A near oil-based drilling fluid composition, its use and a method for preparing a near oil-based drilling fluid base fluid

Abstract

This invention relates to the technical field of drilling fluids, and discloses a near-oil-based drilling fluid composition and its application, as well as a near-oil-based drilling fluid and its preparation method. The near-oil-based drilling fluid composition contains silanolyl alkyl glycosides and cationic chitosan, and the extreme pressure lubrication coefficient of the composition is 0.001-0.05, and the pressure resistance index is 1.3-5. The near-oil-based drilling fluid composition provided by this invention, containing both silanolyl alkyl glycosides and cationic chitosan, exhibits a good synergistic effect, resulting in a base fluid and drilling fluid with excellent properties such as inhibiting collapse, solidifying the wall, lubricating and preventing sticking, and sealing and reducing filtration loss, thus meeting the performance requirements for formulating near-oil-based drilling fluids.

Description

Technical Field

[0001] This invention relates to the technical field of drilling fluids, specifically to a near-oil-based drilling fluid composition and its application, and a method for preparing a near-oil-based drilling fluid base. Background Technology

[0002] During oil and gas drilling, when encountering highly reactive mudstone and shale formations with high clay mineral content and other easily collapsible formations, conventional water-based drilling fluids cannot effectively inhibit the hydration, expansion, and dispersion of these formations. While strong-inhibition water-based drilling fluids offer better anti-collapse effects and are less expensive and environmentally friendly, their performance still does not reach the level comparable to oil-based drilling fluids. Furthermore, when drilling through highly reactive mudstone and other easily collapsible formations, the use of oil-based drilling fluids still presents several shortcomings, including high preparation costs, interference with logging operations, significant losses during lost circulation, and high pressure on environmentally friendly drill cuttings post-processing. These drawbacks limit the large-scale application of oil-based drilling fluids. Therefore, under these circumstances, finding a near-oil-based drilling fluid with a similar mechanism of action, comparable performance, and environmental friendliness has become an urgent technical need in the field. Near-oil-based drilling fluid is a green, safe, and efficient water-based drilling fluid with performance comparable to oil-based drilling fluid. It belongs to the category of water-based drilling fluids, not oil-based drilling fluids.

[0003] For near-oil-based drilling fluids, the most crucial element is the base fluid used in their formulation. The base fluid must possess excellent properties such as inhibiting collapse, solidifying the drilling wall, lubricating and preventing sticking, and sealing to reduce filtration loss. It must also be environmentally friendly and meet the performance requirements for formulating near-oil-based drilling fluids. The development of base fluid products for formulating near-oil-based drilling fluids will significantly promote the research and application of these fluids, enabling green, safe, and efficient drilling in highly active shale and mudstone-bearing formations prone to collapse, and achieving the technical goal of "water replacing oil." Summary of the Invention

[0004] The purpose of this invention is to overcome the problems existing in the prior art and provide a base fluid for formulating near-oil-based drilling fluids and its preparation method. The base fluid for formulating near-oil-based drilling fluids provided by this invention has good properties such as inhibiting collapse, solidifying the wall and cementing, lubricating and preventing jamming, and sealing and reducing filtration loss. It is green and environmentally friendly and can meet the performance requirements for formulating near-oil-based drilling fluids.

[0005] To achieve the above objectives, according to a first aspect of the present invention, a near-oil-based drilling fluid composition is provided, the composition containing silanyl alkyl glycoside and cationic chitosan, and the extreme pressure lubrication coefficient of the composition is 0.001-0.05, and the pressure resistance index is 1.3-5.

[0006] According to a second aspect of the invention, the invention provides the use of the above-described composition in near-oil-based drilling fluids.

[0007] According to a third aspect of the invention, the invention provides a near-oil-based drilling fluid of the composition.

[0008] According to a fourth aspect of the present invention, the present invention provides a method for preparing a near-oil-based drilling fluid, the method comprising:

[0009] By weight, 0-15 parts, preferably 3-12 parts, of multibranched polyetheramine, 0-45 parts, preferably 10-40 parts, of aminocyclodextrin, 1-10 parts, preferably 3-7 parts, of cationic chitosan, 40-60 parts, preferably 42-58 parts, of silanyl alkyl glycoside, and 0-30 parts, preferably 18-24 parts, of sulfaglyceryl glycoside are stirred and mixed evenly at 60-85°C under an inert gas protection.

[0010] The near-oil-based drilling fluid composition provided by this invention contains both silanyl alkyl glycosides and cationic chitosan, which have a good synergistic effect. This results in the obtained base fluid and drilling fluid possessing excellent properties such as anti-collapse, wall consolidation, lubrication, anti-sticking, and plugging / reducing filtration loss, meeting the performance requirements for formulating near-oil-based drilling fluids. According to a preferred embodiment of this invention, when the base fluid simultaneously contains a certain proportion of multi-branched polyetheramine, aminocyclodextrin, cationic chitosan, silanyl alkyl glycosides, and sulfaglyceryl glycosides, the anti-collapse, wall consolidation, lubrication, anti-sticking, and plugging / reducing filtration loss properties of the obtained base fluid and drilling fluid are further improved. Moreover, the above-mentioned base fluid is environmentally friendly and has strong compatibility, meeting the performance requirements for formulating near-oil-based drilling fluids. Attached Figure Description

[0011] Figures 1 to 5 The infrared spectra are for multibranched polyetheramine, aminocyclodextrin, cationic chitosan, silanylalkyl glycoside, and sulfaglyceryl glycoside, respectively.

[0012] Figure 6 Scanning electron microscope image of medium-pressure filter cake of 4 wt% sodium bentonite-based slurry.

[0013] Figure 7 Scanning electron microscope (SEM) image of medium-pressure filter cake after adding 2% of the sample from Example 1 to a 4 wt% sodium bentonite-based slurry. Detailed Implementation

[0014] The endpoints and any values ​​of the ranges 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 endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0015] The near-oil-based drilling fluid composition provided by this invention contains silanyl alkyl glycosides and cationic chitosan, and the extreme pressure lubrication coefficient of the composition is 0.001-0.05, and the pressure resistance index is 1.3-5. Preferably, the extreme pressure lubrication coefficient of the composition is 0.005-0.025, and the pressure resistance index is 1.5-3.

[0016] The near-oil-based drilling fluid composition provided by this invention contains both silanyl alkyl glycosides and cationic chitosan, has a low extreme pressure lubrication coefficient, good lubrication and anti-sticking properties, good plugging and filtration loss reduction properties, and a pressure resistance index in the range of 1.3-5, preferably 1.5-3, thus exhibiting good pressure resistance.

[0017] The presence of silanolyl alkyl glycosides and cationic chitosan in the composition can be confirmed by infrared spectroscopy. For example, the infrared spectrum shows a range of 2830–2950 cm⁻¹. -1 The peak represents the stretching vibration of the CH bond in methyl and methylene groups, at 3380 cm⁻¹. -1 The peak near the OH bond stretching vibration is at 1164 cm⁻¹. -1 The nearby peaks are the stretching vibration peaks of COC, confirming the presence of a glycoside structure; 1419 cm⁻¹ -1 The absorption peak near the CN bond is at 1196 cm⁻¹. -1 The nearby bending vibration peak of the CN bond confirms the presence of an amino group in the structure; 1689 cm⁻¹ -1 Nearby, 1280cm -1 The characteristic peak of the amide group is located nearby; 1093 cm⁻¹ -1 The peak at 1602 cm⁻¹ is a characteristic peak of Si-O. This indicates that amino, amide, and siloxane groups have been incorporated into the glycoside molecule, meaning the composition contains a silaninoalkyl glycoside. -1 The absorption peak for chitosan NH bending vibration is located near 1214 cm⁻¹. -1 The absorption peak at approximately 1405 cm⁻¹ is due to the COC stretching vibration, indicating that the modified chitosan has incorporated ether bonds through a condensation reaction. -1 The absorption peak near the CN stretching vibration indicates that quaternary ammonium groups have been introduced into the modified chitosan. In this invention, "nearby" refers to instrumental and operational errors acceptable to those skilled in the art, such as ±10 cm⁻¹. -1 .

[0018] In this invention, the compressive strength index refers to the ratio of the compressive strength of the core before and after soaking. Compressive strength index = P1 / P0. The core column is placed on a compressive strength tester, and the load is increased at a rate of 0.5-0.8 MPa per second until the core column fails. This pressure is the compressive strength. The compressive strength of the unsoaked original core is recorded as P0, and the compressive strength of the core column measured after soaking in a 2.0% (w / w) near-oil-based drilling fluid composition sample at 210°C for 16 hours is recorded as P1.

[0019] The formula for calculating the extreme pressure lubrication coefficient is:

[0020]

[0021] In the above formula: K is the extreme pressure lubrication coefficient; X and Y are obtained by the following test methods: Immerse the slider in the extreme pressure lubrication instrument into the base fluid sample of 2.0% used to prepare near-oil-based drilling fluid, adjust the torque wrench value to 16.95 N / m, and the value displayed on the instrument after running for 5 minutes is X; Immerse the slider in the instrument into clean water, adjust the torque wrench value to 16.95 N / m, run the instrument for 5 minutes, and read the value displayed on the instrument when the slider is soaked in clean water is Y.

[0022] In this invention, the silamidoalkyl glycoside refers to the product in which one or more hydroxyl groups on the alkyl glycoside structure are replaced by groups containing amine (primary amine, secondary amine, tertiary amine) and siloxane (trialkoxysilane) groups.

[0023] According to a preferred embodiment of the present invention, the silanylalkyl glycoside has the structure shown in Formula I:

[0024]

[0025] In Formula I, R1 is a C1-C14 alkyl group, m is 1-16, and relative to the total amount of silanyl alkyl glycoside, the content of X is 25-60% by mass, preferably 35-55% by mass, the content of Y is 30-55% by mass, preferably 40-50% by mass, and the content of Z is 0.2-60% by mass, preferably 0.2-55% by mass.

[0026] X, Y, and Z are each at least one of H, unsaturated amide residues, unsaturated siloxane residues, polyether groups, and polyene polyamine residues, and X, Y, and Z are different;

[0027] Preferably, X, Y, and Z are each at least one of H, a group represented by formula I-1), a group represented by formula I-2), and a group represented by formula I-3), and X, Y, and Z are different;

[0028] Preferably, Y contains unsaturated amide residues and unsaturated siloxane residues;

[0029]

[0030] In formula I-1), R2 is a C1-C3 alkyl group, n is 1-2, and o is 0-4;

[0031]

[0032] In formula I-2), R3 is H or a C1-C4 alkyl group, and p is 1-30;

[0033] In formula I-3), R4 is a C1-C4 alkyl group, and q is 1-20;

[0034] Preferably, Y contains the groups represented by formula I-2) and the groups represented by formula I-3).

[0035] In this invention, silamidoalkyl glycosides can be prepared according to the method disclosed in CN111320657A. Specifically, the method may include the following steps: 1) reacting alkyl glycosides with epoxy haloalkanes (such as chloroalkanes) under the action of an acidic catalyst to obtain haloalcohol alkyl glycosides; 2) reacting the haloalcohol alkyl glycosides with organic amines to obtain aminoalkyl glycosides; 3) reacting the aminoalkyl glycosides with acrylamides and vinyltrialkoxysilanes under the action of an initiator to obtain silamidoalkyl glycosides.

[0036] The alkyl glycoside can be one or more of methyl glycoside, ethyl glycoside, propyl glycoside, hexyl glycoside, octyl glycoside, decyl glycoside, dodecyl glycoside, and tetradecyl glycoside. That is, corresponding to Formula I above, R1 can be a C1-C14 alkyl group such as methyl, ethyl, propyl, hexyl, octyl, decyl, dodecyl, or tetradecyl.

[0037] The epoxy haloalkane (such as chloroalkane) compound may be one or more of epichlorohydrin, epichlorobutane, and epichloropentane.

[0038] The acrylamide compounds may be, for example, acrylamide or methacrylamide.

[0039] The vinyltrialkoxysilane may be, for example, one or more of vinyltrimethoxysilane, vinyltriethoxysilane, vinyltripropoxysilane, and vinyltributoxysilane.

[0040] The acidic catalyst may be one or more of the following: hydrofluoric acid, hydrochloric acid, sulfuric acid, phosphoric acid, tartaric acid, oxalic acid, p-toluenesulfonic acid, dodecylbenzenesulfonic acid, and aminosulfonic acid.

[0041] The initiator can be a redox initiator or an azo initiator, such as ammonium persulfate, potassium persulfate, cerium ammonium nitrate, azobisisobutyronitrile, dimethyl azobisisobutyrate, or azobisisobutyranin hydrochloride.

[0042] The obtained polymer can be confirmed as the target polymer by analyzing its infrared spectrum. The infrared spectrum ranges from 2830 to 2950 cm⁻¹. -1 The peak represents the stretching vibration of the CH bond in methyl and methylene groups, at 3380 cm⁻¹.-1 The peak near the OH bond stretching vibration is at 1164 cm⁻¹. -1 The nearby peaks are the stretching vibration peaks of COC, confirming the presence of a glycoside structure; 1419 cm⁻¹ -1 The absorption peak near the CN bond is at 1196 cm⁻¹. -1 The peak at 1689 cm⁻¹ represents the bending vibration of the CN bond, indicating the presence of an amine group in the structure. -1 Nearby, 1280cm -1 The characteristic peak of the amide group is located nearby; 1093 cm⁻¹ -1 The nearby peaks are characteristic of Si-O, indicating that amino, amide, and siloxane groups have been incorporated into the glycoside molecule structure.

[0043] In this invention, the cationic chitosan refers to chitosan in which one or more hydroxyl groups are replaced by residues containing cationic groups. The cationic groups are preferably quaternary ammonium cations, and the anions paired with the quaternary ammonium cations can be chloride ions, bromide ions, iodide ions, or nitrate ions. According to a preferred embodiment of the present invention, the cationic chitosan has the structure shown in Formula II below.

[0044]

[0045] In Formula II, R is an alkyl group with 1-3 carbon atoms, m is 1200-3100, and n is 1-2.

[0046] In this invention, cationic chitosan can be prepared according to the method disclosed in CN106432537A. Specifically, it can include the following steps: 1) reacting a mixture containing chitosan, a cosolvent such as a urea compound, an alkaline compound and water with an epoxy haloalkane (such as a chloroalkane) compound to obtain an intermediate product; 2) reacting the intermediate product with an alkaline compound and a tertiary amine hydrochloride to obtain cationic chitosan.

[0047] The epoxy haloalkane (such as chloroalkane) compound may be one or more of epichlorohydrin, 1,2-epoxychlorobutane, and epichloropentane.

[0048] The alkaline compound may be, for example, sodium hydroxide and / or potassium hydroxide.

[0049] The tertiary amine hydrochloride may be one or more of trimethylamine hydrochloride, triethylamine hydrochloride, and tripropylamine hydrochloride.

[0050] The urea compound may be one or more of urea, thiourea, and urea phosphate.

[0051] The obtained polymer can be confirmed as the target polymer by analyzing the infrared spectrum of the product. (At 1602 cm⁻¹)-1 The absorption peak for chitosan NH bending vibration is located near 1214 cm⁻¹. -1 The absorption peak at approximately 1405 cm⁻¹ is due to the COC stretching vibration, indicating that the modified chitosan has incorporated ether bonds through a condensation reaction. -1 The absorption peak of CN stretching vibration is located nearby, indicating that quaternary ammonium groups were introduced into the modified chitosan.

[0052] According to a preferred embodiment of the invention, the composition further comprises a multibranched polyetheramine and a sulfaglyceryl glycoside. This preferred composition can further improve the inhibition and lubrication properties of the drilling fluid.

[0053] Preferably, based on the total amount of the composition, the content of the branched polyetheramine is 1-15% by mass, preferably 3-12% by mass, the content of the silanyl alkyl glycoside is 40-90% by mass, preferably 40-58% by mass, the content of the sulfanyl glyceryl glycoside is 5-30% by mass, preferably 15-25% by mass, and the content of the cationic chitosan is 1-11% by mass, preferably 3-7% by mass.

[0054] In this invention, the multibranched polyetheramine refers to a molecule containing multiple amine groups (primary, secondary, and tertiary amine groups), preferably some or all of which are distributed in a comb-like pattern. Preferably, at least two hydroxyl groups in the glycerol are replaced by amine-containing groups, such as amine-containing segments with 2-30 carbon atoms. Preferably, the multibranched polyetheramine has the structure shown in Formula III.

[0055]

[0056] Preferably, in Formula III, m is 1-16, n is 1-2, and o is 0-4.

[0057] The branched polyetheramine can be prepared according to the method disclosed in CN106432708A. For example, glycerol, a glycol compound, water, and an acidic catalyst are reacted (preferably under stirring) to obtain an intermediate product, wherein the glycol compound includes ethylene glycol or polyethylene glycol; the intermediate product is then reacted with a chlorinated epoxide, a basic compound, and an organic amine to obtain the branched polyetheramine; the chlorinated epoxide includes epichlorohydrin or 1,2-epoxychlorobutane, and the organic amine includes ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, or pentaethylenehexamine. Preferably, the reaction temperature of glycerol, the glycol compound, water, and the acidic catalyst is 90°C-140°C, preferably 100°C-120°C; the reaction time is 2 hours-4 hours, preferably 2.5 hours-3.5 hours. In embodiments of the present invention, the reaction of glycerol, the glycol compound, water, and the acidic catalyst can be carried out under stirring. After obtaining the intermediate product, the present invention reacts the intermediate product with a chlorinated epoxide, a basic compound, and an organic amine to obtain a multibranched polyetheramine. In the embodiments of the present invention, the reaction temperature of the intermediate product with the chlorinated epoxide, the basic compound, and the organic amine is 40℃-60℃, preferably 45℃-55℃; the reaction time is 0.5 hours-2 hours, preferably 1 hour-1.5 hours.

[0058] Preferably, the number average molecular weight of the polyethylene glycol is 400-800, more preferably 500-700, and even more preferably 550-650.

[0059] Preferably, the acidic catalyst can be hydrochloric acid, sulfuric acid, phosphoric acid, tartaric acid, oxalic acid, p-toluenesulfonic acid, dodecylbenzenesulfonic acid, aminosulfonic acid, or phosphotungstic acid.

[0060] Preferably, the chloroepoxide is epichlorohydrin or 1,2-epoxychlorobutane.

[0061] Preferably, the alkaline compound is one or more of sodium hydroxide, potassium hydroxide, and barium hydroxide.

[0062] Preferably, the organic amine includes ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, or pentaethylenehexamine.

[0063] Preferably, the mass ratio of glycerol, diol compound, water, acidic catalyst, chlorinated epoxide, basic compound and organic amine is 10:(8-14):(30-60):(0.8-1.5):(5-15):(0.8-1.2):(10-20), more preferably 10:(9-12):(40-50):(1-1.4):(8-12):(0.9-1.1):(12-18), and even more preferably 10:(10-11):(42-48):(1.1-1.3):(10-11):1:(14-16).

[0064] In this invention, the sulfaglyceroglycoside refers to a glyceroglycoside in which one or more hydroxyl groups are replaced by a polyether amine group and a sulfonated castor oil residue. The polyether amine group refers to a group containing a polyether group with an amine group (primary, secondary, or tertiary amine) attached to its middle or end. The sulfonated castor oil residue refers to the group corresponding to the esterification reaction between sulfonated castor oil and the hydroxyl groups of the glyceroglycoside. Preferably, the sulfaglyceroglycoside has the structure shown in Formula IV below.

[0065]

[0066] In Formula IV, m is 1-3, and the content of X is 30-70% by mass, preferably 35-55% by mass, relative to the total amount of sulfaglyceryl glycoside; the content of Y is 20-50% by mass, preferably 25-40% by mass.

[0067] X and Y are each a group represented by formula IV-1) or a group represented by formula IV-2), and X and Y are different;

[0068]

[0069] In Formula IV-1), R1 and R2 are each independently selected from alkyl groups having 1-3 carbon atoms, n is 1-10, o is 1-10, and p is 0-4.

[0070] Sulfadiazine glycosides can be prepared according to the method disclosed in CN111320659A.

[0071] According to a preferred embodiment of the present invention, the composition further contains aminocyclodextrin, preferably 2-45% by mass based on the total amount of the composition, more preferably 10-40% by mass. This preferred composition can further improve the inhibition, filtration loss reduction, and lubrication properties of drilling fluids.

[0072] In this invention, the aminocyclodextrin refers to a cyclodextrin in which one or more amino groups are substituted, preferably polyene-polyamine groups such as diethylenetriamine, triethylenetetraamine, tetraethylenepentamine, and pentaethylenehexamine. Preferably, the aminocyclodextrin has the structure shown in formula V.

[0073]

[0074] In formula V, based on the total amount of aminocyclodextrin, the content of R is 30-70% by mass, preferably 40-55% by mass, and R has the structure shown in the following structural formula i.

[0075]

[0076] In formula i, m is 1-2 and n is 0-4.

[0077] Aminocytodextrins can be prepared according to the method disclosed in CN106432550A.

[0078] The present invention also provides the application of the above composition in near-oil-based drilling fluids.

[0079] The present invention also provides a near-oil-based drilling fluid containing the above-described composition.

[0080] Preferably, the composition content is 20-60% by mass, based on the total amount of near-oil-based drilling fluid.

[0081] This invention also provides a method for preparing a near-oil-based drilling fluid, the method comprising:

[0082] By weight, 0-15 parts, preferably 3-12 parts, of multibranched polyetheramine, 0-45 parts, preferably 10-40 parts, of aminocyclodextrin, 1-10 parts, preferably 3-7 parts, of cationic chitosan, 40-60 parts, preferably 42-58 parts, of silanylaminoalkyl glycoside, and 0-30 parts, preferably 18-24 parts, of sulfaglyceryl glycoside are stirred and mixed evenly at 60-85°C under an inert gas protection for a preferred time of 2-4 hours.

[0083] Preferably, the inert gas is nitrogen and / or helium.

[0084] In the following examples, multibranched polyetheramines were prepared according to the method disclosed in CN106432708A, aminocyclodextrins were prepared according to the method disclosed in CN106432550A, cationic chitosans were prepared according to the method disclosed in CN106432537A, silanylaminoalkyl glycosides were prepared according to the method disclosed in CN111320657A, and sulfaglyceryl glycosides were prepared according to the method disclosed in CN111320659A. The infrared spectra of the polymers used in Example 1 are shown below. Figure 1-5 As shown. Branched polyetheramines, such as... Figure 1 As shown, 1151cm -1 The peak value for the stretching vibration of COC is 1050–1100 cm⁻¹. -1 The peak at 1419 cm⁻¹ represents the stretching vibration of the CO bond in the hydroxyl group, confirming the presence of a polyether structure. -1 The absorption peak for the CN bond is at 1196 cm⁻¹. -1 The peak for the bending vibration of the CN bond is 3380 cm⁻¹. -1 The absorption peak for NH indicates the presence of an amine structure. Based on these results, the multibranched polyetheramine product contains characteristic structures such as hydroxyl groups, ether bonds, CN bonds, and amino groups.

[0085] The infrared spectrum of aminocyclodextrin is as follows: Figure 2 As shown, 3357cm -1 The stretching vibrations of -OH and primary amine -NH are shown, 2930 cm⁻¹. -1 The absorption peak at 1458 cm⁻¹ is the antisymmetric stretching vibration absorption peak of -CH₂. -1 The absorption peak is the antisymmetric deformation vibration of -CH3, corresponding to the deformation vibration of -CH2, and 1154 cm⁻¹. -1 The absorption peaks are for the CO stretching vibrations of β-CD and the polymer cavity, and the stretching vibrations of COC, at 707 cm⁻¹. -1 The absorption peak of the in-plane rocking vibration of -CH2 is shown.

[0086] The infrared spectrum of cationic chitosan is as follows: Figure 3 As shown, at 1602cm -1 The absorption peak at 1214 cm⁻¹ is the NH bending vibration absorption peak of chitosan. -1 The absorption peak at 1405 cm⁻¹ is due to the COC stretching vibration, indicating that the modified chitosan has introduced ether bonds through a condensation reaction. -1 The absorption peak at this location is the CN stretching vibration peak, indicating that the modified chitosan has introduced quaternary ammonium groups.

[0087] The infrared spectrum of silanyl alkyl glycosides is as follows: Figure 4 As shown, 2830–2950 cm -1 The peak represents the stretching vibration of the CH bond in methyl and methylene groups, at 3380 cm⁻¹. -1 The peak represents the stretching vibration of the OH bond, at 1164 cm⁻¹. -1 The peak at 1419 cm⁻¹ represents the stretching vibration of COC, confirming the presence of a glycoside structure. -1 The absorption peak for the CN bond is at 1196 cm⁻¹. -1 The peak at 1689 cm⁻¹ represents the bending vibration of the CN bond, indicating the presence of an amine group in the structure. -1 1280cm -1 The characteristic peak for amide groups; 1093 cm⁻¹-1 The peaks are characteristic of Si-O, indicating that amino, amide, and siloxane groups have been incorporated into the glycoside molecule.

[0088] The infrared spectrum of sulfaglyceroglycoside is as follows: Figure 5 As shown, 3380cm -1 The peak represents the stretching vibration of the OH bond, 2830–2950 cm⁻¹. -1 The peak at 1151 cm⁻¹ represents the stretching vibration of the CH bond in the methyl and methylene groups, confirming the presence of a glycoside structure. -1 The peak value for the stretching vibration of COC is 1050–1100 cm⁻¹. -1 The peak at 1419 cm⁻¹ represents the stretching vibration of the CO bond in the hydroxyl group, confirming the presence of a glycerol group structure. -1 The absorption peak for the CN bond is at 1196 cm⁻¹. -1 The peak represents the bending vibration of the CN bond, confirming the presence of an amine structure; wavenumber 1170 cm⁻¹. -1 1000cm -1 The peak is a characteristic peak of the sulfonic acid group. This indicates that glycerol, amino, and sulfonic acid groups have been incorporated into the glycoside molecule structure.

[0089] Example 1

[0090] 3g of branched polyetheramine (prepared according to the method of Example 1 of CN106432708A), 10g of aminocyclodextrin (prepared according to the method of Example 1 of CN106432550A), 3g of cationic chitosan (prepared according to the method of Example 1 of CN106432537A), 42g of silanylaminoalkyl glycoside (prepared according to the method of Example 1 of CN111320657A), and 18g of sulfaglyceryl glycoside (prepared according to the method of Example 1 of CN111320659A) were mixed evenly and stirred at 60°C for 2 hours under nitrogen protection to obtain the base fluid for preparing near-oil-based drilling fluid.

[0091] Example 2

[0092] 7g of branched polyetheramine (prepared according to the method of Example 2 of CN106432708A), 20g of aminocyclodextrin (prepared according to the method of Example 2 of CN106432550A), 5g of cationic chitosan (prepared according to the method of Example 2 of CN106432537A), 48g of silanylaminoalkyl glycoside (prepared according to the method of Example 1 of CN111320657A), and 20g of sulfaglyceryl glycoside (prepared according to the method of Example 2 of CN111320659A) were mixed evenly and stirred at 70°C for 3 hours under helium protection to obtain the base fluid for preparing near-oil-based drilling fluid.

[0093] Example 3

[0094] 9g of branched polyetheramine (prepared according to the method of Example 3 of CN106432708A), 30g of aminocyclodextrin (prepared according to the method of Example 3 of CN106432550A), 6g of cationic chitosan (prepared according to the method of Example 3 of CN106432537A), 54g of silanylaminoalkyl glycoside (prepared according to the method of Example 1 of CN111320657A), and 22g of sulfaglyceryl glycoside (prepared according to the method of Example 3 of CN111320659A) were mixed evenly and stirred at 80°C for 4 hours under nitrogen protection to obtain a base fluid for preparing near-oil-based drilling fluid.

[0095] Example 4

[0096] 12g of branched polyetheramine (prepared according to the method of Example 4 of CN106432708A), 40g of aminocyclodextrin (prepared according to the method of Example 4 of CN106432550A), 7g of cationic chitosan (prepared according to the method of Example 4 of CN106432537A), 58g of silanylaminoalkyl glycoside (prepared according to the method of Example 1 of CN111320657A), and 24g of sulfaglyceryl glycoside (prepared according to the method of Example 4 of CN111320659A) were mixed evenly and stirred at 85°C for 4 hours under nitrogen protection to obtain the base fluid for preparing near-oil-based drilling fluid.

[0097] Example 5

[0098] The base fluid for near-oil-based drilling fluid was prepared according to the method in Example 4, except that multibranched polyetheramine, aminocyclodextrin and sulfaglyceryl glycoside were not added, while the proportions of other substances remained unchanged, to obtain the base fluid for preparing near-oil-based drilling fluid.

[0099] Example 6

[0100] The base fluid for near-oil-based drilling fluid was prepared according to the method in Example 4, except that aminocyclodextrin and sulfaglyceryl glycoside were not added, while the proportions of other substances remained unchanged, to obtain the base fluid for preparing near-oil-based drilling fluid.

[0101] Example 7

[0102] The base fluid for near-oil-based drilling fluid was prepared according to the method in Example 4, except that multibranched polyetheramine and aminocyclodextrin were not added, while the proportions of other substances remained unchanged, to obtain the base fluid for preparing near-oil-based drilling fluid.

[0103] Comparative Example 1

[0104] The base fluid for near-oil-based drilling fluid was prepared according to the method in Example 4, except that the above materials were stirred in air at room temperature for 4 hours to obtain a comparative sample.

[0105] Comparative Example 2

[0106] The base fluid for near-oil-based drilling fluid was prepared according to the method in Example 4, except that cationic chitosan was not added, while the proportions of other substances remained unchanged. The above materials were stirred at room temperature for 4 hours in an air environment to obtain the base fluid for preparing near-oil-based drilling fluid.

[0107] Comparative Example 3

[0108] The base fluid for near-oil-based drilling fluid was prepared according to the method in Example 4, except that no silanyl alkyl glycosides were added, while the proportions of other substances remained unchanged. The above materials were stirred at room temperature in an air environment for 4 hours to obtain the base fluid for preparing near-oil-based drilling fluid.

[0109] Performance testing

[0110] The properties of the base fluid prepared in the embodiments of the present invention for formulating near-oil-based drilling fluids, including anti-collapse, wall consolidation and cementation, lubrication and anti-sticking, plugging and filtration reduction, and biotoxicity, were tested.

[0111] 1) Inhibitory

[0112] ① Shale recovery rate

[0113] The near-oil-based liquid provided by this invention was prepared into a near-oil-based liquid aqueous solution with a mass concentration of 2%, and rolled at 210°C for 16 hours. The shale primary recovery rate and shale relative recovery rate were then tested according to the following method:

[0114] The above-mentioned 2% near-oil-based aqueous solution was stirred at 7000 rpm for 5 minutes and then poured into an aging tank for later use. Rock cuttings of 2.0 mm-5.0 mm were dried at 103℃ for 4 hours and then cooled to room temperature. G0g of rock cuttings were weighed and placed in the aging tank with the above-mentioned 2% near-oil-based aqueous solution. The mixture was rolled at 210℃ for 16 hours. After cooling, the rock cuttings were removed and recovered through a 0.42mm sieve. The rock cuttings were dried at 103℃ for 4 hours and then cooled to room temperature. The mass of the recovered rock cuttings was recorded as G1. The recovered rock cuttings that had been weighed were then placed in clean water and rolled at 210℃ for 16 hours. After cooling, the rock cuttings were removed and recovered through a 0.42mm sieve. The rock cuttings were dried at 103℃ for 4 hours and then cooled to room temperature. The mass of the recovered rock cuttings was recorded as G2. The primary recovery rate, secondary recovery rate, and relative recovery rate of shale were calculated according to the following formulas:

[0115] Shale primary recovery rate = G1 / G0 × 100%;

[0116] Shale secondary recovery rate = G2 / G0 × 100%;

[0117] Shale relative recovery rate = Shale secondary recovery rate / Shale primary recovery rate × 100%;

[0118] ② Relative inhibition rate

[0119] The relative inhibition rate is used to express the inhibitory effect; the higher the relative inhibition rate, the higher the inhibitory effect. The evaluation method for the relative inhibition rate is as follows: Take 350 mL of distilled water, add 1.75 g of sodium carbonate, dissolve it, then add 35 g of calcium bentonite, stir at high speed for 20 min to obtain calcium bentonite-based slurry. The drilling fluid was aged at 210℃ for 16 hours, cooled, and stirred at high speed for 5 minutes. The 100 r / min reading of the drilling fluid was measured using a six-speed rotational viscometer, and the reading was φ1 (172). 350 mL of distilled water was taken, and 1.75 g of sodium carbonate and 2.0% of the base fluid sample used to prepare near-oil-based drilling fluid (the mass of the base fluid sample was 2.0% of the mass of distilled water) were added. After complete dissolution, 35 g of calcium bentonite was added, and the mixture was stirred at high speed for 20 minutes. The fluid was then aged at 210℃ for 16 hours, cooled, and stirred at high speed for 5 minutes. The 100 r / min reading of the drilling fluid was measured using a six-speed rotational viscometer, and the reading was φ2. The relative inhibition rate of the base fluid sample used to prepare near-oil-based drilling fluid against the calcium bentonite-based slurry was calculated using the following formula:

[0120]

[0121] 2) Compressive strength

[0122] Compressive strength is expressed by compressive strength and compressive strength coefficient. Core columns were soaked in a 2.0% (w / w) solution of the present invention and comparative samples at 210°C for 16 hours, and the compressive strength P1 of the core columns was tested. The method for testing the compressive strength of the soaked core columns is as follows: the soaked core column is placed on a compressive strength tester, and the load is increased at a rate of 0.5-0.8 MPa per second until the column fails; this pressure is the compressive strength P1. The compressive strength of the unsoaked original core is recorded as P0, which is 6.9 MPa. Compressive strength coefficient = P1 / P0.

[0123] 3) Lubricity

[0124] The test method is as follows: Immerse the slider in the extreme pressure lubrication instrument into the 2.0% base fluid sample used to prepare near-oil-based drilling fluid. Adjust the torque wrench value to 16.95 N / m, run the instrument for 5 minutes, and read the value displayed on the instrument when the 2.0% base fluid sample is immersed in the slider as X; immerse the slider in clean water, adjust the torque wrench value to 16.95 N / m, run the instrument for 5 minutes, and read the value displayed on the instrument when the slider is immersed in clean water as Y. The extreme pressure lubrication coefficient is calculated using the following formula:

[0125]

[0126] In the above formula: K is the extreme pressure lubrication coefficient; X is the value displayed on the instrument when the slider is soaked with a 2.0% base fluid sample used to prepare near-oil-based drilling fluid; Y is the value displayed on the extreme pressure lubricator when the slider is soaked in clean water, which is 41.

[0127] 4) Reduced filtration efficiency

[0128] According to GB / T 16783.1-2014 "Field Testing of Drilling Fluids for Petroleum and Natural Gas Industry - Part 1: Water-based Drilling Fluids", the filtration loss of 4% sodium bentonite-based slurry before and after adding 2% sodium bentonite to the example and comparative samples was tested. The filtration loss of the 4% sodium bentonite-based slurry before addition was 48 mL. The test conditions were: high-temperature aging at 210℃ for 16 h.

[0129] The preparation method of 4% sodium bentonite-based slurry is as follows: Add 2.0g of anhydrous sodium carbonate and 40g of sodium bentonite for drilling fluid testing to 1L of water, stir for 20min, and then cure at room temperature for 24h to obtain the slurry.

[0130] Scanning electron microscope (SEM) images of the medium-pressure filter cake before and after adding 2% sodium bentonite-based slurry to the sample of Example 1 are shown below. Figure 6 and Figure 7 As shown. From Figure 6 and Figure 7 It can be seen that the medium-pressure filter cake prepared by pressure filtration with 4wt% sodium bentonite-based slurry has a rough and uneven surface with large porosity; while the medium-pressure filter cake prepared by pressure filtration with 4wt% sodium bentonite-based slurry and 2% of the sample from Example 1 has a smooth surface, forming a dense adsorption film without voids, which can effectively prevent the filtrate from invading the formation and ensure the stability of the wellbore. At the same time, the presence of the adsorption film can effectively reduce the friction between the drill string and the wellbore rock, showing a better lubrication and anti-sticking effect.

[0131] 5) Biotoxicity

[0132] Biotoxic EC 50 The test method for the value is as follows: The samples from the embodiments and comparative examples provided by this invention are added to a 3% sodium chloride solution to prepare 0 mg / dm³ solutions. -3 5000mg.dm -3 10000mg.dm -3 25000mg.dm -3 50000mg.dm -3 100000mg.dm -310 mL of each of the test sample solutions was added and allowed to stand for 60 min. Then, 10 mg of luminescent bacteria T3 powder was added sequentially to each of the test sample solutions and thoroughly mixed. Using a 3% sodium chloride solution as a control, the EC50 biotoxicity of the luminescent bacteria and the test sample solutions was determined after 15 min of contact. 50 Value. EC 50 A value ≥30000 mg / L is considered non-biotoxic and is an acceptable emission standard.

[0133] The test results are shown in Table 1.

[0134] Table 1 Performance of Examples and Comparative Samples

[0135]

[0136]

[0137] As shown in Table 1, when the above-mentioned cationic chitosan, silanyl alkyl glycosides, and optionally multibranched polyetheramines, aminocyclodextrins, and sulfaglyceryl glycosides are mixed evenly and stirred for a certain time at a certain temperature under inert gas protection, a synergistic effect is achieved. The resulting base fluid for formulating near-oil-based drilling fluid exhibits a shale recovery rate ≥96.95% after aging at 210℃ for 16 hours. The relative inhibition rate of the 2% example sample on calcium-based slurry is ≥97.97%, and the relative inhibition rate of the 2% comparative sample on calcium-based slurry is ≥88.95%. This indicates that the base fluid prepared in the embodiments of the present invention for formulating near-oil-based drilling fluid exhibits outstanding properties such as inhibiting collapse, solidifying the wall, lubricating and preventing jamming, and sealing and reducing filtration loss. It is environmentally friendly and can meet the performance requirements for formulating near-oil-based drilling fluid.

[0138] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A near-oil-based drilling fluid composition comprising silanyl alkyl glycoside and cationic chitosan, wherein the extreme pressure lubrication coefficient of the composition is 0.005-0.025 and the pressure resistance index is 1.5-3; The composition also contains multibranched polyetheramine and sulfaglyceryl glycoside; The composition also contains aminocyclodextrin; Based on the total amount of the composition, the content of branched polyetheramine is 1-15% by mass, the content of silanyl alkyl glycoside is 40-90% by mass, the content of sulfanyl glyceryl glycoside is 5-30% by mass, and the content of cationic chitosan is 1-11% by mass; Based on the total amount of the composition, the content of aminocyclodextrin is 2-45% by mass; The cationic chitosan has the structure shown in Formula II below; Formula II In Formula II, R is an alkyl group with 1-3 carbon atoms, m is 1200-3100, and n is 1-2; The branched polyetheramine has the structure shown in Formula III. Formula III In Equation III, m is 1-16, n is 1-2, and o is 0-4; A method for preparing silanolyl alkyl glycosides includes the following steps: 1) Under the action of an acidic catalyst, alkyl glycosides and epoxy haloalkane compounds are reacted to obtain haloalcohol alkyl glycosides; 2) The haloalcohol alkyl glycoside is reacted with an organic amine to obtain an aminoalkyl glycoside; 3) Under the action of an initiator, the aminoalkyl glycoside is reacted with an acrylamide compound and a vinyltrialkoxysilane to obtain a silanaminoalkyl glycoside. The alkyl glycoside is selected from one or more of methyl glycosides, ethyl glycosides, propyl glycosides, hexyl glycosides, octyl glycosides, decyl glycosides, dodecyl glycosides, and tetradecyl glycosides. The epoxy haloalkane compound is selected from one or more of epichlorohydrin, epichlorobutane, and epichloropentane; The acrylamide compounds are selected from acrylamide and methacrylamide; The vinyltrialkoxysilane is selected from one or more of vinyltrimethoxysilane, vinyltriethoxysilane, vinyltripropoxysilane, and vinyltributoxysilane; The sulfaglyceryl glycoside has the structure shown in Formula IV below. Formula IV In Formula IV, m is 1-3, and the content of X is 30-70% by mass relative to the total amount of sulfaglyceroglycoside, while the content of Y is 20-50% by mass. X and Y are each represented by the group in formula IV-1) and the group in formula IV-2) respectively, and X and Y are different; Formula IV-1). Formula IV-2); In formula IV-1), R1 and R2 are each independently selected from alkyl groups having 1-3 carbon atoms, n is 1-10, o is 1-10, and p is 0-4; The aminocyclodextrin has the structure shown in formula V. Formula V In formula V, based on the total amount of aminocyclodextrin, the content of R is 30-70% by mass, and R has the structure shown in the following structural formula i. Equation i In formula i, m is 1-2 and n is 0-4.

2. The composition according to claim 1, wherein, The content of X is 35-55% by mass relative to the total amount of sulfaglyceroglycoside, and the content of Y is 25-40% by mass.

3. The composition according to claim 1, wherein, Based on the total amount of aminocyclodextrin, the content of R is 40-55% by mass.

4. The use of the composition according to any one of claims 1-3 in near-oil-based drilling fluids.

5. A near-oil-based drilling fluid containing the composition of any one of claims 1-3.

6. The near-oil-based drilling fluid according to claim 5, wherein, Based on the total amount of near-oil-based drilling fluid, the content of the composition is 20-60% by mass.

7. A method for preparing a near-oil-based drilling fluid composition, the method comprising: By weight, 3-12 parts of multibranched polyetheramine, 10-40 parts of aminocyclodextrin, 3-7 parts of cationic chitosan, 42-58 parts of silanyl alkyl glycoside, and 18-24 parts of sulfaglyceryl glycoside are stirred and mixed evenly at 60-85°C under inert gas protection.

8. The preparation method according to claim 7, wherein, The inert gas is nitrogen and / or helium.

Images