CN115725024A - Oil-absorbing expansion type plugging anti-collapse agent for oil-based drilling fluid and preparation method thereof - Google Patents
Oil-absorbing expansion type plugging anti-collapse agent for oil-based drilling fluid and preparation method thereof Download PDFInfo
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Abstract
The invention relates to the technical field of plugging agents for oil-based drilling fluids, in particular to an oil-absorbing expansion type plugging anti-collapse agent for oil-based drilling fluids and a preparation method thereof, wherein the oil-absorbing expansion type plugging anti-collapse agent is obtained according to the following method: mixing and stirring ethylene-vinyl acetate copolymer, styrene, octyl acrylate, 2-hydroxypropyl acrylate, divinylbenzene and span 80 to obtain an internal phase, adding tween 80 into deionized water to mix and stir to obtain an external phase, mixing and shearing the internal phase, the external phase and azobisisobutyronitrile to obtain emulsion, polymerizing the emulsion under certain conditions, and crushing to obtain the product. According to the invention, the macromolecule high-elasticity body component, the oil-based viscous component and the adsorption component are added into the raw materials, so that the oil-based drilling fluid can play roles in expanding, softening, deforming and cementing rocks by using the oil base, and finally, the purposes of plugging broken strata and crack development strata are achieved.
Description
Technical Field
The invention relates to the technical field of oil-based drilling fluid plugging agents, in particular to an oil-absorbing expansion type plugging anti-collapse agent for oil-based drilling fluid and a preparation method thereof.
Background
With the continuous improvement of the exploration and development degree of oil and gas resources, the drilling development gradually moves to deep stratum and complex stratum, and higher requirements are provided for drilling fluid technology. Compared with water-based drilling fluid, the oil-based drilling fluid can solve the problem of shale hydration from the source, has strong thermal stability, strong reservoir protection capability and good lubricity, and is more and more widely applied to complex deep wells.
In recent years, the oil-based drilling fluid system is applied to a plurality of blocks such as southern edges of pseudo-songarian basins in Xinjiang on site, is successful in reducing complexity, increasing speed, optimizing well depth structures and the like, has obvious comprehensive speed increasing effect, but also has the problem of insufficient plugging and anti-collapse performance of the oil-based drilling fluid in the application process, and particularly has great influence on safe implementation and speed increasing efficiency of drilling construction when well wall instability conditions such as broken strata and crack pore development strata, block falling, collapse and the like occur. A large number of researches show that when the oil-based drilling fluid is adopted for construction, the transmission of liquid pressure along cracks and pores is one of main reasons for causing the instability of the well wall, and the improvement of the plugging performance of the oil-based drilling fluid is an important means for solving the instability of the well wall of the oil-based drilling fluid.
At present, the commonly used plugging agent for oil-based drilling fluid mainly comprises inorganic particle materials (such as ultrafine calcium carbonate, silica and modified substances thereof), asphalt materials and high polymer materials. The inorganic particle plugging material is mostly a rigid material, does not have expansibility, is easy to slip at a crack under the condition of pressure fluctuation of a drilling fluid column, influences the plugging effect, is relatively fixed in particle size, is relatively low in size matching degree with a stratum crack, and has tiny pores among materials, the pore gaps and the materials, the capillary suction force is large, and the plugging effect is poor. The asphalt or modified asphalt plugging material needs to have a bottom temperature matched with the softening point of the plugging agent, if the temperature of the stratum is lower than the softening point of the plugging agent, the plugging agent is in a rigid state and is difficult to effectively fill cracks, and if the temperature of the stratum is higher than the softening point of the plugging agent, the plugging agent is in a flowing state in a system and has weak pressure resistance. In addition, for large size apertures, the asphalt plugging effect is limited. Meanwhile, when the additive is added in a large amount, the contained colloid has a large influence on the rheological property of the drilling fluid. In recent years, most of the emerging high-molecular polymer plugging materials do not have expansion performance, are in nanometer level particle size, have poor plugging universality and are mainly applied to compact low-permeability rock stratums.
Therefore, a novel plugging anti-collapse material suitable for the oil-based drilling fluid needs to be developed, and the plugging capability of the oil-based drilling fluid is improved.
Disclosure of Invention
The invention provides an oil-absorbing expansion type plugging anti-collapse agent for oil-based drilling fluid and a preparation method thereof, overcomes the defects of the prior art, and can effectively solve the problem of poor plugging effect of the plugging agent for the oil-based drilling fluid.
One of the technical schemes of the invention is realized by the following measures: an oil absorption expansion type plugging anti-sloughing agent for oil-based drilling fluid is obtained by the following method: step one, mixing ethylene-vinyl acetate copolymer (EVA), styrene, octyl acrylate, 2-hydroxypropyl acrylate and Divinylbenzene (DVB) at normal temperature to obtain a mixture, adding span 80 accounting for 0.3 to 0.4 percent of the total weight of the mixture into the mixture, mixing and stirring to obtain an internal phase, wherein the total weight parts of the mixture are 100 parts, and the weight ratio of the ethylene-vinyl acetate copolymer (EVA), styrene, octyl acrylate, 2-hydroxypropyl acrylate and Divinylbenzene (DVB) in the mixture is 10; secondly, adding tween 80 accounting for 5 to 6 percent of the total weight of the deionized water into 100 parts of deionized water at normal temperature, and mixing and stirring to obtain an external phase; thirdly, pouring the outer phase into the inner phase for shearing and emulsifying under the condition of 0-5 ℃, and then adding azobisisobutyronitrile accounting for 0.4-0.5% of the total weight of the mixed materials for continuously shearing to obtain emulsion; and fourthly, introducing nitrogen into the emulsion to enable the emulsion to be in a nitrogen atmosphere, then heating the emulsion to perform polymerization reaction, and crushing a reaction product to obtain the oil-based drilling fluid oil-absorbing expansion type plugging anti-collapse agent.
The following is a further optimization or/and improvement of one of the above-mentioned technical solutions of the invention:
in the third step, the shearing rotating speed is 11000rpm to 12000rpm, and the shearing time is 5min to 6min.
In the fourth step, nitrogen is introduced for 30-40 min, and the heating temperature is 60-65 ℃.
In the first step and the second step, the stirring speed is 100rpm to 110rpm.
The second technical scheme of the invention is realized by the following measures: a preparation method of an oil-absorbing expansion type plugging anti-collapse agent for oil-based drilling fluid comprises the following steps: step one, mixing ethylene-vinyl acetate copolymer (EVA), styrene, octyl acrylate, 2-hydroxypropyl acrylate and Divinylbenzene (DVB) at normal temperature to obtain a mixture, adding span 80 accounting for 0.3 to 0.4 percent of the total weight of the mixture into the mixture, mixing and stirring to obtain an internal phase, wherein the total weight parts of the mixture are 100 parts, and the weight ratio of the ethylene-vinyl acetate copolymer (EVA), styrene, octyl acrylate, 2-hydroxypropyl acrylate and Divinylbenzene (DVB) in the mixture is 10; secondly, adding tween 80 accounting for 5 to 6 percent of the total weight of the deionized water into 100 parts of deionized water at normal temperature, and mixing and stirring to obtain an external phase; thirdly, pouring the external phase into the internal phase for shearing and emulsifying under the condition of 0-5 ℃, and then adding azobisisobutyronitrile accounting for 0.4-0.5% of the total weight of the mixed materials for continuously shearing to obtain emulsion; and fourthly, introducing nitrogen into the emulsion to enable the emulsion to be in a nitrogen atmosphere, then heating the emulsion to perform polymerization reaction, and crushing a reaction product to obtain the oil-absorbing expansion type plugging anti-collapse agent for the oil-based drilling fluid.
The following is further optimization or/and improvement of the second technical scheme of the invention:
in the third step, the shearing rotating speed is 11000rpm to 12000rpm, and the shearing time is 5min to 6min.
In the fourth step, nitrogen is introduced for 30-40 min, and the heating temperature is 60-65 ℃.
In the above first step and second step, the stirring speed is 100rpm to 110rpm.
The invention has the advantages that:
the plugging agent provided by the invention has a high-polymer high-elastomer component (ethylene-vinyl acetate copolymer (EVA)), an oil-based viscous component (octyl acrylate) and an adsorption component (2-hydroxypropyl acrylate), and can ensure physical filling of plugging particles to apertures and compaction of aperture plugging, fully embody the cementing effect of the plugging agent and exert the maximum effect of the plugging agent. Wherein:
1, the molecular chain of the oil-based viscous component (octyl acrylate) extends after being exposed to oil, a certain viscous effect is achieved, rock pores can be fully filled, the capillary effect is reduced, the plugging efficiency can reach more than 82%, and compared with the conventional superfine calcium carbonate plugging agent, the plugging efficiency is improved by more than 59%;
2, the adsorption component (acrylic acid-2-hydroxypropyl ester) can form a certain cementing effect with a rock base surface when the temperature exceeds 80 ℃, so that not only can the hole seams be effectively blocked, but also the rock strength of the well wall can be greatly enhanced, the stability of the well wall is kept, and the effect of stabilizing the well wall is more obvious along with the rise of the temperature;
3 the high-molecular high-elastic component (ethylene-vinyl acetate copolymer (EVA)) has the characteristic of improving the oil swelling property, can adsorb diesel oil or white oil with the weight being at least 8 times of the self weight, contains an oil phase, and improves the plugging capability and the stability of the well wall.
In a word, the high-molecular high-elasticity body component, the oil-based viscous component and the adsorption component are added into the raw materials, so that the oil-based drilling fluid can achieve the effects of oil-based expansion, softening, deformation and rock cementation when being applied to the oil-based drilling fluid, and finally, the aim of plugging a broken stratum and a crack development stratum is fulfilled.
Detailed Description
The present invention is not limited by the following examples, and specific embodiments may be determined according to the technical solutions and practical situations of the present invention. The chemical reagents and chemical products mentioned in the invention are all well known and commonly used in the prior art unless otherwise specified; the percentages in the invention are mass percentages unless otherwise specified; the normal temperature and room temperature in the present invention generally mean a temperature of 15 ℃ to 25 ℃, and are generally defined as 25 ℃.
The invention is further described below with reference to examples:
example 1: the oil-absorbing expansion type plugging anti-collapse agent for the oil-based drilling fluid is obtained by the following method: step one, mixing ethylene-vinyl acetate copolymer (EVA), styrene, octyl acrylate, 2-hydroxypropyl acrylate and Divinylbenzene (DVB) at normal temperature to obtain a mixture, adding span 80 accounting for 0.3 to 0.4 percent of the total weight of the mixture into the mixture, mixing and stirring to obtain an internal phase, wherein the total weight parts of the mixture are 100 parts, and the weight ratio of the ethylene-vinyl acetate copolymer (EVA), styrene, octyl acrylate, 2-hydroxypropyl acrylate and Divinylbenzene (DVB) in the mixture is 10; secondly, adding tween 80 accounting for 5 to 6 percent of the total weight of the deionized water into 100 parts of deionized water at normal temperature, and mixing and stirring to obtain an external phase; thirdly, pouring the external phase into the internal phase for shearing and emulsifying under the condition of 0-5 ℃, and then adding azobisisobutyronitrile accounting for 0.4-0.5% of the total weight of the mixed materials for continuously shearing to obtain emulsion; and fourthly, introducing nitrogen into the emulsion to enable the emulsion to be in a nitrogen atmosphere, then heating the emulsion to perform polymerization reaction, and crushing a reaction product to obtain the oil-absorbing expansion type plugging anti-collapse agent for the oil-based drilling fluid.
Example 2: as the optimization of the embodiment, in the fourth step, the nitrogen is introduced for 30-40 min, and the heating temperature is 60-65 ℃.
Example 3: as the optimization of the embodiment, in the third step, the shearing rotating speed is 11000rpm to 12000rpm, and the shearing time is 5min to 6min.
Example 4: as an optimization of the above embodiment, in the first step and the second step, the stirring speed is 100rpm to 110rpm.
Example 5: the oil-absorbing expansion type plugging anti-collapse agent for the oil-based drilling fluid is obtained by the following method: step one, mixing ethylene-vinyl acetate copolymer (EVA), styrene, octyl acrylate, 2-hydroxypropyl acrylate and Divinylbenzene (DVB) at normal temperature to obtain a mixture, adding span 80 accounting for 0.3% of the total weight of the mixture to the mixture, mixing and stirring to obtain an internal phase, wherein the total weight of the mixture is 100g, the weight ratio of the ethylene-vinyl acetate copolymer (EVA), styrene, octyl acrylate, 2-hydroxypropyl acrylate and Divinylbenzene (DVB) in the mixture is 10; step two, adding tween 80 accounting for 5 to 6 percent of the total weight of the deionized water into 100g of the deionized water at normal temperature, and mixing and stirring to obtain an external phase, wherein the stirring speed is 100rpm; thirdly, placing the inner phase in an emulsifier in an ice bath (the ice bath temperature is 0 ℃), shearing at the rotating speed of 11000rpm, pouring the outer phase into the emulsifier during shearing, shearing for 5min, then adding azodiisobutyronitrile accounting for 0.4 percent of the total weight of the mixed materials, and continuing shearing to obtain highly uniformly dispersed emulsion; and fourthly, placing the emulsion in a polymerization reactor in a water bath, introducing nitrogen into the polymerization reactor for 30min to enable the emulsion to be in a nitrogen atmosphere, then heating the emulsion to 60 ℃ to carry out polymerization reaction, and crushing reaction products to obtain the oil-based drilling fluid oil-absorbing expansion type plugging anti-collapse agent, wherein the crushing meshes are 600 meshes and 1000 meshes respectively.
Example 6: the oil-absorbing expansion type plugging anti-collapse agent for the oil-based drilling fluid is obtained by the following method: step one, mixing ethylene-vinyl acetate copolymer (EVA), styrene, octyl acrylate, 2-hydroxypropyl acrylate and Divinylbenzene (DVB) at normal temperature to obtain a mixture, adding span 80 accounting for 0.4% of the total weight of the mixture to the mixture, mixing and stirring to obtain an internal phase, wherein the total weight of the mixture is 100g, the weight ratio of the ethylene-vinyl acetate copolymer (EVA), the styrene, the octyl acrylate, the 2-hydroxypropyl acrylate and the Divinylbenzene (DVB) in the mixture is 10; step two, adding Tween 80 accounting for 5 to 6 percent of the total weight of the deionized water into 100g of the deionized water at normal temperature, and mixing and stirring to obtain an external phase, wherein the stirring speed is 110rpm; thirdly, placing the inner phase in an emulsifier in an ice bath (the ice bath temperature is 5 ℃), shearing at the rotating speed of 12000rpm, pouring the outer phase into the emulsifier during shearing, shearing for 6min, then adding azodiisobutyronitrile accounting for 0.5 percent of the total weight of the mixed materials, and continuing shearing to obtain highly uniformly dispersed emulsion; and fourthly, placing the emulsion in a polymerization reactor in a water bath, introducing nitrogen into the polymerization reactor for 40min to enable the emulsion to be in a nitrogen atmosphere, then heating the emulsion to 65 ℃ to perform polymerization reaction, and crushing reaction products to obtain the oil-based drilling fluid oil-absorbing expansion type plugging anti-collapse agent, wherein the crushing meshes are 400 meshes and 800 meshes respectively.
Example 7: the oil-absorbing expansion type plugging anti-collapse agent for the oil-based drilling fluid is obtained by the following method: a first step of mixing ethylene-vinyl acetate copolymer (EVA), styrene, octyl acrylate, 2-hydroxypropyl acrylate and Divinylbenzene (DVB) at normal temperature to obtain a mixture, adding span 80 accounting for 0.35% of the total weight of the mixture into the mixture, mixing and stirring to obtain an internal phase, wherein the total weight of the mixture is 100g, the weight ratio of the ethylene-vinyl acetate copolymer (EVA), the styrene, the octyl acrylate, the 2-hydroxypropyl acrylate and the Divinylbenzene (DVB) in the mixture is 10; step two, adding Tween 80 accounting for 5.5 percent of the total weight of the deionized water into 100g of the deionized water at normal temperature, and mixing and stirring to obtain an external phase, wherein the stirring speed is 105rpm; thirdly, placing the inner phase in an emulsifier in ice bath (the ice bath temperature is 3 ℃), shearing at the rotating speed of 12000rpm, pouring the outer phase into the emulsifier during shearing, shearing for 6min, and then adding azobisisobutyronitrile accounting for 0.45 percent of the total weight of the mixed materials for continuous shearing to obtain highly uniformly dispersed emulsion; and fourthly, placing the emulsion in a polymerization reactor in a water bath, introducing nitrogen into the polymerization reactor for 35min to enable the emulsion to be in a nitrogen atmosphere, then heating the emulsion to 62 ℃, carrying out polymerization reaction, and crushing reaction products to obtain the oil-based drilling fluid oil-absorbing expansion type plugging anti-collapse agent, wherein the crushing meshes are 400 meshes and 600 meshes respectively.
Example 8: the oil-absorbing expansion type plugging anti-collapse agent for the oil-based drilling fluid is obtained by the following method: step one, mixing ethylene-vinyl acetate copolymer (EVA), styrene, octyl acrylate, 2-hydroxypropyl acrylate and Divinylbenzene (DVB) at normal temperature to obtain a mixture, adding span 80 accounting for 0.35% of the total weight of the mixture to the mixture, mixing and stirring to obtain an internal phase, wherein the total weight of the mixture is 100g, the weight ratio of the ethylene-vinyl acetate copolymer (EVA), the styrene, the octyl acrylate, the 2-hydroxypropyl acrylate and the Divinylbenzene (DVB) in the mixture is 10; step two, adding Tween 80 accounting for 5-6% of the total weight of the deionized water into 100g of the deionized water at normal temperature, and mixing and stirring to obtain an external phase, wherein the stirring speed is 105rpm; thirdly, placing the inner phase in an emulsifier in an ice bath (the ice bath temperature is 0 ℃), shearing at the rotating speed of 12000rpm, pouring the outer phase into the emulsifier during shearing, shearing for 6min, then adding azodiisobutyronitrile accounting for 0.45 percent of the total weight of the mixed materials, and continuing shearing to obtain highly uniformly dispersed emulsion; and fourthly, placing the emulsion in a polymerization reactor in a water bath, introducing nitrogen into the polymerization reactor for 35min to enable the emulsion to be in a nitrogen atmosphere, then heating the emulsion to 62 ℃, carrying out polymerization reaction, and crushing reaction products to obtain the oil-based drilling fluid oil absorption expansion type plugging anti-collapse agent, wherein the crushing meshes are 400 meshes and 800 meshes respectively.
The following is the application of the oil absorption expansion type plugging anti-collapse agent for oil-based drilling fluid prepared in examples 5 to 8 of the invention in the oil-based drilling fluid.
Example 9: the oil-based drilling fluid prepared by adopting the oil-absorbing expansion type plugging anti-collapse agent for the oil-based drilling fluid prepared in the embodiment 5 of the invention is prepared by the following method: firstly, 320mL of 0# diesel oil is taken, added with 3% of a main emulsifier, 2.5% of an auxiliary emulsifier and 1% of a wetting agent and then stirred at a high speed for 20min, then 60mL of a calcium chloride aqueous solution (the mass concentration of calcium chloride is 20%) is added and stirred at a high speed for 30min, then 3% of organic soil and 3% of calcium oxide are added and stirred continuously for 20min to obtain 400mL of base oil-based drilling fluid, and finally 3% of the oil-based expansion type plugging anti-collapse agent for the oil-based drilling fluid prepared in the embodiment 5 of the invention (1% of the oil-based expansion type plugging anti-collapse agent for the oil-based drilling fluid of 600 meshes prepared in the embodiment 5 of the invention and 2% of the expansion type plugging anti-collapse agent for the oil-based drilling fluid of 1000 meshes prepared in the embodiment 5 of the invention) are added into the base oil-based drilling fluid, and after stirring at a high speed for 20min, the oil-based drilling fluid is transferred into an aging tank and aged for 16h at 120 ℃ to obtain the oil-based drilling fluid.
Example 10: the oil-based drilling fluid prepared by adopting the oil-absorbing expansion type plugging anti-collapse agent for the oil-based drilling fluid prepared in the embodiment 6 of the invention is prepared by the following method: firstly, 320mL of 0# diesel oil is taken, 3% of a main emulsifier, 2.5% of an auxiliary emulsifier and 1% of a wetting agent are added, the mixture is stirred at a high speed for 20min, 60mL of a calcium chloride aqueous solution (the mass concentration of calcium chloride is 20%) is added, then, 3% of organic soil and 3% of calcium oxide are added, the stirring is continued for 20min, 400mL of base oil-based drilling fluid is obtained, finally, 1.5% of the oil-absorbing expansive type plugging anti-collapse agent for oil-based drilling fluid prepared in the embodiment 6 of the invention (0.5% of the oil-absorbing expansive type plugging anti-collapse agent for oil-based drilling fluid of 400 meshes prepared in the embodiment 6 of the invention and 1% of the oil-absorbing expansive type plugging anti-collapse agent for oil-based drilling fluid of 800 meshes prepared in the embodiment 6 of the invention) are added into the base oil-based drilling fluid, the mixture is stirred at a high speed for 20min, and then transferred into an aging tank, and the oil-based drilling fluid is obtained after the aging is carried out for 16h at a temperature of 120 ℃.
Example 11: the oil-based drilling fluid prepared by adopting the oil-absorbing expansion type plugging anti-collapse agent for the oil-based drilling fluid prepared in the embodiment 7 of the invention is prepared by the following method: firstly, 320mL of 0# diesel oil is taken, 3% of a main emulsifier, 2.5% of an auxiliary emulsifier and 1% of a wetting agent are added, the mixture is stirred at a high speed for 20min, 60mL of a calcium chloride aqueous solution (the mass concentration of calcium chloride is 20%) is added, then, 3% of organic soil and 3% of calcium oxide are added, the stirring is continued for 20min, 400mL of base oil-based drilling fluid is obtained, finally, 4.5% of the oil-absorbing expansive type plugging anti-collapse agent for oil-based drilling fluid prepared in the embodiment 7 of the invention (1.5% of the oil-absorbing expansive type plugging anti-collapse agent for oil-based drilling fluid of 400 meshes prepared in the embodiment 7 of the invention and 3% of the oil-absorbing expansive type plugging anti-collapse agent for oil-based drilling fluid of 600 meshes prepared in the embodiment 7 of the invention) are added into the base oil-based drilling fluid, the mixture is stirred at a high speed for 20min, and then transferred into an aging tank, and the oil-based drilling fluid is obtained after the aging is carried out for 16h at a temperature of 120 ℃.
Example 12: the oil-based drilling fluid prepared by adopting the oil absorption expansion type plugging anti-collapse agent for the oil-based drilling fluid prepared in the embodiment 8 of the invention is prepared by the following method: firstly, 320mL of 0# diesel oil is taken, 3% of a main emulsifier, 2.5% of an auxiliary emulsifier and 1% of a wetting agent are added, the mixture is stirred at a high speed for 20min, 60mL of a calcium chloride aqueous solution (the mass concentration of calcium chloride is 20%) is added, then, 3% of organic soil and 3% of calcium oxide are added, the stirring is continued for 20min, 400mL of base oil-based drilling fluid is obtained, finally, 3% of the oil-based drilling fluid oil-absorption expansion type plugging anti-collapse agent for the oil-based drilling fluid prepared in the embodiment 8 of the invention (1% of the oil-absorption expansion type plugging anti-collapse agent for the oil-based drilling fluid of 400 meshes prepared in the embodiment 8 of the invention and 2% of the oil-based drilling fluid oil-absorption expansion type plugging anti-collapse agent for the oil-based drilling fluid of 800 meshes prepared in the embodiment 8 of the invention) are added into the base oil-based drilling fluid, the base oil-based drilling fluid is obtained after the high-speed stirring for 20min, and the aging is carried out in an aging tank for 16h at 120 ℃.
Comparative example 1: in the oil-based drilling fluid, the oil absorption expansion type plugging anti-collapse agent for the oil-based drilling fluid prepared in the embodiment 5 is not added, and the rest is the same as the preparation method in the embodiment 9.
Comparative example 2: according to the oil-based drilling fluid, 3% of the oil-absorbing expansion type plugging anti-collapse agent for the oil-based drilling fluid prepared in the embodiment 5 is added into the oil-based drilling fluid, the existing plugging agent 3% of calcium carbonate (1% of 600-mesh calcium carbonate and 2% of 1000-mesh calcium carbonate) is added, and the rest steps are the same as the preparation method of the embodiment 9.
Comparative example 3: according to the oil-based drilling fluid, 1.5% of the oil-absorbing expansion type plugging anti-collapse agent for the oil-based drilling fluid prepared in the embodiment 6 is added into the oil-based drilling fluid, 1.5% of calcium carbonate (0.5% of 400-mesh calcium carbonate and 1% of 800-mesh calcium carbonate) of the existing plugging agent is added, and the rest steps are the same as the preparation method of the embodiment 10.
Comparative example 4: according to the oil-based drilling fluid, 4.5% of the oil-absorbing expansion type plugging anti-collapse agent for the oil-based drilling fluid prepared in the embodiment 7 is added into the oil-based drilling fluid, 4.5% of calcium carbonate (1.5% of calcium carbonate of 400 meshes and 3% of calcium carbonate of 600 meshes) of the existing plugging agent is added, and the rest steps are the same as the preparation method of the embodiment 11.
Comparative example 5: according to the oil-based drilling fluid, 3% of the oil-absorbing expansion type plugging anti-collapse agent for the oil-based drilling fluid, which is prepared in the embodiment 8 of the invention, is added into the oil-based drilling fluid, and 3% of calcium carbonate (1% of calcium carbonate with a particle size of 400 meshes and 2% of calcium carbonate with a particle size of 800 meshes) of the existing plugging agent is added, and the rest steps are the same as the preparation method in the embodiment 12.
The application of the oil-absorbing expanded plugging anti-collapse agent for oil-based drilling fluids prepared in examples 5 to 8 of the present invention to oil-based drilling fluids can achieve a plugging effect, and the following is a study on a plugging performance test of the oil-based drilling fluids prepared in examples 9 to 12 of the present invention (oil-based drilling fluids prepared by using the oil-absorbing expanded plugging anti-collapse agent for oil-based drilling fluids prepared in examples 5 to 8 of the present invention).
Plugging performance test:
test method the oil-based drilling fluids prepared in examples 9 to 12 of the present invention and the oil-based drilling fluids prepared in comparative examples 1 to 5 were examined for plugging performance using a high temperature high pressure permeability plugging instrument (PPT). Using sand trays with 250mD and 450mD permeabilities to simulate a leaking layer, the cumulative leakage (mL) of the oil-based drilling fluids provided by the oil-based drilling fluids prepared in examples 9-12 of the present invention and the oil-based drilling fluids prepared in comparative examples 1-5 at different pressure differentials (MPa) was examined.
And (3) taking out the blocked sand disc, flushing the sand disc by using tap water to simulate underground scouring conditions (the diameter of a tap water port is 0.5cm, the sand disc is placed at a position of 0.5cm under the tap water port (the blocking layer is kept upwards), the flow rate of the tap water is 20mL/s, and the flushing time is 1 h), then putting the sand disc into a high-temperature high-pressure permeability blocking instrument again, testing the leakage amount by using the pure oil-based drilling fluid, and inspecting the adhesion capacity of the blocking layer of the sand disc.
And (3) test results: as shown in table 1, it can be seen from table 1 that, in the 250mD sand disc simulation experiment, the leakage amount of the oil-based drilling fluid (without adding a plugging agent) prepared in comparative example 1 is significantly reduced at 3MPa, while the cumulative leakage amount at 7MPa is only 12.3mL for the oil-based drilling fluid (with 3% of the oil-absorbing intumescent plugging and anti-collapse agent (hereinafter referred to as plugging agent) for the oil-based drilling fluid prepared in example 9, while the cumulative leakage amount at 7MPa for the oil-based drilling fluid (with the same addition of the conventional calcium carbonate particles of the same size) prepared in comparative example 2 is 57.5mL, and the leakage reduction rate of the plugging agent of the present invention is 78.6% compared with the conventional plugging agent (conventional calcium carbonate particles), after washing, the leakage amount corresponding to the plugging layer formed by the plugging agent of the present invention is only 1.1mL, while the plugging layer formed by the calcium carbonate is completely free from the leakage loss, and the plugging agent is capable of maintaining strong adhesion between the plugging layer and the sand disc, thereby further improving the plugging capability of forming a tight adhesion between the plugging disc and the plugging layer. For a 400mD sand disc simulation experiment, the oil-based drilling fluid (without the addition of the plugging agent) prepared in comparative example 1 has total leakage at 1MPa, the oil-based drilling fluid (with the addition of 3% of the plugging agent prepared in example 5 of the invention) prepared in example 9 has significantly reduced leakage, the cumulative leakage at 7MPa is only 10.1mL, the oil-based drilling fluid (with the addition of conventional calcium carbonate particles of the same size and the same addition) prepared in comparative example 2 has a cumulative leakage at 7MPa of 120.8mL, the leakage corresponding to the plugging layer formed by the plugging agent of the invention is only 91.6%, the plugging layer still maintains strong plugging capability after scouring, and the leakage is only 4.5mL.
As shown in table 2, it can be seen from table 2 that, in the 250mD sand disc simulation experiment, the oil-based drilling fluid prepared in comparative example 1 (without adding the plugging agent) had total loss at 3MPa, while the oil-based drilling fluid prepared in example 10 (with 1.5% of the plugging agent prepared in example 6 of the present invention added) had significantly reduced loss, and the cumulative loss at 7MPa was only 13.2mL, while the oil-based drilling fluid prepared in comparative example 3 (with the same addition of the conventional calcium carbonate particles of the same size added) had cumulative loss at 7MPa of 137.6mL, and the plugging agent of the present invention had a loss reduction rate of 90.4% as compared with the plugging agent of the prior art (conventional calcium carbonate particles), and after washing, the plugging layer formed by the plugging agent of the present invention had a corresponding loss of only 2.0mL, and the plugging layer formed by calcium carbonate had total loss. For a 400mD sand disc simulation experiment, the oil-based drilling fluid (without the addition of the plugging agent) prepared in comparative example 1 has total leakage at 1MPa, while the oil-based drilling fluid (with the addition of 1.5% of the plugging agent prepared in example 6 of the invention) prepared in example 10 has significantly reduced leakage, the cumulative leakage at 7MPa is only 17.4mL, while the oil-based drilling fluid (with the addition of conventional calcium carbonate particles of the same size and the same addition) prepared in comparative example 3 has the cumulative leakage at 7MPa of 186.2mL, the leakage corresponding to the plugging layer formed by the plugging agent of the invention is only 90.7%, and the plugging layer still maintains strong plugging capability after scouring, and the leakage is only 5.4mL.
As shown in table 3, it can be seen from table 3 that, in the 250mD sand disc simulation experiment, the oil-based drilling fluid prepared in comparative example 1 (without adding the plugging agent) had total leakage at 3MPa, while the oil-based drilling fluid prepared in example 11 (with adding 4.5% of the plugging agent prepared in example 7 of the present invention) had significantly reduced leakage at 7MPa, and the cumulative leakage at 7MPa was only 52.4mL, while the oil-based drilling fluid prepared in comparative example 4 (with adding the same amount of conventional calcium carbonate particles of the same size) had cumulative leakage at 7MPa of 140.6mL, and the leakage rate of the plugging agent of the present invention was 62.7% as compared with the conventional plugging agent (conventional calcium carbonate particles), and after washing, the leakage corresponding to the plugging layer formed by the plugging agent of the present invention was only 6.8mL, and the plugging layer formed by calcium carbonate had total leakage. For a 400mD sand disc simulation experiment, the oil-based drilling fluid (without the addition of the plugging agent) prepared in comparative example 1 has total leakage at 1MPa, while the oil-based drilling fluid (with the addition of 4.5% of the plugging agent prepared in example 7 of the invention) prepared in example 11 has significantly reduced leakage, the cumulative leakage at 7MPa is only 9.8mL, while the oil-based drilling fluid (with the addition of conventional calcium carbonate particles of the same size and the same addition) prepared in comparative example 4 has a cumulative leakage at 7MPa of 156.2mL, the leakage corresponding to the plugging layer formed by the plugging agent of the invention is only 93.7%, and the plugging layer still maintains strong plugging capability after scouring, and the leakage is only 2.1mL.
As shown in table 4, it can be seen from table 4 that, in the 250mD sand disc simulation experiment, the oil-based drilling fluid prepared in comparative example 1 (without adding the plugging agent) had total loss at 3MPa, while the oil-based drilling fluid prepared in example 12 (with 3% of the plugging agent prepared in example 8 of the present invention added) had a cumulative loss of only 58.7mL at 7MPa, while the oil-based drilling fluid prepared in comparative example 5 (with the same addition of the conventional calcium carbonate particles of the same size) had a cumulative loss of 148.6mL at 7MPa, and the plugging agent of the present invention had a loss reduction rate of 60.5% compared to the conventional plugging agent (the conventional calcium carbonate particles), and after washing, the plugging layer formed by the plugging agent of the present invention had a corresponding loss of only 7.9mL, while the plugging layer formed by calcium carbonate had total loss. For a 400mD sand disc simulation experiment, the leakage of the oil-based drilling fluid (without the addition of the plugging agent) prepared in comparative example 1 is reduced at 1MPa, the leakage of the oil-based drilling fluid (with the addition of 3% of the plugging agent prepared in example 8 of the invention) prepared in example 12 is reduced significantly, the cumulative leakage at 7MPa is only 12.6mL, the cumulative leakage of the oil-based drilling fluid (with the addition of conventional calcium carbonate particles of the same size and the same addition) prepared in comparative example 5 at 7MPa is 124.8mL, the leakage corresponding to the plugging layer formed by the plugging agent is only 90%, the plugging layer still maintains strong plugging capability after scouring, and the leakage is only 5.6mL.
From the above, it can be known that the oil absorption expansion type plugging anti-collapse agent for the oil-based drilling fluid, which is prepared in the embodiments 5 to 8 of the present invention, can achieve a better plugging effect when applied to the oil-based drilling fluid.
In conclusion, the high-molecular high-elasticity body component, the oil-based viscous component and the adsorption component are added into the raw materials, and the oil-based drilling fluid can achieve the effects of oil-based expansion, softening, deformation and rock cementation when being applied to the oil-based drilling fluid, and finally achieves the aim of plugging broken stratums and crack development stratums.
The technical characteristics form an embodiment of the invention, which has strong adaptability and implementation effect, and unnecessary technical characteristics can be increased or decreased according to actual needs to meet the requirements of different situations.
Claims (6)
1. An oil absorption expansion type plugging anti-sloughing agent for oil-based drilling fluid is characterized by being prepared by the following method: step one, mixing an ethylene-vinyl acetate copolymer, styrene, octyl acrylate, 2-hydroxypropyl acrylate and divinylbenzene at normal temperature to obtain a mixture, adding span 80 accounting for 0.3 to 0.4 percent of the total weight of the mixture into the mixture, mixing and stirring to obtain an internal phase, wherein the total weight parts of the mixture is 100 parts, and the weight ratio of the ethylene-vinyl acetate copolymer, the styrene, the octyl acrylate, the 2-hydroxypropyl acrylate and the divinylbenzene in the mixture is 10; step two, adding 5 to 6 weight percent of Tween 80 into 100 parts of deionized water at normal temperature, and mixing and stirring to obtain an external phase; thirdly, pouring the external phase into the internal phase for shearing and emulsifying under the condition of 0-5 ℃, and then adding azobisisobutyronitrile accounting for 0.4-0.5% of the total weight of the mixed materials for continuously shearing to obtain emulsion; and fourthly, introducing nitrogen into the emulsion to enable the emulsion to be in a nitrogen atmosphere, then heating the emulsion to perform polymerization reaction, and crushing a reaction product to obtain the oil-absorbing expansion type plugging anti-collapse agent for the oil-based drilling fluid.
2. The oil-absorbing intumescent plugging and anti-sloughing agent for oil-based drilling fluid of claim 1, wherein in the third step, the shearing speed is 11000rpm to 12000rpm, and the shearing time is 5min to 6min.
3. The oil-absorbing intumescent plugging and anti-sloughing agent for oil-based drilling fluid according to claim 1 or 2, wherein in the fourth step, the nitrogen gas is introduced for 30 to 40min, and the heating temperature is 60 to 65 ℃.
4. The oil-absorbing intumescent plugging and anti-sloughing agent for oil-based drilling fluid of claim 1 or 2, wherein in the first step and the second step, the stirring speed is 100rpm to 110rpm.
5. The oil-absorbing intumescent plugging and anti-sloughing agent for oil-based drilling fluid of claim 3, wherein in the first step and the second step, the stirring speed is 100rpm to 110rpm.
6. An oil absorption expansion type plugging anti-collapse agent for oil-based drilling fluid according to claim 2, 3, 4 or 5, which is characterized by being carried out by the following method: step one, mixing an ethylene-vinyl acetate copolymer, styrene, octyl acrylate, 2-hydroxypropyl acrylate and divinylbenzene at normal temperature to obtain a mixed material, adding span 80 accounting for 0.3 to 0.4 percent of the total weight of the mixed material into the mixed material, mixing and stirring to obtain an internal phase, wherein the total weight parts of the mixed material are 100 parts, and the weight ratio of the ethylene-vinyl acetate copolymer, the styrene, the octyl acrylate, the 2-hydroxypropyl acrylate and the divinylbenzene in the mixed material is 10; secondly, adding tween 80 accounting for 5 to 6 percent of the total weight of the deionized water into 100 parts of deionized water at normal temperature, and mixing and stirring to obtain an external phase; thirdly, pouring the outer phase into the inner phase for shearing and emulsifying under the condition of 0-5 ℃, and then adding azobisisobutyronitrile accounting for 0.4-0.5% of the total weight of the mixed materials for continuously shearing to obtain emulsion; and fourthly, introducing nitrogen into the emulsion to enable the emulsion to be in a nitrogen atmosphere, then heating the emulsion to perform polymerization reaction, and crushing a reaction product to obtain the oil-based drilling fluid oil-absorbing expansion type plugging anti-collapse agent.
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