Method and apparatus for delayed flow or pressure change in wells

Information

  • Patent Grant
  • RE46028
  • Patent Number
    RE46,028
  • Date Filed
    Friday, September 19, 2014
    10 years ago
  • Date Issued
    Tuesday, June 14, 2016
    8 years ago
Abstract
Degradable polylactic or polyhydroxyalkanoate polymers may be used to viscosify aqueous fluids for use in wells, Sand control screen or liner can be coated with a solid degradable polymer during placement in a well. Mechanical changes or flow changes in a well can be caused by solid degradable polymer that changes physical properties after it is placed in a well. Parts of devices or entire devices can be made of solid degradable polymer that converts to a fluid after selected times in an aqueous environment in a well.
Description
BACKGROUND OF THE INVENTION

1. Field of the Invention


This invention pertains to mechanical and chemical operations in wells. In one embodiment, polymer and method of preparing viscous fluid for use in wells is provided. In another embodiment, material and methods are provided for coating of sand control screens used in wellbores. In another embodiment, this invention pertains to delayed mechanical or flow changes in a wellbore after equipment is placed in the well. In another embodiment, this invention pertains to equipment that is placed in a wellbore and is degraded in the wellbore by contact with aqueous fluid.


2. Discussion of Related Art


A large number of mechanical and chemical operations are carried out in and around wells. Most of these wells are used for producing hydrocarbons from the earth. They are located at depths ranging from a few hundred feet below the surface of the earth to more than 30,000 feet. The temperature at the bottom of the wells likewise varies over a wide range—from about 100° F. to more than 400° F.


After the hole is drilled in the earth in the process of constructing a well, the process of placing casing in the well and cementing it in place is commenced. Mechanical devices to aid in the cementing process may be placed on the outside of the casing before it is placed in the hole. Instruments and communication cables may be placed on the casing. Multiple lateral holes may be drilled from a single hole and casing may be placed in each. When casing has been cemented, the process of “completing” the well may begin. This involves forming holes (“perforating”) the casing opposite an interval of a formation where fluids are to be produced or injected and, in most cases, placing tubing in the well. Various types of mechanical equipment may be placed in the wellbore, for safety, flow control and other purposes. Viscous, non-damaging fluids having a selected specific gravity are needed in wells during completion operations. In many wells various types of treatment fluids are then injected into the well to provide greater capacity of the well to produce hydrocarbons, in processes such as hydraulic fracturing and acidizing, called “stimulation” processes. The use of a degradable polymer in the form of ball sealers or particulates to divert fluid or control fluid loss from a well during completion or stimulation operations has been disclosed. (U.S. Pat. No. 4,716,964)


In some wells, the formation where hydrocarbons are found has low mechanical strength, which can result in “sand” being produced into the well along with hydrocarbons. The well then requires application of a “sand control” process. One of these processes requires placing a “screen” in the well. The solid particles (cuttings) and drilling fluid in the well may plug or partially plug the screen as it is placed in a well. This problem can be particularly severe in directional or horizontal wells. A recent U.S. Patent Application Publication (US2002/0142919 A1) discloses screen coatings that melt or dissolve within a wellbore and release reactive materials effective in degrading or dissolving materials that could plug a screen. The problem of screen plugging during placement was recognized many years ago (“Downhole Protection of Sand Control Screens,” Society of Petroleum Engineers Paper No. 8803, 1980).


In well operations used for completing or stimulating a well, viscous fluids may be used. In most cases, it is desirable that the fluid become lower viscosity with time after it is placed in a well or formation around a well. When the fluid becomes low viscosity it should contain no significant amount of solid or gel material. One example application of such fluids is hydraulic fracturing of wells. U.S. Patent Application Publication 2003/0060374A1, which is hereby incorporated by reference herein, discloses the use of highly concentrated degradable polymers in an aqueous liquid in such application. As explained in that Publication, there is a need for fracturing fluids that degrade to low viscosity without leaving a residue.


Other applications where a viscous fluid may be injected into a well or used in a well include completion fluids, perforating fluids and fluids for carrying gravel (sand) into a well. These fluids are preferably solids-free and degradable to low viscosity fluid having low solid or gel content that could degrade permeability of a porous rock. Other applications where a viscous liquid in a wellbore may be advantageous include a completion or workover fluid that is placed in a well during running of a mechanical device into the well or other mechanical operation in the well. These fluids may contain high concentrations of compounds soluble in water that increase the density of the fluid, such as sodium bromide or zinc bromide, or solid weighting materials. The viscosifying material in the fluids should degrade with time and leave little or no residue of solid or gel that could damage the permeability of a formation around the well.


A wide variety of mechanical devices are placed in wells during completion and workover operations. These devices are used to control fluid flow, to seal around tubulars in the well, to perform measurements of physical or chemical parameters and various other purposes. These devices may be needed for only a limited time and then an operator may wish to have them no longer effective or to no longer have mechanical strength. For example, packers, bridge plugs and cement retainers may be needed for a limited time in a well. There may be a need to release a mechanical device or open a port after a selected time in an inaccessible portion of a wellbore, such as in an annulus between tubular strings, where an aqueous fluid is located.


What are needed in a variety of well operations or processes are viscous liquids that degrade to low viscosity liquid at a predictable rate and leave low amounts of solid or gel residue, a degradable coating for screens, and solids that lose mechanical strength at a predictable rate in the presence of an aqueous liquid to allow delayed flow or mechanical changes in inaccessible locations in wellbores or degradation of mechanical equipment that is no longer needed in a wellbore.


SUMMARY OF THE INVENTION

Degradable polymers and methods for using in wells are provided. In one embodiment, the degradable polymer is used to viscosify fluids used in wellbore operations. In another embodiment, the degradable polymer is used to protect a sand control screen from plugging as it is placed in a well. In yet another embodiment, the degradable polymer is used to delay to a selected range of time a change in mechanical or flow conditions in a well. In yet another embodiment, the solid degradable polymer is used to form equipment that is temporarily used in well operations.





BRIEF DESCRIPTION OF THE DRAWINGS


FIG. 1 shows a sketch of a cased well having tubing and the surrounding formation.



FIG. 2 shows a cross-section of a wire-wrapped sand control screen protected by a degradable polymer.



FIG. 3 shows spring-loaded apparatus in the annulus between tubing and casing in a well that is released by degradation of a degradable polymer.





DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, wellbore 10 penetrates formation 20 where fluid is to be produced or injected. Wellbore 10 has casing 12 extending through formation 20, casing 12 being cemented in place by cement sheath 17. Perforations 14 have been formed through the wall of casing 12 and cement sheath 17 into formation 20. Perforations 14 may extend over the entire thickness of formation 20 or may extend only over a selected interval of formation 20 less than the total thickness surrounding wellbore 10. In some wells, hydraulic fracture 30 may have been formed around wellbore 10 by a previous treatment employing conventional fracturing fluid and proppant, using techniques well-known in industry. Alternatively, fracture 30 may not be present. Tubing 16 may have been suspended inside casing 12 and packer 18 may have been set near the bottom of tubing 16 to seal the annulus between tubing 16 and casing 12. Packer 18 may not be present in some wells, tubing 16 may not be present in some wells, and even casing 12 may not be present in some wells, although most wells in which the methods disclosed here will be applied contain casing and tubing with a packer near the bottom of the tubing. Packer 18 may have a controllable port for circulating fluids in the annulus of the well (not shown) or tubing 16 may be releasable from packer 18 to allow circulation of fluids down the tubing and up the tubing-casing annulus. Alternatively, tubing 16 may contain a sliding sleeve above and near packer 18, which is well known in industry.


In an embodiment for damage removal near wellbore 10, the materials and methods disclosed in U.S. Patent Application Publication 2003/0060374A1, which is incorporated by reference, may be used to form short hydraulic fracture 32 around wellbore 10 by injecting the degradable fracturing fluid at a pressure above the fracturing pressure of formation 20. The fracturing fluid disclosed herein is similar to fracturing fluids normally used, in which a polymer is dispersed in a liquid to increase viscosity of the liquid, and has rheological properties similar to the conventional fracturing fluids. The fracturing fluid disclosed herein is a more dilute mixture of the degradable polymer contained in the “polymer phase” disclosed in the cited '374 Publication, and it may be used to form hydraulic fracture 30 or hydraulic fracture 32, as shown in FIG. 1. The preferred degradable polymer is a polymer that is polymerized to a preferred range of molecular weight or is degraded (decreased in molecular weight) by reaction with water (herein “water-degradable”) to a desirable range of molecular weight for use in a wellbore fluid. The polymer is dispersed or dissolved in an aqueous liquid and then degrades to mostly water-soluble monomers or oligomers over a period of time in the presence of water.


The use of solid water-degradable polymers in wells is known. Their use in wellbores for diverting fluids between perforations or decreasing fluid loss from a hydraulic fracture when particles of the polymer are dispersed in fracturing fluid has been disclosed. U.S. Pat. No. 4,716,964 discloses use of such polymers in “ball sealers” and as a fluid loss material in well treating fluids. Ball sealers are rigid spheres added to a well treatment fluid to seal on perforations and divert flow of the treatment fluid to other perforations. Fluid loss additives are finely divided solid polymer particles that are dispersed in the fracturing fluid or other well treatment fluid and injected into a well. The polymers disclosed in the '964 patent include poly (D,L-lactide) and copolymers of lactide and glycolide.


A significant amount of research and development has been performed in recent years to commercialize polymers that degrade to water-soluble chemicals. In addition to the polylactic acid (PLA) polymers commercialized by Cargill Dow Polymers LLC, other degradable polymers, including other polyesters (based on polyethylene terephthalate, for example), starches, polycaprolactone, polyhydroxybutyrates and blends of these materials have been developed. Properties of lactide polymers are reviewed in the article “Properties of lactic acid based polymers and their correlation with composition,” A. Sodergard and M. Stolt, Prog. in Pol. Sci., July, 2002. Further development is underway for other degradable or biodegradable polymers. Metabolix, Inc. of Cambridge, Mass., for example, is developing a family of degradable polymers known as PHAs (polyhydroxyalkanoates). PHA polymers (also polyesters) are produced by photosynthesis, either indirectly using highly efficient fermentation processes, or directly in plant crops. The price of these polymers is expected to decrease to about the cost of oil-derived polymers within a few years. The properties of such polymers can be adjusted by molecular weight distribution, crystallinity, co-polymers and additives to control physical properties and degradation time under selected environments. Polymers such as PLAs and selected PHAs, such as polyhydroxybutyrate, can be optimized for the applications disclosed herein by varying manufacturing methods and conditions. Polyhydroxybutyrate will be, in general, more stable to degradation than PLA. Different polymerization variables can be controlled during manufacture and/or compounding to provide desirable degradation times under a broad range of environmental conditions that exist in underground formations. The PHAs can also be optimized by varying microbes used in the fermentation processes.


Degradation of solid polyesters occurs first by water penetrating the bulk of the polymer, preferentially attacking the chemical bonds in the amorphous polymer and converting long chains into shorter water-soluble fragments. Degradation rates can be controlled by incorporation of various additives. The control of properties of thermoplastic polymers by addition of plasticizers and other additives is well known. Of course, exposure of the plastics to moisture before their use can be controlled to prevent premature degradation. Biodegradable polymers may also be degraded by enzymes, which may be used to contact the polymers, as is known in the art. If there is need to increase the degradation rate of polymers left in a wellbore, for example, heating of the polymers in the wellbore can be used to increase degradation rate or the polymer may be contacted by a solution containing enzymes. The Sodergard and Stolt article, cited above, discusses biodegradation of degradable polymers, including polyesters, and polylactic acid in particular. The degradation rate (hydrolysis) of polylactic acids may be increased significantly by enzymes pronase, proteinase K and bromelain.


Since water is always present in hydrocarbon reservoirs and aqueous liquids are usually used in wellbore operations, there is nearly always a mechanism to cause polymer degradation of water-degradable polymers in a wellbore or in a reservoir. Rate of polymer degradation will depend primarily on polymer composition, polymer structure and temperature. For any degradable polymer selected, degradation time can be determined by heating a sample of the polymer to be injected. A water-degradable polymer can be exposed to an aqueous liquid and subjected to a thermal history simulating the conditions the polymer would experience in a well where it is to be used. The thermal history of the polymer as it is placed in a wellbore or injected down a wellbore and resides in the wellbore or the subsurface formation while degrading may be simulated in laboratory tests to select the polymer or copolymers and any additives used with the polymer.


A fracturing fluid, completion or workover wellbore fluid, fluid for carrying gravel into a fracpack or gravel pack or fluid for other well operations may be formed by polymerizing lactic acid to PLA or forming PHA or other biopolymer having a range of molecular weight that can be dissolved in an aqueous liquid to be used in the well operation and adding the resulting polymer to aqueous liquid. If the molecular weight of the manufactured PLA or PHA is too high to allow solubility in the aqueous liquid, the molecular weight of the polymer can be decreased by applying heat to the polymer in the presence of water. For example, steam or hot water may be applied to solid or liquid polymer for a selected time to obtain a molecular weight range of the polymer such that it can be dissolved in the aqueous liquid to be used in a well operation. Polymer having a desired range of molecular weight may be stabilized or partially stabilized against further decrease of molecular weight until it is used in a well operation by removing water from the polymer (drying) or by lowering the temperature of the polymer in an aqueous fluid.


The well treatment fluid disclosed herein may be placed in wellbore 10 (FIG. 1) by pumping the viscous polymer down the well from the surface as fluids of the prior art are pumped. The polymer is added to the aqueous well treatment fluid to a concentration selected to achieve the desired range of viscosity of the treatment fluid. The polymer may be cross-linked to increase the effective viscosity of the solution using well known cross-linking agents.


The properties of polylactide are affected by the isomeric content of the polymer. In addition to the D, L-polylactide disclosed in U.S. Pat. No. 4,716,964, discussed above, which is a racemic mixture, a polylactide formed from 13 percent D-isomer and 87 percent L-isomer, available from Cargill-Dow, is primarily amorphous in the solid state and degrades to form a viscous liquid in the presence of water. Preferably, a polymer that is amorphous or not highly crystalline in the solid state will be used to form the well treatment fluid of this invention. At the boiling point of water, viscous liquid formed from solid pellets of the 13 percent D-isomer material, whereas a polylactide containing only about 6 percent D-isomer did not degrade to a viscous liquid under the same conditions but degraded to a crystalline polymer. Therefore, the relative amount of D- and L-isomer should be selected in the range from about 10 percent to about 90 percent of an isomer or in a range to form an amorphous or not highly crystalline polymer. It is believed that isomer compositions in this range form an amorphous polymer and the lower molecular weight polymers and the oligomers formed during degradation form less crystalline material, allowing formation of the viscous liquid during degradation of the polymer. The viscous liquid can be diluted to form a solution having desired rheological properties. Amorphous forms of other polyesters are preferred for the same reasons.


In addition to the application of degradable polymers to form viscous aqueous liquid for use in wells, the polymers may be applied in the solid form in a variety of processes or methods. The primary characteristic of the polymer in some of these applications is that the mechanical properties of the polymer change in a predictable manner with time in the presence of water or an aqueous liquid. If desired, an initial solid polymer may finally go in solution in the aqueous phase. In some applications, only a decrease in mechanical properties (modulus, bending strength, tensile or compressive strength, for example) in a predictable time range may be necessary for application of the polymer. In other applications, the polymer may maintain its mechanical properties until it is employed, then decrease in mechanical properties and become a low-strength gel or low-strength crystalline solid or become soluble in an aqueous phase in a wellbore.


In one embodiment of the invention disclosed herein, degradable polymer is used to coat a sand control screen or slotted liner before it is placed in a well. Such an application is described in a recently published U.S. Patent Application (No. 2002/0142919A1), which is hereby incorporated by reference. The material used to coat the screen is called a “binder.” In the '919 Publication, it is disclosed that the binder may contain components that “react with potentially plugging materials in the near wellbore area” when the components are released as the binder melts or dissolves. Such components are well known (scale, paraffin and clays, for example). The use of wax and soluble solids as a binder is disclosed. The use of a water-degradable solid polymer that decreases in molecular weight with time is not disclosed.



FIG. 2 shows a cross-section of a wire-wrapped sand control screen. The screen includes basepipe 130, stand-offs 134 and wire 136. Washpipe or tail pipe 132 is shown inside the screen. The protective coating on the screen is designated 122. It should be understood that a screen is illustrated, but a perforated liner or permeable sintered medium may be protected by a protective coating such as coating 122.


The use of PLA, PHA and other polyester polymers makes possible a timed degradation of the coating, rather than the employment of temperature alone or dissolution in a fluid as disclosed in the '919 Publication. The properties of the polyester may be selected to maintain sufficient mechanical strength to prevent displacement of the polymer from the screen as it is placed in a well. This time may be from several hours to days, depending on the time required to place the coated screen in a well. An example of the decrease in molecular weight of poly (DL-lactide) with time is provided in the paper “Further investigations on the hydrolytic degradation of poly (DL-lactide),” Biomaterials 20 (1999) 35-44. The data in the paper were obtained at 37° C. and at 60° C. As can be noted in the U.S. Pat. No. 4,716,964, referenced above, the rate of degradation is much more rapid at temperatures more typical of the temperature in wells. The polymer coating initially should have a melting point higher than the temperature expected in the well. The polymer should degrade to form a material that can be displaced from the well. If the polymer should flow outwardly from the screen, the polymer should not permanently damage permeability of the gravel placed in the well. Some or the entire polymer may be produced from the well as a viscous liquid. The initial strength of the solid polymer should be sufficient to prevent flow across the screen, in the area where the polymer is applied, under pressure differentials across the screen as it is placed in the well. The polymer coating may be used, for example, to prevent flow through only selected areas of the screen as it is put in a well. To increase initial strength of the polymer, a composite may be formed with the polymer by incorporating particles of a rigid solid, which may be a soluble crystalline material, for example, in the polymer before it is placed on the screen. Polymers having varying degradation rates may be used on different areas of a screen. For example, a more rapidly degrading polymer may be used over the lower portion of a screen.


Degradable polymer, such as PLA, may be applied to the screen, for example, by heating the polymer to allow flow or extrusion and coating the polymer on the finished screen. The screen may be heated before application of the polymer to allow more uniform flow of polymer into the screen. Alternatively, the polymer may be applied from solution in a solvent and the solvent removed to form a solid polymer. Alternatively, the base pipe or mandrel of the screen may be coated and the holes plugged with hot PLA or other water-degradable polymer before the wire of a screen is applied. Alternatively, blank pipe to be run into a well may be coated with the degradable polymer. The degradable polymer may be formulated to contain any or all the additives taught by the '919 Publication. The additives would then be released to enter the fluids around the screen or blank pipe as the polymer degrades.


There are reasons to attach various mechanical devices to the outside of tubulars as they are placed in a well. The devices may be used to measure physical or chemical variables or to modify flow conditions in the well, for example. A change in the position, status or operation of the device after a selected time may be desirable. A degradable polymer, such as PLA or a PHA, may be used to form a mechanical part of the device or a support for the device. The degradation rate of the degradable polymer may be selected to allow the desired change to occur in a selected range of time after placement of the device in a well. For example, FIG. 3 is adapted from U.S. Pat. No. 5,509,474. In this example, tubing 106 has been placed in a well inside casing 12. The annulus between tubing and casing will ordinarily be filled by an aqueous fluid. Sensors 111 are designed to be released from the vicinity of the outside surface of tubing 106 and then to spring against the inside wall of casing 12. An electromechanical device could be used to release the spring-loaded sensors. Alternatively, groove 200 may be formed in insulating material collar 114 and the spring-loaded sensors may be held in groove 200 by placing a selected solid water-degradable polymer over the sensor, shown at 111(a), in the groove, using techniques of placement such as described above for a screen. After tubing 106 is placed in a well in an aqueous fluid environment, polymer in groove 200 degrades to a range of mechanical properties (determined by the decrease in molecular weight of the degradable polymer) that allows sensor 111 to be released and to spring into the position shown at 111, which is in contact with the inside surface of casing 12.


The applications of degradable polymers disclosed herein to allow a timed change in location of a part or parts of mechanical devices can be readily seen by one of skill in the art of each device. The degradable polymer may easily be configured to allow the change to occur as compressive strength of the polymer degrades, as tensile strength degrades, as bending strength degrades, or as a combination of properties changes. The time of change can be determined by selecting a degradable polymer that changes in properties at a rate to allow the change to occur in a desired time range. This range may be hours, days or months, depending on the mechanical configuration and the polymer selected.


In other applications, flow configuration or pressure changes may be desired in a well after a selected time. For example, a port may preferably be opened after a selected time, in the range of hours, days or months. The port may be inaccessible or require expensive operations to open. For example, the port may be used to co-mingle fluid streams being produced from a well and be in an aqueous environment. A plug may be formed from a degradable polymer as disclosed herein. Tests can be performed with different polymer compositions to select the polymer providing the opening of the port in the desired time range and at the pressure differential existing across the port when in the well. Measurements of physical properties of a selected degradable polymer as a function of time and at selected temperatures in an aqueous environment may also be used to predict the time of opening of a selected port under selected conditions. Alternative, the polymer can be made in the form of a seal or gasket that degrades in time to allow flow. Such measurements and tests should take into account the dimensions of the degradable polymer body that is degrading, since such changes in properties are known to be affected by dimensions of the body, which affect the length of the diffusion path of water molecules into the degradable material and the diffusion path of reaction products from the polymer.


In another embodiment, mechanical devices or selected parts of mechanical devices that are placed in a well may be formed from solid degradable polymer such as PLA or PHA. For example, parts of a packer, a bridge plug or a cement retainer may be formed of water-degradable polymer. After a selected range of time, from hours, to days or months, the device or selected parts of the device may be designed to decrease in properties so as to release the device and facilitate retrieval. Alternatively, the entire device may be formed of a degradable polymer where strength of the polymer is adequate. For example, a nipple or pipe section may be formed of degradable polymer. The nipple or pipe may degrade and later be produced from a well. The pipe may be the “tail pipe” used in a sand control screen, for example.


Whereas the PLA used in fluids is preferably amorphous, as described above, the PLA used in mechanical or flow control devices may be amorphous or crystalline. The bending strength of rods of poly (D-lactide) (PLA) (which would be crystalline) when made by routine injection molding has been measured to be in the range of 40-140 MPA. Rods formed by solid state extrusion had bending strengths up to 200 MPA (“Enhancement of the mechanical properties of polylactides by solid-state extrusion,” Biomaterials 17, (March, 1996, 529-535). Further information about PLA and its properties is provided in a chapter entitled “Present and Future of PLA Polymers” in the book Degradable Polymers, Recycling, and Plastics Waste Management. Ed. by Ann-Christine Albertsson and S. J. Huang, Marcel Dekker, Inc. It is well known that strength may be increased by the use of composites made of the thermoplastic polymer. Where added strength is desired, composite formed from a degradable polymer may be used. PLA, for example, can be molded as other thermoplastic materials are formed or it may be formed by extrusion other processing steps known in industry.


An example of a simple mechanical device that may be formed or partially formed from PLA or other water-degradable polymer is a flotation container to be attached to casing being run into a horizontal well. Such flotation devices made of metal are well known. The walls and ends of such a container may be formed from degradable polymer, with adequate supports of degradable polymer between the ends to prevent collapse, or the ends and supports may be formed of degradable polymer and designed to allow walls to collapse after a selected time in the well (and before cementing).


Other mechanical parts that may be more easily left in a well than retrieved may also be formed from degradable polymer such as PLA. For example, the case or container of perforating devices may be formed of degradable polymer. After a selected time, the device may then be easily flowed from the well, if desired.


Although the present invention has been described with reference to specific details, it is not intended that such details should be regarded as limitations on the scope of the invention, except as and to the extent that they are included in the accompanying claims.

Claims
  • 1. A method for changing a flow pattern in a well having a casing comprising placing a solid degradable polymer piece in an internal device or internal flow channel in apparatus within the casing in the well such that decrease of a strength of the degradable polymer after a selected range of time causes changing of the flow pattern in the well, wherein the solid degradable polymer piece comprises polylactic acid.
  • 2. The method of claim 1 wherein the solid degradable polymer piece is in the form of a plug, seal or gasket.
  • 3. The method of claim 1 wherein the changing of flow pattern in the well causes co-mingling of fluid streams produced from the well.
  • 4. A method for changing a pressure in a well having a casing comprising placing a solid degradable polymer piece in an internal device or internal flow channel in apparatus within the casing in the well such that decrease of a strength of the degradable polymer after a selected range of time causes changing of the pressure in the well, wherein the solid degradable polymer comprises polylactic acid.
  • 5. The method of claim 4 wherein the solid degradable polymer piece is in the form of a plug, seal or gasket.
  • 6. A method for changing a flow pattern or pressure in a well having a casing comprising placing a solid hydrolytically degradable polymer piece in an internal device or internal flow channel in apparatus within the casing in the well such that decrease of a strength of the degradable polymer after a selected range of time causes changing of the flow pattern in the well, wherein the solid degradable polymer is chemically degraded to polymers having shorter chains that are water soluble.
  • 7. The method of claim 6 wherein the solid degradable polymer piece is in the form of a plug, seal, or gasket.
Parent Case Info

This application is a divisional application of application Ser. No. 11/804,612 filed May 18, 2007, now U.S. Pat. No. 7,625,846, which is a continuation of U.S. application Ser. No. 10/845,737, filed May 14, 2004, now abandoned, which claims the benefit of U.S. Provisional Application No. 60/470,738, filed May 15, 2003.

US Referenced Citations (349)
Number Name Date Kind
RE17217 Burch Feb 1926 E
2040889 Whinnen May 1936 A
2160228 Pustmueller May 1939 A
2223602 Cox Dec 1940 A
2230447 Bassinger Feb 1941 A
2286126 Thornhill Jun 1942 A
2331532 Bassinger Oct 1943 A
2555627 Baker Jun 1951 A
2589506 Morrisett Mar 1952 A
2593520 Baker et al. Apr 1952 A
2616502 Lenz Nov 1952 A
2640546 Baker Jun 1953 A
2713910 Baker et al. Jul 1955 A
2780294 Loomis Feb 1957 A
2830666 Rhodes Apr 1958 A
2833354 Sailers May 1958 A
3013612 Angel Dec 1961 A
3054453 Bonner Sep 1962 A
3062296 Brown Nov 1962 A
3079997 Blydorp Mar 1963 A
3087544 Forsman Apr 1963 A
3088520 Hildebrandt May 1963 A
3126827 McReynolds, Jr. Mar 1964 A
3141513 Thomas Jul 1964 A
3163225 Perkins Dec 1964 A
3273588 Dollison Sep 1966 A
3298437 Conrad Jan 1967 A
3298440 Current Jan 1967 A
3306362 Urbanosky Feb 1967 A
3308895 Oxford et al. Mar 1967 A
3356140 Young Dec 1967 A
3362476 Poollen Jan 1968 A
3447608 Fry et al. Jun 1969 A
3517742 Williams Jun 1970 A
3542130 Stout Nov 1970 A
3623551 Randermann, Jr. Nov 1971 A
3687202 Young et al. Aug 1972 A
3818987 Ellis Jun 1974 A
3851706 Ellis Dec 1974 A
3860066 Pearce et al. Jan 1975 A
3878101 Kennedy Apr 1975 A
3888311 Cooke, Jr. Jun 1975 A
3926253 Duke Dec 1975 A
4035024 Fink Jul 1977 A
4049015 Brown Sep 1977 A
4129308 Hutchison Dec 1978 A
4134455 Read Jan 1979 A
4151875 Sullaway May 1979 A
4182423 Ziebarth et al. Jan 1980 A
4185689 Harris Jan 1980 A
4189183 Borowski Feb 1980 A
4191254 Baughman et al. Mar 1980 A
4222444 Hamilton Sep 1980 A
4248299 Roeder Feb 1981 A
4250960 Chammas Feb 1981 A
4314608 Richardson Feb 1982 A
4381038 Sugden Apr 1983 A
4387769 Erbstoesser et al. Jun 1983 A
4391547 Jackson, Jr. et al. Jul 1983 A
4405017 Allen et al. Sep 1983 A
4432418 Mayland Feb 1984 A
4436151 Callihan et al. Mar 1984 A
4457376 Carmody et al. Jul 1984 A
4502654 Albee, Jr. Mar 1985 A
4532995 Kaufman Aug 1985 A
4548442 Sugden et al. Oct 1985 A
4554981 Davies Nov 1985 A
4566541 Moussy et al. Jan 1986 A
4585067 Blizzard et al. Apr 1986 A
4595052 Kristiansen Jun 1986 A
4688641 Knieriemen Aug 1987 A
4708163 Deaton Nov 1987 A
4715967 Bellis et al. Dec 1987 A
D293798 Johnson Jan 1988 S
4716964 Erbstoesser et al. Jan 1988 A
4776410 Perkin et al. Oct 1988 A
4784226 Wyatt Nov 1988 A
4792000 Perkin et al. Dec 1988 A
4830103 Blackwell et al. May 1989 A
4848459 Blackwell et al. Jul 1989 A
4893678 Stokley et al. Jan 1990 A
4931490 Armeniades Jun 1990 A
4986353 Clark et al. Jan 1991 A
4989673 Sydansk Feb 1991 A
5020590 McLeod Jun 1991 A
5042598 Sherman Aug 1991 A
5052489 Carisella et al. Oct 1991 A
5074063 Vannette Dec 1991 A
5082061 Dollison Jan 1992 A
5095980 Watson Mar 1992 A
5113940 Glaser May 1992 A
5115865 Carisella et al. May 1992 A
5117915 Mueller et al. Jun 1992 A
5154428 Woolhouse Oct 1992 A
5183068 Prosser Feb 1993 A
5188182 Echols, III et al. Feb 1993 A
5195583 Toon et al. Mar 1993 A
5207274 Streich et al. May 1993 A
5209310 Clydesdale May 1993 A
5219380 Young Jun 1993 A
5230390 Zastresek Jul 1993 A
5234052 Coone Aug 1993 A
5253705 Clary Oct 1993 A
5295735 Cobbs Mar 1994 A
5316081 Baski May 1994 A
5318131 Baker Jun 1994 A
D350887 Sjolander et al. Sep 1994 S
5343954 Bohlen Sep 1994 A
D353756 Graves Dec 1994 S
D355428 Hatcher Feb 1995 S
5390737 Jacobi Feb 1995 A
5392540 Cooper Feb 1995 A
RE35088 Gilbert Nov 1995 E
5476543 Ryan Dec 1995 A
5484191 Sollami Jan 1996 A
5490339 Accettola Feb 1996 A
5509474 Cooke, Jr. Apr 1996 A
5540279 Branch Jul 1996 A
5564502 Crow Oct 1996 A
D377969 Grantham Feb 1997 S
5655614 Azar Aug 1997 A
5693292 Choperena Dec 1997 A
5701959 Hushbeck Dec 1997 A
5785135 Crawley Jul 1998 A
5791825 Gardner Aug 1998 A
5803173 Fraser Sep 1998 A
5810083 Kilgore Sep 1998 A
5819846 Bolt Oct 1998 A
5830991 Shiiki Nov 1998 A
D415180 Rosanwo Oct 1999 S
5961185 Friant Oct 1999 A
5984007 Yuan Nov 1999 A
5988277 Vick Nov 1999 A
5990051 Ischy et al. Nov 1999 A
6012519 Allen Jan 2000 A
6082450 Snider et al. Jul 2000 A
6085446 Posch Jul 2000 A
6098716 Hromas Aug 2000 A
6105694 Scott Aug 2000 A
6142226 Vick Nov 2000 A
6152232 Webb Nov 2000 A
6167963 McMahan Jan 2001 B1
6182752 Smith Feb 2001 B1
6189618 Beeman Feb 2001 B1
6199636 Harrison Mar 2001 B1
6220349 Vargus Apr 2001 B1
6220350 Brothers et al. Apr 2001 B1
6283148 Spears Sep 2001 B1
6341823 Sollami Jan 2002 B1
6367569 Walk Apr 2002 B1
6372844 Shinoda et al Apr 2002 B1
6394180 Berscheidt May 2002 B1
6457267 Porter Oct 2002 B1
6491108 Slup Dec 2002 B1
6543963 Bruso Apr 2003 B2
6581681 Zimmerman Jun 2003 B1
6599863 Palmer et al. Jul 2003 B1
6629563 Doane Oct 2003 B2
6695049 Ostocke Feb 2004 B2
6725935 Szarka Apr 2004 B2
6739398 Yokley May 2004 B1
6779948 Bruso Aug 2004 B2
6799633 McGregor Oct 2004 B2
6818594 Freeman et al. Nov 2004 B1
6834717 Bland Dec 2004 B2
6851489 Hinds Feb 2005 B2
6852827 Yamane Feb 2005 B2
6854201 Hunter Feb 2005 B1
6868911 Jacobson et al. Mar 2005 B1
6891048 Yamane May 2005 B2
6902006 Myerley Jun 2005 B2
6916939 Yamane Jul 2005 B2
6918439 Dallas Jul 2005 B2
6938696 Dallas Sep 2005 B2
6944977 Deniau Sep 2005 B2
6949491 Cooke, Jr. Sep 2005 B2
7040410 McGuire May 2006 B2
7055632 Dallas Jun 2006 B2
7059410 Bousche et al. Jun 2006 B2
7067611 Yamane Jun 2006 B2
7069997 Coyes Jul 2006 B2
7093664 Todd Aug 2006 B2
7107875 Haugen Sep 2006 B2
7124831 Turley Oct 2006 B2
7128091 Istre Oct 2006 B2
7134505 Fehr Nov 2006 B2
7150131 Barker Dec 2006 B2
7168494 Starr Jan 2007 B2
7196040 Heath et al. Mar 2007 B2
7235673 Yamane Jun 2007 B2
7281584 McGarian Oct 2007 B2
D560109 Huang Jan 2008 S
7325617 Murray Feb 2008 B2
7337847 McGarian Mar 2008 B2
7353879 Todd et al. Apr 2008 B2
7363967 Burris Apr 2008 B2
7373973 Smith May 2008 B2
D579110 Zink, II et al. Oct 2008 S
7464764 Xu Dec 2008 B2
7501464 Sato Mar 2009 B2
7527104 Branch May 2009 B2
7538178 Sato May 2009 B2
7538179 Sato May 2009 B2
7552779 Murray Jun 2009 B2
7600572 Slup Oct 2009 B2
7604058 McGuire Oct 2009 B2
7622546 Sato Nov 2009 B2
7625846 Cooke Dec 2009 B2
7637326 Bolding Dec 2009 B2
7644767 Kalb Jan 2010 B2
7644772 Avant Jan 2010 B2
7644774 Branch Jan 2010 B2
7647964 Akbar Jan 2010 B2
D612875 Beynon Mar 2010 S
7673677 King Mar 2010 B2
7681645 McMillin Mar 2010 B2
D618715 Corcoran Jun 2010 S
7728100 Sato Jun 2010 B2
7735549 Nish Jun 2010 B1
7775286 Duphorne Aug 2010 B2
7775291 Jacob Aug 2010 B2
7781600 Ogawa Aug 2010 B2
7784550 Nutley Aug 2010 B2
7798236 McKeachnie Sep 2010 B2
7810558 Shkurti Oct 2010 B2
7812181 Ogawa Oct 2010 B2
D629820 Van Ryswyk Dec 2010 S
7866396 Rytlewski Jan 2011 B2
7878242 Gray Feb 2011 B2
7886830 Bolding Feb 2011 B2
7900696 Nish Mar 2011 B1
7909108 Swor Mar 2011 B2
7909109 Angman Mar 2011 B2
D635429 Hakki Apr 2011 S
7918278 Barbee Apr 2011 B2
7921923 McGuire Apr 2011 B2
7921925 Maguire Apr 2011 B2
7926571 Hofman Apr 2011 B2
8025104 Cooke, Jr. Sep 2011 B2
8039548 Ogawa et al. Oct 2011 B2
8074718 Roberts Dec 2011 B2
8113276 Greenlee et al. Feb 2012 B2
8127856 Nish et al. Mar 2012 B1
D657807 Frazier Apr 2012 S
8231947 Vaidya et al. Jul 2012 B2
8304500 Sato et al. Nov 2012 B2
8318837 Sato et al. Nov 2012 B2
8362158 Sato et al. Jan 2013 B2
8404868 Yamane et al. Mar 2013 B2
8580914 Sato et al. Nov 2013 B2
8658758 Sato et al. Feb 2014 B2
8691912 Suzuki et al. Apr 2014 B2
8722907 Suzuki et al. May 2014 B2
8722908 Suzuki et al. May 2014 B2
20010040035 Appleton et al. Nov 2001 A1
20020142919 Constein Oct 2002 A1
20030024706 Allamon Feb 2003 A1
20030060374 Cooke, Jr. Mar 2003 A1
20030188860 Krueger Oct 2003 A1
20040015033 Steiner Jan 2004 A1
20040094300 Sullivan et al. May 2004 A1
20040106525 Willberg et al. Jun 2004 A1
20040114463 Berg et al. Jun 2004 A1
20040149431 Wylie et al. Aug 2004 A1
20040216876 Lee Nov 2004 A1
20040231845 Cooke, Jr. Nov 2004 A1
20050065037 Constien Mar 2005 A1
20050130845 Freeman et al. Jun 2005 A1
20050173126 Starr et al. Aug 2005 A1
20050205266 Todd et al. Sep 2005 A1
20050233425 Matsumura Oct 2005 A1
20050241825 Burris et al. Nov 2005 A1
20050241827 Whitfill et al. Nov 2005 A1
20060001283 Larsen Jan 2006 A1
20060011389 Locati Jan 2006 A1
20060229212 Willberg et al. Oct 2006 A1
20060278405 Turley et al. Dec 2006 A1
20070051521 Fike et al. Mar 2007 A1
20070068670 Booth Mar 2007 A1
20070107908 Vaidya et al. May 2007 A1
20070225175 Cooke, Jr. Sep 2007 A1
20070227745 Roberts et al. Oct 2007 A1
20070240883 Telfer Oct 2007 A1
20080015120 Cooke, Jr. Jan 2008 A1
20080110635 Loretz et al. May 2008 A1
20080115932 Cooke, Jr. May 2008 A1
20090044957 Cho Feb 2009 A1
20090107684 Cooke, Jr. Apr 2009 A1
20090114401 Purkis May 2009 A1
20090126933 Telfer May 2009 A1
20090211749 Nguyen et al. Aug 2009 A1
20100064859 Stephens Mar 2010 A1
20100084146 Roberts Apr 2010 A1
20100101803 Clayton et al. Apr 2010 A1
20100132960 Shkurti et al. Jun 2010 A1
20100155050 Frazier Jun 2010 A1
20100252252 Harris et al. Oct 2010 A1
20100276159 Mailand et al. Nov 2010 A1
20100288503 Cuiper et al. Nov 2010 A1
20110005779 Lembcke Jan 2011 A1
20110036564 Williamson Feb 2011 A1
20110061856 Kellner et al. Mar 2011 A1
20110088915 Stanojcic et al. Apr 2011 A1
20110103915 Tedeschi May 2011 A1
20110168404 Telfer et al. Jul 2011 A1
20110198082 Stromquist et al. Aug 2011 A1
20110240295 Porter et al. Oct 2011 A1
20110259610 Shkurti et al. Oct 2011 A1
20120181032 Naedler et al. Jul 2012 A1
20130008666 Cherewyk Jan 2013 A1
20130008671 Booth Jan 2013 A1
20130014936 Griffith Jan 2013 A1
20130068474 Hofman et al. Mar 2013 A1
20130292123 Murphree et al. Nov 2013 A1
20130300066 Xu Nov 2013 A1
20130306327 Williamson Nov 2013 A1
20130319668 Tschetter Dec 2013 A1
20130319682 Tschetter Dec 2013 A1
20130333891 Fripp Dec 2013 A1
20140000894 Coffey Jan 2014 A1
20140020911 Martinez Jan 2014 A1
20140027127 Frazier et al. Jan 2014 A1
20140027128 Johnson Jan 2014 A1
20140041857 Xu Feb 2014 A1
20140060813 Naedler Mar 2014 A1
20140076571 Frazier et al. Mar 2014 A1
20140083717 Frazier et al. Mar 2014 A1
20140096970 Andrew Apr 2014 A1
20140102709 Arabskyy Apr 2014 A1
20140110112 Jordan, Jr. Apr 2014 A1
20140116677 Sherlin May 2014 A1
20140116721 Hofman May 2014 A1
20140116731 Themig May 2014 A1
20140116775 Coffey May 2014 A1
20140182862 Derby Jul 2014 A1
20140190685 Frazier et al. Jul 2014 A1
20140196899 Jordan Jul 2014 A1
20140224476 Frazier Aug 2014 A1
20140224477 Wiese Aug 2014 A1
20140231069 VanLue Aug 2014 A1
20140231099 Barbee Aug 2014 A1
20140246189 Beason Sep 2014 A1
20140246208 Themig Sep 2014 A1
20140248448 Sjostedt Sep 2014 A1
20140251594 Garcia Sep 2014 A1
20140251612 Powers Sep 2014 A1
20140251636 Hofman Sep 2014 A1
20150090440 Cooke Apr 2015 A1
20150144348 Okura et al. May 2015 A1
Foreign Referenced Citations (25)
Number Date Country
2891507 Jun 2014 CA
2873800 May 2015 EP
914030 Dec 1962 GB
2001-178483 Jul 2001 JP
2057780 Apr 1996 RU
505794 Mar 1976 SU
1501597 Oct 1991 SU
1723309 Mar 1992 SU
WO2001094744 Dec 2001 WO
WO2010127457 Nov 2010 WO
WO2014010267 Jan 2014 WO
WO2014024827 Feb 2014 WO
WO2014077302 May 2014 WO
WO2014092067 Jun 2014 WO
WO2014109347 Jul 2014 WO
WO2014192885 Dec 2014 WO
WO2014208527 Dec 2014 WO
WO2015060246 Apr 2015 WO
WO2015060247 Apr 2015 WO
WO2015098597 Jul 2015 WO
WO2015098801 Jul 2015 WO
WO2015098803 Jul 2015 WO
WO2015098849 Jul 2015 WO
WO 2015098913 Jul 2015 WO
WO 2015099005 Jul 2015 WO
Non-Patent Literature Citations (6)
Entry
Ledlow et al., “Downhole Protection of Sand Control Screens,” Society of Petroleum Engineers [SPE], Paper No. 8803, Jan. 1980, 6 pages.
Li et al., “Further investigations on the hydrolytic degradation of poly (DL-lactide),” Biomaterials, 20(1):35-44, Jan. 1999.
Penner, “The durability of selected geotextile fabrics to heavy oil well fluids,” University of Alberta [thesis], Oct. 1990, 104 pages.
Sodergard et al., “Properties of lactic acid based polymers and their correlation with composition,” Prog Polym Sci., 27 (6):1123-1163, Jul. 2002.
Vert et al., “Present and future of PLA polymers,” Journal of Macromolecular Science, Part A: Pure and Applied Chemistry, A32(4):787-796, Apr. 1, 1995.
Weiler et al., “Enhancement of the mechanical properties of polylactides by solid-state extrusion. I. Poly(D-lactide),” Biomaterials, 17(5):529-535, Mar. 1996.
Provisional Applications (1)
Number Date Country
60470738 May 2003 US
Divisions (1)
Number Date Country
Parent 11804612 May 2007 US
Child 12021036 US
Continuations (1)
Number Date Country
Parent 10845737 May 2004 US
Child 11804612 US
Reissues (1)
Number Date Country
Parent 12021036 Jan 2008 US
Child 14491699 US