Preparation method and application of clay mineral surface hydration inhibitor

Abstract

The invention relates to the technical field of drilling fluid for petroleum drilling, in particular to a preparation method and application of a clay mineral surface hydration inhibitor, the structural formula of the clay mineral surface hydration inhibitor is as follows: # imgabs0 #, the inhibitor is used for water-based drilling fluid to inhibit clay mineral surface hydration, the clay mineral surface hydration can be effectively inhibited, and the clay mineral surface hydration inhibitor has a good application prospect. When the addition amount of the non-toxic inhibitor and the SJ-2 inhibitor which are small in addition amount and low in cost is 1 wt%, hydration of the surface of the clay mineral can be completely inhibited, the substrate spacing of the wet montmorillonite is reduced to 1.38 nm from 1.91 nm, and the substrate spacing of the dry SJ-2-montmorillonite compound is increased to 1.36 nm. The invention shows that the inhibitor can be inserted between montmorillonite crystal layers, reduces the distance between montmorillonite compound substrates, eliminates interlayer water molecules, has good inhibitor capability, and has excellent capability of replacing interlayer exchangeable cations. A toxicity test shows that a 1wt% aqueous solution of the inhibitor is non-toxic.

Description

Technical Field

[0001] The invention relates to the technical field of drilling fluid for petroleum drilling, and in particular to a preparation method and application of a clay mineral surface hydration inhibitor. Background Art

[0002] The National Energy Administration issued the Shale Gas Development Plan (2016-2020), which calls for achieving 30 billion cubic meters of shale gas production by 2020 and 80-100 billion cubic meters by 2030. The development of shale gas has become a strategic resource for national energy development. Achieving safe, high-quality and fast drilling of horizontal wells with long horizontal sections (>2000 meters) has become a difficult point in shale gas development, among which the wellbore stability problem is particularly prominent.

[0003] When drilling fluid is used to drill water-sensitive shale formations, wellbore instability is often a problem. During the drilling process, 75% of the formations drilled are shale formations, and 90% of wellbore instability problems occur in this area. Wellbore instability often leads to complex downhole accidents such as drill bit mud packing, wellbore collapse, high torque, high resistance, drill bit sticking, and reduction in diameter. As a result, wellbore instability will seriously affect the drilling speed, leading to a significant increase in exploration and production costs. Studies have shown that the losses caused by wellbore instability exceed US$100 million per year, accounting for more than 10% of drilling costs.

[0004] Shale gas has become a strategic resource for my country's national energy development. At present, most shale gas horizontal wells are drilled in long horizontal sections mainly using oil-based drilling fluids. Oil-based drilling fluids can completely inhibit the hydration of clay minerals in the formation, so they have advantages that water-based drilling fluids do not have, such as good wellbore stability, stable drilling fluid performance, and less damage to oil and gas layers. However, the high configuration and application costs and environmental pollution issues restrict the application of oil-based drilling fluids. Therefore, the development of water-based drilling fluids with equivalent performance to oil-based drilling fluids has become an important direction for the development of drilling fluid technology at home and abroad.

[0005] In order to replace oil-based drilling fluids, the primary task of water-based drilling fluids is to completely inhibit the surface hydration of clay minerals. At present, the inhibitors used in water-based drilling fluids can inhibit clay penetration hydration, but no inhibitor can effectively solve the problem of surface hydration inhibition. At present, only high-concentration organic acid salts can be used as inhibitors to inhibit surface hydration through the activity balance principle, but too high a concentration will lead to high costs, environmental pollution, and serious effects on the rheology of drilling fluids. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides a clay mineral surface hydration inhibitor and a preparation method and application thereof.

[0007] To achieve the above object, the embodiments of the present invention adopt the following technical solutions:

[0008] The present invention provides a clay mineral surface hydration inhibitor, the structural formula of the clay mineral surface hydration inhibitor is as follows:

[0009]

[0010] The present invention also provides a method for preparing the above-mentioned clay mineral surface hydration inhibitor, comprising the following steps:

[0011] 4 g of tert-butyl 2-(2-(2-aminoethoxy)ethoxy)ethylcarbamate was added to a 100 mL single-mouth bottle, and then 60 ml of acetonitrile, 5.13 g of sodium carbonate and 0.4 g of sodium iodide were added. After stirring for half an hour, 2.09 g of bromo-triethylene glycol-bromo was added, and the temperature was raised to 70° C. and refluxed for 48 hours. The excess sodium iodide and sodium carbonate were removed by suction filtration, and the reaction solution was concentrated by a rotary evaporator to obtain a crude intermediate;

[0012] 30 mL of saturated HCl ethyl acetate solution was added to the intermediate to remove the Boc protecting group, and the mixture was stirred at room temperature overnight. The reaction solution was concentrated using a rotary evaporator, and the product was washed with petroleum ether and dried to obtain 4.24 g of the product, which was a clay mineral surface hydration inhibitor.

[0013] In some embodiments, the drying temperature is 80° C. and the drying time is 12 hours.

[0014] The specific synthesis formula is as follows:

[0015] The present invention also provides an application of the clay mineral surface hydration inhibitor prepared by the above preparation method in water-based drilling fluid.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The inhibitor of the present invention is used for water-based drilling fluid to inhibit the surface hydration of clay minerals. It can effectively inhibit the surface hydration of clay minerals, and is a non-toxic inhibitor with a small addition amount and low cost. When the SJ-2 inhibitor is added at 1wt%, it can completely inhibit the surface hydration of clay minerals, reduce the wet montmorillonite basal spacing from 1.91nm to 1.38nm, and increase the dry SJ-2-montmorillonite composite basal spacing to 1.36nm. It shows that the inhibitor can be inserted into the montmorillonite crystal layer, reduce the montmorillonite composite basal spacing, exclude interlayer water molecules, have good inhibitor ability, and have excellent ability to replace interlayer exchangeable cations. Toxicity test shows that the 1wt% aqueous solution of the inhibitor is non-toxic. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1This is the infrared spectrum of the clay mineral surface hydration inhibitor SJ-2 of the present invention;

[0019] Figure 2 This is the mass spectrum of the clay mineral surface hydration inhibitor SJ-2 of the present invention;

[0020] Figure 3 is the change diagram of the substrate spacing of the inhibitor-montmorillonite composite;

[0021] Figure 4 is the change diagram of the substrate spacing after isothermal adsorption of the inhibitor-montmorillonite composite;

[0022] Figure 5 TG and DTG curves of the inhibitor-montmorillonite complex;

[0023] Figure 6 This is the scanning electron microscopy image of the inhibitor-montmorillonite complex;

[0024] Figure 7 is the N1S diagram of the inhibitor-montmorillonite complex;

[0025] Figure 8 This is the Na1s diagram of the inhibitor-montmorillonite complex. DETAILED DESCRIPTION

[0026] The following will be combined with the accompanying drawings to clearly and completely describe the technical solutions in some embodiments of the present disclosure. Obviously, the described embodiments are only part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments provided by the present disclosure, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present disclosure.

[0027] Example

[0028] 4 g of tert-butyl 2-(2-(2-aminoethoxy)ethoxy)ethylcarbamate (SW4) was added to a 100 mL single-mouth bottle, and then 60 ml of acetonitrile, 5.13 g of sodium carbonate and 0.4 g of sodium iodide were added. After stirring for half an hour, 2.09 g of bromo-triethylene glycol-bromo (SW5) was added, and the temperature was raised to 70° C. and refluxed for 48 hours. The excess sodium iodide and sodium carbonate were removed by suction filtration, and the reaction solution was concentrated by a rotary evaporator to obtain a crude intermediate (SW6);

[0029] 30 mL of saturated HCl ethyl acetate solution was added to the intermediate to remove the Boc protecting group, and the mixture was stirred at room temperature overnight. The reaction solution was concentrated using a rotary evaporator, and the product was washed with petroleum ether and dried at 80°C for 12 h to obtain 4.24 g of the product (SJ-2), which is a clay mineral surface hydration inhibitor.

[0030] The specific synthesis formula is as follows:

[0031]

[0032] Experimental example

[0033] The main experimental reagents and instrument analysis used in the experiment are shown in Table 1 and Table 2 respectively.

[0034] Table 1 Main experimental reagents

[0035] name purity source Sodium montmorillonite 98％ NANOCOR <![CDATA[Mg(NO3)2]]> Analytical grade Chengdu McCahey Chemical Co., Ltd. KCl Analytical grade Chengdu McCahey Chemical Co., Ltd. PEG Analytical grade Chengdu McCahey Chemical Co., Ltd.

[0036] Table 2 Main experimental instruments

[0037]

[0038]

[0039] 1. Infrared spectroscopy analysis

[0040] Figure 1 This is the infrared spectrum of SJ-2. Figure 1 As can be seen, 3428cm -1 Corresponding to the NH stretching vibration peak. 3008cm -1 Corresponding to the CH stretching vibration peak in SJ-2. 1119cm -1 The peaks correspond to the stretching vibration of the ether bond COC in SJ-2. The infrared spectrum data are consistent with the molecular structure of SJ-2, proving the successful synthesis of SJ-2.

[0041] 2. Mass spectrometry analysis

[0042] Molecular formula of SJ-2: C 18 H 42 N4O6, accurate molecular weight: 410.31, molar mass 410.56, mass-to-charge ratio: 410.31 (100.0%), 411.31 (19.5%), 412.32 (1.8%), 411.31 (1.5%), 412.31 (1.2%). Elemental analysis: C, 52.66; H, 10.31; N, 13.65; O, 23.38. According to Figure 4-7 It can be seen that the mass-to-charge ratio measured by LC-MS is 411.31. Due to the positive ion scan, SJ-2 obtains a proton and its molecular weight is 410.31, which is consistent with the theoretical accurate molecular weight.

[0043] 3. Isothermal adsorption analysis

[0044] ① At 25°C, the inorganic salt solution corresponding to the relative humidity of 0.53 is a saturated magnesium nitrate solution. ② Add deionized water to the bottom of the drying dish, and then slowly add magnesium nitrate until a saturated solution is formed, and balance at 25°C for 24 hours. ③ Grind the dry montmorillonite composite and pass it through a 200-mesh sieve. After sieving, dry the montmorillonite composite at 150°C for 24 hours. Add 1g of the dried montmorillonite composite to the weighing bottle, weigh and record. ④ Place the weighing bottle in the balanced drying dish and leave it for 15 days. After the isothermal adsorption equilibrium, take out the weighing bottle with dust-free paper, weigh it on a ten-thousandth balance and record it. Calculate the equilibrium water absorption of the montmorillonite composite according to the following formula.

[0045]

[0046] Where m e ——Amount of water adsorbed by montmorillonite composite (g);

[0047] m0——Weighing bottle mass (g);

[0048] m1——the mass of montmorillonite composite and weighing bottle (g);

[0049] m2——the mass of montmorillonite composite and weighing bottle after isothermal adsorption equilibrium (g);

[0050] m3——The mass of the weighing bottle after isothermal adsorption equilibrium (g).

[0051] The water content of the inhibitor-montmorillonite composite after isothermal adsorption at 25°C and relative humidity of 0.53 was 3.5145%.

[0052] 4. X-ray diffraction analysis

[0053] The clay mineral surface hydration inhibitor prepared in the embodiment was subjected to X-ray diffraction analysis using an X Pert PRO MPD X-ray diffractometer, with Cu as the target. According to the Bragg formula: 2dsinθ=nλ. Where n is the diffraction order, n=1 here; θ is the diffraction half angle (i.e., the θ angle corresponding to the diffraction peak), the diffraction wavelength λ=0.154056nm, the operating voltage is 40kV, the current is 30mA, and the scanning angle 2θ=3-40°.

[0054] Figure 3It is the basal spacing of SJ-2-montmorillonite complex (1wt% SJ-2 + 2wt% montmorillonite, water as solvent). When SJ-2 is added at 1wt%, the basal spacing of hydrated montmorillonite can be reduced to 1.38nm, and the basal spacing of dry SJ-2-montmorillonite complex is increased to 1.36nm. The product obtained by centrifugation after SJ-2, montmorillonite and water are mixed is a wet SJ-2-montmorillonite complex, and after the wet state is dried, it becomes a dry SJ-2-montmorillonite complex. This shows that SJ-2 can insert into the interlayer of montmorillonite crystals, reduce the basal spacing of the montmorillonite complex, and exclude interlayer water molecules, that is, both inhibitors have good inhibitor capabilities.

[0055] Figure 4 is the basal spacing after isothermal adsorption of the SJ-2-montmorillonite composite. Figure 3 The dry basal spacing is consistent. This proves that the adsorption energy of SJ-2 between montmorillonite layers is greater than the adsorption energy of water molecules. In addition, since the dry montmorillonite basal spacing is 1.01nm, the water molecule diameter is 0.25nm, the monolayer sodium hydrate montmorillonite basal spacing is 1.18-1.24nm, and the double layer sodium hydrate montmorillonite basal spacing is 1.45-1.55nm. After isothermal adsorption, the interlayer spacing of the SJ-2-montmorillonite complex is 0.35nm. After deducting the height of a single layer of water molecules, the remaining layer space height is 0.10nm, which is lower than 0.20nm. This shows that after isothermal adsorption, the SJ-2-montmorillonite complex can only accommodate a single layer of water molecules at most.

[0056] 5. Thermogravimetric analysis

[0057] Figure 5 The TG curve and DTG curve of the SJ-2-montmorillonite composite were measured by thermogravimetric analyzer after isothermal adsorption equilibrium at 25°C and relative humidity 0.53. As can be seen from the figure, there is only one step in the TG curve of the SJ-2-montmorillonite composite, which proves that SJ-2 can inhibit the surface hydration and cationic hydration of the montmorillonite interlayer, and the SJ-2-montmorillonite composite only has water adsorbed on the outer surface of the particles.

[0058] The water content of the isothermal adsorption inhibitor-montmorillonite composite was tested at 25°C and relative humidity 0.53. Two peaks appeared in the DTG curve of montmorillonite (2wt% montmorillonite, water as solvent, as a blank group). The first peak was converted to a water content of 7.67%, and the second peak was converted to a water content of 5.36%. SJ-2-montmorillonite had one peak, and the water content was converted to 3.6148%.

[0059] 6. Scanning electron microscopy analysis

[0060] Figure 6This is a scanning electron microscope image of the SJ-2 inhibitor-montmorillonite complex. Figure 6 It can be seen that the addition of the inhibitor (SJ-2) can aggregate the montmorillonite into balls, indicating that the inhibitors have excellent inhibitory properties.

[0061] 7. X-ray Photoelectron Spectroscopy

[0062] Figure 7 It is the N1s graph of the inhibitor-montmorillonite complex. It can be seen from the figure that compared with pure sodium montmorillonite (blank sample, blank group), the SJ-2-montmorillonite complex has an obvious N1s model, which indicates that SJ-2 is adsorbed on the montmorillonite surface. Figure 8 is the Na1s diagram of the inhibitor-montmorillonite complex. Figure 8 It can be seen that compared with pure sodium montmorillonite, SJ-2 can replace interlayer exchangeable ions (sodium ions), which inhibits the surface hydration of clay minerals.

[0063] 8. Atomic absorption spectrophotometer analysis

[0064] Table 3 shows the sodium ion content of the non-toxic intercalation inhibitor-montmorillonite composite. As can be seen from Table 3, the sodium ion content of the non-toxic intercalation inhibitor-montmorillonite composite is lower than that of pure sodium montmorillonite. It can be seen that the non-toxic intercalation inhibitor can effectively replace the sodium ions between the montmorillonite layers, verifying the conclusion of the X-ray photoelectron spectroscopy study.

[0065] Table 3 Sodium ion content of inhibitor montmorillonite composite (mmol / 100g)

[0066] sample Pure sodium montmorillonite SJ-2-montmorillonite composite CEC 113 20

[0067] 9. Toxicity studies

[0068] Table 4 shows the toxicity test results of the inhibitors. As can be seen from Table 4, the inhibitors have very low toxicity and can be considered non-toxic.

[0069] Table 4 Compound toxicity test results

[0070] sample EC50 value SJ-2 46053

[0071] In summary, when the SJ-2 inhibitor is added at 1wt%, it can completely inhibit the surface hydration of clay minerals, reduce the wet montmorillonite basal spacing from 1.91nm to 1.38nm, and increase the dry SJ-2-montmorillonite composite basal spacing to 1.36nm. This shows that the inhibitor can insert into the montmorillonite crystal layer, reduce the montmorillonite composite basal spacing, exclude interlayer water molecules, have good inhibitor ability, and have excellent ability to replace interlayer exchangeable cations. Toxicity tests show that the 1wt% aqueous solution of the inhibitor is non-toxic.

[0072] In the description of this specification, specific features, structures, materials or characteristics may be combined in an appropriate manner in any one or more embodiments or examples.

[0073] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. Clay mineral surface hydration inhibitor, It is characterized in that The structural formula of the clay mineral surface hydration inhibitor is as follows:

2. A method for preparing the clay mineral surface hydration inhibitor according to claim 1, It is characterized in that The following steps are involved: 4 g of tert-butyl 2-(2-(2-aminoethoxy)ethoxy)ethylcarbamate was added to a 100 mL single-mouth bottle, and then 60 ml of acetonitrile, 5.13 g of sodium carbonate and 0.4 g of sodium iodide were added. After stirring for half an hour, 2.09 g of bromo-triethylene glycol-bromo was added, and the temperature was raised to 70° C. and refluxed for 48 hours. The excess sodium iodide and sodium carbonate were removed by suction filtration, and the reaction solution was concentrated by a rotary evaporator to obtain a crude intermediate; 30 mL of saturated HCl ethyl acetate solution was added to the intermediate to remove the Boc protecting group, and the mixture was stirred at room temperature overnight. The reaction solution was concentrated using a rotary evaporator, and the product was washed with petroleum ether and dried to obtain 4.24 g of the product, which was a clay mineral surface hydration inhibitor.

3. The preparation method according to claim 2, It is characterized in that The drying temperature is 80° C. and the drying time is 12 h.

4. Use of the clay mineral surface hydration inhibitor prepared by the preparation method according to claim 2 or 3 in water-based drilling fluid.

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