets-Sheet 2 INVENTOR. LP/5 56077 A Trae/vary March 10, 1970 L. B. scoTT 3,499,486,

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5b Breda 4 A 1 I -42 e 33 i e@ I /7 Z INVENTOR 4x36 V 5. 56077 y BY/-f7 United States Patent O "ice 3,499,486 METHOD F AND APPARATUS FOR TREATING WELLS Lyle B. Scott, South Gate, Calif., assignor to Byron .lackson Inc., Long Beach., Calif., a corporation of Delaware Filed Feb. 8, 1968, Ser. No. 703,983 Int. Cl. E21b 23/00 U.S. Cl. 166-147 4 Claims ABSTRACT 0F THE DISCLOSURE A method of preventing the flow of fluid into a low pressure zone of earth formation traversed by a well bore when said fluid is placed in the well bore, in which a liner is temporarily employed to block off said low pressure zone. Apparatus for performing such method in which the liner is provided with a by-pass valve, opposing packers, and a releasable connection with a running-in string of pipe.

Background of the invention In the performance of certain operations in wells such as oil and gas wells, wherein it is desired to displace fluid into a particular zone of the earth formation traversed by the well bore, the operations are impossible when there is another zone traversed by the well bore at a location spaced from the zone to be treated and having a lower formation pressure if the two zones are in communication with the well bore. Such low pressure zones may be of such a character that it is undesirable to permanently cement the zone 0E, but due to the low pressure condition in such zone, fluid will flow off into the earth at said zone, thereby making it impossible to perform, for example, such operations as may require reverse circulation as a phase of the operation, wherein fluid will be caused to flow down the casing and upwardly through an inner string of tubing, or alternatively downwardly through a string of tubing and then upwardly through the tubing-casing annulus.

On the other hand, the presence of such a low pressure zone interferes with the filling of the well bore with fluid whereby to effectively cause the packing olf of a well packer in the well bore below the low pressure zone, when it is desired to set such a packer to treat a formation below the packer or straddled by the packer and a bridge plug set below the formation to be treated. An example of the need for reverse circulation in the lastmentioned type of well treatment is the need to circulate sand off of the bridge plug which settles thereon or which is placed thereon in certain operations, whereby the bridge plug will be freed so as to be released from anchored engagement with the Well casing.

In any event, the problem involves the fact that the low pressure formation zone will not support a column of fluid in the well casing, but instead such fluid will flow off into the low pressure zone, in some instances where the fluid is drilling mud, contaminating the zone, and in other instances where the fluid may be a treating fluid, causing the undesirable loss of the treating fluid, on the one hand, or the inability to maintain sufllcient fluid head above the packer so as to cause the packer to 'be effectively set and anchored in the well casing, on the other hand. This problem is obviated by the present invention inasmuch as a liner is provided which, during the running of the tools into the well bore on a runningin string of pipe, is placed in a position at which it straddles the low pressure zone and prevents communication between that zone and the well bore, so as to effectively provide an annular space between the linear and the running-in string of pipe in which a column of fluid 3,499,486 Patented Mar. 10, 1970 may be supported while that column of fluid is blocked off from access to the low pressure zone.

A typical problem to be solved by the method of the present invention exists, -for example, in areas where three separate and distinct productive earth zones are traversed by a well bore, and the upper and lower zones are productive and therefore are to be preserved, but these upper and lower zones are relatively low pressure zones while the intermediate zone is one which requires stimulation, but which, following stimulation, will produce at a comparatively high pressure, requiring that the formation pressure fbe well contained following the treating operation. Under these circumstances, it will `be apparent that not only must the upper and lower zones be isolated from the intermediate zone, but also, following completion of the treatment of the intermediate zone, it may be necessary that the well be killed by the placement in the well of a body of weighted fluid which will contain the formation pressure until it is desired that the well be put back on production. Such operations are impossible in the event that the upper zone is in communication with the well bore and is incapable of supporting the hydrostatic column of weighted fluid which will bleed off into the upper zone, reducing the effectiveness of the weighted fluid and also contaminating the upper zone. In such operations, it will be apparent that the lower zone may be effectively isolated from the intermediate zone by the setting of a retrievable bridge plug in the well casing between the intermediate and lower zones; but, in order to assure retrievability of such a bridge plug, it is necessary in some instances that reverse circulation 'be employed to wash sand from above the bridge plug so that the same is free for recovery.

Description of the prior art Heretofore in the fluid treatment of wells, such as in the selective fracturing or acidizing of subsurface earth formation zones, various approaches have been taken in an effort to prevent loss of treating fluids into low pressure sections of the earth, so as to more effectively perform the treating operations by assuring that all of the section of earth has been treated. Soluble solids have been employed, entrained in the treating fluid so as to block the flow of fluid into more permeable or lower pressure regions; temporary sealing elements, entrained in the fluid, have also been employed for such purposes (see United States Letters Patent No. 2,754,910). On the other hand, means have heretofore been provided Whereby a liner may ibe placed at a particular earth Zone within the well bore to block the flow of fluid into that zone While another zone is being treated or for other reasons to prevent the loss of fluid into a low pressure zone (see United States Letters Patent No. 3,067,819).

As distinguished from these prior efforts, however, the present invention contemplates not merely preventing the flow of fluid into a low pressure zone, as in the case of the soluble solid blocking agents or the temporary perforation sealing elements, but also the formation of an annular clearance space about the string of drill pipe or tubing through which the treating fluid is being injected into a selected formation, whereby not only is the selected formation effectively treated but also, without regard to the time necessary to complete the operations and without regard to temporarily halting the flow of treating fluid, reverse circulation may bc accomplished through a region of the casing which is inherently incapable of supporting a fluid column which would enable such reverse circulation. Moreover, the present invention contemplates the formation of such an annulus about the aforementioned pipe string whereby the annular space may be loaded with fluid above a packer, for example, so as to assure that the packer will be effectively set and will 3 be capable of withstanding substantial pressure from below, both during the following the well treatment.

Summary Accordingly, an object of the invention is to provide an apparatus for preventing the flow of flunds from a Well bore into a low pressure zone of the earth formation traversed by the well bore when such fluid is placed in the well bore.

More specifically, an object of the invention is to -provide an apparatus for preventing the flow of fluid into a low pressure Well zone including a liner placed within the well bore so as to seal off the low pressure zone from the well bore, whereby an annular space will be provided between the liner and a running-in string of pipe, on which the usual tools may be run into the well for the treating of another zone within the well.

Still another object is to provide a liner apparatus useful in the prevention of fluid flow into a selected low pressure zone, such apparatus comprising a body and opposing spaced packers forming a seal, whereby to block off a loW pressure zone in well bore, and the body further being provided with valve means whereby fluid pressure differential is balanced when the liner is to be retrieved.

Still another object of the invention is to provide such a liner, wherein a releasable connection is provided with the running-in string of pipe, whereby the line1 may be placed in the well bore at a desired location so as to effectively seal off a low pressure zone, the liner being run into the well bore on a running-in string of pipe having other usual tools mounted therein, and the liner being retrievable by the running-in string of pipe following the treatment of the Well as desired.

Other objects and advantages of the invention will be hereinafter described or will become apparent to those skilled in the art, and the novel features of the invention will be defined in the appended claims.

Brief description of the drawings FIGS. la and 1b are views partly in longitudinal section and partly in elevation showing a well extending through an earth formation, with a liner located at the low pressure zone and the high pressure zone being straddled 'by a packer and la retrievable bridge plug, FIG. lb being a downward continuation of FIG. la;

FIGS. 2a and 2b are enlarged longitudinal sectional views, showing a liner made in accordance with the invention in a running-in condition;

FIG. 3 is 1a transverse sectional view as taken on the line 3-3 of FIG. 2b and looking in the direction of the arrows;

FIG. 4 is a transverse sectional view as taken on the line `4--4 of FIG. 2b and looking in the direction of the arrows;

FIG. 5 is a detail view illustrating the connector means for releasably connecting the liner to the running-in string of pipe and in a running-in condition;

FIG. `6 is a view corresponding to FIG. 5, but showing the connector means in an intermediate condition for closing the liner bypass passage;

FIG. 7 is a view diagrammatically illustrating the manipulative steps for running, closing, releasing, and retrieving the liner;

FIG. 8 is a fragmentary view in longitudinal section and elevation, showing the liner bypass passage closed;

FIG. 9 is a fragmentary view in longitudinal section and elevation, showing the connector means released; and

FIG. 10 is a fragmentary view in longitudinal section and elevation, showing the liner bypass passage re-opened for retrieval from the well.

Description of the preferred embodiment As shown in FIGS.l la and 1b, the present invention involves apparatus whereby fluids, such as well treating fluid, formation fracturing fluid, acid, or other fluids, may

.4 be placed in a subsurface earth Zone A, while such fluid is prevented from entering another earth zone B. In the illustration, the Zone B is above the Zone A and will herein be referred to as a low pressure zone in the sense that fluid will enter the low pressure Zone B from the -well bore W at a pressure less than is required to cause the entry of fluid into the formation A from the well bore. As is customary in many wells, the well bore has well casing C set therein and dening the effective well wall, the casing having been perforated at P1 at the zone A and at P2 at the zone B. These perforations P1 and P2 may be suitably made as by conventional bullet or jet perforators so as to establish communication between the respective Zones A and B and the well bore W. If both zones are productive of well fluids they may be produced through separate conduits, one zone producing through the casing C and the other Zone producing through a tubing, not shown, for example.

As an example of the problems solved by the present invention, it may occur that the zone B is a low pressure but productive zone which should be preserved when it is necessary or desirable to treat the lower zone A which has a formation pressure greater than zone B or has a greater resistance to penetration by treating fluids than zone B. Under these conditions, the zone B must be isolated from the well bore if the zone A is to be treated with fluid. On the other hand, the zone B may be incapable of sustaining in the well bore a column of fluid sufficient to enable treatment of the zone A, since in some operations a packer must be set above zone A and be effectively held anchored by a column of fluid thereabove, and it is impossible to circulate fluid to iwash zone A or wash sand from a packer or bridge plug set below zone A.

A specific problem is illustrated in FIGS. la and lb, wherein a bridge plug assembly 1 is set in the casing C below the zone A, and a packer assembly Z is set in the casing C above the zone A. This bridge plug 1 may be constructed in accordance with the disclosure of United States Letters Patent No. 3,332,494, and typically includes packing cup means 3 carried by a body 4, and adapted to form a seal between the body 4 and the well casing C. Also carried by the body 4 and actuatable in response to fluid pressure acting on the packing cup 3 are anchor slips 5, expansible by a cone 6 when the body tends to move axially relative to friction drag means 7 which prevent movement of the anchor slips 5. The bridge plug also has a running and recovery head S, whereby the plug may be run into the well and located at the desired position to enable treatment of the Zone A and may later be retrieved. In the present illustration, the head 8 is adapted to be engaged by a running and recovery tool 9 carried beneath the packer 2 in a conventional manner, whereby the packer 2 and the bridge plug 1 connected thereto by the tool 9 may be run into the well together on a runningin string of pipe or tubing S, the bridge plug being released from the tool 9 when it is in its desired location, and the packer 2 then being elevated in the well bore W to a location above zone A where the packer 2 may lbe set. This packer is of a conventional type, an example of which is disclosed in United States Letters Patent No. 3,094,169. In any event, the packer 2 includes a packer rubber 11 adapted to form a seal between the body of t-he packer 2 and the casing C when the packer is set, the packer also including anchor slips 12 and hold downslips 13, respectively expansible into gripping engagement with the casing C to anchor the packer assembly 2 in position in the casing C. In some instances the packer 2 is held firmly set and anchored bythe pressure of fluid in the casing C above the packer 2. In order to relieve this pressure by effecting fluid balancing of the packer 2 when it is to be released, an unloader valve 14 is in the pipe string S above the packer 2, such a valve being disclosed in detail in United States Letters Patent No. 3,094,306.

In accordance with the present invention, there is also set in the casing C a retrievable liner assembly L, the purpose of which is to block off the formation B from the well bore while defining with the running-in string S an annular space which is a continuation of the annular space 16 between the casing C and the running-in string S. The running-in string S has a connector member 17 cooperable with means in the liner L, as will be hereinafter more fully described, whereby the liner assembly may be run into the well on the string S and released from the connector 17 when the liner is at the desired location in the casing C. As illustrated in FIG. la, the liner is located at a position at -which it extends through the region of the easing spanning zone B, the liner having packer cups 18 and 19 in sealing engagement with the casing C at locations straddling the zone B. Valve ports 20 in the liner L are closed during treatment of formation zone A, but, as will be hereinafter more fully described, these ports 20 will be opened to balance the pressure across the liner when the liner is to be retrieved.

This liner assembly L will now be more specifically described with reference to FIGS. 2a and 2'b. At its upper end, the liner assembly includes a tubular coupling 21 which supports the rubber or other elastomeric packer cup 18, the coupling being threadedly connected as at 22 to a downwardly extended tubular body 23 which is of indefinite length, depending upon the depth of the zone B to be straddled by the liner. As its lower end, the liner body is provided with a tubular valve housing 24 having the above-mentioned valve ports 20 therein, the valve housing being threaded as at 25 or otherwise made a part of or connected to the tubular body 23.

Reciprocably disposed in the valve housing 24 is a tubular inner body section 26 having an outwardly extended ange 27, the body section 26 being held in assembly with the housing 24 by means of a coupling nut 28 threaded on the housing 24 and having an inturned flange 29 in spaced relation to the lower extremity of the housing 24 so as to limit reciprocation or telescopic movement of the housing 24 vand the inner body section 26. This body section 26 extends downwardly from the housing 24 and supports the lower rubber or other elastomeric packing cup 19 previously referred to; and a tubular connector body 30 is threaded as at 31 to the body 26 and extends down- Iwardly therefrom for cooperation with the connector 17 in the running-in string S, as will be hereinafter described.

Within the housing 24, the body section 26 is provided with sealing ring means at 32 sealingly engageable with the inside of the housing. At its upper extremity, the body section 26 has a valve seating surface 33, cooperable with a valve sleeve 34 which is reciprocably disposed in a bore 35 in the valve housing 24. This valve sleeve 34 has a lower surface 36 cooperable with the seating surface 33 on the body section 26 to close the ports 20 (see FIG. 8) when the body section 26 and the sleeve 34 are in one relative position, the ports 20` otherwise being open (see FIG. 2b) so as to establish communication between the axially extended space outside of the valve housing 24 between the packer cups 18 and 19 and the inside of the body section 26. In other words, when the ports 20 are open, then the pressure across the packing cups is balanced.

The valve sleeve 34 is provided with a seal ring 37 sealingly engaged in the bore 35, and spring means in the form of a coiled spring 38 seating at the top of bore 35 and acting downwardly on the sleeve 34 normally act to hold the Sleeve in a lowermost position at which stops, in the form of radially inwardly extending pins 39 engaging at the upper ends of slots in the valve sleeve 34, limit downward movement of the sleeve 34.

Now it is apparent that the inner body section 26 when in its lowermost position as seen in FIG. 2b, with its flange 27 engaged with ange 29 of nut 28, has its seating surface 33 downwardly displaced from the lower limit of movement of the sleeve 34; but when the inner body 26 is moved upwardly, as seen in FIG. 8, the seat- 6 ing surface 33 will engage the surface 36 of valve sleeve 34 and partially compress spring 38, thereby moving the sleeve 34 upwardly. Thereafter, fluid pressure in bore 35 will provide a force tending to hold the valve means tightly closed.

Means are provided for releasably connecting the connector means 17 in the pipe string S and the connector body 30 of the liner L. In the illustrative embodiment, the body 30 has a bore 40 in which a connector sleeve 41 is retained by a ring 42 welded to or otherwise made a part of the connector body 30. The details of the sleeve 41 are best understood from FIGS. 5, 6 and 7. This sleeve 41 has diametrically opposed Z like slots 43, 43, each slot including parallel slot sections 43a and 43b, and a diagonal slot section 43C extending between the upper end of slot section 43b and the lower end of slot section 43u. The slot sections y43a open upwardly between divergent walls 43d while the slot sections 43b open downwardly between divergent walls 43e. Connector member 17 in the pipe string S has diametrically outwardly projecting pins adapted to fit in the slots 43 as diagrammed in FIG. 7 and indicated by the arrows, and as will be more apparent from the following description of the running and recovery of a liner L.

The liner L is shown in the running condition in FIGS. 2a and 2b, wherein it will be noted that the connector pins 44 are engaged at the lower extremities of slot sections 43a. Thus, as the string S is moved downwardly in the casing C the pins 44 pull downwardly on the connector body 30 and the inner body section 26, the flange 27 of the latter, in turn, pulling downwardly on the valve housing 24 and tubular body 23, so that the liner assembly, as a whole, will move downwardly, with valve ports 20 open.

When the liner L has been moved downwardly in the casing C to a position at which the packer cups 18 and 19 straddle the zone to be blocked olf, say the zone B of FIG. 1, the string S is then simultaneously rotated to the right and lifted, to cause pins 44 to pass through the diagonal slot sections 43C to the top of slot sections 43b, whereupon an upward force will be transmitted from the string S to the connector housing 30` and to the inner body section 26 of the valve means, moving the body section 26 to the position shown in FIG. 8, at which the valve means is closed. Thereafter, the strings S is lowered to any desired location, and the liner L will hang in the casing C due to friction of the cups 18 and 19 on the casing. If desired, additional anchor means may be provided to assist in securely holding the liner L in the desired location. In any event, with the liner L so disposed in the casing C, the casing perforations P2 are isolated between the packer rubbers 18 and 19 and the body of the liner, so that no uid in the casing can pass into the formation B; but the annular space 1'6 between the liner body and the running in string is unobstructed to permit filling of the casing with fluid or the pumping of fluid into the casing, or circulation of lluid through the casing.

When the pipe string S is being removed from the well, the pins 44 of connector member 17 will enter the slot sections 43, and by manipulation of the string may be caused totraverse slot section 43C into slot section 43a, from which the pins 44 may move upwardly. Such upward movement of the pins 44 will cause them to engage an internal shoulder `45 in the valve sleeve 34 so as to pull the sleeve upwardly, opening the ports 20 to balance pressure across the liner. Thereupon the liner assembly may be pulled from the well along with the pipe string S, following completion of a well treating operation now to be described.

Assuming that the well is as shown in FIGS. 1a and 1b, completed through the upper zone B and the lower Zone A, and it is desired to treat Zone A, while zone B is blocked off, the steps are as follows.

First the packer assembly 2, with the bridge plug 1 attached thereto by the tool 9, is connected to the lower end of a length of the pipe string S, including, if necessary, the unloader valve 14. This length of string is then run into the well in the usual manner. The liner L is then installed in the well below a length of the pipe string having a coupling member 17 therein, so that as the string is run further into the well, the liner will be pulled downwardly. Further lengths of pipe string are added and lowered into the well until the liner L is at its desired location, with the packing cups 18 and 19 straddling the zone B.

Thereupon, the string S is raised slightly and rotated to move the inner valve body 26 to the valve closing position and release the connector means 17 from the liner. Next, the pipe string S will be further lowered, until the bridge plug 1 is at its desired location in the well, below the zone A. At this point, the pipe string will be operated to release the bridge plug 1 from the tool 9, as is customary, and the pipe string S will then be raised until the packer 2 is positioned at the desired location in the well above the zone A. Then the packer 2 may be set, as by manipulating the pipe string.

Now the tools are all located in the well so that treating fluid may be placed in the zone A, as by pumping treating fluid from the earths surface to force the iluid into the zone A. If high pressure is required to so place the treating fluid, and the height of the uid column in the casing C is not sufficient to assure that the packer 2 will hold, the casing annulus may be lilled with fluid, such as weighted drilling fluid, to a level above the liner L if necessary, and the zone B will not ybe contaminated by the drilling or other uid in the annulus.

After the treating operation is completed, the pipe string S is manipulated to open the unloader value 14 and release the packer 2, whereupon the liuids in the well bore may be circulated out, as by pumping a iiushing uid down the string S and out of the casing C, such flushing operation washing away any sand or other sediment that has been purposely placed or settled out on top of the bridge plug 1, as indicated at 50.

Then the pipe string is lowered to effect reengagement of the tool 9 with the head 8 of the bridge plug 1, so that the packer and plug are again joined for removal from the well. Upward movement of the pipe string S then results in engagement of the connector member 17 in the connector sleeve 41; whereupon manipulation of the string S will allow passage of the connector member through the sleeve 41 and engagement of the pins 44 with the valve sleeve 34, whereby the valve means will be opened to facilitate the removal of the entire string of tools, including the liner L from the well bore.

Opening of the valve means as just described establishes communication between the space defined between the liner body 23 and the casing C and the annular space between the running in string S and the casing C so that diiferential pressure will not interfere with removal of the liner assembly, the same merely moving upwardly through any fluid in the well casing as such fluid bypasses through the liner body 23, flowing through the valve member 34 about the connector member 17. In order that the connector member 17 may be of sufficient size and strength so as to effectively interconnect adjacent lengths of the pipe string S, it must be of substantial diameter, in the illustrative embodiment leaving only a small annular clearance between itself and the valve member 34. Therefore, in the preferred embodiment, connector member 17 is provided with a suitable number of longitudinally extended grooves 17a constituting iiow passages enabling large volume ow of uid as the liner is moved upwardly in the well casing C.

While a bridge plug 1 has been referred to which is run in and retrieved below a packer 2, it will be understood that the plug 1 may be separately run in some instances, say on wireline equipment as is well known. In any event, the invention has application with or Without a bridge plug in the well, as for example where only the packer must be set, but an upper low pressure zone prevents circulation back to the surface of the earth or loading of the annulus with weighted iluid to assure proper functioning of the packer 2.

IOther changes in the details of the liner or other tools and the method herein disclosed may be made without departing from the spirit of the invention. For example, if a low pressure zone is below the zone to -be treated, the liner L may be turned end for end and run into the well below a packer, such as the packer 2, and placed so as to straddle the lower low pressure zone during treating of the higher pressure zone above.

I claim:

1. A liner adapted to be run into a well bore on a pipe string to form an annular space between said liner and said pipe string, comprising an elongated tubular body having upper and lower axially spaced packer .means sealingly engageable with the well wall, and connector means in said body for releasably connecting said ybody to the pipe string extending through said body, said liner including ports in said body leading from the inside of said body to the outside of said body between said packer means, valve means in said Ibody for opening and closing said ports, said body including an inner body section and an outer body `section telescopically engaged therewith, said inner body section having a seating surface at its longitudinally inner end, said valve means including a valve member in said body engageable with said seating surface when said inner body section is moved longitudinally inwardly with respect to said body, and said connector means including means for moving said inner body section longitudinally inwardly and outwardly with respect to said body.

2. A liner as defined in claim 1, wherein said valve member is reciprocable between a first position engageable with said seating surface and a second position spaced from said seating surface, and said member has means engageable by said pipe string to move said member t0 said second position.

3. A liner as defined in claim 1, wherein said valve member is reciprocable between a rst position engageable with said seating surface and a second position spaced from said seating surface, said member having means engageable by said pipe string to move said member to said second position, and said member and said body having abutting portions when -said member is in said second position for causing movement of said liner as a whole along with said pipe string to remove said liner from the well bore.

4. A liner as defined in claim 1, wherein said connector means includes Z slot means comprising parallel axially extended slots and a diagonal connecting slot, one of said parallel `slots opening endwise in one direction andthe other of said parallel slots opening endwise in the other direction.

References Cited UNITED STATES PATENTS 2,098,494 11/1937 Grant 166-147 2,343,076 2/ 1944 Otis et al 166-127 2,681,705 6/ 1954 Tappmeyer 166--150 2,845,126 7/1958 Brown 166--128 JAMES A. LEPPINK, Primary Examiner U.S. Cl. X.R. 166--150

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