US3791448A

US3791448A - Well completion method

Info

Publication number: US3791448A
Application number: US00313991A
Authority: US
Inventors: F Schuh
Original assignee: Atlantic Richfield Co
Current assignee: Atlantic Richfield Co
Priority date: 1972-12-11
Filing date: 1972-12-11
Publication date: 1974-02-12
Anticipated expiration: 1991-02-12
Also published as: CA956883A

Abstract

A downhole well tool having at least one aperture therein for communication between the interior and exterior thereof and means for sealably opening and closing said aperture, the means for opening said aperture having means for receiving an opening plug, the opening plug being adapted to receive a bypass wiper, and the means for closing the aperture being adapted to receive a shutoff plug. A well completion method utilizing the tool above-described wherein residual liquid outside the tool is removed by passing a second liquid into the interior of the tool, through the aperture of the tool, and up the annulus between the tool and the wellbore. The second liquid is followed by a third liquid. The third liquid is displaced into said annulus through said aperture by cement, after which the tool is closed.

Description

United States Patent [191 Schuh Feb. 12, 1974 WELL COMPLETION METHOD Primary Examiner-Stephen J. Novosad Inventor: Frank J. Schuh Dallas TeX Attorney, Agent, or FzrmRoder1ck W. MacDonald [73] Assignee: Atlantic Richfield Company, New

York, NY. [57] ABSTRACT Filedi m 1972 A downhole well tool having at least one aperture 21 A L N 313,991 therein for communication between the interior and I I pp 0 exterior thereof and means for sealably opening and closing said aperture, the means for opening said aper- [52] U.S. Cl. 166/291, l66/DIG. 1 {me having means for receiving an opening plug, the [51] Int. Cl E2lb 33/16, E2lb 21/00 opening plug being adapted to receive a bypass wiper, Field of Seal'dl166/291, and the means for closing the aperture being adapted 1 to receive a shutoff plug. A well completion method utilizing the tool above-described wherein residual liq- [56] References Cited uid outside the tool is removed by passing a second UNITED STATES PATENTS liquid into the interior of the tool, through the aper- 2 249 511 7/1941 Westall 166/291 of the and the annulus between the 2:848:05] 8/1958 Williams... 166/291 and the Wellbore- The Second liquid is'followed y 9 3,213,940 10/1965 w H 291 X third liquid, The third liquid is displaced into said an- 3,l30,783 4/1964 Orr 166/289 X nulus through said aperture by cement, after which 3,653,441 4/1972 Tuttle 1 166/291 the {00] is closed. 3,730,267 5/1973 Scott 166/291 X 9 Claims, 4 Drawing Figures PAIfmmrgntemm sum 1 or 2 WELL COMPLETION METHOD BACKGROUND OF THE INVENTION Heretofore, in placing cement between the exterior of casing in a wellbore and the wall of the wellbore, the prior art has employed a bypass plug through which cement can be passed to fill up a lower interval in the annulus between the casing and the wellbore. The bypass plug is followed by a shutoff plug for the lower interval that has been cemented. The shutoff plug is in turn followed by an opening bomb which will open a port above said cemented interval so that cement can be placed in the annulus above said cemented interval. Lastly, a shutoff plug is employed to close said port. Such apparatus is fully and completely disclosed in the Composite Catalogue of Oil Field Equipment and Services, published by WORLD OIL, Gulf Publishing Company, Houston, Tex., 1964, Vol. 2, page 2,154, 26th revision, the disclosure of which is incorporated herein by reference.

Although this apparatus and the method for using same works quite well for conventional completions, in permafrost areas, after a well has been drilled with a freezable fluid such as a water-base drilling fluid, it is desirable to displace the .freezable fluid with a nonfreezable fluid so that any liquid left in the well after completion will not freeze into a solid. The abovedescribed prior art apparatus and method for employing same does not accommodate the displacement of a freezable liquid, particularly when the freezable fluid is heavier than the non-freezable displacement fluid. It is extremely difficult to displace a heavier liquid with'a lighter liquid and to substantially completely remove the heavier liquid since the lighter liquid will tend to finger through the heavier liquid thereby leaving por- BRIEF SUMMARY OF THE INVENTION By'this invention a tool is employed which is particularly adapted to allow for displacement of residual or first liquid from a well. This first liquid can be quite heavy, e.g., the water-base drilling fluid with which the well was drilled, and is displaced from the well by a washing step with a second liquid. The second liquid, which can be freezable, is displaced with a third liquid. Between the second and third liquids a bypass wiper is employed, the bypass wiper being received by the opening plug in the tool. Thereafter the third liquid, which can be a nonfreezable liquid, is displaced into the annulus between the toolv and the wellbore by cement.

The tool of this invention allows the displacement of a light second liquid with a heavier-third liquid down the interior of a pipe string without substantial mixing of the second and third liquids due to the use of the bypass wiper.

This invention also applies to a method as abovedescribed and which utilizes said tool in the manner described so that the exterior annulus of the tool and any piping, e.g., casing, connected to the tool contains either cement or non-freezable liquid, substantially no freezable liquid being left. Further, the substantially complete displacement of heavy first liquid is achieved withoutusing an even heavier second or third liquid, the second liquid actually being lighter than the first liquid and the third liquid actually being no heavier than the first liquid.

Accordingly, it is an object of this invention to provide a new and improved method and apparatus for completing a well. It is another object to provide a new and improved method and apparatus for completing a well in permafrost. It is another object to provide a new and improved method and apparatus for cementing a well. It is another Object to provide a new and improved method and apparatus for displacing undesired residual liquid from a well. It is another object to substantially completely displace residual liquid from a well using liquids that are no heavier than said residual liquid. I

Other aspects, objects and advantages of this invention will be apparent to those skilled in the art from this disclosure, and the appended claims.

DETAILED DESCRIPTION OF THE INVENTION FIGS. 1 through 4 show a tool embodying this invention as used in the method of this invention.

More specifically, FIG. 1 shows the earth 1 having a wellbore 2 therein. The tool according to this invention is shown generally at 3 and is spaced inwardly from the wellbore wall 4 to provide an annulus 5 which is between the exterior of tool 3 (including associated casing) and wall 4. Tool3 is disposed between an upper casing string 6 and a lower casing string 7, the tool being composedof an annular housing 8 having at least one aperture 9 therein so that communication can be established between the interior 10 of the tool and annulus 5. Housing 3 contains an internal recessed portion 11 which carries upper and lower annular sleeve means 12 and 13, respectively. Annular recess 11 is sized so that the inner surfaces 12' and 13' of sleeves l2 and 13, respectively, do not extend into interior l0 beyond the inner surface 8' of housing 8.

Sleeve means l3 is fixed in place over aperture 9 by shear means 14 and sealably isolates interior 10 from annulus 5 by means of seal means 15. Sleeve 13 has a seat 16 upon which rests an annular opening seat 17. Seat 17 is adapted to receive an opening plug as shown in FIG. 2 for shearing shear means 14 and for sliding sleeve 13 downwardly until it abuts stop shoulder 18 thereby opening aperture 9 for communication between interior l0 and annulus 5. Sleeve 12 is carried in recess 11 by a shear means 19 and also carries seal means 20 which is designed to sealably shut off aperture 9 from annulus 5 when sleeve 12 is slid down to cover aperture 9. Sleeve'12 carries annular closing seat 21 which is adapted to receive a shutoff or closing plug (wiper) as shown in FIG. 4.

Upper casing 6 can extend to the surface of the earth or be connected to other casing sections which do extend to the surface of the earth and which are supported somewhere above tool 3. Lower casing 7 terminates at 22 so that a fluid can pass from interior 10' around bottom 22 and into annulus 5 as shown by arrow 23, this fluid passing downwardly from the surface Of the earth in interior 10 as shown by arrow 24. For example, lower casing end 22 can be connected to a conventional float collar and float or guide shoe to allow a conventional first stage cementing operation to be carried out to emplace cement between the casing and wellbore. The first stage cement will not normally rise as high as tool 3 but will stop below tool 3. However, first stage cement can reach to or above tool 3 but the excess cement which reaches tool 3 must be circulated out of the wellbore before it hardens.

With tool 3 in the configuration shown in FIG. 1 aperture9 is sealably closed by sleeve 13 so that any fluid in interior 10 cannot pass through aperture 9 but rather must pass down around end 22 of casing 7. Cement can be passed through interior 10 around end 22 and upwardly in annulus 5 to a point below aperture 9. In this way the annulus between casing 7 and wellbore wall 4 can be sealed with cement as shown by 24 in FIG. 2.

FIG. 2 shows the tool of FIG. 1 after cement has been displaced into annulus 5 up to point 26 which is below aperture 9 so that cement extends from below seat 17 around and under end 22 and up to point 26.

In FIG. 2 opening plug 27 has been passed from the earths surface through interior 10 until it abuts seat 17 at shoulder 28 in a sealing manner as shown by seal means 29. When opening plug 27 engages seat 17 it shears shear means 14 thus moving sleeve 13 downwardly away from aperture 9 and opening aperture 9 for communication from interior 10 to the remainder of annulus 5 which does not contain cement.

In the conventional drilling process, interior l and annulus as shown in FIG. 1 are substantially filled with water-base drilling fluid so that in FIG. 2 all of interior l0 and annulus 5 above plug 27, seat 17, and cement top 26 still contains residual water-base drilling fluid or some other type aqueous liquid. In the case where the residual first liquid just referred to is a drilling fluid it is normally a heavy fluid in that it has been weighted with various materials such as barite to give it weight during drilling for known reasons. Thus, in the normal situation not only is the residual liquid in interior and annulus 5 of FIG. 5 freezable, but it is also a relatively heavy liquid which makes it more difficult to displace from interior l0 and'annulus 5.

By this invention a second or wash liquid is passed from the earths surface downwardly through interior 10 as shown by arrow 30, outwardly through aperture 9 as shown'by arrow 31, and upwardly through annulus 5 back to the earths surface. This second liquid is for washing the first liquid out of the well. Since the second liquid is a wash liquid, it can be used in large volumes and can be substantially lighter than the first liquid. For example, the second'liquid can-be water (salt or sweet) which is lighter than conventional water-base drilling fluid but is used in large amounts to minimize the amount of water-base drilling fluid left by the lighter second fluid by-passing parts of the first heavier fluid. Thus, the second liquid is normally lighter than the first liquid and also lighter than the third liquid.

The second liquid is followed by a bypass wiper (plug) which is shown as 32 in FIG. 3. The prior art tools and apparatus do not provide for this second liquid or wash step. Nor does the prior art provide for the use of bypass wiper 32.

Wiper 32 is shown to have a projection 33 on its lower end which mates with a corresponding depression 34 in opening plug 27. Projection 33 is useful to help keep wiper 32 from being tipped to one side when in the position shown in FIG. 3 but is not essential to the invention.

After the second liquid wash has been performed and bypass wiper 32 seated on opening plug 27 as shown in FIG. 3, substantially only the second (wash) liquid'is present in interior It) and annulus 5. This second liquid is then displaced by the introduction into interior 10 of a heavy, nonfreezable liquid such as an oil-base drilling fluid or packer fluid which passes downwardly as shown by arrow 40, around vanes 41 of bypass wiper 32 as shown by arrow 42, through aperture 9, and upwardly into annulus 5 as shown by arrow 43. Since this third liquid is heavier, e.g., has a higher weight per unit volume, than the second liquid there is no problem of fingering through or by-passing of the second liquid when being displaced by this third liquid. Since wiper 32 is used there is substantially no mixing between the second and third liquids. Therefore, substantially all of the second or wash liquid, which can be freezable, is removed by the nonfreezable third liquid, and all that remains in interior 10 and annulus 5 at that time is nonfreezable liquid. The third liquid is also preferably more viscous than the second liquid. The third liquidis also preferably no heavier than, still more preferably lighter than, the first liquid.

After the emplacement of the nonfreezable liquid, cement is passed downwardly, through aperture 9, and upwardly into annulus 5 as represented by

arrows

40, 42 and 43 so that annulus 5.is filled with'cement. However, should any liquid in annulus 5 be bypassed by cement and therefore trapped in the annulus, this liquid will be nonfreezable so that no damage is done should the portion of annulus 5 in which the nonfreezable liquid is trapped be adjacent a permafrost portion of the well-bore. The cement is followed by a shutoff or closing wiper (plug) which contacts shoulder 45 of seat 21.

The shutoff wiper is shown in FIG. 4 as element 46 and upon contact of same with seat 21 shears shear means 19 and forces sleeve 12 over aperture 9.

As shown in FIGS. 1 through 3 the lower portion of sleeve 12 has an annular cutout portion 47 between sleeve 12 and housing 8 thereby leaving a projection 48 which telescopes over sleeve 13. Seal means 20 of projection 48 seals with the interior surface of sleeve 13 while the upper seal means 20 on sleeve 12 seals with the interior surface of housing 8. Sleeve 12 thereby effectively seals off communication between interior l0 and annulus 5. Annulus 5 is now substantially completely full of cement as is interior 10 below shutoff wiper 46 and even above shutoff wiper 46 in that a small amount, for example one barrel, of cement is sometimes left above the shutoff wiper.

Elements

46, 21, 32, 18, and 34 as well as the cement surrounding same are all drillable so that all of this material left in interior 10 can be drilled out thereby leaving only casing

strings

6 and 7 and tool 3 (

elements

8, 12, and 13) present during subsequent production of gas and/or oil through interior 10.

Casing strings

6 and 7 and tool 3 are cemented in place by the cement extending below bottom 22 and in annulus 5.

The first liquid employed in this invention can be any suitable liquid as can the second liquid but are preferably aqueous since such liquids are less expensive and oftentimes easier to handle. The second liquid can even be fresh or salt water locally available and can contain various chemicals such as thinning agents like sodium acid pyrophosphate. The thinning agent will be transrnitted to the first liquid to thin same and, because of its reduced viscosity therefrom, render the first liquid more easily washed out by the second liquid. Since the second liquid is just a wash liquid it can be lighter, e.g., have a lower specific gravity than the first liquid without fear of leaving freezable liquid in the well.

Bypass wiper 32 is employed between the second liquid and the third liquid to prevent the as heavy or heavier third liquid from channeling or fingering into the lighter second liquid as the third liquid passes down through interior 10 and upwardly in annulus 5 displacing the second liquid before it. The third liquid can have a freezing depressant liquid as various salts, e.g., sodium chloride, sodium sulfate, and the like. The salts will be passed to any second liqaud or even first liquid that may remain behind. The salts being passed to these first and second liquids act as freeze point depressants for these liquids so that should any minute amount of water he left in interior 10 or annulus 5, there is freezing point depressant available to prevent even this minute amount of residual water from freezing. Further,

the third liquid can contain conventionaloil-wetting agents to make all the metal parts in the tool and the surfaces'of casing string 6 oil wet. In this way not even a film of water is left on these metal surfaces.

EXAMPLE Using the apparatus as shown in FIG. I, wherein wall 4 of wellbore 2 is permafrost, the wellbore is drilled using a water-base drilling fluid weighing about eleven pounds per gallon so that in the stage of the completion process as represented by FIG. 1 interior 10 and annulus 5 are substantially filled with water-base drilling fluid.

Conventional cement is employed below opening plug 27 to achieve the .stage of the completion shown by FIG. 2. After this first cementing step below apertures 9, the tool is opened and the remaining waterbase drilling fluid is washed out of interior 10 and annulus 5 with fresh water which has a weight of 8.3 pounds per gallon. After a large volume of fresh water (second liquid) is employed to wash most of the heavier waterbase drilling fluid out of interior 10 and annulus 5, bypass wiper 32 is inserted into interior l and forced downwardly into contact with opening plug 27 as shown in FIG. 3. Plug 27 is followed by an oil-base packer fluid which weighs about ten pounds per gallon, the oil-base packer fluid leaving bypass wiper 32 in the position shown in FIG. 3, passing by wiper 32, through apertures 9 and upwardly in annulus to displace fresh water from annulus 5.

Efficient displacement of fresh water from annulus 5 is achieved because the oil-base fluid (third liquid) is heavier than the water (second liquid). This would not be so if the oil-base liquid were used directly to displace the heavier water-base drilling fluid (first liquid). Thus, by the use of the apparatus and method of this invention the heavy water-base drilling fluid is efficiently and substantially completely removed from interior l0 and annulus 5 leaving a nonfreezable oil-base fluid in interior 10 and annulus 5. Thus, upon carrying out the second cementing step to emplace cement above level 26, if any liquid is bypassed by the cement it will be nonfreezable liquid.

After the emplacement of the third, nonfreezable, oil-base liquid in interior It! and annulus 5 the second cementing step is carried out wherein cement is forced downwardly in interior 10 through apertures 9 and upwardly in annulus 5 until cement has reached the'desired level in annulus 5 (if cementing is to be stopped below the earths surface) or until the cement reaches the earths surface. Upon pumping the desired quantity of cement shutoff wiper 46 is employed to close apertures 9 with sleeve 12 and to displace substantially all cement from interior 10 into annulus 5 except for that cement which remains between the bottom of seat 118 and the top of shutoff wiper 46 plus any slight residual amount of cement above wiper 46.

Reasonable variations and modifications are possible within the scope of this disclosure without departing from the spirit and scope of this invention.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows.

l. A well completion method in a wellbore comprising placing a string of casing in said wellbore, said casing having at an intermediate point along the length thereof a tool which can be opened to establish communication at the tool between the inside and outside of said casing and then closed to terminate such communication, said casing and tool containing a first liquid, placing cement below said tool, opening said tool, washing residual first liquid out of the interior of said casing and tool with second liquid, displacing remaining second liquid from the interior of said casing and tool with a third liquid, said second liquid weighing less per unit volume than said first liquid, said third liquid weighing no more per unit volume than said first liquid, displacing said third liquid fromsaid casing and tool with cement, and closing said tool.

2. A method according to claim ll wherein said first liquid is a water-base drilling fluid which is heavier than said third liquid, and said third liquid is an oil-base liquid.

3. A method according to claim 2 wherein said second liquid is water and is lighter than said third liquid.

4. A method according to claim Slwherein said third liquid contains a freezing point depressant for transfer to any remaining second liquid. 7 I

5. A method according to claim 2 wherein said third liquid contains an oil-wetting agent to render metal parts in said wellbore preferentially oil wet to prevent leaving an aqueous film thereon.

6. A method according to claim 1 wherein said second liquid contains a thinner for decreasing the viscosity of said first liquid. i

7. A method according to claim I wherein a bypass wiper is employed between said second and third liquids.

8. A method according to claim 1 wherein said third liquid is more viscous than said second liquid, and said third liquid is lighter than said first liquid.

9. A method according to claim 1 wherein said third liquid is lighter than said first liquid, and said secondv third liquid.

Claims

1. A well completion method in a wellbore comprising placing a string of casing in said wellbore, said casing having at an intermediate point along the length thereof a tool which can be opened to establish communication at the tool between the inside and outside of said casing and then closed to terminate such communication, said casing and tool containing a first liquid, placing cement below said tool, opening said tool, washing residual first liquid out of the interior of said casing and tool with second liquid, displacing remaining second liquid from the interior of saiD casing and tool with a third liquid, said second liquid weighing less per unit volume than said first liquid, said third liquid weighing no more per unit volume than said first liquid, displacing said third liquid from said casing and tool with cement, and closing said tool.

2. A method according to claim 1 wherein said first liquid is a water-base drilling fluid which is heavier than said third liquid, and said third liquid is an oil-base liquid.

4. A method according to claim 3 wherein said third liquid contains a freezing point depressant for transfer to any remaining second liquid.

6. A method according to claim 1 wherein said second liquid contains a thinner for decreasing the viscosity of said first liquid.

7. A method according to claim 1 wherein a bypass wiper is employed between said second and third liquids.

9. A method according to claim 1 wherein said third liquid is lighter than said first liquid, and said second liquid is lighter than said third liquid.