CN113956855A

CN113956855A - Cationic anti-sloughing agent for water-based drilling fluid and preparation method and application thereof

Info

Publication number: CN113956855A
Application number: CN202111362703.5A
Authority: CN
Inventors: 吕开河; 刘佳; 金家锋; 孙金声; 黄贤斌; 王金堂; 白英睿; 刘敬平
Original assignee: China University of Petroleum East China
Current assignee: China University of Petroleum East China
Priority date: 2021-11-17
Filing date: 2021-11-17
Publication date: 2022-01-21
Anticipated expiration: 2041-11-17
Also published as: CN113956855B

Abstract

The invention provides a cationic anti-sloughing agent for water-based drilling fluid and a preparation method and application thereof. The cation anti-collapse agent comprises the following raw materials in parts by weight: 6-10 parts of acrylamide, 1.5-2.5 parts of cationic monomer, 1-2 parts of hydrophobic monomer, 0.3-0.5 part of modified silicon dioxide, 0.1-0.3 part of initiator and 30-50 parts of ethanol. The invention also provides a preparation method of the cation anti-collapse agent. The cation anti-collapse agent for the water-based drilling fluid has the advantages of strong inhibition, high rolling recovery rate of the shale, capability of inverting the wettability of the shale surface from the liquid wettability to the strong hydrophobicity and effectively inhibiting hydration expansion of shale clay minerals.

Description

Cationic anti-sloughing agent for water-based drilling fluid and preparation method and application thereof

Technical Field

The invention relates to a cationic anti-sloughing agent for water-based drilling fluid and a preparation method and application thereof, belonging to the field of oilfield chemistry in the petroleum industry.

Background

Shale gas is an important growth point for increasing oil gas storage and increasing yield in China. The shale gas drilling process is under the influence of shale self acting force and drilling fluid, adverse reactions are formed among the clay, mineral substances and water bodies of a shale well wall, so that the clay mineral hydration expansion is caused, the rock strength near the well wall is reduced, and further underground complex conditions such as well wall instability, drill sticking and the like are caused. At present, oil-based drilling fluid with good inhibition is generally adopted for drilling in a long horizontal section of shale gas, but the large-scale application of the oil-based drilling fluid is restricted by the defects of high cost, poor environmental protection, difficult post-treatment and the like. The high-performance shale gas water-based drilling fluid is expected to replace oil-based drilling fluid.

The cation anti-collapse agent is an important component of high-performance water-based drilling fluid and is a main material for preventing the collapse of well walls in the drilling process. The cation anti-collapse agent mainly reduces the negative charges on the surface of the shale through charge neutralization, further inhibits the hydration of the shale, achieves the effect of stabilizing a well wall, and can be adsorbed on the surface of the shale through electrostatic action, so that the surface of the shale is wetted and reversed, the hydration effect of the shale is further reduced, and the anti-collapse effect is enhanced. At present, the cation anti-sloughing agent generally has the problem of poor compatibility with drilling fluid, which causes the increase of the filtration loss of the drilling fluid and the deterioration of the rheological property; partial cation anti-collapse agents have insufficient wetting reversal effect and can inhibit insufficient hydration of the shale surface.

Chinese patent document CN112877041A (application No. 202110064041.7) provides a nano organosilicon film-forming hydrophobic shale surface hydration inhibitor and a preparation method and application thereof, the inhibitor is prepared by carrying out hydrophobic modification on nanoparticles by long-chain organosilicon and a surfactant, the inhibitor can form a layer of compact hydrophobic film on the surface of a rock core, so as to inhibit the hydration dispersion of the shale surface, but the compatibility of the inhibitor and drilling fluid is not ideal, after the inhibitor is added, the normal-temperature normal-pressure filtration loss of the drilling fluid is increased from 22mL to 30mL, and the increase of the filtration loss is not beneficial to the stability of a well wall. Chinese patent document CN112920783A (application No. 201911231259.6) provides a wetting reversal inhibitor for drilling fluid and a preparation method thereof, wherein the synthetic raw materials of the inhibitor comprise: the alkylated isocyanate and the amino silane coupling agent can generate chemical adsorption with clay minerals to change the wettability of the water-sensitive clay mineral surface, thereby inhibiting the hydration of the shale surface. However, this inhibitor has the following disadvantages: 1. the hydration expansion of the shale can not be effectively inhibited, the linear expansion rate of the shale still reaches more than 40 percent after 0.5 percent of the shale is treated by the inhibitor, and the rolling recovery rate of the shale is improved from 12 percent to about 82 percent; 2. the wet reversal performance was insufficient and the contact angle of the water phase increased from 20 ° to 76 ° after the addition of 0.5% of the inhibitor treatment.

Therefore, it is highly desirable to prepare a novel cationic anti-sloughing agent for water-based drilling fluids, which has strong inhibition performance and good compatibility with drilling fluids.

Disclosure of Invention

Aiming at the defects of the prior art, in particular to the defects of poor compatibility with drilling fluid, poor wetting reversal effect and poor inhibition effect on the surface hydration of shale of the conventional cationic anti-sloughing agent for the water-based drilling fluid, the invention provides the cationic anti-sloughing agent for the water-based drilling fluid and the preparation method and the application thereof. The cation anti-collapse agent can effectively reduce the negative charge of clay, remarkably change the wettability of the rock surface, effectively inhibit the hydration expansion of shale, prevent the well wall from collapsing in the drilling process, and has good compatibility with drilling fluid.

The technical scheme of the invention is as follows:

a cationic anti-sloughing agent for water-based drilling fluid comprises the following raw materials in parts by weight: 6-10 parts of acrylamide, 1.5-2.5 parts of cationic monomer, 1-2 parts of hydrophobic monomer, 0.3-0.5 part of modified silicon dioxide, 0.1-0.3 part of initiator and 30-50 parts of ethanol.

According to the invention, the cationic monomer is preferably one or a combination of more than two of dimethyldiallylammonium chloride, methacryloyloxyethyltrimethyl ammonium chloride and acryloyloxyethyltrimethyl ammonium chloride.

According to a preferred embodiment of the invention, the hydrophobic monomer is butyl acrylate, dodecyl acrylate or dioctyl maleate.

According to the invention, the initiator is preferably ammonium persulfate.

According to the invention, the modified silica is obtained by modifying nano silica by using a silane coupling agent; the silane coupling agent is one or the combination of more than two of KH550, KH570 and n-octyl trimethoxy silane; the particle size of the nano silicon dioxide is 20-30 nm.

According to the invention, the modified silica is prepared according to the following method:

adding nano silicon dioxide into ethanol, performing ultrasonic dispersion uniformly, then adding a silane coupling agent, and reacting for 7-9h at 75-85 ℃; after the reaction is finished, filtering, washing and drying to obtain modified silicon dioxide; the mass ratio of the ethanol to the nano silicon dioxide is 15-25:1, and the mass ratio of the silane coupling agent to the nano silicon dioxide is 2-5: 1; the washing is 3-5 times by using deionized water.

According to the invention, the preparation method of the cationic anti-collapse agent for the water-based drilling fluid comprises the following steps:

adding modified silicon dioxide into ethanol, and uniformly dispersing by ultrasonic to obtain modified silicon dioxide dispersion liquid; then under the condition of stirring, sequentially adding acrylamide, cationic monomer and hydrophobic monomer into the modified silicon dioxide dispersion liquid, uniformly mixing, deoxidizing nitrogen, heating to 55-75 ℃, adding an initiator, and reacting; and after the reaction is finished, removing the solvent, and drying to obtain the cation anti-sloughing agent for the water-based drilling fluid.

According to the invention, the stirring speed is 200-400r/min, and the time for removing oxygen by nitrogen is 15-30 min.

According to the invention, the initiator is preferably added to the reaction system in the form of an aqueous initiator solution; the concentration of the initiator aqueous solution is 0.01g/mL, and the dropping time is 1-5 min.

Preferably, according to the invention, the reaction time is between 5 and 7 hours.

Preferably, according to the invention, the drying is carried out at a temperature of between 70 and 80 ℃ to a constant weight.

According to the invention, the application of the cationic anti-collapse agent for the water-based drilling fluid is used for inhibiting hydration and expansion of shale and stabilizing a well wall; the specific application method comprises the following steps: the obtained cationic anti-collapse agent for the water-based drilling fluid is added into the water-based drilling fluid, and the addition amount of the cationic anti-collapse agent for the water-based drilling fluid is 0.5-1.5 wt%.

The invention has the following technical characteristics and beneficial effects:

1. the cation anti-collapse agent prepared by the invention can form a layer of hydrophobic adsorption film with high roughness and low surface energy on the surface of the rock core, can obviously change the wettability of the surface of the well wall, and effectively prevent the invasion of a water phase; the cation anti-sloughing agent prepared by the invention has strong inhibition on the shale stratum with strong water sensitivity, the rolling recovery rate of the shale is high, and the cation anti-sloughing agent has excellent inhibition and anti-sloughing performances; meanwhile, the drilling fluid has excellent compatibility with the drilling fluid.

2. The cationic monomer in the cationic anti-sloughing agent can be effectively adsorbed on the clay surface with negative electricity, the negative charge on the clay surface is reduced, the osmotic hydration is inhibited, the adhesion capacity of the hydrophobic monomer and the modified nano-silica on the rock surface is increased, the cationic monomer and the modified nano-silica are better adsorbed on the rock surface to form a hydrophobic isolation zone, the formation water is prevented from contacting with the rock, and the effect of well maintaining the stability of a well wall is achieved under the synergistic effect.

Detailed Description

The present invention is further illustrated by, but not limited to, the following examples.

Meanwhile, the experimental methods described in the following examples are all conventional methods unless otherwise specified; the reagents and materials are commercially available, unless otherwise specified.

Example 1

A cationic anti-sloughing agent for water-based drilling fluid comprises the following raw materials in parts by weight: 6 parts of acrylamide, 1.5 parts of cationic monomer, 1 part of hydrophobic monomer, 0.5 part of modified silicon dioxide, 0.1 part of initiator and 40 parts of ethanol;

wherein the cationic monomer is dimethyl diallyl ammonium chloride; the hydrophobic monomer is dioctyl maleate; the initiator is ammonium persulfate.

The modified silicon dioxide is prepared by the following method:

adding nano silicon dioxide with the particle size of 20nm into ethanol, performing ultrasonic dispersion uniformly, then adding a silane coupling agent KH570, and reacting for 8 hours at 80 ℃; after the reaction is finished, carrying out suction filtration, washing for 3 times by using deionized water, and drying to obtain modified silicon dioxide; the mass ratio of the ethanol to the nano silicon dioxide is 20:1, and the mass ratio of the silane coupling agent KH570 to the nano silicon dioxide is 3: 1.

The preparation method of the cationic anti-collapse agent for the water-based drilling fluid comprises the following steps:

adding modified silicon dioxide into ethanol, and uniformly dispersing by ultrasonic to obtain modified silicon dioxide dispersion liquid; under the condition that the stirring speed is 300r/min, sequentially adding acrylamide, cationic monomer and hydrophobic monomer into the modified silicon dioxide dispersion liquid, uniformly mixing, then deoxidizing for 20min by nitrogen, heating to 55 ℃, dropwise adding an initiator aqueous solution with the concentration of 0.01g/mL for 3min, and after dropwise adding is finished, reacting for 5h at 55 ℃; and after the reaction is finished, removing the solvent, and drying at 75 ℃ to constant weight to obtain the cation anti-sloughing agent for the water-based drilling fluid.

Example 2

A cationic anti-sloughing agent for water-based drilling fluids is described in example 1, and is prepared as described in example 1, except that: the reaction temperature was 65 ℃.

Example 3

A cationic anti-sloughing agent for water-based drilling fluids is described in example 1, and is prepared as described in example 1, except that: the reaction temperature was 75 ℃.

Example 4

A cationic anti-sloughing agent for water-based drilling fluids is as described in example 1, except that: 8 portions of acrylamide.

The preparation method of the cationic anti-collapse agent is described in example 1.

Example 5

A cationic anti-sloughing agent for water-based drilling fluids is as described in example 1, except that: 10 portions of acrylamide.

Example 6

A cationic anti-sloughing agent for water-based drilling fluids is as described in example 1, except that: the cationic monomer is 2.5 parts.

Example 7

A cationic anti-sloughing agent for water-based drilling fluids is as described in example 1, except that: the hydrophobic monomer is 2 parts.

Example 8

A cationic anti-sloughing agent for water-based drilling fluids is as described in example 1, except that: the cationic monomer is methacryloyloxyethyl trimethyl ammonium chloride.

Example 9

A cationic anti-sloughing agent for water-based drilling fluids is as described in example 1, except that: the hydrophobic monomer is dodecyl acrylate.

Example 10

A cationic anti-sloughing agent for water-based drilling fluids is as described in example 1, except that: n-octyltrimethoxysilane was used in place of KH570 in the preparation of the modified silica.

Comparative example 1

A cationic anti-sloughing agent for water-based drilling fluids is described in example 1, and is prepared as described in example 1, except that: the reaction was carried out at 55 ℃ for 4 h.

Comparative example 2

A cationic anti-sloughing agent for water-based drilling fluids is described in example 1, and is prepared as described in example 1, except that: the reaction was carried out at 55 ℃ for 8 h.

Comparative example 3

A cationic anti-sloughing agent for water-based drilling fluids is as described in example 1, except that: unmodified nanosilica was used instead of modified silica and was prepared as described in example 1.

Comparative example 4

A cationic anti-sloughing agent for water-based drilling fluids is as described in example 1, except that: the preparation was carried out as described in example 1 without addition of modified silica.

Comparative example 5

A cationic anti-sloughing agent for water-based drilling fluids is as described in example 1, except that: the preparation was carried out as described in example 1 without addition of cationic monomers.

Comparative example 6

A cationic anti-sloughing agent for water-based drilling fluids is as described in example 1, except that: the hydrophobic monomer was not added and the preparation was as described in example 1.

Comparative example 7

A cationic anti-sloughing agent for water-based drilling fluids is as described in example 1, except that: water was used instead of ethanol and the preparation was as described in example 1.

Test examples

The cationic anti-sloughing agents prepared in examples 1 to 10 and comparative examples 1 to 7 were subjected to shale linear expansion rate, compatibility test, shale high-temperature rolling recovery rate and wettability reversal performance test.

1. Shale linear expansion rate experiment

Each time, 10.0g of bentonite was weighed, poured evenly into the same linear dilatometer mould and pressed to 10.0MPa with a press for 5 minutes. After 5min, the bentonite pellets were taken out, and put into a linear expansion instrument, and the aqueous solution of the cationic anti-sloughing agent prepared in example and comparative example in a mass fraction of 1%, distilled water, a KCl solution in a mass fraction of 5%, and a polyamine YZJ solution in a mass fraction of 1% were added, and the addition amount of each solution was 150mL, and the height of swelling of the bentonite pellets after 16 hours was measured, and the linear expansion ratio was calculated, and the results are shown in table 1.

TABLE 1 Linear expansion ratio of Bentonite in different solutions

As can be seen from table 1, the linear swelling of bentonite in distilled water is the most severe. Different cation anti-collapse agents have certain effect on inhibiting the linear expansion of bentonite, but after the cation anti-collapse agent prepared in the embodiment is added, the linear expansion rate of the bentonite is lower, and the performance of the cation anti-collapse agent is superior to that of the commonly used shale inhibitor KCl and polyamine inhibitor YZJ.

2. Drilling fluid compatibility test

Weighing 16.0g of bentonite, uniformly pouring the bentonite into 400mL of distilled water, uniformly stirring, and aging for 24h to obtain bentonite-based slurry with the concentration of 4% (w/v). 4g of the anti-collapse agent prepared in different examples and comparative examples are respectively added into 400mL of base slurry and stirred for 20 minutes at the speed of 8000 rpm to obtain the drilling fluid with the concentration of 1% (w/v). The rheology and normal temperature and pressure fluid loss of the formulated drilling fluid were measured using a water-based drilling fluid field test (APIRP 13B-1,2009) and the results are shown in Table 2.

TABLE 2 drilling fluid compatibility test

As can be seen from Table 2, after the cationic anti-sloughing agent prepared in the example is added, the apparent viscosity of the drilling fluid is obviously increased, the normal temperature and pressure filtration loss is obviously reduced, and the compatibility of the cationic anti-sloughing agent to the drilling fluid is obviously superior to that of the common shale inhibitor KCl and polyamine inhibitor YZJ.

3. Shale high-temperature rolling recovery experiment

The cation anti-collapse agents prepared in the examples 1 to 10 and the comparative examples 1 to 7 are prepared into cation anti-collapse agent solution with the mass fraction of 1%, 20.0g of 6-10-mesh dry rock debris is weighed and respectively filled into an aging tank containing 350.0mL of the cation anti-collapse agent solution. Rolling and aging for 16h at 120 ℃, taking out, pouring liquid and rock debris in the tank into a 40-mesh sample sieve, leaching with tap water, sieving residual rock debris, drying at a constant temperature of 105 ℃ for 4h, cooling, weighing, and calculating the shale recovery rate, wherein the shale recovery rate is the percentage of the mass of the residual rock debris to the mass of the initial rock debris; the recovery rates of shale in distilled water, a 5% by mass KCl solution, and a 1% by mass polyamine YZJ solution were measured as described above, and the results are shown in Table 3.

Experimental result of rock debris recovery rate after aging at 3120 ℃ in table

As can be seen from Table 3, the shale rolling recovery rate is over 90% after the cationic anti-collapse agent prepared in the example is added, and the performance is superior to that of the commonly used shale inhibitor KCl and polyamine inhibitor YZJ.

4. Wetting inversion experiment

And putting the cut shale slices into the bottom of an aging tank, respectively adding 350mL of cation anti-collapse agent solution (mass fraction is 1%) prepared in different embodiments and in different proportions, sealing the tank, and heating for 16h at 150 ℃. Cooling, taking out the shale slices, drying the shale slices at 105 ℃ for 30min, measuring the water phase contact angle of the shale slices by adopting an OCA-25 type optical contact angle measuring instrument, and evaluating the wettability of the shale slices treated by different cation anti-collapse agents; the wettability of the shale pieces treated with the KCl solution having a mass fraction of 5% and the polyamine YZJ solution having a mass fraction of 1% was measured by the above-described method, and the results are shown in table 4.

TABLE 4 Water phase contact angle of shale flakes after action of cation anti-sloughing agent solution

It can be seen from the combination of table 1, table 2, table 3 and table 4 that the rolling recovery rate of shale drilling cuttings in distilled water is only 4-5%, which indicates that shale has strong water sensitivity, large activity, is very easy to hydrate and disperse, and is easy to collapse and fall blocks in the drilling process. The high-concentration potassium chloride does not basically improve the rolling recovery rate of the shale, and although the polyamine YZJ has an obvious inhibiting effect on the hydration and dispersion of the shale, the polyamine YZJ cannot change the wettability of the rock surface, and compared with the product prepared by the embodiment of the invention, the performance is poorer. The dioctyl maleate selected by the invention has double-hydrophobic long chains, and the nano-silica modified by KH570 has a double-bond structure, so that the dioctyl maleate can be better grafted with other cations, acrylamide and other monomers through physicochemical action, and the clay mineral surface can be better inhibited from hydration and expansion through charge adsorption and double adsorption of the nano-silica.

In conclusion, the cation anti-collapse agent prepared by the invention has higher inhibition performance, anti-collapse performance and good wetting reversal performance; meanwhile, the drilling fluid has good compatibility with the drilling fluid.

Claims

1. The cation anti-sloughing agent for the water-based drilling fluid is characterized by comprising the following raw materials in parts by weight: 6-10 parts of acrylamide, 1.5-2.5 parts of cationic monomer, 1-2 parts of hydrophobic monomer, 0.3-0.5 part of modified silicon dioxide, 0.1-0.3 part of initiator and 30-50 parts of ethanol.

2. The cationic collapse prevention agent for the water-based drilling fluid according to claim 1, wherein the cationic monomer is one or a combination of more than two of dimethyldiallylammonium chloride, methacryloyloxyethyltrimethyl ammonium chloride and acryloyloxyethyltrimethyl ammonium chloride.

3. The cationic anti-sloughing agent for water-based drilling fluids according to claim 1 wherein the hydrophobic monomer is butyl acrylate, lauryl acrylate or dioctyl maleate; the initiator is ammonium persulfate.

4. The cationic anti-sloughing agent for water-based drilling fluid as claimed in claim 1, wherein the modified silica is obtained by modifying nano silica by using a silane coupling agent; the silane coupling agent is one or the combination of more than two of KH550, KH570 and n-octyl trimethoxy silane; the particle size of the nano silicon dioxide is 20-30 nm.

5. The cationic anti-sloughing agent for water-based drilling fluid according to claim 4, wherein the modified silica is prepared by the following method:

6. The method for preparing the cationic anti-collapse agent for the water-based drilling fluid as claimed in any one of claims 1 to 5, which comprises the following steps:

7. The preparation method of the cationic anti-sloughing agent for the water-based drilling fluid as claimed in claim 6, wherein the stirring rate is 200-400r/min, and the time for nitrogen to remove oxygen is 15-30 min.

8. The method for preparing the cationic anti-sloughing agent for the water-based drilling fluid according to claim 6, wherein the initiator is added dropwise into the reaction system in the form of an aqueous initiator solution; the concentration of the initiator aqueous solution is 0.01g/mL, and the dropping time is 1-5 min.

9. The preparation method of the cationic anti-sloughing agent for the water-based drilling fluid as claimed in claim 6, wherein the reaction time is 5-7 h; the drying is carried out at 70-80 ℃ until the weight is constant.

10. The use of the cationic anti-sloughing agent for water-based drilling fluid according to any one of claims 1 to 5, for inhibiting the hydration and expansion of shale and stabilizing the well wall; the specific application method comprises the following steps: the obtained cation anti-collapse agent is added into the water-based drilling fluid, and the addition amount of the cation anti-collapse agent is 0.5-1.5 wt%.