CN109971441B - Bicontinuous phase microemulsion, preparation method thereof, drilling fluid containing microemulsion and preparation method thereof - Google Patents
Bicontinuous phase microemulsion, preparation method thereof, drilling fluid containing microemulsion and preparation method thereof Download PDFInfo
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Abstract
The invention provides a bicontinuous phase microemulsion, which comprises an emulsifier, a water-soluble acid, an oil phase and a water phase, wherein the emulsifier is an amine non-ionic emulsifier. The invention also discloses a drilling fluid containing the microemulsion, which comprises the microemulsion, an oil-based stabilizer, organic soil and a weighting material. The invention also discloses a preparation method of the microemulsion and the drilling fluid, which comprises the steps of mixing other raw materials, adding water-soluble acid for induction to obtain the bicontinuous phase microemulsion and the drilling fluid, or mixing other raw materials with water-soluble acid to obtain the bicontinuous phase microemulsion, and then adding the drilling fluid additive to obtain the bicontinuous drilling fluid. The bicontinuous micro-emulsion has the advantages that the bicontinuous micro-emulsion has unique oil phase and water phase bicontinuous characteristics and rheological characteristics of high shearing force, low plastic viscosity and viscoelasticity, can simultaneously show the respective advantages of oil-based drilling fluid and water-based drilling fluid when being used for drilling fluid, and enhances the capabilities of the drilling fluid in transmitting hydrodynamic force, suspending and carrying cuttings and cleaning a borehole.
Description
Technical Field
The invention belongs to the technical field of oilfield chemistry and colloids, and particularly relates to a bicontinuous phase microemulsion, a preparation method thereof, a drilling fluid containing the microemulsion and a preparation method thereof.
Background
During drilling, the drilling fluid reaches the formation through the drill string, is ejected out of the drill bit into the annular space between the drill string and the well wall, and finally returns to the ground. In this process, the drilling fluid mainly provides the functions of suspending and carrying cuttings, balancing formation pressure and stabilizing the borehole wall, cooling and lubricating the drill bit and drilling tool, transmitting hydrodynamic force, and the like, and reduces the influence on the oil and gas reservoir and the ecological environment as much as possible, and therefore, the drilling fluid is called the blood for drilling.
In the prior art, the commonly used drilling fluids mainly comprise water-based drilling fluids and oil-based drilling fluids. The water-based drilling fluid is easy to clean, but easily causes hydration expansion of shale stratum, and is not beneficial toThe well wall is stable, the lubricity is not good, the drill sticking is easy to cause, and the well wall is particularly not favorable for drilling a well with larger inclination angle. Compared with water-based drilling fluid, the oil-based drilling fluid has advantages in inhibiting hydration expansion and lubricity of shale formation, and is particularly suitable for drilling in complex drilling environment and severe oil and gas reservoirs such as shale gas. However, conventional oil-based drilling fluids are not easy to clean, resulting in difficulties in completing and cementing wells, contamination of oil-bearing drill cuttings, and the like. The reversible invert emulsion drilling fluid is a novel oil-based drilling fluid and has reversible characteristics, namely: the oil-based drilling fluid is in the form of an oil-based drilling fluid during drilling, shows excellent fluid loss, inhibition and lubricity, and can be treated by a water-soluble acid or be transformed into a water-based drilling fluid in a mode of changing the salinity of a system during the operation after drilling, so that the oil-based drilling fluid is convenient to clean. The reversible invert emulsion drilling fluid combines the advantages of both oil-based drilling fluids and water-based drilling fluids. For example, US5888944 and US6218342 provide a reversible reverse emulsion drilling fluid with phase inversion controlled by pH, the drilling fluid adopts linear alkyl amine surfactant as core emulsifier, and is compounded with conventional treating agent to form W/O type oil-based drilling fluid, which has good drilling performance equivalent to that of the conventional oil-based drilling fluid, and after contacting with water-soluble acid such as hydrochloric acid, the drilling fluid system can be converted from W/O type to O/W type, and has the characteristic of easy cleaning equivalent to that of water-based drilling fluid. Although such reversible invert emulsion drilling fluids have been successfully used in west africa, north sea, etc., the use of acidic cleaning fluids has brought about a number of considerable inconveniences: special chemical additives and equipment are required to solve the problems of temperature control, speed control and corrosion prevention of the acid liquor conveying system, so that the cost is increased, the process is complicated, the engineering quantity is increased, and the risk of environmental pollution is increased. For example, the SPE/IATMIAsia Pacific Oil held in Yagara, Indonesian in 2017 by Jinheng Ren et al&A Gas Conference and inhibition published as The reversible emulsion Controlled by organic Salt at High Temperature or Low permaabilityReservoir provides a reversible invert emulsion drilling fluid with phase inversion Controlled by salinity, which uses a combination of sodium dodecyl sulfate, sodium dodecyl benzene sulfonate and sodium petroleum sulfonateThe compound is used as a core emulsifier, and the system is prepared by using a polyvalent metal salt (such as MgCl)2，AlCl3，CrCl3.6H2O) induced reversible conversion to W/O form, followed by anion (such as CO)3 2-，OH-，SiO3 2-) Inducing the reversion back to O/W type. The reversible reverse emulsification drilling fluid with phase inversion regulated by salinity is still in the laboratory research stage, and has a plurality of defects, such as: the W/O type system used in the drilling stage can be obtained by adding high-valence inorganic salt, and the obtained W/O type system is very unstable (the demulsification voltage is less than or equal to 160V and far lower than the drilling engineering requirement and is more than or equal to 400V, and the temperature-resistant range is less than or equal to 90 ℃), and moreover, the environmental pollution problem of the drilling fluid is aggravated by adding a large amount of multivalent metal salt.
Disclosure of Invention
The invention provides a bicontinuous phase microemulsion, a preparation method thereof, a drilling fluid containing the microemulsion and a preparation method thereof, and aims to obtain the bicontinuous phase microemulsion with good viscoelasticity, high dynamic shear force and low plastic viscosity, and the drilling fluid prepared by the microemulsion can avoid drill bit sticking and effectively inhibit hydration expansion of shale stratum, thereby being beneficial to well wall stability and being easily cleaned by neutral aqueous solution.
In order to achieve the above object, the present invention provides a bicontinuous phase microemulsion, which comprises an emulsifier, a water-soluble acid, an oil phase and a water phase, wherein the emulsifier is an amine non-ionic emulsifier, the water-soluble acid is one or more of hydrochloric acid, acetic acid, propionic acid, butyric acid, lactic acid, halogenated acetic acid, glycolic acid and tartaric acid, the oil phase is one or more of mineral oil, diesel oil, gas oil and synthetic base fluid, and the water phase is one or more of seawater, organic salt brine, inorganic salt brine and water phase containing water-soluble organic matters;
the hydrophilic-lipophilic balance value of the amine non-ionic emulsifier is 4-6, and the amine non-ionic emulsifier has a molecular structure general formula shown in a formula 1;
in the formula 1, R is a hydrophobic carbon chain with the chain length of C8-C20, at least one unsaturated bond is contained, and R' is H, C1、C2Or C3A is O or NH, 1 is more than or equal to m + n is less than or equal to 3.
Further, the content of the amine non-ionic emulsifier in the microemulsion is 0.10-0.2mol/L, the amount of the water-soluble acid is 40-70% of the molar content of the amine non-ionic emulsifier, and the volume of the oil phase and the water phase is 40: 60-60:40.
The bicontinuous phase microemulsion obtained by adopting the raw materials and the mass ratio relationship is non-protonated under the alkaline condition (pH is more than 8) and can be used for stabilizing a water-in-oil type emulsion (an oil phase is a continuous phase, and a water phase is a dispersed phase); after water-soluble acid is added, part of the main emulsifier reacts with the acid to be protonated, at the moment, the water-in-oil emulsion is changed into a bicontinuous phase microemulsion (both an oil phase and a water phase are continuous phases), and the bicontinuous microemulsion is accompanied by a liquid crystal phase and has the unique rheological characteristics of excellent viscoelasticity, high dynamic shear and low plastic viscosity.
Further, the amine non-ionic emulsifier is ethoxylated higher fatty alkylamine and has a molecular structural general formula shown in a formula 2;
in the formula 2, R is a hydrophobic carbon chain, at least one unsaturated bond is contained, and C is12-C20An even number of carbon chain distributions.
Further, the amine non-ionic emulsifier is tallow based propylene diamine, and has a molecular structure general formula shown as a formula III:
in the formula III, R is a hydrophobic carbon chain, at least one unsaturated bond is contained, and the structure is C14-C18An even number of carbon chain distributions.
The invention also discloses a method for preparing the bicontinuous phase microemulsion, which comprises the steps of mixing the oil phase, the emulsifier and the water phase, shearing and stirring to prepare a water-in-oil type emulsion; then, adding water-soluble acid under continuous stirring to obtain a bicontinuous phase microemulsion;
or mixing oil phase, emulsifier, water phase and water soluble acid, shearing, and stirring to obtain bicontinuous phase microemulsion.
The invention also discloses a drilling fluid containing the bicontinuous phase microemulsion, which comprises the bicontinuous phase microemulsion, an oil-based stabilizer, organic soil and a weighting material, wherein the oil-based stabilizer is an amide oil-based stabilizer.
Furthermore, when 100ml of the bicontinuous phase microemulsion is taken in the drilling fluid, the mass of the oil-based stabilizer is 3-4g, and the mass of the organic soil is 0-4 g.
When the bicontinuous phase microemulsion is matched with the drilling fluid additive, the drilling fluid with unique bicontinuous characteristics of oil phase and water phase can be obtained, which is equivalent to the oil-based drilling fluid in the prior art, has good drilling performance, is easy to be removed by neutral aqueous solution and seawater in the subsequent stage of drilling, and can continuously clean filter cakes and oil-containing drill cuttings of the drilling fluid only by adopting neutral clear water and seawater. Therefore, the drilling fluid obtained by the invention has good characteristics in the oil-based and water-based drilling fluids in the prior art, is applied to the field of drilling, greatly simplifies the drilling operation procedure, saves the workload and obviously improves the drilling operation efficiency.
The invention also discloses a method for preparing the drilling fluid, wherein the bicontinuous-phase amine non-ionic emulsifier is used as a main emulsifier of the drilling fluid, the amine non-ionic emulsifier is mixed with an oil-based stabilizer, organic soil and a weighting material to prepare the water-in-oil type drilling fluid, and then water-soluble acid is added to induce the water-in-oil type drilling fluid to be in phase inversion to the bicontinuous-phase emulsified drilling fluid.
Or, the water-in-oil type emulsion is prepared by taking the amine non-ionic surfactant as a main emulsifier, then water-soluble acid is added to induce the water-in-oil type emulsion to be converted into the bicontinuous phase microemulsion, and then the oil-based stabilizer, the organic soil and the weighting material are added to the bicontinuous phase microemulsion.
Further, the preparation method of the oil-based stabilizer used in the present invention comprises: (1) a250 mL three-neck flask was taken, connected to a condensing reflux unit, and charged with tall oil fatty acid (38.5g, about 0.136 mol); under reflux stirring at 60 deg.C, gradually adding liquid tallow-1, 3-propylene diamine (25.5g, about 0.124mol) melted in advance, and finishing within about 30 min; then, heating to 165 ℃ and continuously reacting for 16 hours to obtain an intermediate product 1; (2) cooling to 100 ℃, continuously dropwise adding the previously melted maleic acid glycoside (13.24g, 0.135mol) into the product 1 in an amount of 1-2 hr under reflux stirring; the reaction was stirred under reflux at 100 ℃ for 3 hr. To obtain the final product 2, namely the oil-based stabilizer. The first amidation is completed by the reaction of the above step (1), and is tallow-1, 3 propylenediamine (R1-NH (CH)2)nNH2) With tall oil fatty acid (R2-CO)2H) Amidation reaction to obtain product 1(R1-NH (CH)2) nNHCO-R2); the second amidation is completed by the reaction in the step (2), namely, the amidation reaction is performed on the product 1 and maleic anhydride to obtain a product 2(HO-CO-CH ═ CH-CO-N (R1) - (CH)2)n-NH-CO-R2)。
By adopting the technical scheme, the bicontinuous-phase microemulsion has the beneficial effects that (1) the bicontinuous-phase microemulsion obtained by the method has unique bicontinuous characteristics of an oil phase and a water phase, and when the bicontinuous-phase microemulsion is used for a drilling fluid, the drilling fluid also has the bicontinuous characteristics of the oil phase and the water phase, and in a drilling stage, the drilling fluid has good drilling performance (such as low filtration loss, good inhibition and good lubricity) equivalent to that of the traditional oil-based drilling fluid, and in a well completion stage and a subsequent stage, the drilling fluid is easily removed by a neutral aqueous solution, so that the advantages of easy removal of filter cakes and residual mud equivalent to that of a water-based drilling fluid and easy oil removal of oil-containing.
(2) The bicontinuous phase microemulsion obtained by the invention has excellent shearing dilutability and viscoelasticity. Based on the characteristics, the drilling fluid prepared by the bicontinuous phase microemulsion can show unique rheological characteristics of high dynamic shear force and low plastic viscosity. This is beneficial for enhancing the ability of the drilling fluid to transmit hydrodynamic forces, suspend and carry cuttings, and clean the wellbore.
Drawings
FIG. 1 is a cryo-transmission electron micrograph of the bicontinuous microemulsion microstructure of the present invention, in which the left image: magnification 200 times, right panel: amplifying by 1000 times;
fig. 2 is a macro-photograph comparison of viscoelastic behavior of the drilling fluids of the present invention versus conventional oil-based drilling fluids, in which the left panel: the invention relates to a drilling fluid; right panel: a conventional oil-based drilling fluid;
FIG. 3 is a rheological profile of a drilling fluid of the present invention;
FIG. 4 is a plot of the elastic modulus G ', plastic modulus G' of the inventive drilling fluid versus time (a), shear stress (b), and oscillation frequency (c);
FIG. 5 is a macroscopic and microscopic photograph of a high temperature high pressure filter cake (120 ℃, 3.5MPa) of the drilling fluid of the present invention before water washing, wherein the left image: macro-looking; the middle graph is as follows: micrographs of SEM at 5000 Xmagnification; right panel: microscopic photograph of SEM magnification 20000 times;
FIG. 6 is a macroscopic and microscopic photograph of a high-temperature high-pressure filter cake (120 ℃, 3.5MPa) of the drilling fluid of the present invention after washing, wherein, the left image: macro-looking; right panel: micrographs of SEM at 5000 Xmagnification.
Detailed Description
The present invention is further described below. The condition parameters not mentioned in the present invention are all the condition parameters referred to in the prior art, and all the raw materials are commercially available.
The first embodiment is as follows: the invention provides a bicontinuous phase microemulsion, which comprises raw materials of an emulsifier, a water-soluble acid, an oil phase and a water phase, wherein the emulsifier is an amine non-ionic emulsifier, the water-soluble acid is a mixture of hydrochloric acid, acetic acid and propionic acid, the oil phase is a mixture of mineral oil and diesel oil, and the water phase is a mixture of seawater and organic salt brine such as ammonium salt;
the hydrophilic-lipophilic balance value of the amine non-ionic emulsifier is 4-6, and the amine non-ionic emulsifier has a molecular structure general formula shown in a formula 1;
in the formula 1, R is a hydrophobic carbon chain with the chain length of C8-C20, at least one unsaturated bond is contained, and R' is H, C1、C2Or C3A is O or NH, 1 is more than or equal to m + n is less than or equal to 3.
For example, the emulsifier is ethoxylated higher fatty alkylamine and has a molecular structural general formula shown in formula 2;
in the formula 2, R is a hydrophobic carbon chain, at least one unsaturated bond is contained, and C is12-C20An even number of carbon chain distributions. Such as ethoxylated tallow amine.
Specifically, the content of the amine non-ionic emulsifier in the microemulsion is 0.10mol/L, the amount of the water-soluble acid is 40% of the molar content of the amine non-ionic emulsifier, and the volume of the oil phase and the water phase is 60: 40.
the method for preparing the microemulsion of claim, mixing the oil phase, the emulsifier and the water phase, and preparing the water-in-oil emulsion by shearing and stirring; then, adding water-soluble acid under continuous stirring to obtain the bicontinuous phase microemulsion.
The invention also discloses a drilling fluid containing the microemulsion, which comprises the bicontinuous phase microemulsion, an oil-based stabilizer, organic soil and a weighting material, wherein the oil-based stabilizer is an amide oil-based stabilizer. The weighting material may be barite powder.
Furthermore, when 100ml of the bicontinuous phase microemulsion is taken as the component drilling fluid, the mass of the oil-based stabilizer is 3g, organic soil can not be added, and the system density is increased to 1.2g/cm by adopting a weighting material3。
The invention provides a method for preparing the drilling fluid, which comprises the steps of taking a bicontinuous-phase amine non-ionic emulsifier as a main emulsifier of the drilling fluid, mixing the amine non-ionic emulsifier with an oil-based stabilizer, organic soil and a weighting material to prepare the water-in-oil drilling fluid, and then adding water-soluble acid to induce the water-in-oil drilling fluid to be in phase inversion to the bicontinuous-phase emulsified drilling fluid.
The preparation method of the oil-based stabilizer used in the invention comprises the following steps: (1) a250 mL three-neck flask was taken, connected to a condensing reflux unit, and charged with tall oil fatty acid (38.5g, about 0.136 mol); under reflux stirring at 60 deg.C, gradually adding liquid tallow-1, 3-propylene diamine (25.5g, about 0.124mol) melted in advance, and finishing within about 30 min; then, heating to 165 ℃ and continuously reacting for 16 hours to obtain an intermediate product 1; (2) cooling to 100 ℃, continuously dropwise adding the previously melted maleic acid glycoside (13.24g, 0.135mol) into the product 1 in an amount of 1-2 hr under reflux stirring; the reaction was stirred under reflux at 100 ℃ for 3 hr. To obtain the final product 2, namely the oil-based stabilizer. The first amidation is completed by the reaction of the above step (1), and is tallow-1, 3 propylenediamine (R1-NH (CH)2)nNH2) With tall oil fatty acid (R2-CO)2H) Amidation reaction to obtain product 1(R1-NH (CH)2) nNHCO-R2); the second amidation is completed by the reaction in the step (2), namely, the amidation reaction is performed on the product 1 and maleic anhydride to obtain a product 2(HO-CO-CH ═ CH-CO-N (R1) - (CH)2)n-NH-CO-R2)。
Referring to fig. 1, the microemulsion obtained by the raw materials and the preparation method is shown in the figure, and it can be seen that the oil phase and the water phase of the microemulsion obtained by the invention are mutually staggered, are both continuous phases and are simultaneously mixed with a bright liquid crystal phase. Fig. 2 is a macro-photograph comparing viscoelastic behavior of the drilling fluids of the present invention with conventional oil-based drilling fluids, from which it can be seen that: the drilling fluid shows an obvious gel state and obvious viscoelasticity after being dripped from a dropper; the conventional oil-based drilling fluid is dripped like broken raindrops after being dripped from a dropper, and the viscoelastic characteristic is not seen apparently.
Example two: the invention provides a bicontinuous phase microemulsion, which comprises raw materials of an emulsifier, a water-soluble acid, an oil phase and a water phase, wherein the emulsifier is an amine non-ionic emulsifier, the water-soluble acid is the mixture of lactic acid, halogenated acetic acid and glycollic acid, the oil phase is the mixture of gas oil and synthetic base liquid, and the water phase is the mixture of inorganic salt brine such as sodium chloride and water-soluble organic matter-containing water phase such as glycerol;
the hydrophilic-lipophilic balance value of the amine non-ionic emulsifier is 4-6, and the amine non-ionic emulsifier has a molecular structure general formula shown in a formula 1;
in the formula 1, R is a hydrophobic carbon chain with the chain length of C8-C20, at least one unsaturated bond is contained, and R' is H, C1、C2Or C3A is O or NH, 1 is more than or equal to m + n is less than or equal to 3.
For example, the emulsifier is aliphatic trimethylene diamine and has a molecular structure general formula shown in the formula III:
in the formula III, R is a hydrophobic carbon chain, at least one unsaturated bond is contained, and the structure is C14-C18Even-numbered poly-carbon chain distributions, for example: c143%, C1630% and C1867%.
Specifically, the content of the amine non-ionic emulsifier in the microemulsion is 0.15mol/L, the amount of the water-soluble acid is 70% of the molar content of the amine non-ionic emulsifier, and the volume of the oil phase and the water phase is 60: 40.
a process for preparing the microemulsion of claim, wherein the oil phase, emulsifier, water phase and water-soluble acid are mixed, sheared and stirred to obtain the bicontinuous microemulsion.
The invention also discloses a drilling fluid containing the microemulsion, which comprises the bicontinuous phase microemulsion, an oil-based stabilizer, organic soil and a weighting material, wherein the oil-based stabilizer is an amide oil-based stabilizer. The weighting material can be iron ore powder.
Furthermore, when the bicontinuous phase microemulsion is 100ml, the mass of the oil-based stabilizer is 4g, and the organic stabilizer is organicThe soil is 1g, and the density of the system is increased to 1.10g/cm by adopting a weighting material3。
The preparation method of the oil-based stabilizer used in the invention comprises the following steps: (1) a250 mL three-neck flask was taken, connected to a condensing reflux unit, and charged with tall oil fatty acid (38.5g, about 0.136 mol); under reflux stirring at 60 deg.C, gradually adding liquid tallow-1, 3-propylene diamine (25.5g, about 0.124mol) melted in advance, and finishing within about 30 min; then, heating to 165 ℃ and continuously reacting for 16 hours to obtain an intermediate product 1; (2) cooling to 100 ℃, continuously dropwise adding the previously melted maleic acid glycoside (13.24g, 0.135mol) into the product 1 in an amount of 1-2 hr under reflux stirring; the reaction was stirred under reflux at 100 ℃ for 3 hr. To obtain the final product 2, namely the oil-based stabilizer. The first amidation is completed by the reaction of the above step (1), and is tallow-1, 3 propylenediamine (R1-NH (CH)2)nNH2) With tall oil fatty acid (R2-CO)2H) Amidation reaction to obtain product 1(R1-NH (CH)2) nNHCO-R2); the second amidation is completed by the reaction in the step (2), namely, the amidation reaction is performed on the product 1 and maleic anhydride to obtain a product 2(HO-CO-CH ═ CH-CO-N (R1) - (CH)2)n-NH-CO-R2)。
The invention provides a method for preparing the drilling fluid, which comprises the steps of firstly preparing a water-in-oil type emulsion by taking an amine non-ionic surfactant as a main emulsifier, then adding water-soluble acid to induce the water-in-oil type emulsion to be converted into a bicontinuous phase microemulsion, and then adding an oil-based stabilizer, organic soil and a weighting material into the bicontinuous phase microemulsion. The rheological profile of the drilling fluid obtained by the invention is shown in figure 3, and the rheological profile of the drilling fluid comprises two regions, namely a low shear region and a high shear region. In the low shear region, the viscosity of the system is hardly affected by shear, meaning that the system exhibits good gel structure strength in this region; in the high shear region, the viscosity of the system decreased rapidly with increasing shear, indicating that the system exhibited excellent shear thinning in this region. FIG. 4 is a relationship between the elastic modulus G 'and the plastic modulus G' of the drilling fluid of the present invention, and the time (a), the shear stress (b) and the oscillation frequency (c), and it can be seen from the graph that G 'is always greater than G' in the linear shear range, indicating that the drilling fluid of the present invention has good viscoelasticity.
Example three: the invention provides a bicontinuous phase microemulsion, which comprises raw materials of an emulsifier, a water-soluble acid, an oil phase and a water phase, wherein the emulsifier is an amine non-ionic emulsifier, the water-soluble acid is tartaric acid, the oil phase is mineral oil, and the water phase is formed by mixing inorganic salt brine such as calcium chloride and seawater;
the hydrophilic-lipophilic balance value of the amine non-ionic emulsifier is 4-6, and the amine non-ionic emulsifier has a molecular structure general formula shown in a formula 1;
in the formula 1, R is a hydrophobic carbon chain with the chain length of C8-C20, at least one unsaturated bond is contained, and R' is H, C1、C2Or C3A is O or NH, 1 is more than or equal to m + n is less than or equal to 3.
For example, the emulsifier is ethoxylated higher fatty alkylamine and has a molecular structural general formula shown in formula 2;
in the formula 2, R is a hydrophobic carbon chain, at least one unsaturated bond is contained, and C is12-C20An even number of carbon chain distributions. Such as ethoxylated oleylamine.
Specifically, the content of the amine non-ionic emulsifier in the microemulsion is 0.2mol/L, the amount of the water-soluble acid is 60% of the molar content of the amine non-ionic emulsifier, and the volume of the oil phase and the water phase is 50: 50.
a process for preparing the microemulsion of claim, wherein the oil phase, emulsifier, water phase and water-soluble acid are mixed, sheared and stirred to obtain the bicontinuous microemulsion.
The invention also discloses a drilling fluid containing the microemulsion, which comprises the bicontinuous phase microemulsion, an oil-based stabilizer, organic soil and a weighting material, wherein the oil-based stabilizer is an amide oil-based stabilizer. The weighting material can be ilmenite powder.
Further, when 100ml of the bicontinuous phase microemulsion is taken as the component drilling fluid, the mass of the oil-based stabilizer is 3.5g, the mass of the organic soil is 2g, and the system density is increased to 1.25g/cm by adopting a weighting material3。。
The invention provides a method for preparing the drilling fluid, which comprises the steps of firstly preparing a water-in-oil type emulsion by taking an amine non-ionic surfactant as a main emulsifier, then adding water-soluble acid to induce the water-in-oil type emulsion to be converted into a bicontinuous phase microemulsion, and then adding an oil-based stabilizer, organic soil and a weighting material into the bicontinuous phase microemulsion.
The preparation method of the oil-based stabilizer used in the invention comprises the following steps: (1) a250 mL three-neck flask was taken, connected to a condensing reflux unit, and charged with tall oil fatty acid (38.5g, about 0.136 mol); under reflux stirring at 60 deg.C, gradually adding liquid tallow-1, 3-propylene diamine (25.5g, about 0.124mol) melted in advance, and finishing within about 30 min; then, heating to 165 ℃ and continuously reacting for 16 hours to obtain an intermediate product 1; (2) cooling to 100 ℃, continuously dropwise adding the previously melted maleic acid glycoside (13.24g, 0.135mol) into the product 1 in an amount of 1-2 hr under reflux stirring; the reaction was stirred under reflux at 100 ℃ for 3 hr. To obtain the final product 2, namely the oil-based stabilizer. The first amidation is completed by the reaction of the above step (1), and is tallow-1, 3 propylenediamine (R1-NH (CH)2)nNH2) With tall oil fatty acid (R2-CO)2H) Amidation reaction to obtain product 1(R1-NH (CH)2) nNHCO-R2); the second amidation is completed by the reaction in the step (2), namely, the amidation reaction is performed on the product 1 and maleic anhydride to obtain a product 2(HO-CO-CH ═ CH-CO-N (R1) - (CH)2)n-NH-CO-R2)。
FIG. 5 is a macroscopic and microscopic photograph of the high-temperature high-pressure filter cake (120 ℃, 3.5MPa) of the drilling fluid of the invention before water washing, so that it can be seen that before water washing, a layer of film is covered on the surface of the filter cake, which is compact and smooth, and fully fills the gaps among clay particles, thus the fluid loss property is good; FIG. 6 is a macroscopic and microscopic photograph of the high-temperature and high-pressure filter cake (120 deg.C, 3.5MPa) of the drilling fluid after washing, and it can be seen from the figure that after washing, the film covering the filter cake surface disappears, exposing the originally coated solid-phase particles, and thus being easily removed by neutral water.
The drilling fluid prepared by adopting the bicontinuous phase microemulsion of the invention is subjected to performance test:
(1) and (3) loading the prepared viscoelastic bicontinuous emulsified drilling fluid into an aging tank, aging for 16h at 120 ℃, and testing the rheological property, the filtration loss property and the like of the drilling fluid.
(2) The shale debris (6-10 meshes) is mixed into the drilling fluid, hot rolling is carried out for 16 hours at the temperature of 120 ℃, and the hot rolling yield is calculated to evaluate the inhibitive performance of the drilling fluid.
(3) The filter cake from the fluid loss test is soaked in a neutral aqueous solution (e.g., tap water) and the removal of the filter cake from the neutral aqueous solution is observed and recorded.
(4) And soaking the sandstone cuttings polluted by the drilling fluid in a neutral aqueous solution (such as tap water), and calculating the clearance rate of the neutral aqueous solution on the residual mud on the sandstone cuttings.
(5) The shale cuttings obtained from the rolling recovery experiment are soaked in a neutral aqueous solution (such as deionized water), and the dispersion condition of the shale is observed and recorded. The results of the above tests are shown in Table 1.
TABLE 1 Properties of viscoelastic bicontinuous phase microemulsion drilling fluids of the present invention
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (8)
1. A bicontinuous phase microemulsion is characterized in that raw materials comprise an emulsifier, a water-soluble acid, an oil phase and a water phase, wherein the emulsifier is an amine non-ionic emulsifier, the water-soluble acid is acetic acid, the oil phase is one or more of mineral oil, diesel oil, gas-made oil and synthetic base fluid, and the water phase is one or more of seawater, organic salt brine, inorganic salt brine and a water phase containing water-soluble organic matters;
the hydrophilic-lipophilic balance value of the amine non-ionic emulsifier is 4-6, and the amine non-ionic emulsifier has a molecular structure general formula shown in a formula 1;
in the formula 1, R is a hydrophobic carbon chain with the chain length of C8-C20, at least one unsaturated bond is contained, and R' is H, C1、C2Or C3A is O or NH, 1 is more than or equal to m + n is more than or equal to 3;
the content of the amine non-ionic emulsifier in the microemulsion is 0.10-0.2mol/L, the amount of the water-soluble acid is 40-70% of the molar content of the amine non-ionic emulsifier, and the volume of the oil phase and the water phase is 40: 60-60:40.
2. The bicontinuous microemulsion of claim 1 wherein said amine-type nonionic emulsifier is an ethoxylated higher aliphatic amine having a general molecular structural formula shown in formula 2;
and a bond, is C12-C20An even number of carbon chain distributions.
3. The bicontinuous microemulsion according to claim 1, characterized in that said amine-type nonionic emulsifier is of the general molecular structure formula shown in formula 3:
in formula 3, R is a hydrophobic carbon chain, contains at least one unsaturated bond and is C14-C18An even number of carbon chain distributions.
4. A process for preparing a microemulsion as claimed in any one of claims 1 to 3, wherein the oil phase, the emulsifier and the aqueous phase are mixed and subjected to shear stirring to prepare a water-in-oil emulsion; then, adding water-soluble acid under continuous stirring to obtain a bicontinuous phase microemulsion;
or mixing oil phase, emulsifier, water phase and water soluble acid, shearing, and stirring to obtain bicontinuous phase microemulsion.
5. A drilling fluid containing the microemulsion of any one of claims 1-3, wherein the drilling fluid comprises the bicontinuous microemulsion, an oil-based stabilizer, an organic soil and a weighting material, wherein the oil-based stabilizer is an amide oil-based stabilizer;
when 100ml of the bicontinuous phase microemulsion is taken in the drilling fluid, the mass of the oil-based stabilizer is 3-4g, and the mass of the organic soil is 0-4 g.
6. A method for preparing the drilling fluid as claimed in claim 5, wherein the amine non-ionic emulsifier is used as the main emulsifier of the drilling fluid, and is mixed with the oil-based stabilizer, the organic soil and the weighting material to prepare the water-in-oil type drilling fluid, and then the water-soluble acid is added to induce the water-in-oil type drilling fluid to be in phase inversion to the bicontinuous phase emulsified drilling fluid.
7. A method for preparing the drilling fluid as claimed in claim 5, wherein the water-in-oil emulsion is prepared by using the amine non-ionic surfactant as a main emulsifier, then the water-soluble acid is added to induce the water-in-oil emulsion to be converted into the bicontinuous phase microemulsion, and then the oil-based stabilizer, the organic soil and the weighting material are added to the bicontinuous phase microemulsion.
8. The drilling fluid of claim 5, wherein the preparation method of the oil-based stabilizer comprises the following steps: (1) connecting a 250mL three-neck flask with a condensation reflux device, and filling 38.5g of tall oil fatty acid; under reflux stirring at 60 deg.C, 25.5g tallow-1, 3-propylene diamine melted into liquid in advance is added gradually, and the addition is completed in 30 min; then, heating to 165 ℃ and continuously reacting for 16 hours to obtain an intermediate product 1; (2) cooling to 100 ℃, continuously dripping 13.24g of maleic anhydride melted in advance into the intermediate product 1 one by one under the reflux stirring, and finishing the addition for 1-2 hr; maintaining at 100 deg.C, refluxing, stirring, and reacting for 3 hr; obtaining a final product 2, namely the oil-based stabilizer; finishing the first amidation by the reaction in the step (1), wherein the amidation reaction is carried out on the tallow-1, 3 propylene diamine and tall oil fatty acid to obtain an intermediate product 1; and (3) finishing the second amidation by the reaction in the step (2), wherein the intermediate product 1 and maleic anhydride are subjected to amidation reaction to obtain a product 2.
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