Casing, wellbore strengthening completion string and completion cementing method and application thereof

Abstract

The present invention discloses a casing, a wellbore strengthening completion string, a completion cementing method and an application thereof. The casing comprises an inner layer base pipe and an expandable outer pipe sleeved on the outer side of the inner layer base pipe; the inner layer base pipe is made of a soluble polyurethane elastic material, and the expandable outer pipe is made of a shape memory material; the outer diameter of the inner layer base pipe is 50 to 250 mm, the inner diameter of the expandable outer pipe is greater than 50 mm to greater than 250 mm, and the outer diameter of the expandable outer pipe is 60 to 300 mm. The casing provided by the present invention, the expandable outer pipe can expand and cling to the inner wall of the wellbore, generate a positive extrusion force on the wellbore wall, reduce the formation shear effect, solve the problem of wellbore wall stability, and at the same time the inner diameter can be expanded by 20% to 100%. When the inner layer base pipe is dissolved or taken out, it is convenient for subsequent secondary operations.

Description

Technical Field

[0001] The invention relates to a casing, a wellbore strengthening completion pipe string, a completion cementing method and applications thereof. Background Art

[0002] In the drilling and completion projects, the wellbore stability problem is a complex problem that is often encountered. Wellbore instability will not only affect the drilling speed and cementing quality, but also cause some well sections to collapse and fall off, resulting in accidents such as drill sticking and encountering obstacles. In the completion and production stage, the induced wellbore collapse caused by acid fracturing will cause the oil pipe to fail to be lowered into place, which will directly affect subsequent production operations. At the same time, sand production in the oil well will increase the workload and reduce the life of the equipment.

[0003] The anti-collapse completion technology is one of the main methods to solve the above-mentioned wellbore stability problem. One of them is the mechanical anti-collapse method, which uses various conventional pipes such as perforated tubing, slotted liner, wire-wound screen, etc. to provide a certain flow space for the downhole fluid. Another method is to lower an expandable screen, and use a special expansion and sealing tool to expand the screen from bottom to top in the well, so as to achieve the function of supporting the wellbore wall. However, this type of expansion and sealing tool does not have a certain thickness after expansion and sealing, and the expansion and sealing effect of the entire collapsed layer needs to be further improved. Another method is to modify the drilling fluid, and the modification method includes physical and chemical means. Among them, physical means include increasing the density and viscosity of the drilling fluid to reduce pressure and diffusion effects to reduce pressure excitement. Chemical means include adding chemicals to the drilling fluid to reduce water penetration into mud shale, inhibit formation hydration dispersion, or help to quickly form a dense and tough mud cake.

[0004] At present, people have developed many drilling fluid formulas for different geological conditions and drilling processes, but they have the following disadvantages: (1) The stabilizing effect of the drilling fluid's own liquid column pressure and mud cake formation on the wellbore is difficult to control and has poor stability. (2) Drilling fluids need to be formulated for different formations, have poor adaptability, and many formations do not have suitable drilling fluids. (3) For water-based drilling fluids, mudstones absorb water and expand, causing wellbore shrinkage, conglomerates and volcanic rocks to collapse when in contact with water, and salt rocks to form caves when in contact with water, resulting in adverse consequences such as stuck drills and even the scrapping of wellbores. (4) Drilling fluids often contain crude oil, diesel, various oils, and a large amount of chemical treatment agents, which may have adverse effects on formations, soil, the environment, and ecology.

[0005] CN101362938 discloses a drilling well wall stabilizer, which is mainly used to solve the technical problems of reservoir damage caused by well wall instability and clay expansion during well completion. The stabilizer of the present invention participates in the formation of well wall mud cake of the rock formation, blocks pores, makes the well wall flexible and retractable, can significantly reduce the lubrication coefficient of mud cake, and plays a role in stabilizing the well wall.

[0006] CN103013482A discloses a composite well wall stabilizer, which is composed of potassium trimethyl silicate powder and nanmu powder as the main components that work together, and paraffin and graphite as auxiliary components. It is used in water-based mud (including brine mud), and can effectively inhibit shale hydration expansion, improve the quality of mud cake, make it dense, tough and lubricated, and stabilize the well wall of mud shale layer. At the same time, the composite well wall stabilizer of the present invention also has a plugging effect on the formation with micro-cracks, making it not easy to collapse and stable, and plays a role in protecting the well wall.

[0007] CN104405371A discloses a method for increasing wellbore stability and reducing filtration loss, which simulates the deposition of biominerals in drilling fluid wellbore stabilization technology, and quickly forms an organic / inorganic composite film with a dense structure and excellent mechanical properties on the wellbore through layer-by-layer deposition, so as to change the microstructure and mechanical properties of the mud cake or the sedimentary layer around the wellbore, stabilize and harden the wellbore, thereby improving the stability and pressure bearing capacity of the wellbore, while reducing the filtration loss and preventing the intrusion of drilling fluid.

[0008] CN102224321A discloses a shape memory polyurethane foam for underground sand filter. It adopts polycarbonate shape memory polyurethane, and compresses the foam with a mold above its glass transition temperature in advance; cools to room temperature and shapes it into a high-density small-volume foam; transports it to the designed position underground, and expands the foam by heating it above the glass transition temperature, and uses it as a sand filter foam for oil wells. In the material synthesis process of the present invention, the glass transition temperature of the soft segment of the foam material is controlled to give the material a thermal shape memory function, thereby realizing the foam volume memory. The shape memory polyurethane foam provided by the present invention has the following problems during use: the hollow cylinder formed by the shape memory polyurethane foam has low compressive strength, and can be used for bottom sand filtering, but the radial extrusion strength of the well wall generated is insufficient, and it is not convenient to be used directly for wellbore strengthening, and the inner diameter is small after being lowered into the bottom of the well and expanded, which is not convenient for secondary operation.

[0009] US8664318A1 discloses a shape memory structure, which includes an elastic material in which an elastic material and a viscoelastic material are mixed together. The shape memory structure is configured to be smaller in volume when in a first shape than in a second shape to facilitate entry into a well. The shape memory structure can be restored from the first shape to the second shape when exposed to environmental changes that soften the viscoelastic material, thereby allowing the stress stored in the elastomer by the shape memory structure to be gradually released to achieve volume change. The technical solution of the present invention also has the problem that the shape memory structure has low strength and is easy to be damaged. In addition, excessive thickness of the elastic material is also likely to affect the flow efficiency, that is, the fluid flows through unnecessary filtering paths, increasing energy consumption.

[0010] CN105626002A discloses a filling-free expandable screen tube, which includes an expandable base tube, a filter screen tube on the outside of the expandable base tube, and an expansion body on the outside of the filter screen tube. The expansion body includes a shape memory polymer layer coated on the outside of the filter screen tube, and a water-soluble polymer layer coated on the outside of the shape memory polymer layer as a whole. The two ends of the filter screen tube are fixed to the expandable base tube by a first positioning ring. The two ends of the shape memory polymer layer are fixed to the filter screen tube by a second positioning ring. The two ends of the expandable base tube are respectively provided with an expansion base tube extension section protruding from the first positioning ring. The technical solution of this invention is similar to that of the above-mentioned US8664318A1 in terms of structural design, outer layer expansion body material, etc., and also has the problem of small inner diameter after expansion, which is inconvenient for secondary operation. Summary of the invention

[0011] In view of the above problems existing in the prior art, the present invention provides a casing, a wellbore strengthening completion string, and a completion cementing method and application. The casing provided by the present invention comprises an inner layer base pipe and an expandable outer pipe sleeved on the outer side of the inner layer base pipe, wherein the inner layer base pipe is made of a soluble polyurethane elastic material, and its hydrolysis rate is controllable, and the expandable outer pipe is made of a shape memory material, which can be compressed or expanded at a suitable temperature. When used in the completion cementing process, it can solve the problem of well wall stability and can expand the inner diameter of the outer pipe, facilitating subsequent secondary operations.

[0012] The first aspect of the present invention provides a casing, comprising an inner base tube and an expandable outer tube sleeved outside the inner base tube; the inner base tube is made of a soluble polyurethane elastic material, and the expandable outer tube is made of a shape memory material; the outer diameter of the inner base tube is 50 to 250 mm, the inner diameter of the expandable outer tube is greater than 50 to greater than 250 mm, and the outer diameter of the expandable outer tube is 60 to 300 mm. Preferably, the outer diameter of the expandable outer tube is 60 to 260 mm.

[0013] According to some embodiments of the casing of the present invention, the compression temperature for compressing the expandable outer tube to an inner diameter of 50 to 250 mm is 70 to 180° C., preferably, the compression temperature is 100 to 180° C., and more preferably 120 to 180° C. After the expandable outer tube is compressed, the compressed expandable outer tube can be shaped at a temperature ≤ 50° C.

[0014] According to some embodiments of the casing described in the present invention, the expansion temperature of the expandable outer tube to expand the inner diameter to 60-260 mm is 45-120°C, preferably, the outer diameter of the expandable outer tube is expanded to 100-350 mm, preferably, the expansion temperature is 100-120°C.

[0015] In different embodiments of the present invention, the inner base pipe of the casing and the expandable outer pipe may be fixedly connected or not fixedly connected.

[0016] For the expandable outer tube provided by the present invention, when the components are different, the expansion temperature and the compression temperature are selected differently, and the expansion temperature increases with the increase of the compression temperature and decreases with the decrease of the compression temperature.

[0017] According to some embodiments of the sleeve of the present invention, the raw materials for preparing the soluble polyurethane elastic material include a prepolymer component and a polyol component.

[0018] According to some embodiments of the sleeve of the present invention, the raw materials for preparing the prepolymer component include 20 to 65 weight % of polyisocyanate and 35 to 80 weight % of the first polyester polyol.

[0019] According to a preferred embodiment of the sleeve of the present invention, the content of isocyanate in the prepolymer component is 5 to 20% by weight.

[0020] According to some embodiments of the sleeve of the present invention, the polyol component includes 70 to 100 parts by weight of a second polyester polyol, 4 to 10 parts by weight of a chain extender, 0.5 to 2 parts by weight of a catalyst and 1 to 25.5 parts by weight of a hydrophilic agent.

[0021] According to some embodiments of the sleeve of the present invention, the weight ratio of the prepolymer component to the polyol component is 30:100 to 90:100.

[0022] According to some embodiments of the sleeve of the present invention, the tensile strength of the soluble polyurethane elastic material is 5 to 30 MPa.

[0023] According to some embodiments of the sleeve of the present invention, the Shore A hardness of the soluble polyurethane elastic material is 40-90.

[0024] According to some embodiments of the sleeve of the present invention, the polyisocyanate is selected from at least one of toluene diisocyanate, diphenylmethane diisocyanate (MDI, liquefied modified MDI) and polyphenylmethane polyisocyanate (PAPI).

[0025] According to a preferred embodiment of the sleeve of the present invention, the toluene diisocyanate is selected from at least one of TDI-65 / 35, TDI-80 / 20 and TDI-100.

[0026] According to some embodiments of the sleeve of the present invention, the first polyester polyol and the second polyester polyol are each independently adipic acid polyester polyol and / or castor oil polyester polyol.

[0027] According to a preferred embodiment of the sleeve of the present invention, the polymerization monomers of the adipic acid-based polyester polyol include adipic acid and alcohols.

[0028] According to some embodiments of the sleeve of the present invention, the alcohol is at least one of ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, methylpropylene glycol and diethylene glycol.

[0029] According to a preferred embodiment of the sleeve described in the present invention, the adipic acid-based polyester polyol is at least one of polyethylene adipate glycol (PEA) having a number average molecular weight of 2000-4000, polybutylene adipate glycol (PBA) having a number average molecular weight of 2000-4000, polyneopentyl adipate glycol (PNA) having a number average molecular weight of 1000-5000, polyethylene adipate glycol butylene adipate glycol (PEBA) having a number average molecular weight of 1000-5000, and polyethylene adipate glycol neopentyl glycol (PENA) having a number average molecular weight of 1000-5000.

[0030] According to a specific embodiment of the sleeve described in the present invention, the adipic acid-based polyester polyol is at least one of polyethylene adipate glycol with a number average molecular weight of 2000, polyethylene adipate glycol with a number average molecular weight of 4000, polybutylene adipate glycol with a number average molecular weight of 2000, polybutylene adipate glycol with a number average molecular weight of 4000, polyneopentyl adipate glycol with a number average molecular weight of 4000, polyethylene adipate glycol butylene adipate glycol with a number average molecular weight of 4000 and polyethylene adipate glycol neopentyl glycol with a number average molecular weight of 4000.

[0031] The present invention does not limit the specific type of polyester polyol used. Preferably, the polyester polyol used in the present invention is homemade in the laboratory, and is obtained by polycondensation reaction using adipic acid, ethylene glycol and 1,4-butanediol in different proportions according to the required different number average molecular weights. In addition, the conditions of the polycondensation reaction are not limited in the present invention, and the reaction can be carried out under conventional process conditions. Of course, commercially available polyester polyols of different molecular weights can also be used.

[0032] According to some embodiments of the sleeve of the present invention, the chain extender is an aliphatic chain extender and / or an aromatic chain extender.

[0033] According to a preferred embodiment of the sleeve of the present invention, the chain extender is selected from at least one of 3,3′-dichloro-4,4′-diaminodiphenylmethane (MOCA), diaminodimethylthiotoluene (DMTDA), ethylene glycol (EG), 1,4-butanediol (BDO), diethylene glycol (DEG), trimethylolpropane (TMP), triethanolamine (TGA) and diethanolamine (DEOA).

[0034] According to some embodiments of the sleeve of the present invention, the catalyst is a tertiary amine catalyst and / or an organic metal catalyst.

[0035] According to a preferred embodiment of the sleeve of the present invention, the tertiary amine catalyst is selected from at least one of triethylenediamine (A-33), tetramethylethylenediamine (TMEDA) and dimethylcyclohexylamine (DMCHA).

[0036] According to a preferred embodiment of the sleeve of the present invention, the organic metal catalyst is selected from at least one of dibutyltin dilaurate (DBTDL), stannous octoate, potassium isooctanoate, potassium acetate, potassium oleate, phenylmercuric acetate and zinc isooctanoate.

[0037] According to some embodiments of the cannula of the present invention, the hydrophilic agent is polyethylene glycol and / or a water-absorbing resin.

[0038] According to some embodiments of the cannula of the present invention, when the hydrophilic agent is polyethylene glycol, the content of the polyethylene glycol is 6 to 23.5 parts by weight.

[0039] According to some embodiments of the sleeve of the present invention, when the hydrophilic agent is a water-absorbing resin, the content of the water-absorbing resin is 1 to 2 parts by weight. In the present invention, a highly water-absorbing resin is preferred, and the type of the highly water-absorbing resin used is not limited.

[0040] According to some embodiments of the sleeve of the present invention, the shape memory material is prepared by mixing and foaming polyurethane and hot melt adhesive. In different embodiments of the present invention, the shape memory material is prepared by mixing and foaming polyurethane and hot melt adhesive by rolling or rolling. Specifically, the polyurethane foam and the hot melt adhesive are mixed and rolled or rolled in a fixed mold according to a required weight ratio, compressed into a polygonal hollow cylinder by a multi-petal shaping device, and the hot melt adhesive is solidified and fixed after cooling to form an expandable outer tube.

[0041] According to some embodiments of the sleeve described in the present invention, the hot melt adhesive is selected from at least one of styrene-isoprene-styrene copolymer hot melt adhesive, polyurethane hot melt adhesive, ethylene-vinyl acetate copolymer hot melt adhesive, water-based polyurethane hot melt adhesive, nylon and reactive polyurethane hot melt adhesive.

[0042] According to some embodiments of the sleeve of the present invention, the weight ratio of the polyurethane to the hot melt adhesive is: 30% to 80%: 20% to 70%.

[0043] Polyethylene glycol has good hydrophilicity. After adding an appropriate amount of polyethylene glycol to the polyol component, when the polyol component reacts with the prepolymer component, the hydrophilicity of the obtained soluble polyurethane elastic material can be increased, thereby accelerating the hydrolysis rate. The water-absorbing resin (SAP) does not participate in the reaction process, but can play a role in increasing the hydrophilicity of the soluble polyurethane elastic material and is used to adjust its hydrolysis rate.

[0044] For the polyester polyol for synthesizing the soluble polyurethane elastic material, the ester group content and the side group content on the main chain of the polyester polyol will affect the hydrolysis rate of the polyurethane elastic material. Specifically, the higher the ester group content on the main chain of the polyester polyol molecule and the lower the side group content, the faster the hydrolysis rate of the prepared soluble polyurethane elastic material. Therefore, in the present invention, the ester group content and the side group density of the main chain of the polyester polyol molecule can be adjusted by adjusting the molecular weight and structure of the diol, and then the hydrolysis rate can be adjusted, so that the hydrolysis rate of the soluble polyurethane elastic material obtained by the present invention is controllable.

[0045] In the casing provided by the present invention, the density of the expandable outer tube is preferably 0.035 to 0.65 g / cm 3 , 50% compression strength is preferably 1-5.4 MPa. Further, the volume compression rate of the expandable outer tube is preferably 15-4000, the volume expansion rate is preferably 7.5-3500, and the volume recovery rate is preferably 50-100.

[0046] The casing provided by the present invention has an expandable outer tube of the outer layer made of shape memory material, which can be compressed or expanded at a suitable temperature. When lowered into the wellbore, it can expand and cling to the inner wall of the wellbore, generating a positive extrusion force on the wellbore wall to stabilize the formation, reduce the shear effect of the formation, and solve the problem of wellbore wall stability. At the same time, the inner diameter can be expanded by 20% to 100%. When the inner layer base pipe is dissolved or taken out, it is convenient for subsequent secondary operations.

[0047] The second aspect of the present invention provides a wellbore strengthening completion string, comprising the above-mentioned casing and a connecting device, the inner base pipe and the expandable outer pipe of the casing are fixed by the connecting device, and the connecting device is made of the soluble polyurethane elastic material.

[0048] In different embodiments of the present invention, the connection method between the inner base pipe and the expandable outer pipe is not limited.

[0049] In an open hole or a cased well, after the wellbore strengthening completion string of the present invention is lowered into a predetermined position, the formation temperature is used to stimulate the expansion of the expandable outer tube, which is then pressed against the inner wall of the wellbore to generate a positive squeezing force on the wellbore wall to stabilize the formation, reduce the formation shear effect, solve the problem of wellbore wall stability, and at the same time expand the inner diameter. When the inner base pipe and the fixing device are dissolved or lifted out, subsequent secondary operations are convenient.

[0050] The third aspect of the present invention provides a completion and cementing method, which comprises: lowering the wellbore strengthening completion string into the wellbore, wherein the expandable outer tube expands at 45-120°C to an outer diameter of 100-350 mm and contacts the inner wall of the wellbore.

[0051] According to some embodiments of the well completion and cementing method of the present invention, the inner diameter of the wellbore is 100-138 m, and the outer diameter of the expandable outer tube can be closely attached to the well wall after expansion.

[0052] According to a preferred embodiment of the well completion and cementing method of the present invention, the expandable outer tube is expanded at 100-120° C. to an outer diameter of 100-350 mm.

[0053] According to some embodiments of the completion and cementing method of the present invention, before the casing is lowered into the wellbore, the method further includes: the expandable outer tube is compressed to an inner diameter of 50 to 250 mm at 70 to 180° C. and contacts the outer wall of the inner layer base tube. Preferably, the compression temperature is 100 to 180° C., more preferably 120 to 180° C.

[0054] According to some embodiments of the well completion and cementing method of the present invention, the connecting device is made of the soluble polyurethane elastic material.

[0055] According to some embodiments of the well completion and cementing method of the present invention, the inner base pipe and the connecting device are hydrolyzed or dissolved in the completion fluid.

[0056] According to some embodiments of the well completion and cementing method of the present invention, the preparation method of the soluble polyurethane elastic material is:

[0057] Step A, mixing and reacting a polyisocyanate with a first polyester polyol to obtain a prepolymer component;

[0058] Step B, mixing the second polyester polyol, a chain extender, a catalyst and a hydrophilic agent to obtain a polyol component;

[0059] Step C: mixing and reacting the prepolymer component and the polyol component.

[0060] According to a preferred embodiment of the well completion and cementing method of the present invention, the reaction conditions of step A include: a temperature of 0 to 90° C. and a time of 2 to 3 hours.

[0061] According to a preferred embodiment of the well completion and cementing method of the present invention, the reaction temperature of step C is 30-60°C.

[0062] According to a preferred embodiment of the well completion and cementing method of the present invention, in step C, the weight ratio of the prepolymer component and the polyol component when mixed is 30:100 to 90:100.

[0063] According to some embodiments of the well completion and cementing method of the present invention, the raw materials for preparing the prepolymer component include 20 to 65 weight % of polyisocyanate and 35 to 80 weight % of the first polyester polyol.

[0064] According to a preferred embodiment of the well completion and cementing method of the present invention, the content of isocyanate in the prepolymer component is 5 to 20% by weight.

[0065] According to some embodiments of the well completion and cementing method of the present invention, the polyol component includes 70 to 100 parts by weight of a second polyester polyol, 4 to 10 parts by weight of a chain extender, 0.5 to 2 parts by weight of a catalyst and 1 to 25.5 parts by weight of a hydrophilic agent.

[0066] According to some embodiments of the well completion and cementing method of the present invention, the tensile strength of the soluble polyurethane elastic material is 5 to 30 MPa.

[0067] According to some embodiments of the well completion and cementing method of the present invention, the Shore A hardness of the soluble polyurethane elastic material is 40-90.

[0068] According to some embodiments of the well completion and cementing method of the present invention, the polyisocyanate is selected from at least one of toluene diisocyanate, diphenylmethane diisocyanate (MDI, liquefied modified MDI) and polyphenylmethane polyisocyanate (PAPI).

[0069] According to a preferred embodiment of the well completion and cementing method of the present invention, the toluene diisocyanate is selected from at least one of TDI-65 / 35, TDI-80 / 20 and TDI-100.

[0070] According to some embodiments of the well completion and cementing method of the present invention, the first polyester polyol and the second polyester polyol are each independently adipic acid polyester polyol and / or castor oil polyester polyol.

[0071] According to a preferred embodiment of the well completion and cementing method of the present invention, the polymerization monomers of the adipic acid-based polyester polyol include adipic acid and alcohols.

[0072] According to some embodiments of the well completion and cementing method of the present invention, the alcohol is at least one of ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, methyl propylene glycol and diethylene glycol.

[0073] According to a preferred embodiment of the well completion and cementing method of the present invention, the adipic acid-based polyester polyol is at least one of polyethylene adipate glycol (PEA) having a number average molecular weight of 2000-4000, polybutylene adipate glycol (PBA) having a number average molecular weight of 2000-4000, polyneopentyl adipate glycol (PNA) having a number average molecular weight of 1000-5000, polyethylene adipate glycol butylene adipate glycol (PEBA) having a number average molecular weight of 1000-5000, and polyethylene adipate glycol neopentyl glycol (PENA) having a number average molecular weight of 1000-5000.

[0074] According to a specific embodiment of the well completion and cementing method described in the present invention, the adipic acid-based polyester polyol is at least one of polyethylene adipate glycol with a number average molecular weight of 2000, polyethylene adipate glycol with a number average molecular weight of 4000, polybutylene adipate glycol with a number average molecular weight of 2000, polybutylene adipate glycol with a number average molecular weight of 4000, polyneopentyl adipate glycol with a number average molecular weight of 4000, polyethylene adipate glycol butylene adipate glycol with a number average molecular weight of 4000 and polyethylene adipate glycol neopentyl glycol with a number average molecular weight of 4000.

[0075] According to some embodiments of the well completion and cementing method of the present invention, the chain extender is an aliphatic chain extender and / or an aromatic chain extender.

[0076] According to a preferred embodiment of the well completion and cementing method of the present invention, the chain extender is selected from at least one of 3,3′-dichloro-4,4′-diaminodiphenylmethane (MOCA), diaminodimethylthiotoluene (DMTDA), ethylene glycol (EG), 1,4-butanediol (BDO), diethylene glycol (DEG), trimethylolpropane (TMP), triethanolamine (TGA) and diethanolamine (DEOA).

[0077] According to some embodiments of the well completion and cementing method of the present invention, the catalyst is a tertiary amine catalyst and / or an organic metal catalyst.

[0078] According to a preferred embodiment of the well completion and cementing method of the present invention, the tertiary amine catalyst is selected from at least one of triethylenediamine (A-33), tetramethylethylenediamine (TMEDA) and dimethylcyclohexylamine (DMCHA).

[0079] According to a preferred embodiment of the well completion and cementing method of the present invention, the organic metal catalyst is selected from at least one of dibutyltin dilaurate (DBTDL), stannous octoate, potassium isooctanoate, potassium acetate, potassium oleate, phenylmercuric acetate and zinc isooctanoate.

[0080] According to some embodiments of the well completion and cementing method of the present invention, the hydrophilic agent is polyethylene glycol and / or a water-absorbing resin.

[0081] According to some embodiments of the well completion and cementing method of the present invention, when the hydrophilic agent is polyethylene glycol, the content of the polyethylene glycol is 6 to 23.5 parts by weight.

[0082] According to some embodiments of the well completion and cementing method of the present invention, when the hydrophilic agent is a water-absorbing resin, the content of the water-absorbing resin is 1 to 2 parts by weight.

[0083] According to some embodiments of the well completion and cementing method of the present invention, the shape memory material is prepared by mixing and foaming polyurethane and hot melt adhesive. In different embodiments of the present invention, the shape memory material is prepared by mixing and foaming polyurethane and hot melt adhesive by rolling or rolling.

[0084] According to some embodiments of the completion and cementing method of the present invention, the hot melt adhesive is selected from at least one of styrene-isoprene-styrene copolymer hot melt adhesive, polyurethane hot melt adhesive, ethylene-vinyl acetate copolymer hot melt adhesive, water-based polyurethane hot melt adhesive, nylon and reactive polyurethane hot melt adhesive.

[0085] According to some embodiments of the well completion and cementing method of the present invention, the weight ratio of the polyurethane to the hot melt adhesive is: 30% to 80%: 20% to 70%.

[0086] According to some embodiments of the well completion and cementing method of the present invention, after obtaining the soluble polyurethane elastic material, it also includes a curing and aging process; preferably, the curing conditions include: a temperature of 20 to 40°C and a time of 10 to 30 minutes; preferably, the aging conditions include a temperature of 60 to 90°C and a time of 1 to 4 hours.

[0087] According to a preferred embodiment of the well completion and cementing method of the present invention, the curing process is to cure at room temperature for 20 minutes.

[0088] According to a preferred embodiment of the well completion and cementing method of the present invention, the aging process is aging at 80° C. for 2 hours.

[0089] The well completion fixing method provided by the present invention comprises the following steps: after the expandable outer tube and the inner base tube are sleeved together, the expandable outer tube is compressed so that it is wrapped around the outer wall of the inner base tube, and then the expandable outer tube is lowered into a predetermined position in the wellbore together, and the formation temperature or circulating hot water is used to expand the expandable outer tube and make it close to the inner wall of the wellbore, thereby generating a positive extrusion force on the wellbore wall to stabilize the formation, reduce the formation shear effect, solve the problem of wellbore wall stability, and at the same time expand the inner diameter of the outer tube. At the same time, the inner base tube and the connecting device will dissolve or hydrolyze under the action of the completion fluid, or the inner base tube can be directly lifted out, thereby expanding the inner diameter of the outer tube (the inner diameter can be expanded by 20% to 100%) and facilitating subsequent secondary operations.

[0090] The fourth aspect of the present invention provides an application of the above-mentioned casing, wellbore strengthening completion string and completion cementing method in oil and gas completion technology, more preferably in oil wells, natural gas wells and water wells, but not limited thereto.

[0091] In the actual completion process, the wellbore reinforcement completion string is transported to the target layer using a drill pipe or tubing, and the outer tube is stimulated to expand by the formation temperature or the temperature of the circulating hot water. Since the initial shape of the outer tube is larger than the wellbore size, it will stick to the well wall after expansion, and produce positive extrusion pressure on the well wall to stabilize the formation and reduce the formation shear effect. In addition, the inner base tube is dissolved under the action of the completion fluid. After the inner base tube is dissolved, the inner diameter of the outer tube will be increased, which will facilitate subsequent secondary operations.

[0092] Beneficial effects of the present invention:

[0093] The sleeve provided by the present invention comprises an inner layer base pipe and an expandable outer pipe, wherein the inner layer base pipe is made of a soluble polyurethane elastic material, and the soluble polyurethane elastic material of the present invention has the effect of controllable hydrolysis speed. The expandable outer pipe adopts a shape memory material, so that when the casing is used as a wellbore strengthening completion string in the process of working underground, the expandable outer pipe will expand at high temperature and stick to the well wall, thereby generating a positive extrusion force to stabilize the formation, and after the inner layer base pipe is dissolved under the action of the completion fluid, the inner diameter of the outer pipe will be increased, thereby facilitating subsequent secondary operations.

[0094] The preparation method of the invention is simple, easy to operate, safe and environmentally friendly. DETAILED DESCRIPTION

[0095] In order to make the present invention more easily understood, the present invention will be described in detail below in conjunction with embodiments. These embodiments are only for illustration and are not intended to limit the application scope of the present invention.

[0096] The test method of the present invention and the equipment used in the test are as follows:

[0097] (1) The hardness test was performed using a TH110 hardness tester.

[0098] (2) The tensile strength and compressive strength tests were performed using a universal testing machine model WE-300.

[0099] The sources of the chemical reagents used in the present invention are:

[0100]

[0101]

[0102] [Example 1]

[0103] Preparation of inner base pipe for wellbore strengthening completion string:

[0104] (1) Preparation of prepolymer component: In terms of weight percentage, 2-functionality PEA-2000 is 49.2 wt % and MDI-100 is 50.8 wt %. The two are mixed and reacted at 80° C. for 2.5 hours to obtain a prepolymer component with an isocyanate content of 15 wt %.

[0105] (2) Preparation of polyol component: 20 parts by weight of PEA-2000, 70 parts by weight of PEA-4000, 10 parts by weight of PEG4000, 5 parts by weight of BDO, and 0.5 parts by weight of stannous octoate were placed in a high-speed stirrer and stirred uniformly to obtain a polyol component.

[0106] (3) Preparation of inner layer substrate: The prepolymer component and the polyol component obtained in the above step are mixed at a chain extension coefficient of 0.95 and reacted. The temperature of the mixing reaction is 50° C. After the mixing reaction, it is sprayed into a 2 mm thick sheet, and then subjected to a 2 min gel treatment and a 5 min curing molding treatment to obtain an inner layer substrate.

[0107] [Example 2]

[0108] Preparation of inner base pipe for wellbore strengthening completion string:

[0109] (1) Preparation of prepolymer component: In terms of weight percentage, 49.2 wt % of 2-functionality PBA-2000 and 50.8 wt % of MDI-100 were mixed and reacted at 80° C. for 2.5 hours to obtain a prepolymer component with an isocyanate content of 15 wt %.

[0110] (2) Preparation of polyol component: 30 parts by weight of PBA-2000, 60 parts by weight of PEA-4000, 10 parts by weight of PEG600, 5 parts by weight of HDO, and 0.5 parts by weight of stannous octoate were placed in a high-speed stirrer and stirred uniformly to obtain a polyol component.

[0111] (3) Preparation of inner layer substrate: The prepolymer component and the polyol component obtained in the above step are mixed at a chain extension coefficient of 0.95 and reacted. The temperature of the mixing reaction is 50° C. After the mixing reaction, it is sprayed into a 2 mm thick sheet, and then subjected to a 2 min gel treatment and a 5 min curing molding treatment to obtain an inner layer substrate.

[0112] [Example 3]

[0113] Preparation of inner base pipe for wellbore strengthening completion string:

[0114] (1) Preparation of prepolymer component: In terms of weight percentage, 2-functionality PNA-4000 is 60.5 wt % and MDI-100 is 39.5 wt %. The two are mixed and reacted at 80° C. for 2.5 hours to obtain a prepolymer component with an isocyanate content of 12 wt %.

[0115] (2) Preparation of polyol component: 80 parts by weight of PNA-4000, 20 parts by weight of PENA-4000, 2 parts by weight of SAP, 5 parts by weight of BDO, and 0.5 parts by weight of stannous octoate were placed in a high-speed stirrer and stirred uniformly to obtain a polyol component.

[0116] (3) Preparation of inner layer substrate: The prepolymer component and the polyol component obtained in the above step are mixed at a chain extension coefficient of 0.95 and reacted. The temperature of the mixing reaction is 50° C. After the mixing reaction, it is sprayed into a 2 mm thick sheet, and then subjected to a 2 min gel treatment and a 5 min curing molding treatment to obtain an inner layer substrate.

[0117] [Example 4]

[0118] Preparation of inner base pipe for wellbore strengthening completion string:

[0119] (1) Preparation of prepolymer component: In terms of weight percentage, 49.2 wt % of 2-functionality PBA-2000 and 50.8 wt % of MDI-100 were mixed and reacted at 80° C. for 2.5 hours to obtain a prepolymer component with an isocyanate content of 15 wt %.

[0120] (2) Preparation of polyol component: 30 parts by weight of PBA-2000, 50 parts by weight of PEA-2000, 20 parts by weight of PEG600, 2 parts by weight of SAP, 5 parts by weight of BDO, and 0.5 parts by weight of stannous octoate.

[0121] The mixture is placed in a high-speed mixer and stirred evenly to obtain a polyol component.

[0122] (3) Preparation of inner layer substrate: The prepolymer component and the polyol component obtained in the above step are mixed at a chain extension coefficient of 0.95 and reacted. The temperature of the mixing reaction is 50° C. After the mixing reaction, it is sprayed into a 2 mm thick sheet, and then subjected to a 2 min gel treatment and a 5 min curing molding treatment to obtain an inner layer substrate.

[0123] [Example 5]

[0124] Preparation of inner base pipe for wellbore strengthening completion string:

[0125] (1) Preparation of prepolymer component: In terms of weight percentage, 68 wt % of 2-functionality PEBA-4000 and 32 wt % of TDI-100 were mixed and reacted at 80° C. for 2.5 hours to obtain a prepolymer component with an isocyanate content of 14 wt %.

[0126] (2) Preparation of polyol component: 30 parts by weight of PBA-2000, 60 parts by weight of PEA-2000, 10 parts by weight of PEG4000, 2 parts by weight of SAP, 4 parts by weight of DMTDA, and 0.5 parts by weight of stannous octoate were placed in a high-speed stirrer and stirred uniformly to obtain a polyol component.

[0127] (3) Preparation of inner layer substrate: The prepolymer component and the polyol component obtained in the above step are mixed at a chain extension coefficient of 0.95 and reacted. The temperature of the mixing reaction is 50° C. After the mixing reaction, it is sprayed into a 2 mm thick sheet, and then subjected to a 2 min gel treatment and a 5 min curing molding treatment to obtain an inner layer substrate.

[0128] The inner base pipes for wellbore strengthening completion strings prepared in the above-mentioned Examples 1 to 5 have the following properties, as shown in Table 1:

[0129] Table 1

[0130]

[0131]

[0132] For the expandable outer tube of the wellbore strengthening completion string, the present invention uses a shape memory material obtained by chemical reaction of polyurethane with different formulations and hot melt adhesive. As shown in Table 2 below, the performance test of the expandable outer tube material prepared by using polymers with different formulations in Examples 6 to 11 of the present invention is shown.

[0133] Table 2

[0134]

[0135]

[0136] Remark:

[0137] SIS: styrene-isoprene-styrene copolymer.

[0138] EVA: Ethylene-vinyl acetate copolymer.

[0139] PA:Nylon.

[0140] [Example 12]

[0141] The material of Example 2 was processed by shaping and shearing to prepare an inner base pipe (with an outer diameter of 73 mm, a length of 2000 mm, and a pore size of 62 mm). The material of Example 6 was processed by shaping and shearing to prepare an expandable outer pipe (with an outer diameter of 90 mm, an inner diameter of 73.6 mm, and a length of 2000 mm). The outer pipe was sleeved on the outer side of the inner base pipe, and the outer pipe was compressed at 120°C to make it close to the outer side of the inner base pipe. Then the two were lowered into an oil well together. The formation temperature in the oil well was 55°C. At this time, the outer pipe expanded to an outer diameter of 162 mm and was close to the well wall. The inner base pipe gradually dissolved under the flow of the crude oil. At this time, the inner diameter of the outer pipe expanded to 100 mm.

[0142] [Example 13]

[0143] The material of Example 3 was prepared into an inner base pipe (outer diameter of 88.9 mm, length of 2000 mm, and pore diameter of 76 mm) by shaping and shearing treatment, and the material of Example 7 was prepared into an expandable outer pipe (outer diameter of 132 mm, inner diameter of 89.3 mm, and length of 2000 mm) by shaping and shearing treatment. The outer pipe was sleeved on the outside of the inner base pipe, and the outer pipe was compressed at 140°C to make it close to the outside of the inner base pipe, and then the two were lowered into the oil well together. The formation temperature in the oil well was 65°C. At this time, the outer pipe expanded to an outer diameter of 245 mm and was close to the well wall. The inner base pipe gradually dissolved under the flow of petroleum raw liquid. At this time, the inner diameter of the outer pipe expanded to 120 mm.

[0144] [Example 14]

[0145] The material of Example 4 was processed by shaping and shearing to prepare an inner base pipe (outer diameter of 63 mm, length of 2000 mm, pore diameter of 50 mm), and the material of Example 6 was processed by shaping and shearing to prepare an expandable outer pipe (outer diameter of 120 mm, inner diameter of 63.5 mm, length of 2000 mm). The outer pipe was sleeved on the outer side of the inner base pipe, and the outer pipe was compressed at 150°C to make it close to the outer side of the inner base pipe. Then the two were lowered into an oil well together. The formation temperature in the oil well was 75°C. At this time, the outer pipe expanded to an outer diameter of 245 mm and was close to the well wall. The inner base pipe gradually dissolved under the flow of petroleum raw liquid. At this time, the inner diameter of the outer pipe expanded to 90 mm.

[0146] In the present invention, the expandable outer tube expands under the stimulation of the formation temperature or the temperature of circulating hot water. Since the initial shape of the outer tube is larger than the borehole size, it will stick to the well wall after expansion and produce positive extrusion pressure on the well wall to stabilize the formation and reduce the formation shear effect. In addition, the inner layer base tube dissolves under the action of the completion fluid. After the inner layer base tube dissolves, the inner diameter of the outer tube will be increased (the inner diameter can be expanded by 20% to 100%), which will facilitate subsequent secondary operations.

[0147] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this field, under the technical enlightenment provided by the present invention, as common knowledge in the field, other equivalent variations and improvements can also be made, which should also be regarded as the protection scope of the present invention.

Claims

1. A well completion and cementing method, the method comprising: Lowering a wellbore strengthening completion string into the wellbore, wherein the wellbore strengthening completion string includes a casing and a connecting device; The casing comprises an inner layer base pipe and an expandable outer pipe sleeved outside the inner layer base pipe; the inner layer base pipe is made of a soluble polyurethane elastic material, and the expandable outer pipe is made of a shape memory material; the outer diameter of the inner layer base pipe is 50 to 250 mm, the inner diameter of the expandable outer pipe is greater than 50 mm to greater than 250 mm, and the outer diameter of the expandable outer pipe is 60 to 300 mm; The inner base pipe and the expandable outer pipe of the casing are fixed by the connecting device, and the connecting device is made of soluble polyurethane elastic material; Wherein, the expandable outer tube expands to an outer diameter of 100 to 350 mm at 45 to 120° C. and contacts the inner wall of the wellbore.

2. The well completion and cementing method according to claim 1, characterized in that: The inner diameter of the expandable outer tube is compressed to 50-250 mm at a compression temperature of 70-180° C.; The expansion temperature for expanding the expandable outer tube to an inner diameter of 60 to 260 mm is 45 to 120°C.

3. The well completion and cementing method according to claim 2, characterized in that: The compression temperature for compressing the expandable outer tube to an inner diameter of 50 to 250 mm is 100 to 180°C.

4. The well completion and cementing method according to claim 3, characterized in that: The compression temperature for compressing the expandable outer tube to an inner diameter of 50 to 250 mm is 120 to 180°C.

5. The well completion and cementing method according to any one of claims 1 to 4, characterized in that: The expansion temperature for expanding the expandable outer tube to an outer diameter of 100 to 350 mm is 100 to 120°C.

6. The well completion and cementing method according to any one of claims 1 to 4, characterized in that: The raw materials for preparing the soluble polyurethane elastic material include a prepolymer component and a polyol component; The raw materials for preparing the prepolymer component include 20 to 65 weight percent of polyisocyanate and 35 to 80 weight percent of a first polyester polyol; The polyol component comprises 70 to 100 parts by weight of a second polyester polyol, 4 to 10 parts by weight of a chain extender, 0.5 to 2 parts by weight of a catalyst and 1 to 25.5 parts by weight of a hydrophilic agent; and / or, The weight ratio of the prepolymer component to the polyol component is 30:100 to 90:100; and / or, The soluble polyurethane elastic material has a tensile strength of 5 to 30 MPa; and / or, The polyisocyanate is selected from at least one of toluene diisocyanate, diphenylmethane diisocyanate and polyphenylmethane polyisocyanate; and / or, The first polyester polyol and the second polyester polyol are each independently adipic acid polyester polyol and / or castor oil polyester polyol; and / or, The chain extender is selected from at least one of 3,3'-dichloro-4,4'-diaminodiphenylmethane, diaminodimethylthiotoluene, ethylene glycol, 1,4-butanediol, diethylene glycol, trimethylolpropane, triethanolamine and diethanolamine; and / or, The catalyst is a tertiary amine catalyst and / or an organic metal catalyst; and / or, The hydrophilic agent is polyethylene glycol and / or a water-absorbing resin.

7. The well completion and cementing method according to claim 6, characterized in that: The content of isocyanate in the prepolymer component is 5 to 20% by weight.

8. The well completion and cementing method according to claim 6, characterized in that: The polymerization monomers of the adipic acid-based polyester polyol include adipic acid and alcohols.

9. The well completion and cementing method according to claim 8, characterized in that: The alcohol is selected from at least one of ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, methylpropylene glycol and diethylene glycol.

10. The well completion and cementing method according to claim 6, characterized in that: The adipic acid polyester polyol is at least one of polyethylene adipate diol with a number average molecular weight of 2000-4000, polybutylene adipate diol with a number average molecular weight of 2000-4000, polyneopentyl adipate diol with a number average molecular weight of 1000-5000, polyethylene adipate butanediol diol with a number average molecular weight of 1000-5000 and polyethylene adipate neopentyl glycol diol with a number average molecular weight of 1000-5000.

11. The well completion and cementing method according to claim 6, characterized in that: The tertiary amine catalyst is selected from at least one of triethylenediamine, tetramethylethylenediamine and dimethylcyclohexylamine.

12. The well completion and cementing method according to claim 6, characterized in that: The organic metal catalyst is selected from at least one of dibutyltin dilaurate, stannous octoate, potassium isooctanoate, potassium acetate, potassium oleate, phenylmercuric acetate and zinc isooctanoate.

13. The well completion and cementing method according to claim 6, characterized in that: The content of the polyethylene glycol is 6 to 23.5 parts by weight, and the content of the water-absorbing resin is 1 to 2 parts by weight.

14. The well completion and cementing method according to any one of claims 1 to 4 and 7 to 13, characterized in that: The shape memory material is prepared by mixing and foaming polyurethane and hot melt adhesive.

15. The well completion and cementing method according to claim 14, characterized in that: The hot melt adhesive is selected from at least one of styrene-isoprene-styrene copolymer hot melt adhesive, polyurethane hot melt adhesive, ethylene-vinyl acetate copolymer hot melt adhesive, water-based polyurethane hot melt adhesive, nylon and reactive polyurethane hot melt adhesive; and / or, The weight ratio of the polyurethane to the hot melt adhesive is: 30%-80%: 20%-70%.

16. The well completion and cementing method according to any one of claims 1-4, 7-13 and 15, characterized in that: Before the casing is lowered into the wellbore, the method further comprises: compressing the expandable outer pipe at 70-180° C. to an inner diameter of 50-250 mm and contacting the outer wall of the inner layer base pipe.

17. The well completion and cementing method according to any one of claims 1-4, 7-13 and 15, characterized in that: The inner layer base pipe and the connecting device are hydrolyzed or dissolved in the completion fluid.

18. The well completion and cementing method according to any one of claims 1-4, 7-13 and 15, characterized in that: The preparation method of the soluble polyurethane elastic material is: Step A, mixing and reacting a polyisocyanate with a first polyester polyol to obtain a prepolymer component; Step B, mixing the second polyester polyol, a chain extender, a catalyst and a hydrophilic agent to obtain a polyol component; Step C: mixing and reacting the prepolymer component and the polyol component.

19. The well completion and cementing method according to claim 18, characterized in that: After obtaining the soluble polyurethane elastic material, it also includes a curing and aging process; and / or, The reaction conditions in step A include: temperature of 0 to 90° C. and time of 2 to 3 h; and / or, The reaction temperature in step C is 30-60°C.

20. The well completion and cementing method according to claim 19, characterized in that: The curing conditions include: a temperature of 20 to 40° C. and a time of 10 to 30 minutes.

21. The well completion and cementing method according to claim 19 or 20, characterized in that: The aging conditions include: temperature of 60 to 90° C. and time of 1 to 4 hours.

22. Application of the well completion and cementing method according to any one of claims 1 to 21 in oil and gas well completion technology.

23. The use according to claim 22, characterized in that The well completion and cementing method is applied in oil wells, natural gas wells and water wells.

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