Resin cement slurry and its preparation method and application

Abstract

The present invention relates to the field of drilling engineering and discloses a resin cement slurry, a preparation method thereof, and applications thereof. The resin cement slurry comprises the following components, measured in parts by weight: 100 parts of cement, 1-100 parts of epoxy resin, 1-80 parts of curing agent, 1-100 parts of skeleton material I, 1-100 parts of skeleton material II, 0.1-40 parts of setting agent, 0.1-40 parts of toughening agent, 1-40 parts of dispersant, 0.1-20 parts of fluid loss additive, 0.1-40 parts of defoaming agent, 1-100 parts of water, and 0-100 parts of density modifier. The resin cement slurry is prepared by selecting the components in the above-mentioned specific weight proportions. The slurry has good rheological properties and is easy to use for cementing construction. The resulting resin cement slurry has higher compressive strength, lower elastic modulus, and can be used for a long time at an operating temperature of 45-95°C.

Description

Technical Field

[0001] The present invention relates to the field of drilling engineering, and in particular to a resin cement slurry and a preparation method and application thereof. Background Art

[0002] Efficient development of shale gas reservoirs requires large-scale hydraulic fracturing to create artificial fractures that provide seepage channels for production. However, this leads to rapid production decline and a short period of stable production after the initial stimulation. Refracturing is a technology used to treat horizontal shale gas well sections that have insufficient initial stimulation or insufficient production but still have potential. This involves running small casing into the original wellbore, cementing the casing, and then performing refracturing to increase shale gas well production. This technique of running small casing into older shale gas wells for cementing is known as casing-in-casing technology.

[0003] Compared with traditional oil and gas well cementing, the main difficulties of the casing-in-casing technology are: (1) The single-sided annular gap of the casing-in-casing technology is small, and the annular pressure loss increases during the injection and displacement process, which brings great technical difficulties to leak prevention and channeling prevention. (2) The late perforation and large-scale hydraulic fracturing have a significant impact on the thin cement sheath interface, making it difficult to ensure the sealing integrity of the thin cement sheath, which is prone to annular pressure.

[0004] Currently, cement is primarily used to seal the annular space between casings to prevent water loss after repeated fracturing in shale gas wells. However, the disadvantage is that conventional cement annuli are highly brittle and can break or even shatter under pressure, leading to annular pressure after repeated fracturing in shale gas wells. Using only epoxy resin for casing-in-casing sealing is also very expensive and has difficult-to-control rheological properties.

[0005] Therefore, a fluid system with low elastic modulus and high toughness is needed to ensure the sealing integrity of the casing in the casing and reduce the problem of annular pressure after repeated fracturing of shale gas wells. Summary of the Invention

[0006] The purpose of the present invention is to overcome the problems of increased annular pressure loss during injection and replacement in existing casing-in-casing technology and the easy annular pressure after repeated fracturing of shale gas wells, and to provide a resin cement slurry and its preparation method and application.

[0007] In order to achieve the above-mentioned object, the first aspect of the present invention provides a resin cement slurry, wherein the resin cement slurry comprises the following components in parts by weight: 100 parts of cement, 1-100 parts of epoxy resin, 1-80 parts of curing agent, 1-100 parts of skeleton material-I, 1-100 parts of skeleton material-II, 0.1-40 parts of setting regulator, 0.1-40 parts of toughening agent, 1-40 parts of dispersant, 0.1-20 parts of fluid loss additive, 0.1-40 parts of defoaming agent, 1-100 parts of water and 0-100 parts of density regulator.

[0008] A second aspect of the present invention provides a method for preparing the aforementioned resin cement slurry, characterized in that it comprises the following steps:

[0009] (1) Mix cement, epoxy resin, curing agent, skeleton material-II, setting agent, toughening agent, dispersant, fluid loss additive, defoaming agent, water and density regulator and add them to a mixer;

[0010] (2) Stirring with a stirrer at a low speed, adding the skeleton material-Ⅰ powder within 5-15 seconds, stirring with a stirrer at a high speed for 20-50 seconds, and stirring evenly to obtain the resin cement slurry.

[0011] A third aspect of the present invention provides an application of the aforementioned resin cement slurry in casing cementing in refracturing casing of a shale gas well.

[0012] Through the above technical solution, the beneficial technical effects achieved by the present invention are as follows:

[0013] (1) The resin cement slurry of the present invention is a composite system of epoxy resin and cement, which has excellent heat resistance, good compressive strength and toughness, and excellent adhesion;

[0014] (2) The resin cement slurry of the present invention has good rheological properties, is easy to cement, and has a controllable curing time, which can meet the needs of cementing casing in repeated fracturing casing of shale gas wells at a temperature below 95°C;

[0015] (3) The present invention introduces epoxy resin materials and toughening agents into cement, which can effectively increase the elasticity of the solidified material while maintaining the original high strength of the cement, and has high impact resistance, which can meet the long-term sealing of the cement ring after the impact of large-scale hydraulic fracturing after perforation of thin cement ring;

[0016] (4) In the present invention, preferably, the use of a skeleton material can further improve or regulate the density, strength, rheology, curing time and other properties of the resin cement slurry system;

[0017] (5) In the present invention, the resin cement slurry has lower cost than the simple use of resin system and has broad application prospects. DETAILED DESCRIPTION

[0018] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0019] A first aspect of the present invention provides a resin cement slurry, wherein the resin cement slurry comprises the following components in parts by weight: 100 parts of cement, 1-100 parts of epoxy resin, 1-80 parts of curing agent, 1-100 parts of skeleton material-I, 1-100 parts of skeleton material-II, 0.1-40 parts of setting regulator, 0.1-40 parts of toughening agent, 1-40 parts of dispersant, 0.1-20 parts of fluid loss additive, 0.1-40 parts of defoaming agent, 1-100 parts of water and 0-100 parts of density regulator.

[0020] The present invention selects each component according to the above-mentioned specific weight parts to prepare resin cement slurry. The two skeleton materials and the added toughening agent and dispersant act synergistically. The resin cement slurry prepared in combination with other components has good rheological properties and is easy to use for cementing construction. The obtained resin cement slurry has higher compressive strength, smaller elastic modulus, better hydrophilicity, and can be used for a long time at an operating temperature of 45-95°C.

[0021] In the present invention, the casing-in-casing technology of shale gas wells requires higher strength and lower elastic modulus than traditional oil and gas well cementing due to the thinner cement ring and higher construction pump pressure. In order to meet the impact of large-scale hydraulic fracturing on the thin sealing ring, lower friction resistance is also required during construction to avoid high construction pump pressure, which in turn causes leakage in the formation and causes complex conditions underground.

[0022] According to the present invention, preferably, the weight proportions of the components in the resin cement slurry, calculated based on the amount of cement, are as follows: 100 parts of cement, 5-25 parts of epoxy resin, 5-50 parts of curing agent, 2-15 parts of skeleton material-I, 5-50 parts of skeleton material-II, 0.1-0.5 parts of setting regulator, 1-10 parts of toughening agent, 1-5 parts of dispersant, 1-15 parts of fluid loss additive, 1-20 parts of defoaming agent, 20-80 parts of water and 0-80 parts of density regulator.

[0023] In the present invention, preferably, the cement is not particularly limited, and is preferably a Class G cement material in the field of cementing engineering.

[0024] In the present invention, the skeleton material can further improve or regulate the density, strength, rheology, curing time and other properties of the resin cement slurry system.

[0025] According to the present invention, the average particle size of the powder of the Framework Material I is preferably 10-1000 μm, more preferably 10-500 μm. In the present invention, controlling the particle size of the Framework Material I powder within this preferred range allows it to fully react with the active ingredients in the cement. The average particle size can be determined by sieving.

[0026] According to the present invention, preferably, the framework material-I is light-burned magnesium oxide.

[0027] In the present invention, preferably, the framework material-I can be prepared by the following method:

[0028] (1) dissolving magnesium nitrate and sodium bicarbonate in a certain amount of deionized water at a molar ratio of 1:1-3, then adjusting the pH value of the solution to 3-4 with dilute nitric acid to obtain solution A, heating solution A in a water bath to 50-70°C, dissolving anhydrous Na2CO3 in deionized water to obtain solution B with a concentration of 1-2 mol / L, adjusting the pH value to 9-10 with concentrated nitric acid, and then heating solution B in a water bath at 50-70°C;

[0029] (2) While stirring at a speed of 500-1500 r / min, solution B is rapidly added to solution A and the stirring is continued for 2-10 minutes. The solution is then allowed to stand for aging for 10-60 minutes. The product is then filtered, washed with ultrapure water and ethanol, and dried at 80-120°C to obtain MgCO3.

[0030] (3) Calcinate MgCO3 at 300-900°C for 10-24h to obtain MgO, ball mill it for 20-60min, and then take it out to obtain MgO particles.

[0031] According to the present invention, the weight of the skeleton material I is preferably 1-100 parts, and can be 1 part, 5 parts, 10 parts, 20 parts, 30 parts, 40 parts, 50 parts, 60 parts, 70 parts, 80 parts, 90 parts, 100 parts, or any value within a range consisting of any two of the above values, preferably 2-15 parts. Adding the above preferred weight of skeleton material I can improve the thickening properties and compressive strength of the cement slurry. However, adding too much skeleton material I will result in an excessively high elastic modulus of the resin cement slurry, which cannot meet the requirements of large-scale fracturing in the later stages of shale gas wells.

[0032] According to the present invention, preferably, the framework material-II is selected from at least one of magnesium chloride, magnesium phosphate and magnesium sulfate.

[0033] In the present invention, preferably, the weight portion of the skeleton material-II is 1-100 parts, which can be 1 part, 5 parts, 10 parts, 20 parts, 30 parts, 40 parts, 50 parts, 60 parts, 70 parts, 80 parts, 90 parts, 100 parts, and any value in the range composed of any two of the above values, preferably 5-50 parts.

[0034] According to the present invention, preferably, the epoxy resin is selected from at least one of bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin and hydrogenated bisphenol A epoxy resin, preferably selected from at least one of bisphenol F epoxy resin, bisphenol S epoxy resin and hydrogenated bisphenol A epoxy resin.

[0035] In the present invention, preferably, the weight portion of the epoxy resin is 1-100 parts, which can be 1 part, 5 parts, 10 parts, 20 parts, 25 parts, 30 parts, 40 parts, 50 parts, 60 parts, 70 parts, 80 parts, 90 parts, 100 parts, and any value in the range consisting of any two of the above values, preferably 5-25 parts.

[0036] According to the present invention, preferably, the viscosity of the epoxy resin is 10-1000 mPa·s, preferably 100-800 mPa·s.

[0037] According to the present invention, preferably, the epoxy equivalent of the epoxy resin is 10-2000 g / mol, preferably 100-1000 g / mol.

[0038] In the present invention, preferably, by adding epoxy resin to the resin cement slurry, the elasticity of the cured product can be effectively increased while maintaining a high strength, and the product has a high impact resistance, which can meet the long-term sealing of the cement ring after the impact of large-scale hydraulic fracturing after perforation of a thin cement ring.

[0039] According to the present invention, preferably, the curing agent is selected from at least one of monofunctional anhydride, difunctional anhydride, free acid anhydride, maleic anhydride, novolac resin, polyester resin, styrene-maleic anhydride copolymer resin and polysulfide rubber.

[0040] Preferably, the curing agent is selected from at least one of monofunctional acid anhydride, difunctional acid anhydride, free acid anhydride, styrene-maleic anhydride copolymer resin and polysulfide rubber. More preferably, the curing agent is selected from at least one of phthalic anhydride, succinic anhydride and maleic anhydride.

[0041] According to the present invention, preferably, the weight portion of the curing agent is 1-80 parts, and can be 1 part, 5 parts, 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, 55 parts, 60 parts, 65 parts, 70 parts, 75 parts, 80 parts, and any value in the range consisting of any two of the above values, preferably 5-50 parts.

[0042] In the present invention, preferably, the epoxy resin is an epoxy resin emulsion, which forms a thermosetting resin gelling system with a curing agent.

[0043] The thermosetting resin cementitious material in the thermosetting resin cementitious system described herein crosslinks and solidifies under heating and pressure to form a network-like structure. This structure resists deformation under pressure and exhibits advantages such as good adhesion, impact resistance, a low elastic modulus, and high toughness. The use of the skeleton material described herein can further improve or regulate the density, strength, rheology, and curing time of the thermosetting resin system, meeting the basic requirements of cementing engineering while also addressing challenges such as the difficulty in ensuring the sealing integrity of thin cement sheaths and poor bonding.

[0044] According to the present invention, the toughening agent is preferably an elastic material, preferably a plasma-modified elastic material. Plasma modification of the elastic material in the present invention can alter its surface activity. Unmodified rubber particles have fewer polar groups on their surface and poor hydrophilicity. Plasma-modified elastic materials, however, have polar groups generated on their surface, significantly increasing their hydrophilicity and reducing their surface tension, thereby improving the toughness of the resin cement slurry.

[0045] In the present invention, preferably, the elastic material is rubber particles.

[0046] In the present invention, the plasma modification adopts a plasma treatment apparatus, which mainly includes a discharge system, a reaction chamber, an air intake system, an electromagnetic shield, a vacuum system and a gas discharge system, with a discharge frequency of 13.56 MHz and a maximum power of 400 W.

[0047] In the present invention, preferably, the modification process includes: subjecting the elastic material to plasma treatment under an inert atmosphere, wherein the plasma is argon gas with a purity of 98%-99.999%, the plasma flow rate is 1-100 sccm, the discharge power is 10-400 W, and the treatment time is 2-10 min.

[0048] In the present invention, preferably, the inert atmosphere is argon with a purity greater than 99.999%.

[0049] According to a preferred embodiment of the present invention, the plasma modification process is performed at a power of 80W and a modification time of 180s. The low-temperature plasma instrument is preheated for 30 minutes. The vacuum pump is turned on until the vacuum level in the chamber drops below 10Pa. The purity of the modified gas is ensured. The flow valve is opened and the modified gas is introduced at a steady flow rate of 60sccm. The modification time is set to 180s and the process is terminated after reaching the set parameters. The modified elastic material is then placed in a planetary ball mill and ball milled for 1 hour to obtain the plasma-modified elastic material.

[0050] In the present invention, the surface activity of the elastic material before and after modification was determined. The contact angle between the sample surface and a liquid droplet (deionized water) in an atmospheric environment was measured using a CA500S fully automatic optical contact angle meter with an integral tilt. The surface wettability and aging properties of the elastic material before and after modification were characterized according to ASTM 5725 (Standard Method for Testing the Surface Wettability and Absorption of Sheet Materials Using an Automatic Contact Angle Tester).

[0051] According to the present invention, preferably, the weight portion of the toughening agent is 0.1-40 parts, which can be 0.1 parts, 1 parts, 5 parts, 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, and any value in the range consisting of any two of the above values, preferably 1-10 parts.

[0052] According to the present invention, preferably, the dispersant is selected from polycarboxylic acid dispersants and / or aldehyde ketone dispersants, preferably polycarboxylic acid dispersants.

[0053] In the present invention, the dispersant can effectively disperse the solid particles at room temperature and high temperature, and improve the rheological properties of the slurry.

[0054] In the present invention, preferably, the weight portion of the dispersant is 0.1-40 parts, which can be 0.1 parts, 1 parts, 5 parts, 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, and any value in the range consisting of any two of the above values, preferably 1-5 parts.

[0055] According to the present invention, preferably, the coagulant is selected from at least one of polyphosphate coagulants, citrate coagulants and gluconate coagulants, preferably a polyphosphate coagulant.

[0056] In the present invention, the setting regulator can control the thickening time of the resin cement slurry within the temperature range of 45-95°C.

[0057] According to the present invention, preferably, the weight portion of the setting agent is 0.1-40 parts, and can be 0.1 parts, 0.5 parts, 1 parts, 2 parts, 3 parts, 4 parts, 5 parts, 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, and any value in the range consisting of any two of the above values, preferably 0.1-0.5 parts.

[0058] According to the present invention, preferably, the defoaming agent is selected from at least one of silicone oil defoaming agents, polyether defoaming agents, and aldehyde ketone defoaming agents. In the present invention, the use of the above defoaming agents can effectively control the generation of foam in the cement slurry system and improve the compressive strength of the resin cement slurry.

[0059] According to the present invention, preferably, the weight portion of the defoaming agent is 0.1-40 parts, and can be 0.1 parts, 0.5 parts, 1 parts, 2 parts, 3 parts, 4 parts, 5 parts, 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, and any value in the range consisting of any two of the above values, preferably 1-20 parts.

[0060] According to the present invention, preferably, the fluid loss additive is selected from polyvinyl alcohol fluid loss additives and / or 2-acrylamido-2-methylpropanesulfonic acid fluid loss additives, preferably polyvinyl alcohol fluid loss additives, more preferably polyvinyl pyrrolidone and / or polyvinyl alcohol.

[0061] In the present invention, the fluid loss additive can control the filtration rate of cement slurry in the resin cement slurry system, thereby preventing annular air leakage.

[0062] According to the present invention, preferably, the weight portion of the fluid loss additive is 0.1-20 parts, and can be 0.1 parts, 0.5 parts, 1 parts, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 8 parts, 10 parts, 12 parts, 14 parts, 15 parts, 20 parts, and any value in the range consisting of any two of the above values, preferably 1-15 parts.

[0063] According to the present invention, the density regulator is a lightening agent or a weighting agent, and the density regulator is used to adjust the density of the resin cement slurry to 1.2-1.7 g / cm 3 within the range.

[0064] According to the present invention, preferably, the lightening agent is floating beads, preferably high-anti-extrusion glass beads.

[0065] According to the present invention, preferably, the weighting agent is selected from at least one of hematite powder, iron ore powder and magnetite powder.

[0066] According to the present invention, preferably, the weight portion of the density regulator is 0-100 parts, which can be 0 parts, 10 parts, 20 parts, 30 parts, 40 parts, 50 parts, 60 parts, 70 parts, 80 parts, 90 parts, 100 parts, and any value in the range consisting of any two of the above values, preferably 0-80 parts.

[0067] According to the present invention, preferably, the water is not particularly limited, as long as it can be used to prepare the resin cement slurry. The weight of the water is 1-100 parts, and can be 1 part, 5 parts, 10 parts, 20 parts, 30 parts, 40 parts, 50 parts, 60 parts, 70 parts, 80 parts, 90 parts, 100 parts, or any value within a range consisting of any two of the above values, preferably 20-80 parts.

[0068] A second aspect of the present invention provides a method for preparing the aforementioned resin cement slurry, comprising the following steps:

[0069] (1) Mix cement, epoxy resin, curing agent, skeleton material-II, toughening agent, setting agent, dispersant, fluid loss additive, defoamer, water and density regulator and add them to a mixer;

[0070] (2) Stirring with a stirrer at a low speed, adding the skeleton material-Ⅰ powder within 5-15 seconds, stirring with a stirrer at a high speed for 20-50 seconds, and stirring evenly to obtain the resin cement slurry.

[0071] In the present invention, the stirring speed of the stirrer for low-speed stirring is 3500-4500 rpm, and the stirring speed for high-speed stirring is 10000-14000 rpm.

[0072] Furthermore, the stirring speed of the stirrer is 3800-4200 rpm for low-speed stirring and 11000-13000 rpm for high-speed stirring. Under the above stirring conditions, the components and the skeleton material-I powder can be quickly mixed and uniformly obtained to obtain a resin cement slurry with good rheological properties and good impact resistance.

[0073] A third aspect of the present invention provides an application of the aforementioned resin cement slurry in casing cementing in refracturing casing of a shale gas well.

[0074] In the present invention, the resin cement slurry can be used at 45-95° C., has a wide temperature application range and good sealing effect.

[0075] According to a particularly preferred embodiment of the present invention, the resin cement slurry comprises the following components in parts by weight: 100 parts of cement, 5-20 parts of epoxy resin, 5-50 parts of curing agent, 2-10 parts of skeleton material-I, 5-50 parts of skeleton material-II, 0.1-0.4 parts of setting regulator, 1-10 parts of toughening agent, 1-5 parts of dispersant, 1-15 parts of fluid loss additive, 1-20 parts of defoaming agent, 20-80 parts of water and 0-80 parts of density regulator.

[0076] In the following examples and comparative examples, if specific conditions are not specified, the experiments were carried out under conventional conditions or those recommended by the manufacturer. All reagents and instruments used, if the manufacturer is not specified, are commercially available conventional products.

[0077] The epoxy equivalent weight of the bisphenol F epoxy resin and the bisphenol S epoxy resin in the examples and comparative examples is 170 g / mol, and the viscosity is 200 mPa·s;

[0078] Polyvinyl alcohol was polyvinyl alcohol 1788, purchased from Aladdin.

[0079] The density, thickening performance, API water loss, stability, compressive strength, and rheological parameters of resin cement slurry are measured in accordance with GB / T 19139-2012 Test Methods for Oil Well Cement;

[0080] The elastic modulus of the resin cement slurry was measured by a mechanical properties testing machine in accordance with "Mechanical properties of high temperature and high pressure resistant ultra-high density cement stone" (Song He, Yang Wei, Tang Junfeng, et al. "Drilling Fluid and Completion Fluid" [J], 2021 (038-006)).

[0081] Skeleton Material-Ⅰ Preparation Example

[0082] Dissolve 1 mol of magnesium nitrate and 1 mol of sodium bicarbonate in 500 mL of deionized water. Adjust the pH of the solution to 4 with dilute nitric acid to obtain Solution A. Heat Solution A in a water bath to 65°C. Dissolve 1 mol of anhydrous sodium carbonate in 500 mL of deionized water to prepare Solution B. Adjust the pH to 10 and heat Solution B in a 65°C water bath. While stirring at 1000 rpm, quickly add Solution B to Solution A, continue stirring for 4 minutes, and allow to age for 30 minutes.

[0083] The product was then filtered, washed five times with ultrapure water and ethanol, and dried at 100°C for 12 hours to obtain MgCO3. The MgCO3 was then calcined in a muffle furnace at 600°C for 12 hours to obtain MgO. The MgO was then milled in a planetary ball mill for 30 minutes and then removed to obtain MgO with a particle size of 10-500 μm.

[0084] Test Example 1

[0085] The surface activity of the elastic material before and after modification was determined, and the elastic material samples were subjected to tableting treatment.

[0086] The contact angle between the sample surface and the liquid droplet (deionized water) in the atmospheric environment was measured using a contact angle instrument CA500S integral tilt fully automatic optical contact angle meter. The standard ASTM 5725, a standard method for testing the surface wettability and absorptivity of sheet materials using an automatic contact angle tester, was implemented to characterize the surface wettability and aging properties of the elastic material before and after modification. The contact angle was measured three times, and the results are shown in Table 1.

[0087] Table 1

[0088] Elastic material before modification Modified elastic material Contact angle (°) 136 / 128 / 127 38 / 39 / 37

[0089] As can be seen from Table 1, the water contact angles of the elastic material surface before plasma modification are 136 / 128 / 127°, showing hydrophobic properties. From the contact angles of the elastic material after plasma modification, it can be seen that plasma significantly improves the wettability of the elastic material surface, and the water contact angles are all reduced to below 40°, greatly improving the hydrophilicity of the elastic material.

[0090] Example 1

[0091] (1) 100 parts of Grade G cement (used in cementing engineering), 20 parts of epoxy resin, 20 parts of curing agent, 5 parts of magnesium chloride, 0.2 parts of setting agent, 4 parts of toughening agent, 3 parts of dispersant, 3 parts of fluid loss additive, 2 parts of defoaming agent, 50 parts of water and 50 parts of density regulator were mixed and added to a blender. The specific types of substances are shown in Table 2.

[0092] (2) The stirrer is stirred at a low speed of 4000 rpm, and the skeleton material-Ⅰ powder is added within 15 seconds. The stirrer lid is closed and the stirrer is stirred at a high speed for 35 seconds. The resin cement slurry is obtained by stirring evenly.

[0093] Example 2-20

[0094] Resin cement slurry was prepared according to the formula (parts by weight) in Table 2 with reference to the preparation method of Example 1.

[0095] Table 2 Table 2 (continued)

[0096]

[0097]

[0098] Table 2 (continued)

[0099]

[0100] Table 2 (continued)

[0101]

[0102]

[0103] Table 2 (continued)

[0104]

[0105]

[0106] Comparative Examples 1-5

[0107] Resin cement slurry was prepared according to the formula (parts by weight) in Table 3 and the preparation method of Example 1.

[0108] Table 3

[0109]

[0110]

[0111] Test Case

[0112] The density, API water loss, thickening performance and compressive strength of the resin cement slurries of Examples 1-8 and Comparative Example 1 were measured according to the aforementioned method. The specific results are shown in Table 4.

[0113] Table 4

[0114]

[0115] Table 4 shows that the resin cement slurries of the present invention exhibit strong stability. The preferred epoxy resin and curing agent types have an impact on thickening time, but are within an adjustable range. The API water loss is less than 50 mL / 30 min. In the comparative example, the epoxy resin dosage exceeds the recommended range, so the thickening time fails to meet construction requirements. Changing the setting agent type in Example 7 has little impact on the overall cement slurry system. Changing the type of skeleton material II in Example 8 has a slight impact on thickening time, but remains acceptable.

[0116] The density, compressive strength and elastic modulus of the resin cement slurries of Examples 9-10, 15-16 and Comparative Example 4 were measured according to the aforementioned test methods. The specific results are shown in Table 5.

[0117] Table 5

[0118] serial number <![CDATA[Density, g / cm 3 > Compressive strength, 95℃ / 48h, MPa Elastic modulus, GPa Example 1 1.65 25.3 4.8 Example 9 1.60 22.1 4.5 Example 10 1.55 20.2 4.0 Example 15 1.66 22.2 4.4 Example 16 1.67 20.6 4.1 Comparative Example 4 1.65 28.8 6.9

[0119] Table 5 shows that the resin cement slurry prepared in Example 1 exhibits higher compressive strength. As density decreases, the compressive strength of the cement paste also decreases, and the elastic modulus also changes accordingly. This allows the cement sheath to maintain a low elastic modulus while meeting high strength requirements, with the elastic modulus remaining below 5 GPa. This ensures the toughness of the resin cement slurry, enabling it to meet the requirements of large-scale fracturing in the later stages of shale gas wells. In Examples 15 and 16, the increased amount of toughening agent results in a decrease in elastic modulus and an increase in compressive strength. Comparative Example 4, without the addition of a toughening agent, exhibits higher compressive strength and elastic modulus than the examples. However, for the sleeve-in-sleeve process, the narrow-gap, thin cement sheath requires higher compressive strength and lower elastic modulus to meet development requirements.

[0120] The density, API water loss and thickening performance of the resin cement slurries of Examples 11-12 and Comparative Examples 1-2 were measured according to the aforementioned method. The specific results are shown in Table 6.

[0121] Table 6

[0122]

[0123] Table 6 shows that the thickening time of the resin cement slurry in Example 1 of the present invention is adjustable due to the setting regulator, and does not affect the API water loss. In contrast, since the dosage of Comparative Examples 1 and 2 exceeds the recommended range, the thickening time cannot meet the on-site process requirements.

[0124] The density and thickening properties of the resin cement slurries of Examples 13-14 were measured according to the aforementioned method. The specific results are shown in Table 7.

[0125] Table 7

[0126] serial number <![CDATA[Density, g / cm 3 > Thickening performance 95℃ / 45MPa,min Example 1 1.65 431 Example 13 1.62 587 Example 14 1.60 634 Comparative Example 1 1.45 82

[0127] It can be seen from Table 7 that the resin cement slurries of Examples 13 and 14 of the present invention have a slightly longer thickening time due to the larger amount of epoxy resin added, but are still within the adjustable range.

[0128] The rheological parameters and elastic modulus of the resin cement slurries of Examples 15-18 and Comparative Examples 3-4 at room temperature and high temperature were measured according to the aforementioned method. The specific results are shown in Table 8.

[0129] Table 8

[0130]

[0131] It can be seen from Table 8 that the resin cement slurries of Examples 15 and 16 of the present invention have higher rheological parameters compared to the resin cement slurries of Example 1 due to the larger amount of toughening agent added. The rheological parameters tested at the same rotation speed are much higher than those of Example 1. The slurries are basically unable to flow. Although the elastic modulus can be reduced, it cannot meet the rheological requirements of on-site construction. The resin cement slurries of Examples 17 and 18 have better rheological properties and are in a thinner state due to the increased amount of dispersant added. In Comparative Example 3, the rheological properties are poor because no dispersant is added. In Comparative Example 4, the rheological properties are better because no toughening agent is added. However, due to the higher elastic modulus, it cannot meet the requirements of the cement slurry for the casing of shale gas wells.

[0132] The density, thickening performance and compressive strength of the resin cement slurries of Examples 19-20 and Comparative Example 5 were measured according to the aforementioned method. The specific results are shown in Table 9.

[0133] Table 9

[0134]

[0135] Table 9 shows that the changes in the amount of Skeleton Material-I in the resin cement slurries of Examples 19 and 20 affect their thickening properties and compressive strength. Increasing the amount of Skeleton Material-I reduces the thickening time of the slurry and increases the compressive strength of the cement paste. Comparative Example 5, due to the lack of a skeleton material, exhibits a prolonged thickening time and lower compressive strength.

[0136] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A resin cement slurry, characterized in that: The resin cement slurry comprises the following components in parts by weight: 100 parts of cement, 1-100 parts of epoxy resin, 1-80 parts of curing agent, 1-100 parts of skeleton material-I, 1-100 parts of skeleton material-II, 0.1-40 parts of setting agent, 0.1-40 parts of toughening agent, 1-40 parts of dispersant, 0.1-20 parts of fluid loss additive, 0.1-40 parts of defoaming agent, 1-100 parts of water and 0-100 parts of density regulator; The average particle size of the powder of the skeleton material-Ⅰ is 10-1000 μm; The skeleton material-Ⅰ is light-burned magnesium oxide; The framework material-II is selected from at least one of magnesium chloride, magnesium phosphate and magnesium sulfate.

2. The resin cement slurry according to claim 1, wherein The weight proportions of the components in the resin cement slurry based on the amount of cement are as follows: 100 parts of cement, 5-25 parts of epoxy resin, 5-50 parts of curing agent, 2-15 parts of skeleton material-I, 5-50 parts of skeleton material-II, 0.1-0.5 parts of setting agent, 1-10 parts of toughening agent, 1-5 parts of dispersant, 1-15 parts of fluid loss additive, 1-20 parts of defoaming agent, 20-80 parts of water and 0-80 parts of density regulator.

3. The resin cement slurry according to claim 1 or 2, wherein: The average particle size of the powder of the skeleton material-Ⅰ is 10-500 μm.

4. The resin cement slurry according to claim 1, wherein The epoxy resin is selected from at least one of bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin and hydrogenated bisphenol A epoxy resin.

5. The resin cement slurry according to claim 4, wherein The epoxy resin is selected from at least one of bisphenol F epoxy resin, bisphenol S epoxy resin and hydrogenated bisphenol A epoxy resin.

6. The resin cement slurry according to claim 1, wherein The viscosity of the epoxy resin is 10-1000 mPa·s.

7. The resin cement slurry according to claim 6, wherein: The viscosity of the epoxy resin is 100-800 mPa·s.

8. The resin cement slurry according to claim 1, wherein The epoxy equivalent of the epoxy resin is 10-2000 g / mol.

9. The resin cement slurry according to claim 8, wherein The epoxy equivalent of the epoxy resin is 100-1000 g / mol.

10. The resin cement slurry according to claim 1, wherein The curing agent is selected from at least one of monofunctional acid anhydride, difunctional acid anhydride, free acid anhydride, maleic anhydride, phenolic resin, polyester resin, styrene-maleic anhydride copolymer resin and polysulfide rubber.

11. The resin cement slurry according to claim 10, wherein The curing agent is selected from at least one of monofunctional acid anhydride, difunctional acid anhydride, free acid anhydride, styrene-maleic anhydride copolymer resin and polysulfide rubber.

12. The resin cement slurry according to claim 1, wherein The dispersant is a polycarboxylic acid dispersant and / or an aldehyde ketone dispersant.

13. The resin cement slurry according to claim 12, wherein: The dispersant is a polycarboxylic acid dispersant.

14. The resin cement slurry according to claim 1, wherein The toughening agent is an elastic material.

15. The resin cement slurry according to claim 14, wherein The toughening agent is a plasma-modified elastic material.

16. The resin cement slurry according to claim 15, wherein The contact angle of the plasma-modified elastic material is less than 50°.

17. The resin cement slurry according to claim 16, wherein: The contact angle of the plasma-modified elastic material is 20°-40°.

18. The resin cement slurry according to claim 1, wherein The coagulant is selected from at least one of polyphosphate coagulants, citrate coagulants and gluconate coagulants.

19. The resin cement slurry according to claim 18, wherein The coagulant is a polyphosphate coagulant.

20. The resin cement slurry according to claim 1, wherein The defoaming agent is selected from at least one of silicone oil defoaming agents, polyether defoaming agents and aldehyde ketone defoaming agents.

21. The resin cement slurry according to claim 1, wherein The fluid loss additive is a polyvinyl alcohol-based fluid loss additive and / or 2-acrylamido-2-methylpropanesulfonic acid.

22. The resin cement slurry according to claim 21, wherein The fluid loss additive is a polyvinyl alcohol-based fluid loss additive.

23. The resin cement slurry according to claim 1, wherein The density regulator is a lightening agent or a weighting agent.

24. The resin cement slurry according to claim 23, wherein The lightening agent is floating beads; The weighting agent is selected from at least one of hematite powder, iron ore powder and magnetite powder.

25. A method for preparing the resin cement slurry according to any one of claims 1 to 24, characterized in that: The following steps are involved: (1) Mix cement, epoxy resin, curing agent, skeleton material-II, setting regulator, toughening agent, dispersant, fluid loss additive, defoaming agent, water and density regulator and add them into the mixer; (2) Stir the mixture at a low speed and add the skeleton material-Ⅰ powder within 5-15 seconds. Stir the mixture at a high speed for 20-50 seconds until the mixture is evenly mixed to obtain the resin cement slurry.

26. Use of the resin cement slurry according to any one of claims 1 to 24 in casing cementing in refracturing casing of shale gas wells.

Images