A double-effect spacer fluid for cementing a polymeric salt mud and a preparation method and use method thereof

Abstract

The application provides a double-effect isolation fluid for cementing of polymer salt mud, and a preparation method and use method thereof. The double-effect isolation fluid is composed of the following substances in percentage by weight: water 55-64%, gel-breaking type suspending agent 30-40%, penetrating agent 3-4%, and interface reinforcing agent 1-2%. The gel-breaking type suspending agent is composed of the following substances in parts by weight: water 300-400 parts, natural cellulose 45-55 parts, acrylamide 10-20 parts, 2-acrylamido-2-methylpropanesulfonic acid 20-30 parts, sodium hydroxide 1-6 parts, initiator 0.3-0.6 parts, and sodium metaaluminate 1-3 parts. The water-soluble ternary polymer is obtained by polymerization of natural cellulose, acrylamide and 2-acrylamido-2-methylpropanesulfonic acid, the water-soluble ternary polymer is used as the gel-breaking type suspending agent, and the double-effect isolation fluid for cementing is formed by adding the penetrating agent and the interface reinforcing agent.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of cementing slurry additive, and particularly relates to a double-effect spacer fluid for polymer salt slurry cementing, and a preparation method and use method thereof. BACKGROUND

[0002] After the general drilling fluid and the cementing slurry are mixed, they will pollute each other, form some gel structures difficult to destroy, affect the performance of the cementing slurry, and cause poor cementation at the second interface. The prominent problems are long cementing time of the cementing slurry and slow development of the strength of the cementing slurry, especially under the condition of shallow well, because of the shallow well and low ground temperature, the cementing slurry is difficult to form high enough strength within the normal required waiting time, and cannot meet the needs of production and exploitation.

[0003] An invention patent with the publication number CN109370550A and the publication date of February 22, 2019 discloses a double-effect flushing type spacer fluid for cementing and a preparation method thereof. The flushing type spacer fluid comprises 100 parts of clean water, 20-40 parts of flushing agent, 1-5 parts of suspending agent, 1-3 parts of retarder, 100-400 parts of weighting agent and 0.1-0.2 parts of defoaming agent. According to the weight fraction, the raw materials of the flushing agent comprise 70-80 parts of water, 5-30 parts of fatty alcohol ether polyoxyethylene ether sodium sulfate, 1-10 parts of polyoxyethylene octylphenol ether-10, 1-10 parts of fatty alcohol polyoxyethylene ether, 5-20 parts of alkyl glycoside and 5-10 parts of cleaning aid. The flushing type spacer fluid takes anionic surfactant AES and nonionic surfactant OP-10 as main agents, and plays the role of oil cleaning. The cleaning aid can help cleaning and improve the compatibility with the cementing slurry and the mud, solve the pollution, adopt JFC as a penetrating agent, mainly aiming at the dense filter cake formed by the oil-based drilling fluid, reverse the wetting of the filter cake, remove the oil film on the casing, and eliminate the gas channeling caused by the micro gap of the oil film in cementing. The alkyl glycoside APG is used as a surfactant, and is one of the components of the flushing agent for cleaning oil stains. The invention is used for oil-based drilling fluid, and enhances the solubility and permeability of the filter cake by using the isolation and high-efficiency flushing of the oil-based mud filter cake, so as to promote the penetration, dissolution and dilution of the spacer fluid to the filter cake. However, the invention cannot effectively isolate the water-based drilling fluid and the cementing slurry. SUMMARY

[0004] The present application aims to provide a double-effect spacer fluid for polymer salt slurry cementing, and overcome the above technical problems in the prior art.

[0005] Another object of the present application is to provide a preparation method of the double-effect spacer fluid for polymer salt slurry cementing.

[0006] Another object of the present application is to provide a use method of the double-effect spacer fluid for polymer salt slurry cementing, which can flush the loose mud cake on the well wall and the casing, and improve the cementation strength at the second interface.

[0007] To this end, the technical scheme provided by the present application is as follows:

[0008] A double-effect spacer fluid for polymer salt mud well cementing, which is composed of the following substances in percentage by weight: water 55-64%, gel-breaking type suspending agent 30-40%, penetrating agent 3-4%, and interface reinforcing agent 1-2%.

[0009] The gel-breaking type suspending agent comprises the following substances in parts by weight: water 300-400 parts, natural cellulose 45-55 parts, acrylamide 10-20 parts, 2-acrylamido-2-methylpropane sulfonic acid 20-30 parts, sodium hydroxide 1-6 parts, initiator 0.3-0.6 parts, and sodium metaaluminate 1-3 parts.

[0010] The interface reinforcing agent is a mixture of aluminum chloride and potassium fluosilicate, and the mass ratio of the two is 1:1.

[0011] The penetrating agent is sodium polystyrene sulfonate, fatty alcohol polyoxyethylene ether or polyoxyethylene ether.

[0012] The initiator is ammonium persulfate or potassium persulfate.

[0013] A preparation method of a double-effect spacer fluid for polymer salt mud well cementing, which comprises the following steps: adding formula amount of water, gel-breaking type suspending agent, penetrating agent and interface reinforcing agent into a sealed reaction container in sequence, stirring and heating while adding, stopping heating when the reaction temperature reaches 50-60℃, stirring for 30-40 min, and cooling to obtain the double-effect spacer fluid.

[0014] The preparation process of the gel-breaking type suspending agent is as follows:

[0015] Step 1) adding formula amount of water into a sealed reaction container, adding formula amount of natural cellulose while stirring, and after fully dissolving, adding formula amount of acrylamide, 2-acrylamido-2-methylpropane sulfonic acid and sodium metaaluminate, and continuing to stir for 0.5-1 h while introducing nitrogen;

[0016] Step 2) adding formula amount of initiator and stirring for 2-3 h when the reaction temperature reaches 50-60℃ by heating;

[0017] Step 3) stopping adding, adding formula amount of sodium hydroxide to adjust the pH value to 7, and then cooling and drying to obtain powder.

[0018] A use method of a double-effect spacer fluid for polymer salt mud well cementing, which comprises the following steps: mixing water, the double-effect spacer fluid for polymer salt mud well cementing and weighting agent to obtain a front spacer fluid, wherein the parts by weight of water, the double-effect spacer fluid for polymer salt mud well cementing and the weighting agent are 85-95 parts, 5-15 parts and 25-40 parts, respectively.

[0019] The beneficial effects of the present application are:

[0020] The double-effect spacer fluid for cementing of the polymeric salt mud provided by the present application is prepared by polymerization of natural cellulose, acrylamide and 2-acrylamido-2-methylpropanesulfonic acid to obtain water-soluble ternary polymer, the water-soluble ternary polymer is used as a broken gel type suspending agent, and is supplemented with a penetrating agent and an interface reinforcing agent to form a double-effect spacer fluid for cementing.

[0021] The present application changes the physical and chemical properties of the wellbore drilling fluid by introducing the broken gel type suspending agent, destroys the colloid system of the drilling fluid, promotes the aggregation of the fine particles suspended around the wellbore into flocculation, reduces the viscosity of the wellbore drilling fluid, effectively removes the virtual mud cake on the well wall by using the suspending and separating effects of the broken gel type suspending agent, and the generated flocculation is suspended in the spacer fluid; the penetrating agent is introduced to mainly play the roles of floatation and solubilization, and enhance the solubility and permeability of the spacer fluid to the mud cake.

[0022] The broken gel type suspending agent has high viscosity and suspending performance, forms a certain viscosity difference with the drilling fluid, is beneficial to improving the displacement efficiency, can make the mud cake broken and destabilized, and effectively flushes the loose mud cake on the well wall and casing; the interface reinforcing agent enhances the interface cementing strength of the cement slurry in the filling section through the interface reinforcing effect. DETAILED DESCRIPTION

[0023] The embodiments of the present application are described below by specific examples, and other advantages and effects of the present application can be easily understood by those skilled in the art from the content disclosed in the specification.

[0024] The exemplary embodiments of the present application are now described, however, the present application can be implemented in many different forms and is not limited to the embodiments described herein, these embodiments are provided to thoroughly and completely disclose the present application and fully convey the scope of the present application to those skilled in the art. The terms expressed in the exemplary embodiments are not a limitation of the present application.

[0025] Unless otherwise defined, the terms used herein (including technical terms) have the meanings commonly understood by those skilled in the art. In addition, it can be understood that the terms defined in commonly used dictionaries should be understood in the context of the relevant art and should not be understood in an idealized or overly formal sense.

[0026] Example 1

[0027] The present embodiment provides a double-effect spacer fluid for cementing of polymeric salt mud, which is composed of the following substances in weight percentage: water 55-64%, broken gel type suspending agent 30-40%, penetrating agent 3-4%, and interface reinforcing agent 1-2%.

[0028] Principle of the present application:

[0029] The present application changes the physical and chemical properties of the wellbore drilling fluid by introducing the gel-breaking type suspending agent, destroys the colloid system of the drilling fluid, promotes the small particles suspended around the wellbore to aggregate into flocculation, reduces the viscosity of the wellbore drilling fluid, effectively removes the virtual mud cake on the well wall by using the suspending and isolating effect of the gel-breaking type suspending agent, and the generated flocculation is suspended in the spacer fluid; the main effect of the introduced permeating agent is to increase the solubility and permeability of the spacer fluid to the mud cake; the interfacial reinforcing agent enhances the interfacial cementing strength of the cement slurry in the filling section through the interfacial reinforcing effect.

[0030] The gel-breaking type suspending agent comprises the following substances in parts by weight: water 300-400 parts, natural cellulose 45-55 parts, acrylamide 10-20 parts, 2-acrylamido-2-methylpropanesulfonic acid 20-30 parts, sodium hydroxide 1-6 parts, initiator 0.3-0.6 parts, and sodium metaaluminate 1-3 parts.

[0031] The gel-breaking type suspending agent is designed by molecular structure, with cellulose as the main monomer. The cellulose increases the viscosity of the spacer fluid and improves the suspending capacity. The long side chain-containing and adsorptive hydroxyl group-containing monomers acrylamide and 2-acrylamido-2-methylpropanesulfonic acid (AMPS) are introduced. The AMPS structure contains a sulfonic acid group which has strong hydration capacity, is not easy to hydrolyze, has good temperature resistance, and is not sensitive to the attack of external metal cations, so the temperature resistance and salt tolerance of the spacer fluid can be improved. The adsorptive amide group and carboxyl group are introduced into the molecular chain to improve the flocculation and adsorption capacity of the gel-breaking type suspending agent at high temperature and the compatibility with other additives. The long side chain-containing hydroxyl group-containing monomer cellulose is introduced. The cellulose is a monomer containing a long side chain and an adsorptive hydroxyl group. On the one hand, the long side chain improves the rheological properties of the preflush by the space steric hindrance effect and lubrication effect. On the other hand, the hydroxyl group can form a hydrogen bond network structure on the surface of the cement particles to improve the flocculation capacity of the polymer. The addition of sodium metaaluminate makes the gel-breaking type suspending agent have a positive charge, and the diffusion double electric layer of the mud is destroyed by ion exchange.

[0032] The gel-breaking principle is that the adsorption capacity of the gel-breaking type suspending agent containing long side chains and adsorptive hydroxyl groups makes the small particles in the drilling fluid become large particles and easily settle, thereby enhancing the net trapping effect on the particles after gel breaking.

[0033] The interfacial reinforcing agent is a mixture of aluminum chloride and potassium fluosilicate, and the mass ratio of the two is 1:1. The introduction of aluminum chloride and potassium fluosilicate in the spacer fluid enhances the interfacial cementing strength of the cement slurry in the filling section through the chloride ion effect and the interfacial reinforcing effect.

[0034] The penetrating agent is sodium polystyrene sulfonate, fatty alcohol polyoxyethylene ether or polyoxyethylene ether. The penetrating agent forms intermolecular force with long-chain hydrocarbon molecules in the polymer, reduces the interfacial tension, forms very strong penetrating force on the high molecular film on the interface, and accelerates the dissolution and separation rate of the high molecular film on the interface.

[0035] The initiator is ammonium persulfate or potassium persulfate.

[0036] Example 2

[0037] On the basis of Example 1, the present embodiment provides a double-effect spacer fluid for polymer salt mud slurry cementing, which is composed of the following substances in percentage by weight: water 55%, gel-breaking type suspending agent 40%, penetrating agent 3%, and interfacial enhancer 1%.

[0038] The gel-breaking type suspending agent comprises the following substances in parts by weight: water 400 parts, natural cellulose 50 parts, acrylamide 20 parts, 2-acrylamido-2-methylpropane sulfonic acid 25 parts, sodium hydroxide 4 parts, initiator 0.3 parts, and sodium metaaluminate 2 parts.

[0039] Preparation process:

[0040] Under room temperature conditions, the formula amount of water, gel-breaking type suspending agent, penetrating agent and interfacial enhancer are sequentially added in a closed enamel reaction kettle, and stirring and heating are performed while adding, when the reaction temperature reaches 50-60℃, stirring is performed for 30-40 min, heating is stopped, and cooling is performed, and then the double-effect spacer fluid is prepared.

[0041] The preparation process of the gel-breaking type suspending agent is as follows:

[0042] Step 1) In a sealed reaction container, the formula amount of water is added, and the formula amount of natural cellulose is added while stirring, after fully dissolving, the formula amount of acrylamide, 2-acrylamido-2-methylpropane sulfonic acid and sodium metaaluminate are added, and nitrogen is introduced for continuous stirring for 0.5-1 h;

[0043] Step 2) When the reaction temperature reaches 50-60℃, the formula amount of initiator is added for stirring reaction for 2-3 h;

[0044] Step 3) Stopping adding, the formula amount of sodium hydroxide is added to adjust the pH value to 7, and then cooling and drying are performed, and then powder is obtained.

[0045] In the present embodiment, the penetrating agent is sodium polystyrene sulfonate; the interfacial enhancer is a mixture of aluminum chloride and potassium fluosilicate, and the mass ratio of the two is 1:1; the initiator is ammonium persulfate. The natural cellulose adopts Shaanxi Rangan Biological Technology Co., Ltd., and the execution standard is GB / T5005-200.

[0046] Example 3

[0047] On the basis of embodiment 1, the embodiment provides a double-effect spacer fluid for polymer salt mud well cementing, which is composed of the following substances in percentage by weight: water 60%, gel-breaking type suspending agent 35%, penetrating agent 3.5%, and interface reinforcing agent 1.5%.

[0048] The gel-breaking type suspending agent comprises the following substances in parts by weight: water 300 parts, natural cellulose 45 parts, acrylamide 15 parts, 2-acrylamido-2-methylpropane sulfonic acid 30 parts, sodium hydroxide 1 part, initiator 0.45 part, and sodium metaaluminate 1 part.

[0049] The preparation process is the same as that of embodiment 2.

[0050] In the embodiment, the penetrating agent is a fatty alcohol polyoxyethylene ether, the interface reinforcing agent is a mixture of aluminum chloride and potassium fluosilicate, and the mass ratio of the two is 1:1, and the initiator is potassium persulfate.

[0051] Embodiment 4

[0052] On the basis of embodiment 1, the embodiment provides a double-effect spacer fluid for polymer salt mud well cementing, which is composed of the following substances in percentage by weight: water 64%, gel-breaking type suspending agent 30%, penetrating agent 4%, and interface reinforcing agent 2%.

[0053] The gel-breaking type suspending agent comprises the following substances in parts by weight: water 350 parts, natural cellulose 55 parts, acrylamide 10 parts, 2-acrylamido-2-methylpropane sulfonic acid 20 parts, sodium hydroxide 6 parts, initiator 0.6 part, and sodium metaaluminate 3 parts.

[0054] The preparation process is the same as that of embodiment 2.

[0055] In the embodiment, the penetrating agent is a polyoxyethylene ether, the interface reinforcing agent is a mixture of aluminum chloride and potassium fluosilicate, and the mass ratio of the two is 1:1, and the initiator is ammonium persulfate.

[0056] In order to further illustrate the effect of the double-effect spacer fluid for polymer salt mud well cementing, the double-effect spacer fluid for polymer salt mud well cementing prepared in embodiments 2-4 is subjected to the following performance tests:

[0057] I. Gel-breaking experiment

[0058] The double-effect spacer fluid for polymer salt mud well cementing prepared in embodiments 2-4 is respectively prepared into a pre-spacer fluid with water and a weighting agent to obtain pre-spacer fluid A, pre-spacer fluid B and pre-spacer fluid C, and the gel-breaking conditions of a low solid-phase polymer drilling fluid with the double-effect spacer fluid are investigated. The low solid-phase polymer drilling fluid is mixed with the double-effect spacer fluid in a volume ratio of 1:1, and the experimental results are shown in Table 1.

[0059] The preflushing spacer fluid A comprises the following components in parts by weight: 90 parts of water, 10 parts of the double-effect spacer fluid for polymer salt mud well cementing (Example 2), and 25 parts of a weighting agent; the water is drinking water on a well site, and the weighting agent is barite powder.

[0060] The preflushing spacer fluid B comprises the following components in parts by weight: 85 parts of water, 15 parts of the double-effect spacer fluid for polymer salt mud well cementing (Example 3), and 40 parts of a weighting agent; the water is drinking water on a well site, and the weighting agent is barite powder.

[0061] The preflushing spacer fluid C comprises the following components in parts by weight: 95 parts of water, 5 parts of the double-effect spacer fluid for polymer salt mud well cementing (Example 4), and 25 parts of a weighting agent; the water is drinking water on a well site, and the weighting agent is barite powder.

[0062] The low-solid polymer drilling fluid comprises the following components in percentage by weight: 4% of bentonite, 0.3% of a polyionic cellulose sodium salt, 0.5% of caustic soda, and the balance of water.

[0063] The formula for calculating the gel breaking rate is: gel breaking rate = (AV0-AV) / AV0.

[0064] AV0 is the viscosity of the blank low-solid polymer drilling fluid;

[0065] AV is the viscosity after adding the double-effect spacer fluid.

[0066] Table 1 shows the gel breaking of the low-solid polymer drilling fluid

[0067]

[0068] According to the experimental results, when the amount of the double-effect spacer fluid in the application exceeds 5%, the drilling fluid is obviously broken, the base slurry is completely destabilized and broken, the solid-liquid is obviously layered, the flocculation body is large, dense and in the form of a gel, the upper clear liquid is colorless and transparent, the gel breaking rate reaches more than 90%, the virtual mud cake formed by the polymer salt system is broken and destabilized, the loose mud cake on the well wall and the casing is effectively flushed, and the cementing strength of the second interface is improved.

[0069] II. Rheological property test

[0070] The rheological properties of the preflushing spacer fluid A, the preflushing spacer fluid B and the preflushing spacer fluid C at 25 DEG C, 45 DEG C and 80 DEG C are tested (Method for Evaluating Oil Well Cement Admixtures Part 3: Drag Reducers, SY / T 5504.3-2018), and the test result data are shown in Table 2. The conventional spacer fluid comprises the following components in parts by weight: 98 parts of water, 2 parts of hydroxyethyl cellulose and 25 parts of a weighting agent.

[0071] Table 2 shows the test results of the rheological properties

[0072]

[0073] Wherein, K is consistency coefficient, ηp is plastic viscosity, τ0 is dynamic shear stress. From the results of Table 2, the viscosity and shear force of the pre-pad fluid increase with the increase of density; the plastic viscosity and dynamic shear stress of the pre-pad fluid with the same component increase with the increase of temperature. The rheological curve of the pre-pad fluid under the condition of 45℃ and 80℃ is more regular, and the value of n always changes in the range of 0.6-0.75, and the pre-pad fluid has good rheological property and mud cake carrying property in this range. Compared with the commonly used pad fluid, the flow index is less than the commonly used formula, and the pre-pad fluid has good advantages in rheological property and mud cake carrying property.

[0074] Three, suspension stability

[0075] The pre-pad fluid A, the pre-pad fluid B and the pre-pad fluid C are placed in a water bath at 25℃, 45℃ and 80℃ for 8 hours, and then the density of the solution in the upper, middle and lower parts is measured (GB / T19139-2012 Oil Well Cement Test Method), and the test results are shown in Table 3. The conventional pad fluid comprises the following components in parts by weight: water 98 parts, hydroxyethyl cellulose 2 parts, weighting agent 25 parts.

[0076] Table 3 Suspension stability results

[0077]

[0078] From Table 3, it can be seen that the density difference of the pre-pad fluid in each group is small after being placed for 8 hours at normal temperature, 45℃ and 80℃, but it can meet the construction requirements; compared with the commonly used pad fluid on the market, the pre-pad fluid has obvious advantages.

[0079] Four, investigate the compatibility of the pre-pad fluid in the application with the polymer salt drilling fluid:

[0080] The polymer salt mud cementing double-effect pad fluid prepared in Example 3 and the polymer salt drilling fluid (water+4% bentonite+0.3% poly anionic cellulose sodium salt+0.5% caustic soda) are mixed in the proportions and order shown in the following table, and are fully stirred and mixed on a high-speed stirring machine, and then are moved to a flow rate rotary viscometer to measure the rheological property, and the test result data are shown in Table 4.

[0081] Table 4 Rheological property of the double-effect pad fluid and the polymer salt drilling fluid in different proportions

[0082]

[0083] As shown in Table 4, with the increase of the addition amount of the double-effect isolation fluid, the dynamic shear stress τ0 of the drilling fluid is reduced, and is smaller than that of the original drilling fluid after mixing at any ratio, which shows that the double-effect isolation fluid of the present application does not increase the dynamic shear stress value of the drilling fluid, but has the functions of gel breaking and viscosity reducing, and reduces the dynamic shear stress of the drilling fluid, and the double-effect isolation fluid is located in front of the cement slurry in the displacement process, and directly contacts with the drilling fluid to reduce the shear stress of the drilling fluid to be displaced, reduce the flow resistance, and is beneficial to the displacement of the drilling fluid and the stripping and removal of the virtual mud cake.

[0084] The above examples are only illustrative of the present application, and do not constitute a limitation on the protection scope of the present application, and any design identical or similar to the present application falls within the protection scope of the present application.

Claims

1. A two-in-one spacer fluid for polymer salt mud well cementation, characterized in that: It is composed of the following substances in weight percentage: water 55-64%, gel-breaking suspending agent 30-40%, penetrating agent 3-4%, interface reinforcing agent 1-2%; ​ The gel-breaking suspending agent comprises the following substances in weight percentage: water 300-400 parts, natural cellulose 45-55 parts, acrylamide 10-20 parts, 2-acrylamido-2-methylpropane sulfonic acid 20-30 parts, sodium hydroxide 1-6 parts, initiator 0.3-0.6 parts, sodium metaaluminate 1-3 parts; The interface reinforcing agent is a mixture of aluminum chloride and potassium fluosilicate, and the mass ratio of the two is 1:

1.

2. The dual-purpose spacer fluid for cementing with a polymer salt slurry according to claim 1, characterized in that: The penetrating agent is sodium polystyrene sulfonate or polyoxyethylene ether.

3. The dual-purpose spacer fluid for cementing with polymeric salt muds according to claim 1, characterized in that: The initiator is ammonium persulfate or potassium persulfate.

4. A method of preparing a dual-purpose spacer fluid for use in cementing a polymeric salt mud well according to any one of claims 1 to 3, characterized in that: In a sealed reaction container, the formula amount of water, gel-breaking suspending agent, penetrating agent and interface reinforcing agent are added in sequence, and stirred and heated while adding, when the reaction temperature reaches 50-60℃, stirring for 30-40min, stop heating, cooling, ready.

5. The method of claim 4, wherein the method is characterized by: The preparation process of the gel-breaking suspending agent is as follows: Step 1) In a sealed reaction container, add the formula amount of water, and add the formula amount of natural cellulose while stirring, after fully dissolving, add the formula amount of acrylamide, 2-acrylamido-2-methylpropane sulfonic acid and sodium metaaluminate, and continue to stir for 0.5-1h while blowing nitrogen; Step 2) When the reaction temperature reaches 50-60℃, add the formula amount of initiator and stir for 2-3h; Step 3) Stop adding, add the formula amount of sodium hydroxide to adjust the pH value to 7, then cool and dry, powder, ready.

6. A method of using a dual purpose spacer fluid according to any one of claims 1 to 3, wherein: Mix water, polymer salt mud slurry cementing double-effect spacer fluid and weighting agent to obtain a pre-spacer fluid, wherein the weight percentage of water, polymer salt mud slurry cementing double-effect spacer fluid and weighting agent is 85-95 parts, 5-15 parts and 25-40 parts respectively.

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