Patent Grant
7322412
This invention relates to cementing casing in subterranean formations. In particular, this invention relates to methods for cementing a casing annulus by reverse-circulating the cement composition into the annulus without excessive cement composition entering the casing inner diameter.
It is common in the oil and gas industry to cement casing in well bores. Generally, a well bore is drilled and a casing string is inserted into the well bore. Drilling mud and/or a circulation fluid is circulated through the well bore by casing annulus and the casing inner diameter to flush excess debris from the well. As used herein, the term “circulation fluid” includes all well bore fluids typically found in a well bore prior to cementing a casing in the well bore. Cement composition is then pumped into the annulus between the casing and the well bore.
Two pumping methods have been used to place the cement composition in the annulus. In the first method, the cement composition slurry is pumped down the casing inner diameter, out through a casing shoe and/or circulation valve at the bottom of the casing and up through to annulus to its desired location. This is called a conventional-circulation direction. In the second method, the cement composition slurry is pumped directly down the annulus so as to displace well fluids present in the annulus by pushing them through the casing shoe and up into the casing inner diameter. This is called a reverse-circulation direction.
In reverse-circulation direction applications, it is sometimes not desirable for the cement composition to enter the inner diameter of the casing from the annulus through the casing shoe and/or circulation valve. This may be because, if an undesirable amount of a cement composition enters the inner diameter of the casing, once set it typically has to be drilled out before further operations are conducted in the well bore. Therefore, the drill out procedure may be avoided by preventing the cement composition from entering the inner diameter of the casing through the casing shoe and/or circulation valve.
This invention relates to cementing casing in subterranean formations. In particular, this invention relates to methods for cementing a casing annulus by reverse-circulating the cement composition into the annulus without undesirable amount of a cement composition entering the casing inner diameter.
The invention provides a method of cementing casing in a well bore, the method having the following steps: running a circulation valve comprising a reactive material into the well bore on the casing; reverse-circulating an activator material in the well bore until the activator material contacts the reactive material of the circulation valve; reconfiguring the circulation valve by contact of the activator material with the reactive material; and reverse-circulating a cement composition in the well bore until the reconfigured circulation valve decreases flow of the cement composition.
According to an aspect of the invention, there is provided a method of cementing casing in a well bore, wherein the method has steps as follows: running an annulus packer comprising a reactive material into the well bore on the casing; reverse-circulating an activator material in the well bore until the activator material contacts the reactive material of the packer; reconfiguring the packer by contact of the activator material with the reactive material; and reverse-circulating a cement composition in the well bore until the reconfigured packer decreases flow of the cement composition.
Another aspect of the invention provides a method of cementing casing in a well bore, the method having: running a circulation valve comprising a reactive material and a protective material into the well bore on the casing; reverse-circulating an activator material in the well bore until the activator material contacts the protective material of the circulation valve, wherein the activator material erodes the protective material to expose the reactive material; reconfiguring the circulation valve by exposing the reactive material to a well bore fluid; and reverse-circulating a cement composition in the well bore until the reconfigured circulation valve decreases flow of the cement composition.
According to still another aspect of the invention, there is provided a method of cementing casing in a well bore, the method having the following steps: running an annulus packer comprising a reactive material and a protective material into the well bore on the casing; reverse-circulating an activator material in the well bore until the activator material contacts the protective material of the packer, wherein the activator material erodes the protective material to expose the reactive material; reconfiguring the packer by contact of the reactive material with a well bore fluid; and reverse-circulating a cement composition in the well bore until the reconfigured packer decreases flow of the cement composition.
Still another aspect of the invention provides a circulation valve for cementing casing in a well bore, the valve having: a valve housing connected to the casing and comprising a reactive material; a plurality of holes in the housing, wherein the plurality of holes allow fluid communication between an inner diameter of the housing and an exterior of the housing, wherein the reactive material is expandable to close the plurality of holes.
According to a still further aspect of the invention, there is provided a circulation valve for cementing casing in a well bore, the valve having: a valve housing connected to the casing; at least one hole in the valve housing, wherein the at least one hole allows fluid communication between an inner diameter of the valve housing and an exterior of the valve housing; a plug positioned within the valve housing, wherein the plug is expandable to decrease fluid flow through the inner diameter of the valve housing.
A further aspect of the invention provides a circulation valve for cementing casing in a well bore, the valve having: a valve housing connected to the casing; at least one hole in the valve housing, wherein the at least one hole allows fluid communication between an inner diameter of the valve housing and an exterior of the valve housing; a flapper positioned within the valve housing, wherein the flapper is biased to a closed position on a ring seat within the valve housing; and a lock that locks the flapper in an open configuration allowing fluid to pass through the ring seat, wherein the lock comprises a reactive material.
Another aspect of the invention provides a circulation valve for cementing casing in a well bore, the valve having: a valve housing connected to the casing; at least one hole in the valve housing, wherein the at least one hole allows fluid communication between an inner diameter of the valve housing and an exterior of the valve housing; a sliding sleeve positioned within the valve housing, wherein the sliding sleeve is slideable to a closed position over the at least one hole in the valve housing; and a lock that locks the sliding sleeve in an open configuration allowing fluid to pass through the at least one hole in the valve housing, wherein the lock comprises a reactive material.
According to still another aspect of the invention, there is provided a circulation valve for cementing casing in a well bore, the valve having: a valve housing connected to the casing; at least one hole in the valve housing, wherein the at least one hole allows fluid communication between an inner diameter of the valve housing and an exterior of the valve housing; a float plug positioned within the valve housing, wherein the float plug is moveable to a closed position on a ring seat within the valve housing; and a lock that locks the float plug in an open configuration allowing fluid to pass through the ring seat in the valve housing, wherein the lock comprises a reactive material.
Another aspect of the invention provides a packer for cementing casing in a well bore wherein an annulus is defined between the casing and the well bore, the system having the following parts: a packer element connected to the casing, wherein the packer element allows fluid to pass through the a well bore annulus past the packer element when it is in a non-expanded configuration, and wherein the packer element restricts fluid passage in the annulus past the packer element when the packer element is expanded; an expansion device in communication with the packer element; and a lock that prevents the expansion device from expanding the packer element, wherein the lock comprises a reactive material.
According to another aspect of the invention, there is provided a method of cementing casing in a well bore, the method comprising: running a circulation valve into the well bore on the casing; reverse-circulating a particulate material in the well bore until the particulate material contacts the circulation valve; accumulating the particulate material around the circulation valve, whereby the particulate material forms a cake that restricts fluid flow; and reverse-circulating a cement composition in the well bore until the accumulated particulate material decreases flow of the cement composition.
The objects, features, and advantages of the present invention will be readily apparent to those skilled in the art upon a reading of the description of the preferred embodiments which follows.
The present invention may be better understood by reading the following description of non-limitative embodiments with reference to the attached drawings wherein like parts of each of the several figures are identified by the same referenced characters, and which are briefly described as follows.
It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, as the invention may admit to other equally effective embodiments.
Referring to
Referring to
In the embodiment illustrated in
When the expandable plug 19 is not expanded, as illustrated, fluid may also flow through the gap 36 (see
Referring to
Referring to
In some embodiments of the invention, a certain amount of circulation fluid is injected into the annulus between the activator material 14 and the cement composition 15. Where the expandable material of the circulation valve 20 has a delayed or slow reaction time, the circulation fluid buffer allows the circulation valve enough time to close in advance of the arrival of the leading edge of the cement composition 15 at the valve.
In some embodiments of the invention, a portion of the circulation valve is coated with a protective coating that is dissolved by the activator material to expose the portion of the circulation valve to the circulation fluid and/or cement composition. In particular, the circulation valve may be a pipe with holes as illustrated in
For example, the expandable material may be encapsulated in a coating that is dissolvable or degradable in the cement slurry either due to the high pH of the cement slurry or due to the presence of a chemical that is deliberately added to the slurry to release the expandable material from the encapsulated state. Examples of encapsulating materials which breakdown and degrade in the high pH cement slurry include thermoplastic materials containing base-hydrolysable functional groups, for example ester, amides, and anhydride groups. Examples of polymers with such functional groups include polyesters such as polyethylene terephalate (PETE), 3-hydroxybutyrate/3-hydroxyvalerate polymer, lactic acid containing polymer, glycolic acid containing polymers, polycaprolactone, polyethyelen succinate, polybutylene succinate, poly(ethylenevinylacetate), poly(vinylacetate), dioxanone containing polymers, cellulose esters, oxidized ethylene carbonmonoxide polymers and the like. Polyesters and polycaprolactone polymers are commercially available under the trade name TONE from Union Carbide Corporation. Suitable polymers containing a carbonate group include polymers comprising bisphenol-A and dicarboxylic acids. Amide containing polymers suitable according to the present invention include polyaminoacids, such as 6/6 Nylon, polyglycine, polycaprolactam, poly(gamma-glutamic acid) and polyurethanes in general. Encapsulating materials which swell upon exposure to high pH fluids include alkali swellable latexes which can be spray dried on to the expandable material in the unswollen acid form. An example of an encapsulating material which require the presence of a special chemical, for example a surfactant, in the cement slurry to expose the encapsulated expandable material to the cement slurry includes polymers containing oxidizable monomers such as butadiene, for example styrene butadiene copolymers, butadiene acrylonitrile copolymers and the like. In alternative embodiments, any encapsulating or coating material known to persons of skill in the art may be used.
Isolation valves may also be used as part of the invention to ensure that the cement composition is retained in the annulus while the cement composition solidifies.
Referring to
Referring to
In an alternative embodiment, the flapper 22 is held in the open position by a glue (reactive material) that dissolves upon contact with an activator material. The glue is any type of sticky or adhesive material that holds the flapper 22 in the open position. Upon contact by the activator material, the glue looses its adhesive property and releases the flapper 22. Any adhesive known to persons of skill in the art may be used.
In an alternative embodiment of the valve lock 26, illustrated in
Referring to
The circulation valve 20 of
In some embodiments, the sliding sleeve valve also has an automatic locking mechanism which locks the sliding sleeve in a closed position. In
In an alternative embodiment, the restrictor plate 34 of
In a further embodiment, the restrictor plate is rigid structure. Rather than expanding the material of the restrictor plate, a particulate material is circulated in a slurry down the annulus and in through the holes 21. The particulate material is collected or accumulated at the underside of the restrictor plate so as to form a cake. The cake of particulate material restricts fluid flow through and around the restrictor plate so that fluid pressure building behind the restrictor plate pushes the restrictor plate and sliding sleeve to a closed position.
The circulation valve 20 of
Alternative sliding sleeve valves may also be used with the invention. While the above-illustrated sliding sleeve is biased to the closed position by a spring, alternative embodiments may bias the sliding sleeve by a pre-charged piston, a piston that charges itself by external fluid pressure upon being run into the well bore, magnets, or any other means known to persons of skill.
Referring to
Referring the
Referring to
Referring to
The operation of the packer 50 is illustrated with reference to
The packer 50 also has a fill chamber 64 and a packer element 65 positioned below the charge chamber 61. The packer element 65 is an annular-shaped, elastic structure that is expandable to have an outside diameter larger than the casing 4. When the pressure pin 63 is opened, charged gas from the charge chamber 61 is allowed to bleed past the pressure pin 63 into the fill chamber 64. The charge gas in the fill chamber 64 expands the packer element 65.
A cross-sectional, side view of the packer 50 of
In alternative embodiments, various packer elements which are known to persons of skill are employed to restrict fluid flow through the annulus. These packer elements, as used in the present invention, have a trigger or initiation device that is activated by contact with an activator material. Thus, the packer may be a gas-charge, balloon-type packer having an activator material activated trigger. Once the trigger is activated by contact with an activator material, the trigger opens a gas-charged cylinder to inflate the packer. Packers and triggers known to persons of skill may be combined to function according to the present invention. For example, inflatable or mechanical packers such as external cam inflatable packers (ECIP), external sleeve inflatable packer collars (ESIPC), and packer collars may be used.
Various embodiments of the invention use micro spheres to deliver the activator material to the circulation valve. Microspheres containing an activator material are injected into the leading edge of the cement composition being pumped down the annulus. The microspheres are designed to collapse upon contact with the circulation valve. The microspheres may also be designed to collapse upon being subject to a certain hydrostatic pressure induced by the fluid column in the annulus. These microspheres, therefore, will collapse upon reaching a certain depth in the well bore. When the microspheres collapse, the activator material is then dispersed in the fluid to close the various circulation valves discussed herein.
In the illustrated well bore configurations, the circulation valve is shown at the bottom of the well bore. However, the present invention may also be used to cement segments of casing in the well bore for specific purposes, such as zonal isolation. The present invention may be used to set relatively smaller amounts of cement composition in specific locations in the annulus between the casing and the well bore.
Further, the present invention may be used in combination with casing shoes that have a float valve. The float valve is closed as the casing is run into the well bore. The casing is filled with atmospheric air or a lightweight fluid as it is run into the well bore. Because the contents of the casing weigh less than the fluid in the well bore, the casing floats in the fluid so that the casing weight suspended from the derrick is reduced. Any float valve known to persons of skill may be used with the present invention, including float valves that open upon bottoming out in the rat hole.
The reactive material and the activator material may comprise a variety of compounds and material. In some embodiments of the invention, xylene (activator material) may be used to activate rubber (reactive material). Radioactive, illuminating, or electrical resistivity activator materials may also be used. In some embodiments, dissolving activator material, like an acid (such as HCL), may be pumped downhole to activate a dissolvable reactive material, such as calcium carbonate. Nonlimiting examples of degradable or dissolvable materials that may be used in conjunction with embodiments of the present invention having a degradable or dissolvable valve lock or other closure mechanism include but are not limited to degradable polymers, dehydrated salts, and/or mixtures of the two.
The terms “degradation” or “degradable” refer to both the two relatively extreme cases of hydrolytic degradation that the degradable material may undergo, i.e., heterogeneous (or bulk erosion) and homogeneous (or surface erosion), and any stage of degradation in between these two. This degradation can be a result of, inter alia, a chemical or thermal reaction or a reaction induced by radiation. The degradability of a polymer depends at least in part on its backbone structure. For instance, the presence of hydrolyzable and/or oxidizable linkages in the backbone often yields a material that will degrade as described herein. The rates at which such polymers degrade are dependent on the type of repetitive unit, composition, sequence, length, molecular geometry, molecular weight, morphology (e.g., crystallinity, size of spherulites, and orientation), hydrophilicity, hydrophobicity, surface area, and additives. Also, the environment to which the polymer is subjected may affect how it degrades, e.g., temperature, presence of moisture, oxygen, microorganisms, enzymes, pH, and the like.
Suitable examples of degradable polymers that may be used in accordance with the present invention include but are not limited to those described in the publication of Advances in Polymer Science, Vol. 157 entitled “Degradable Aliphatic Polyesters” edited by A. C. Albertsson. Specific examples include homopolymers, random, block, graft, and star- and hyper-branched aliphatic polyesters. Polycondensation reactions, ring-opening polymerizations, free radical polymerizations, anionic polymerizations, carbocationic polymerizations, coordinative ring-opening polymerization, and any other suitable process may prepare such suitable polymers. Specific examples of suitable polymers include polysaccharides such as dextran or cellulose; chitins; chitosans; proteins; aliphatic polyesters; poly(lactides); poly(glycolides); poly(ε-caprolactones); poly(hydroxybutyrates); poly(anhydrides); aliphatic polycarbonates; ortho esters, poly(orthoesters); poly(amino acids); poly(ethylene oxides); and polyphosphazenes.
Aliphatic polyesters degrade chemically, inter alia, by hydrolytic cleavage. Hydrolysis can be catalyzed by either acids or bases. Generally, during the hydrolysis, carboxylic end groups are formed during chain scission, and this may enhance the rate of further hydrolysis. This mechanism is known in the art as “autocatalysis,” and is thought to make polyester matrices more bulk eroding. Suitable aliphatic polyesters have the general formula of repeating units shown below:
where n is an integer between 75 and 10,000 and R is selected from the group consisting of hydrogen, alkyl, aryl, alkylaryl, acetyl, heteroatoms, and mixtures thereof. Of the suitable aliphatic polyesters, poly(lactide) is preferred. Poly(lactide) is synthesized either from lactic acid by a condensation reaction or more commonly by ring-opening polymerization of cyclic lactide monomer. Since both lactic acid and lactide can be the same repeating unit, the general term poly(lactic acid) as used herein refers to Formula I without any limitation as to how the polymer was made such as from lactides, lactic acid, or oligomers, and without reference to the degree of polymerization or level of plasticization.
The lactide monomer exists generally in three different forms: two stereoisomers L- and D-lactide and racemic D,L-lactide (meso-lactide). The oligomers of lactic acid, and oligomers of lactide are defined by the formula:
where m is an integer 22≦m≦75. Preferably m is an integer and 2≦m≦10. These limits correspond to number average molecular weights below about 5,400 and below about 720, respectively. The chirality of the lactide units provides a means to adjust, inter alia, degradation rates, as well as physical and mechanical properties. Poly(L-lactide), for instance, is a semicrystalline polymer with a relatively slow hydrolysis rate. This could be desirable in applications of the present invention where a slower degradation of the degradable particulate is desired. Poly(D,L-lactide) may be a more amorphous polymer with a resultant faster hydrolysis rate. This may be suitable for other applications where a more rapid degradation may be appropriate. The stereoisomers of lactic acid may be used individually or combined to be used in accordance with the present invention. Additionally, they may be copolymerized with, for example, glycolide or other monomers like ε-caprolactone, 1,5-dioxepan-2-one, trimethylene carbonate, or other suitable monomers to obtain polymers with different properties or degradation times. Additionally, the lactic acid stereoisomers can be modified to be used in the present invention by, inter alia, blending, copolymerizing or otherwise mixing the stereoisomers, blending, copolymerizing or otherwise mixing high and low molecular weight polylactides, or by blending, copolymerizing or otherwise mixing a polylactide with another polyester or polyesters.
Plasticizers may be present in the polymeric degradable materials of the present invention. The plasticizers may be present in an amount sufficient to provide the desired characteristics, for example, (a) more effective compatibilization of the melt blend components, (b) improved processing characteristics during the blending and processing steps, and (c) control and regulation of the sensitivity and degradation of the polymer by moisture. Suitable plasticizers include but are not limited to derivatives of oligomeric lactic acid, selected from the group defined by the formula:
where R is a hydrogen, alkyl, aryl, alkylaryl, acetyl, heteroatom, or a mixture thereof and R is saturated, where R′ is a hydrogen, alkyl, aryl, alkylaryl, acetyl, heteroatom, or a mixture thereof and R′ is saturated, where R and R′ cannot both be hydrogen, where q is an integer and 2≦q≦75; and mixtures thereof. Preferably q is an integer and 2≦q≦10. As used herein the term “derivatives of oligomeric lactic acid” includes derivatives of oligomeric lactide. In addition to the other qualities above, the plasticizers may enhance the degradation rate of the degradable polymeric materials. The plasticizers, if used, are preferably at least intimately incorporated within the degradable polymeric materials.
Aliphatic polyesters useful in the present invention may be prepared by substantially any of the conventionally known manufacturing methods such as those described in U.S. Pat. Nos. 6,323,307; 5,216,050; 4,387,769; 3,912,692; and 2,703,316, the relevant disclosures of which are incorporated herein by reference.
Polyanhydrides are another type of particularly suitable degradable polymer useful in the present invention. Polyanhydride hydrolysis proceeds, inter alia, via free carboxylic acid chain-ends to yield carboxylic acids as final degradation products. The erosion time can be varied over a broad range of changes in the polymer backbone. Examples of suitable polyanhydrides include poly(adipic anhydride), poly(suberic anhydride), poly(sebacic anhydride), and poly(dodecanedioic anhydride). Other suitable examples include but are not limited to poly(maleic anhydride) and poly(benzoic anhydride).
The physical properties of degradable polymers depend on several factors such as the composition of the repeat units, flexibility of the chain, presence of polar groups, molecular mass, degree of branching, crystallinity, orientation, etc. For example, short chain branches reduce the degree of crystallinity of polymers while long chain branches lower the melt viscosity and impart, inter alia, elongational viscosity with tension-stiffening behavior. The properties of the material utilized can be further tailored by blending, and copolymerizing it with another polymer, or by a change in the macromolecular architecture (e.g., hyper-branched range. Also, poly(lactic acid) may be suitable for higher temperature wells. Some stereoisomers of poly(lactide) or mixtures of such stereoisomers may be suitable for even higher temperature applications. Dehydrated salts may also be suitable for higher temperature wells.
The degradable material can be mixed with inorganic or organic compound to form what is referred to herein as a composite. In preferred alternative embodiments, the inorganic or organic compound in the composite is hydrated. Examples of the hydrated organic or inorganic solid compounds that can be utilized in the self-degradable diverting material include, but are not limited to, hydrates of organic acids or their salts such as sodium acetate trihydrate, L-tartaric acid disodium salt dihydrate, sodium citrate dihydrate, hydrates of inorganic acids or their salts such as sodium tetraborate decahydrate, sodium hydrogen phosphate heptahydrate, sodium phosphate dodecahydrate, amylose, starch-based hydrophilic polymers, and cellulose-based hydrophilic polymers.
Referring to
The circulation valves of
The particulate material 72 may comprise flakes, fibers, superabsorbents, and/or particulates of different dimensions. Commercial materials may be used for the particulate material such as FLOCELE (contains cellophane flakes), PHENOSEAL (available from Halliburton Energy Services), BARACARB (graded calcium carbonate of, for example, 600-2300 microns mean size), BARAPLUG (a series of specially sized and treated salts with a wide distribution of particle sizes), BARARESIN (a petroleum hydrocarbon resin of different particle sizes) all available from Halliburton Enegy Serivices, SUPER_SWEEP (a synthetic fiber) available from Forta Corporation, Grove City, Pa., and any other fiber capable of forming a plugging matt structure upon deposition and combinations of any of the above. Upon deposition around the circulation valve, these particulate materials form a cake, filter-cake, or plug around the circulation valve 20 to restrict and/or stop the flow of fluid through the circulation valve.
Therefore, the present invention is well adapted to carry out the objects and attain the ends and advantages mentioned as well as those that are inherent therein. While numerous changes may be made by those skilled in the art, such changes are encompassed within the spirit of this invention as defined by the appended claims. polymers, star-shaped, or dendrimers, etc.). The properties of any such suitable degradable polymers (e.g., hydrophobicity, hydrophilicity, rate of degradation, etc.) can be tailored by introducing select functional groups along the polymer chains. For example, poly(phenyllactide) will degrade at about ⅕th of the rate of racemic poly(lactide) at a pH of 7.4 at 55° C. One of ordinary skill in the art with the benefit of this disclosure will be able to determine the appropriate degradable polymer to achieve the desired physical properties of the degradable polymers.
Dehydrated salts may be used in accordance with the present invention as a degradable material. A dehydrated salt is suitable for use in the present invention if it will degrade over time as it hydrates. For example, a particulate solid anhydrous borate material that degrades over time may be suitable. Specific examples of particulate solid anhydrous borate materials that may be used include but are not limited to anhydrous sodium tetraborate (also known as anhydrous borax), and anydrous boric acid. These anhydrous borate materials are only slightly soluble in water. However, with time and heat in a subterranean environment, the anhydrous borate materials react with the surrounding aqueous fluid and are hydrated. The resulting hydrated borate materials are highly soluble in water as compared to anhydrous borate materials and as a result degrade in the aqueous fluid. In some instances, the total time required for the anhydrous borate materials to degrade in an aqueous fluid is in the range of from about 8 hours to about 72 hours depending upon the temperature of the subterranean zone in which they are placed. Other examples include organic or inorganic salts like sodium acetate trihydrate or anhydrous calcium sulphate.
Blends of certain degradable materials may also be suitable. One example of a suitable blend of materials is a mixture of poly(lactic acid) and sodium borate where the mixing of an acid and base could result in a neutral solution where this is desirable. Another example would include a blend of poly(lactic acid) and boric oxide.
In choosing the appropriate degradable material, one should consider the degradation products that will result. These degradation products should not adversely affect other operations or components. The choice of degradable material also can depend, at least in part, on the conditions of the well, e.g., well bore temperature. For instance, lactides have been found to be suitable for lower temperature wells, including those within the range of 60° F. to 150° F., and polylactides have been found to be suitable for well bore temperatures above this
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