CN113403046B - Shrinkage-expansion agent for preventing borehole wall instability in oil production and drilling processes of high-argillaceous oil reservoirs and preparation method of shrinkage-expansion agent - Google Patents

Abstract

The invention provides a shrinkage agent and a preparation method thereof for preventing well wall instability during oil recovery drilling in high-shale oil reservoirs, and relates to the technical field of drilling fluids. The shrinkage agent is prepared from quaternary ammonium salt, calcium chloride solution and acrylic acid solution. The mass ratio of quaternary ammonium salt, calcium chloride and acrylic acid is 1:2:2. Among them, the quaternary ammonium salt is composed of bimolecular quaternary ammonium salt and Composed of long-chain quaternary ammonium salt polymers, bimolecular quaternary ammonium salts are synthesized from N,N dimethyl dodecyl tertiary amine and 1,3 dibromopropane in ethanol solution, quaternary ammonium salt long-chain polymers are azo Diisobutyronitrile is used as an initiator, synthesized from N,N dimethyl dodecyl tertiary amine and epichlorohydrin in ethanol solution. The shrinkage agent prepared by the invention has good water solubility, can firmly adsorb clay particles, and has a remarkable shrinkage effect. When the mass fraction is 2%, the shrinkage ratio can reach more than 40%, effectively solving the problem caused by mud shale expansion. Various problems, make up for the vacancy of high-efficiency shrinking agent in the domestic market, and are conducive to the development of the oil recovery industry.

Description

A shrinkage agent and its Preparation

technical field

The invention relates to the technical field of drilling fluids, in particular to a shrinkage agent for preventing well wall instability during oil recovery drilling in high shale oil reservoirs and a preparation method thereof.

Background technique

In the process of oil production and drilling, drilling fluid must be injected into the well in order to carry, suspend cuttings, and lubricate and protect the drill bit. Because the downhole formation environment is very complex, injecting drilling fluid will also cause a series of problems of wellbore instability. And as the drilling depth deepens, wellbore instability will also cause a series of problems, not only leading to a significant reduction in production efficiency, but also causing safety accidents. Through the analysis of the wellbore instability, it is generally believed that the wellbore instability is caused by the hydration expansion of mud shale.

The shrinkage agent currently used is a new generation of mud shale inhibitor. Compared with conventional clay stabilizers, it not only has better expansibility, but also has a certain effect of sand suppression and shrinkage, which helps to improve the performance of water injection wells. The acidizing and plugging removal can greatly shorten the effective period of drilling anti-swelling. Swelling agent, as the name implies, can restore the permeability of oil and gas reservoirs to a certain extent by reducing the volume of the expanded clay, thereby reducing the water injection pressure and increasing oil recovery.

The research found that there are generally four shrinkage mechanisms for shrinkage agents acting on montmorillonite:

(1) The mechanism of compressing the electric double layer; neutralizing the negative charge on the surface of the montmorillonite crystal through the cation in the shrinking agent, thereby reducing the Zeta potential, compressing the electric double layer, and shrinking the volume of the clay macroscopically. (2) The mechanism of removing water molecules: the strong oxidizing substances carried in the shrinking agent act on the clay crystals to remove the water molecules adsorbed in the montmorillonite crystals, shrink the volume of the clay, and restore the permeability of the reservoir. (3) Ion replacement mechanism; each cation has different hydration energy, and the expansion of montmorillonite crystals is often caused by ions with larger hydration energy, and particles with larger hydration energy can absorb more water Molecules, so the cations with low hydration energy carried in the shrinking agent can be used to replace ions with high hydration energy, thereby reducing the volume of montmorillonite crystals, and these cations can also play an anti-swelling effect when adsorbed on the crystal surface . (4) Multi-point adsorption mechanism: a long-chain expansion agent molecule is used to play the bridging effect of the expansion agent molecule through multi-point adsorption, and the dispersed clay crystals are adsorbed together, thereby preventing the dispersion of a part of the clay crystals and transshipment, and finally achieve the purpose of improving the permeability of oil and gas reservoirs and improving oil recovery efficiency.

For example, the patent document CN 107338036 A proposes "a shrinkage-swelling solid-free workover fluid and its preparation method", by combining potassium chloride, sodium chloride, sodium sulfite, cationic quaternary ammonium salt, nonionic surfactant, Silicone surface, polysorbate, and xanthan gum are compounded in a certain proportion, which can greatly improve the effective permeability of fluid in the experimental well, and the shrinkage rate measured in the laboratory reaches 82%. However, the preparation process of the shrinkage-swelling solid-free workover fluid in this patent is complicated and cumbersome, and is not suitable for large-scale production.

In addition, the patent document CN 111607375 A proposes "an anti-swelling and shrinking agent for low-permeability sensitive oil reservoirs and its preparation method", which consists of methacryloyloxyethyltrimethylammonium chloride, 3-ene Propoxy-2-hydroxyl-1-propanesulfonic acid is polymerized. When the concentration is 500ppm, the anti-expansion rate can reach more than 98%, and the shrinkage rate is 40%. However, the shrinkage agent synthesized by this patented method has the problems of too large a molecular weight, poor control of the degree of polymerization, cumbersome reaction process, and deviation in water solubility, and the process of configuring the drilling fluid is time-consuming, which is not conducive to actual on-site construction.

Contents of the invention

Aiming at the phenomenon of wellbore instability occurring in the process of oil production drilling in high shale oil reservoirs, the present invention proposes a shrinking agent for preventing well wall instability in the process of oil production drilling in high shale oil reservoirs and a preparation method thereof, which effectively solves the problems caused by The various problems caused by the expansion of mud shale make up for the vacancy of high-efficiency shrinkage agents in the domestic market, which is conducive to the development of the oil recovery industry.

The present invention adopts following technical scheme:

A shrinkage agent for preventing wellbore instability during drilling in high-shale oil reservoirs. The shrinkage agent is prepared from quaternary ammonium salt, calcium chloride solution and acrylic acid solution, wherein the calcium chloride solution and acrylic acid solution To achieve the effect of synergistic shrinkage, the quaternary ammonium salt is composed of bimolecular quaternary ammonium salt and long-chain quaternary ammonium salt polymer; the bimolecular quaternary ammonium salt is composed of N, N dimethyl dodecyl tertiary amine and 1,3 dibromo Propane is synthesized in ethanol solution, using NH ₄ ⁺ with low hydration energy to replace high hydration energy cations in clay crystals, releasing water molecules adsorbed in the crystals, and playing the role of ion replacement; quaternary ammonium salt long-chain polymer Using azobisisobutyronitrile as the initiator, it is synthesized from N,N dimethyl dodecyl tertiary amine and epichlorohydrin in ethanol solution, which plays the role of multi-point adsorption, and the clay dispersed in water Particle bridging to prevent dispersion and transport of clay particles;

The reaction equation is:

Preferably, the mass ratio of quaternary ammonium salt, calcium chloride, and acrylic acid in the shrinkage agent is 1:(1.9-2.1):(1.9-2.1), and the total mass fraction is 2%-4%.

Preferably, the mass ratio of quaternary ammonium salt, calcium chloride, and acrylic acid in the expansion shrinkage agent is 1:2:2, and the total mass fraction is 2%.

Preferably, the mass fraction of the initiator azobisisobutyronitrile is 0.2%-0.4%, and the molar ratio of 1,3-dibromopropane to epichlorohydrin is (3.5-4.5):1.

Preferably, the mass fraction of the ethanol solution is 60%, the mass fraction of the initiator azobisisobutyronitrile is 0.2%, and the molar ratio of 1,3-dibromopropane to epichlorohydrin is 4:1.

The above-mentioned preparation method of the expansion shrinkage agent used to prevent wellbore instability during oil recovery drilling in high-shale oil reservoirs comprises the following steps:

a. Add the ethanol solution and N, N dimethyl dodecyl tertiary amine to the three-necked flask in turn to obtain the amine solution, stir the amine solution, raise the system temperature to the preheating temperature of 55-65°C, and use 0.5-1ml/min Slowly drop 1,3-dibromopropane into the system at a dropping rate of 1,3-dibromopropane. After the addition of 1,3-dibromopropane is completed, raise the temperature of the system to a reaction temperature of 75-80°C for quaternization reaction to prepare bimolecular quaternary ammonium compound;

b. Lower the system temperature to the preheating temperature of 55-65°C, add the initiator azobisisobutyronitrile and epichlorohydrin into the three-necked flask, then raise the system temperature to the reaction temperature of 80-85°C for ring-opening addition Polymerization reaction, keep the temperature constant, after the reaction is over, put the three-necked flask into a vacuum oven to dry the solvent in the system, and it is used as a shrinking agent to prevent well wall instability during oil recovery drilling in high-shale oil reservoirs.

Preferably, in the step a, the duration of the quaternization reaction is 10-12 hours.

Preferably, in the step b, the duration of the ring-opening polyaddition reaction is 6-8 hours.

Preferably, in the step b, the temperature of the vacuum oven is 60° C., and the drying time is 5-7 hours.

The beneficial effects that the present invention has are:

① The shrinkage agent proposed by the present invention adopts bimolecular quaternary ammonium salt cations, and utilizes high-density cations to greatly improve the efficiency of ion exchange and improve the shrinkage efficiency of clay.

②The expansion shrinkage agent proposed by the present invention has good water solubility, convenient on-site construction, greatly improved work efficiency, low raw material cost, simple synthesis process, and is suitable for large-scale production.

③The shrinking agent proposed by the present invention can be firmly adsorbed on the surface of clay minerals, and has a long acting time and stable effect. When the shrinking agent mass fraction is 2%, the shrinkage rate can reach more than 40%.

Description of drawings

Fig. 1 is the infrared spectrogram of bimolecular quaternary ammonium salt in shrinkage agent of the present invention.

Fig. 2 is the infrared spectrogram of the quaternary ammonium salt long-chain polymer in the expansion shrinkage agent of the present invention.

detailed description

The present invention is specifically described below in conjunction with accompanying drawing and embodiment:

A shrinkage agent for preventing wellbore instability during drilling in high-shale oil reservoirs. It is prepared from quaternary ammonium salt, calcium chloride solution and acrylic acid solution. The mass fraction of calcium chloride solution is 2%, and the mass fraction of acrylic acid solution is The fraction is 3%, the mass ratio of quaternary ammonium salt, calcium chloride, and acrylic acid is 1: (1.9～2.1): (1.9～2.1), and the total mass fraction is 2%～4%, wherein, quaternary ammonium salt consists of bimolecular Composed of quaternary ammonium salt and long-chain quaternary ammonium salt polymer, bimolecular quaternary ammonium salt is synthesized by N,N dimethyl dodecyl tertiary amine and 1,3 dibromopropane in ethanol solution, as shown in Figure 1 The infrared spectrogram of the molecular quaternary ammonium salt; the quaternary ammonium salt long-chain polymer uses azobisisobutyronitrile as an initiator with a mass fraction of 0.2% to 0.4%, and is composed of N,N dimethyl dodecyl tertiary amine and Epichlorohydrin is synthesized in ethanol solution, and the molar ratio of 1,3-dibromopropane to epichlorohydrin is (3.5-4.5): 1. Figure 2 shows the infrared spectrum of the quaternary ammonium salt long-chain polymer , the mass fraction of ethanol solution used in the preparation process is 60%.

The above-mentioned preparation method of the expansion shrinkage agent used to prevent wellbore instability during oil recovery drilling in high-shale oil reservoirs comprises the following steps:

a. Add the ethanol solution and N, N dimethyl dodecyl tertiary amine to the three-necked flask in turn to obtain the amine solution, stir the amine solution, raise the system temperature to the preheating temperature of 55-65°C, and use 0.5-1ml/min Slowly drop 1,3-dibromopropane into the system at a dropping rate of 1,3-dibromopropane. After the addition of 1,3-dibromopropane is completed, raise the temperature of the system to a reaction temperature of 75-80°C for 10-12 hours of quaternization reaction to prepare bimolecular quaternary ammonium salt compounds.

b. Lower the temperature of the system to the preheating temperature of 55-65°C, add the initiator azobisisobutyronitrile and epichlorohydrin into the three-necked flask, then raise the temperature of the system to the reaction temperature of 80-85°C for 6-8 hours For the ring-opening polyaddition reaction, keep the temperature constant. After the reaction is over, put the three-necked flask into a vacuum oven at 60°C to dry for 5-7 hours, and dry the solvent in the system to obtain Swelling agent for wellbore instability during reservoir oil drilling.

Example 1

The swelling agent is prepared from quaternary ammonium salt, calcium chloride solution and acrylic acid solution, the mass fraction of calcium chloride solution is 2%, the mass fraction of acrylic acid solution is 3%, the mass ratio of quaternary ammonium salt, calcium chloride, acrylic acid 1:1.9:1.9, the total mass fraction is 2%, wherein, the quaternary ammonium salt is composed of bimolecular quaternary ammonium salt and long-chain quaternary ammonium salt polymer, and the bimolecular quaternary ammonium salt is composed of N,N dimethyl dodecane The base tertiary amine and 1,3 dibromopropane are synthesized in ethanol solution, and the quaternary ammonium salt long-chain polymer uses azobisisobutyronitrile as the initiator with a mass fraction of 0.2%, and is prepared from N,N dimethyl dodecane The base tertiary amine and epichlorohydrin were synthesized in ethanol solution, the molar ratio of 1,3-dibromopropane to epichlorohydrin was 3.5:1, and the mass fraction of ethanol solution was 60%.

The preparation method of above-mentioned expansion shrinkage agent, comprises the following steps:

a. Add the ethanol solution and N,N dimethyl dodecyl tertiary amine to the three-necked flask in turn to obtain the amine solution, stir the amine solution with a magnetic stirrer, raise the system temperature to the preheating temperature of 55°C, and add 0.5-1ml Slowly drop 1,3-dibromopropane into the system at a dropping rate of 1,3-dibromopropane. After the addition of 1,3-dibromopropane is completed, raise the temperature of the system to a reaction temperature of 75°C for 10 hours of quaternization reaction. A bimolecular quaternary ammonium salt compound is prepared.

b. Reduce the temperature of the system to the preheating temperature of 55°C, add the initiator azobisisobutyronitrile and epichlorohydrin into the three-necked flask, and then raise the temperature of the system to the reaction temperature of 80°C for 6h of ring-opening polyaddition reaction , keep the temperature constant, after the reaction is finished, put the three-neck flask into a vacuum oven at 60°C for 5 hours to dry, and obtain a shrinking agent for preventing wellbore instability during oil recovery drilling in high-shale oil reservoirs.

Example 2

The swelling agent is prepared from quaternary ammonium salt, calcium chloride solution and acrylic acid solution, the mass fraction of calcium chloride solution is 2%, the mass fraction of acrylic acid solution is 3%, the mass ratio of quaternary ammonium salt, calcium chloride, acrylic acid 1:2:2, the total mass fraction is 3%, wherein, the quaternary ammonium salt is composed of bimolecular quaternary ammonium salt and long-chain quaternary ammonium salt polymer, and the bimolecular quaternary ammonium salt is composed of N,N dimethyl dodecane The base tertiary amine and 1,3 dibromopropane are synthesized in ethanol solution, and the quaternary ammonium salt long-chain polymer uses azobisisobutyronitrile as the initiator with a mass fraction of 0.3%, and is prepared from N,N dimethyl dodecane The base tertiary amine and epichlorohydrin were synthesized in ethanol solution, the molar ratio of 1,3-dibromopropane to epichlorohydrin was 4:1, and the mass fraction of ethanol solution was 60%.

The preparation method of above-mentioned expansion shrinkage agent, comprises the following steps:

a. Add the ethanol solution and N,N dimethyl dodecyl tertiary amine to the three-necked flask in turn to obtain the amine solution, stir the amine solution with a magnetic stirrer, raise the temperature of the system to the preheating temperature of 60°C, and add 0.5-1ml Slowly drop 1,3-dibromopropane into the system at a dropping rate of 1,3-dibromopropane. After the addition of 1,3-dibromopropane is completed, raise the temperature of the system to a reaction temperature of 75°C for 11 hours of quaternization reaction. A bimolecular quaternary ammonium salt compound is prepared.

b. Lower the system temperature to the preheating temperature of 60°C, add the initiator azobisisobutyronitrile and epichlorohydrin into the three-necked flask, then raise the system temperature to the reaction temperature of 85°C for 7h of ring-opening polyaddition reaction , keep the temperature constant, after the reaction is finished, put the three-necked flask into a vacuum oven with a temperature of 60°C and dry for 6 hours to obtain a shrinkage agent for preventing wellbore instability during oil production drilling in high-shale oil reservoirs.

Example 3

The swelling agent is prepared from quaternary ammonium salt, calcium chloride solution and acrylic acid solution, the mass fraction of calcium chloride solution is 2%, the mass fraction of acrylic acid solution is 3%, the mass ratio of quaternary ammonium salt, calcium chloride, acrylic acid 1:2.1:2.1, the total mass fraction is 4%, wherein, the quaternary ammonium salt is composed of bimolecular quaternary ammonium salt and long-chain quaternary ammonium salt polymer, and the bimolecular quaternary ammonium salt is composed of N,N dimethyl dodecane The base tertiary amine and 1,3 dibromopropane are synthesized in ethanol solution, and the quaternary ammonium salt long-chain polymer uses azobisisobutyronitrile as the initiator with a mass fraction of 0.4%, and is prepared from N,N dimethyl dodecane The base tertiary amine and epichlorohydrin were synthesized in ethanol solution, the molar ratio of 1,3-dibromopropane to epichlorohydrin was 4.5:1, and the mass fraction of ethanol solution was 60%.

The preparation method of above-mentioned expansion shrinkage agent, comprises the following steps:

a. Add the ethanol solution and N,N dimethyl dodecyl tertiary amine to the three-necked flask in turn to obtain the amine solution, stir the amine solution with a magnetic stirrer, raise the temperature of the system to the preheating temperature of 65°C, and add 0.5-1ml Slowly drop 1,3-dibromopropane into the system at a dropping rate of 1,3-dibromopropane. After the addition of 1,3-dibromopropane is completed, raise the temperature of the system to a reaction temperature of 80°C for 11 hours of quaternization reaction. A bimolecular quaternary ammonium salt compound is prepared.

b. Lower the system temperature to the preheating temperature of 65°C, add the initiator azobisisobutyronitrile and epichlorohydrin into the three-necked flask, then raise the system temperature to the reaction temperature of 80°C for 8h of ring-opening polyaddition reaction , keep the temperature constant, after the reaction is finished, put the three-neck flask into a vacuum oven with a temperature of 60°C and dry for 7 hours to obtain a shrinkage agent for preventing wellbore instability during oil recovery drilling in high-shale oil reservoirs.

In order to further measure the performance of the shrinkage agent prepared in Examples 1 to 3, the shrinkage agent was prepared for each embodiment, and the following methods were used to measure the shrinkage effect of the shrinkage agent, including the following steps:

(1) Take an appropriate amount of clay and put it in a beaker, put the beaker into a blast-type constant temperature drying oven with a temperature of 105°C and dry it for 3 hours, weigh 0.5g of dry clay and place it in the 10ml centrifuge of No. 1 and No. 2 Add the same amount of kerosene to the centrifuge tube No. 1 respectively, and add the same amount of water to the centrifuge tube No. 2 respectively. The amount of kerosene and water is equal. Centrifuge at a speed of ^-1 for 15 minutes, record the liquid volume in the centrifuge tube No. 1 as V ₀ , and record the liquid volume in the centrifuge tube No. 2 as V ₁ .

(2) Pour out the water in the number 2 centrifuge tube, add a fixed mass fraction shrinkage agent, shake it slightly and let it stand for 2 hours, centrifuge at a speed of 1500r·min ^-1 for 15 minutes, record the centrifugation time of number 2 at this time The volume of the liquid in the tube is V ₂ , and the shrinkage ratio of the shrinkage agent is calculated, the formula is as follows:

In the formula, P represents the expansion rate.

Measure the shrinkage ratio of the shrinkage agent prepared by each embodiment by experiment, observe the clay before and after the treatment of the shrinkage agent under a microscope, compare the contact angle of the clay before and after the treatment, and use the shrinkage ratio to represent the shrinkage of the shrinkage agent The effect is shown in Table 1.

Each embodiment of table 1 prepares the shrinkage effect of shrinkage agent

It can be obtained from Table 1 that the expansion rate of the shrinkage agent prepared by the present invention is more than 40%, and the expansion rate of the shrinkage agent prepared in Example 2 is the highest at 44.1%, which is suitable for solving the problem of high muddy oil reservoirs in drilling. The problem of well wall instability during operation effectively overcomes the drawbacks of the existing clay stabilizers, which are not effective and do not have the effect of shrinking the expanded clay, and have important engineering application value.

Of course, the above descriptions are not intended to limit the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or replacements made by those skilled in the art within the scope of the present invention shall also belong to the present invention. protection scope of the invention.

Claims (7)

1. A shrinkage agent for preventing well wall instability in the oil recovery drilling process of high shale oil reservoir, it is characterized in that, described shrinkage agent is formulated by quaternary ammonium salt, calcium chloride solution and acrylic acid solution, wherein, quaternary ammonium The salt is composed of bimolecular quaternary ammonium salt and long-chain quaternary ammonium salt polymer. The salt long-chain polymer uses azobisisobutyronitrile as the initiator, and is synthesized from N,N dimethyl dodecyl tertiary amine and epichlorohydrin in ethanol solution; The mass ratio of quaternary ammonium salt, calcium chloride and acrylic acid in the shrinkage agent is 1:(1.9～2.1):(1.9～2.1), and the total mass fraction is 2%～4%; The mass fraction of the initiator azobisisobutyronitrile is 0.2%-0.4%, and the molar ratio of 1,3-dibromopropane to epichlorohydrin is (3.5-4.5):1. 2. according to claim 1, a kind of expansion agent preventing wellbore instability in the oil recovery drilling process of high shale oil reservoir, it is characterized in that, the quality of quaternary ammonium salt, calcium chloride, acrylic acid in the described expansion agent The ratio is 1:2:2, and the total mass fraction is 2%. 3. A kind of shrinkage agent for preventing wellbore instability in the drilling process of high shale reservoir oil recovery according to claim 2, characterized in that, the mass fraction of the ethanol solution is 60%, and the initiator azobisiso The mass fraction of butyronitrile is 0.2%, and the molar ratio of 1,3-dibromopropane to epichlorohydrin is 4:1. 4. according to any one of claims 1 to 3, the preparation method of the shrinkage agent for preventing wellbore instability in the process of oil recovery drilling in high shale reservoirs, is characterized in that it comprises the following steps: a. Add the ethanol solution and N, N dimethyl dodecyl tertiary amine to the three-necked flask in turn to obtain the amine solution, stir the amine solution, raise the system temperature to the preheating temperature of 55-65°C, and use 0.5-1ml/min Slowly drop 1,3-dibromopropane into the system at a dropping rate of 1,3-dibromopropane. After the addition of 1,3-dibromopropane is completed, raise the temperature of the system to a reaction temperature of 75-80°C for quaternization reaction to prepare bimolecular quaternary ammonium compound; b. Lower the system temperature to the preheating temperature of 55-65°C, add the initiator azobisisobutyronitrile and epichlorohydrin into the three-necked flask, then raise the system temperature to the reaction temperature of 80-85°C for ring-opening addition Polymerization reaction, keep the temperature constant, after the reaction is over, put the three-necked flask into a vacuum oven to dry, and obtain a shrinking agent for preventing wellbore instability during oil recovery drilling in high-shale oil reservoirs. 5. according to claim 4, be used to prevent the preparation method of the expansion shrinkage agent of well wall instability in the oil recovery drilling process of high shale oil reservoir, it is characterized in that, in described step a, the time length of quaternization reaction is 10 ~12h. 6. according to claim 4, be used to prevent the preparation method of the expansion shrinkage agent of wellbore instability in the oil recovery drilling process of high shale oil reservoir, it is characterized in that, in described step b, the time length of ring-opening polyaddition reaction is 6～8h. 7. according to claim 5 or 6, be used to prevent the preparation method of the expansion shrinkage agent of well wall instability in the oil recovery drilling process of high shale oil reservoir, it is characterized in that, in described step b, the temperature of vacuum oven is 60 ℃, the drying time is 5~7h.

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