Slow-release acid for acidification plug removal of deep coal-bed gas well as well as preparation method and application of slow-release acid

Abstract

The invention discloses a slow-release acid for acidification plug removal of a deep coal-bed gas well and a preparation method and application of the slow-release acid, and relates to the technical field of oil-gas exploration and development.The method comprises the steps that a solid acid and scale inhibitor compounding method is utilized, a compound product is prepared into micron particles through an air-flowing type ultrafine pulverizer, and the micron particles are prepared into the slow-release acid for acidification plug removal of the deep coal-bed gas well; atomization equipment is used for spraying light-cured acrylic resin to the surfaces of the microparticles, the slow-release acid with the slow-release function for deep coal-bed gas well acidification blockage removal is prepared, the problem that cracks are prone to being closed due to conventional acid is solved, the process that scale cores block microcracks after acidification of the conventional acid is slowed down, and the service life of the microcracks is prolonged. And the problem that vehicles and pipelines are easily corroded by conventional acid liquor is avoided. The preparation method has the advantages of simple synthesis process, easiness in equipment operation and easiness in popularization, and has a wide application prospect.

Description

Technical Field

[0001] The present application relates to the technical field of oil and gas exploration and development, and particularly relates to a sustained-release acid for acidizing and removing blockages in deep coalbed methane wells, a preparation method thereof, and an application thereof. Background Art

[0002] With the continuous increase in the demand for oil and gas at home and abroad, coalbed methane, as a clean energy source, plays a crucial role in the field of unconventional natural gas and has been increasingly valued in the oil and gas field industry. In recent years, breakthroughs have been made in deep coalbed methane technology, and the output has increased significantly.

[0003] However, with the extension of the development time, gas well blockage may occur in gas fields to varying degrees. Especially for gas wells in the middle and late production stages, there are varying degrees of scaling in downhole strings, throttling positions, and perforation gun holes, which have different degrees of impact on gas well production and workover measures; at the same time, there are problems such as pore throat blockage in the reservoir, resulting in reduced permeability and inability to release production capacity. In the new situation of energy structure adjustment, strong demand for oil and gas, and rapid technological development, how to remove gas well blockages and increase gas well production is an important research field.

[0004] Using acidizing and blockage removal technology can effectively remove gas well blockages, increase the permeability of gas wells, and achieve the purpose of increasing oil and gas production. As early as the 1990s, scientists proposed an acidizing and blockage removal technology for oil reservoir transformation. The initially used acid solution was nicotinic acid. With the progress of technology, the acid solution gradually became hydrochloric acid, mud acid, etc., and specific selection needed to be based on the depth of the oil reservoir and other actual situations. Currently, starting from the actual situation, studying the application of acidizing and blockage removal technology in the development of low-permeability oil fields is of great significance for China's economic development and stable energy supply.

[0005] Currently, the conventional acidizing and blockage removal technology is to use a workover vehicle and tools to squeeze the mixed acid solution into the wellbore and rock formation, corrode the wellbore and rock formation to form a certain network of fractures for oil and gas to flow through. Although the application of acidizing and blockage removal technology can achieve blockage removal and increased oil and gas production, there are still the following problems in the use process:

[0006] 1. After the conventional acidification is pumped into the reservoir, it undergoes a chemical reaction with the reservoir instantaneously. The size of the acidification fractures is uncontrollable, and the acidification fractures are prone to closure after acidification, so that the distal microfractures cannot remain persistently unobstructed;

[0007] 2. Cations such as calcium, magnesium, barium, and strontium generated after acidification are prone to form new scale nuclei to block the acidified microfractures, so that the distal microfractures cannot remain persistently unobstructed;

[0008] 3. Conventional acid solutions are prone to corrode workover vehicles and pipelines. Summary of the Invention

[0009] The present application provides a slow-release acid for acidizing and removing blockages in deep coalbed methane wells, a preparation method thereof, and an application thereof, so as to solve the technical problem that existing conventional acids easily cause cracks to close.

[0010] In a first aspect, the present application provides a preparation method of a slow-release agent for acidizing and removing blockages in deep coalbed methane wells, comprising the following steps:

[0011] Compound a solid acid and a scale inhibitor to obtain a compound product;

[0012] Prepare the compound product into micron particles;

[0013] Spray a photocurable acrylic resin on the surface of the micron particles to prepare a slow-release acid.

[0014] Optionally, the raw materials of the slow-release agent include a solid acid and a scale inhibitor, and the mass ratio of the solid acid to the scale inhibitor is 3:1 to 1:1.

[0015] Optionally, the solid acid includes at least one of p-toluenesulfonic acid, ethylenediaminetetraacetic acid, and diatomaceous earth.

[0016] Optionally, the scale inhibitor is sodium hexamethylenediaminetetraphosphate.

[0017] Optionally, compounding the solid acid and the scale inhibitor to obtain a compound product specifically includes: stirring the solid acid and the scale inhibitor to obtain a compound product.

[0018] Optionally, the rotation speed is 500 r / min to 2000 r / min, and the stirring time is 24 h.

[0019] Optionally, preparing the compound product into micron particles specifically includes: preparing the compound product into micron particles through a pneumatic ultrafine pulverizer.

[0020] Optionally, the micron particles are 325 mesh to 40 mesh.

[0021] Optionally, spraying the photocurable acrylic resin on the surface of the micron particles specifically includes: spraying the photocurable acrylic resin on the surface of the micron particles through an atomizing device.

[0022] Optionally, the mass of the sprayed photocurable acrylic resin material accounts for 10 - 15 parts of the compound product, and the thickness is about 10 - 15 microns.

[0023] In a second aspect, the present invention also provides a slow-release acid for acidizing and removing blockages in deep coalbed methane wells prepared by using the preparation method of the slow-release acid for acidizing and removing blockages in deep coalbed methane wells described in the first aspect.

[0024] In a third aspect, the present invention also provides an application of the sustained-release acid for acidizing and unplugging deep coalbed methane wells described in the second aspect in acidizing and unplugging deep coalbed methane wells.

[0025] The above technical solutions provided by the present invention have the following advantages compared with the prior art:

[0026] The present invention provides a sustained-release acid for acidizing and unplugging deep coalbed methane wells, a preparation method thereof, and an application thereof. The sustained-release acid in the present invention solves the problem that cracks are easily closed by conventional acids, slows down the process of scale nuclei blocking microcracks after conventional acidification, and avoids the corrosion problem of conventional acid solutions to vehicles and pipelines. The preparation method of the present invention has the advantages of simple synthesis process, easy operation of equipment, and easy promotion, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings herein are incorporated into the specification and form a part of the specification, showing embodiments consistent with the present application, and are used together with the specification to explain the principles of the present application.

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0029] Figure 1 It is a flowchart of a preparation method of a sustained-release acid for acidizing and unplugging deep coalbed methane wells provided by an embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present application.

[0031] The various embodiments of the present application may exist in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be construed as a rigid limitation on the scope of the present application; therefore, it should be considered that the description of the range has specifically disclosed all possible sub-ranges and individual values within the range. For example, it should be considered that the description of the range from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and individual numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any cited number (fraction or integer) within the indicated range.

[0032] In the present application, unless otherwise stated, terms including "comprising" and the like mean "including but not limited to". In this text, relative terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this text, "and / or" describes the associated relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. Wherein A and B may be singular or plural. In this text, "at least one" means one or more, and "a plurality" means two or more. "At least one kind", "at least one of the following items (pieces)" or similar expressions refer to any combination of these items, including any combination of single item (piece) or plural items (pieces). For example, "at least one of a, b, or c", or, "at least one of a, b, and c" can both represent: a, b, c, a - b (i.e., a and b), a - c, b - c, or a - b - c, where a, b, and c can be single or multiple respectively.

[0033] Unless otherwise specifically stated, various raw materials, reagents, instruments, equipment, etc. used in the present application can be obtained through market purchase or can be prepared by existing methods.

[0034] In a first aspect, the present application provides a preparation method of a slow-release agent for acidizing and removing blockages in deep coalbed methane wells. The flowchart is as Figure 1 shown, and includes the following steps:

[0035] Compound a solid acid and a scale inhibitor to obtain a compound product;

[0036] Prepare the compound product into micron particles;

[0037] Spray a photocurable acrylic resin on the surface of the micron particles to prepare a slow-release acid.

[0038] In the above embodiments, the preparation method provided by the present invention has the advantages of simple synthesis process, easy operation of equipment, and easy promotion, and has broad application prospects.

[0039] In an alternative embodiment, the raw materials of the slow-release agent include a solid acid and a scale inhibitor, and the mass ratio of the solid acid to the scale inhibitor is 3:1 to 1:1.

[0040] In the above embodiments, the mass ratio of the solid acid to the scale inhibitor can be 3:1, 2:1, and 1:1.

[0041] In an alternative embodiment, the solid acid includes at least one of p-toluenesulfonic acid, ethylenediaminetetraacetic acid, and diatomaceous earth.

[0042] In the above embodiments, the solid acid can be used alone as p-toluenesulfonic acid, ethylenediaminetetraacetic acid, or diatomaceous earth, or a mixture of p-toluenesulfonic acid and ethylenediaminetetraacetic acid, p-toluenesulfonic acid and diatomaceous earth, or ethylenediaminetetraacetic acid and diatomaceous earth can be selected. A mixture of p-toluenesulfonic acid, ethylenediaminetetraacetic acid, and diatomaceous earth can also be selected.

[0043] In an alternative embodiment, the scale inhibitor used is sodium hexamethylenediaminetetraphosphate.

[0044] In an alternative embodiment, optionally, the compounded solid acid and scale inhibitor are obtained to form a compounded product, which specifically includes: stirring the solid acid and the scale inhibitor to obtain the compounded product.

[0045] In an alternative embodiment, the rotation speed is 500 r / min to 2000 r / min, and the stirring time is 24 h.

[0046] In an alternative embodiment, the compounded product is prepared into micron particles, which specifically includes: passing the compounded product through a pneumatic ultrafine grinder to prepare it into micron particles.

[0047] In an alternative embodiment, the micron particles are 325 mesh to 40 mesh.

[0048] In an alternative embodiment, spraying photocurable acrylic resin on the surface of the micron particles specifically includes: spraying photocurable acrylic resin on the surface of the micron particles through an atomization device.

[0049] In the above embodiments, wrapping the resin on the surface of the micron particles can effectively protect the internal solid acid and scale inhibitor from reaching the inside of the required deep coalbed methane well. In addition, the release rate and time can be controlled physically.

[0050] In an alternative embodiment, the sprayed photocurable acrylic resin material accounts for 10-15 parts by mass of the compound product, and the thickness is about 10-15 microns.

[0051] In a second aspect, based on a general inventive concept, the present invention also provides a sustained-release acid for acidizing and removing blockages in deep coalbed methane wells, which is prepared by using the preparation method of the sustained-release acid for acidizing and removing blockages in deep coalbed methane wells described in the first aspect.

[0052] The sustained-release acid is realized based on the above-mentioned preparation method of the sustained-release acid. The specific steps of the preparation method of the sustained-release acid can refer to the above embodiments. Since the sustained-release acid adopts some or all of the technical solutions of the above embodiments, it at least has all the beneficial effects brought by the technical solutions of the above embodiments, and will not be elaborated one by one here.

[0053] In a third aspect, based on a general inventive concept, the present invention also provides the application of the sustained-release acid for acidizing and removing blockages in deep coalbed methane wells described in the second aspect in acidizing and removing blockages in deep coalbed methane wells.

[0054] The following further elaborates the present application in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present application and not to limit the scope of the present application. The experimental methods without specific conditions noted in the following embodiments are usually determined according to industry standards. If there is no corresponding industry standard, they are carried out according to general international standards, conventional conditions, or the conditions recommended by the manufacturer.

[0055] Example 1

[0056] This example provides a sustained-release acid for acidizing and removing blockages in deep coalbed methane wells. The preparation method of the sustained-release acid includes the following steps:

[0057] Take 30 kg of p-toluenesulfonic acid and 10 kg of hexamethylenediamine tetramethylphosphate disodium, place them in a stirrer with a rotation speed of 1000 r / min for stirring. After stirring for 24 h, stop stirring and let it stand for 2 h to obtain a compound product; place the compound product in a pneumatic ultrafine mill, control the parameters to crush the compound product to 40 mesh to obtain micron particles; place the micron particles in an atomization device, and spray the pre-prepared photocurable acrylic resin on the surface of the micron particles with the atomization device to obtain a sustained-release acid for acidizing and removing blockages in deep coalbed methane wells.

[0058] Example 2

[0059] This example provides a sustained-release acid for acidizing and removing blockages in deep coalbed methane wells. The preparation method of the sustained-release acid includes the following steps:

[0060] Take 30 kg of ethylenediaminetetraacetic acid and 10 kg of sodium hexamethylenediaminetetraphosphate, place them in a stirrer with a rotation speed of 1000 r / min for stirring. After stirring for 24 h, stop stirring and let it stand for 2 h to obtain a compound product; place the compound product in a pneumatic ultrafine mill, control the parameters to crush the compound product to 40 mesh to obtain micron particles; place the micron particles in an atomization device, and spray the pre-prepared photocurable acrylic resin on the surface of the micron particles with the atomization device to obtain a slow-release acid for acidizing and plugging removal in deep coalbed methane wells.

[0061] Example 3

[0062] This example provides a slow-release acid for acidizing and plugging removal in deep coalbed methane wells. The preparation method of the slow-release acid includes the following steps:

[0063] Take 30 kg of diatomite and 10 kg of sodium hexamethylenediaminetetraphosphate, place them in a stirrer with a rotation speed of 1000 r / min for stirring. After stirring for 24 h, stop stirring and let it stand for 2 h to obtain a compound product; place the compound product in a pneumatic ultrafine mill, control the parameters to crush the compound product to 40 mesh to obtain micron particles; place the micron particles in an atomization device, and spray the pre-prepared photocurable acrylic resin on the surface of the micron particles with the atomization device to obtain a slow-release acid for acidizing and plugging removal in deep coalbed methane wells.

[0064] Example 4

[0065] This example provides a slow-release acid for acidizing and plugging removal in deep coalbed methane wells. The preparation method of the slow-release acid includes the following steps:

[0066] Take 20 kg of p-toluenesulfonic acid and 10 kg of sodium hexamethylenediaminetetraphosphate, place them in a stirrer with a rotation speed of 500 r / min for stirring. After stirring for 24 h, stop stirring and let it stand for 2 h to obtain a compound product; place the compound product in a pneumatic ultrafine mill, control the parameters to crush the compound product to 40 mesh to obtain micron particles; place the micron particles in an atomization device, and spray the pre-prepared photocurable acrylic resin on the surface of the micron particles with the atomization device to obtain a slow-release acid for acidizing and plugging removal in deep coalbed methane wells.

[0067] Example 5

[0068] This example provides a slow-release acid for acidizing and plugging removal in deep coalbed methane wells. The preparation method of the slow-release acid includes the following steps:

[0069] Take 10 kg of p-toluenesulfonic acid and 10 kg of sodium hexamethylenediaminetetramethylenephosphonate, place them in a stirrer with a rotation speed of 1000 r / min for stirring. After stirring for 24 h, stop stirring and let it stand for 2 h to obtain a compound product; place the compound product in a pneumatic ultrafine grinder, control the parameters to grind the compound product to 40 mesh to obtain micron particles; place the micron particles in an atomizing device, and spray the pre-prepared photocurable acrylic resin on the surface of the micron particles with the atomizing device to obtain a slow-release acid for acidizing and unplugging deep coalbed methane wells.

[0070] Example 6

[0071] This example provides a slow-release acid for acidizing and unplugging deep coalbed methane wells. The preparation method of the slow-release acid includes the following steps:

[0072] Take 30 kg of p-toluenesulfonic acid and 10 kg of sodium hexamethylenediaminetetramethylenephosphonate, place them in a stirrer with a rotation speed of 1000 r / min for stirring. After stirring for 24 h, stop stirring and let it stand for 2 h to obtain a compound product; place the compound product in a pneumatic ultrafine grinder, control the parameters to grind the compound product to 325 mesh to obtain micron particles; place the micron particles in an atomizing device, and spray the pre-prepared photocurable acrylic resin on the surface of the micron particles with the atomizing device to obtain a slow-release acid for acidizing and unplugging deep coalbed methane wells.

[0073] Example 7

[0074] This example provides a slow-release acid for acidizing and unplugging deep coalbed methane wells. The preparation method of the slow-release acid includes the following steps:

[0075] Take 30 kg of p-toluenesulfonic acid and 10 kg of sodium hexamethylenediaminetetramethylenephosphonate, place them in a stirrer with a rotation speed of 2000 r / min for stirring. After stirring for 24 h, stop stirring and let it stand for 2 h to obtain a compound product; place the compound product in a pneumatic ultrafine grinder, control the parameters to grind the compound product to 100 mesh to obtain micron particles; place the micron particles in an atomizing device, and spray the pre-prepared photocurable acrylic resin on the surface of the micron particles with the atomizing device to obtain a slow-release acid for acidizing and unplugging deep coalbed methane wells.

[0076] Comparative Example 1

[0077] This comparative example provides a slow-release acid, including 80 parts of hydrochloric acid with a mass fraction of 15% and 20 parts of hydrofluoric acid with a mass fraction of 5%.

[0078] Comparative Example 2

[0079] This comparative example provides a slow-release acid, including 70 parts of hydrochloric acid with a mass fraction of 12% and 30 parts of hydrofluoric acid with a mass fraction of 3%.

[0080] Comparative Example 3

[0081] In this comparative example, a slow-release acid was provided, including 85 parts of hydrochloric acid with a mass fraction of 10% and 15 parts of ammonium bifluoride with a mass fraction of 15%.

[0082] The slow-release acids in Examples 1-7 and Comparative Examples 1-3 were used in the acid stimulation and plug removal process of deep coalbed methane wells, and their slow-release times and final dissolution times are shown in Table 1:

[0083] Table 1 Slow-release times and dissolution times of the slow-release acids in Examples 1-7 and Comparative Examples 1-3

[0084] Group Sustained release time / min Dissolution time / min Example 1 220 240 Example 2 230 250 Example 3 225 235 Example 4 260 275 Example 5 235 250 Example 6 220 265 Example 7 235 265 Comparative Example 1 0 0 Comparative Example 2 0 3 Comparative Example 3 0 4

[0085] From the data in the above table, it can be seen that the slow-release acid provided in this application for acid stimulation and plug removal of deep coalbed methane wells has a good slow-release effect.

[0086] The above are only specific embodiments of the present application, enabling those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A preparation method of a slow-release acid for acidizing and removing blockages in deep coalbed methane wells, characterized in that, It includes the following steps: Compound a solid acid and a scale inhibitor to obtain a compound product; Prepare the compound product into micron particles; Spray a photocurable acrylic resin on the surface of the micron particles to prepare a slow-release acid for acidizing and plugging removal in deep coalbed methane wells.

2. The preparation method according to claim 1, characterized in that, The mass ratio of the solid acid to the scale inhibitor is 3:1 to 1:

1.

3. The preparation method according to claim 1, characterized in that, The solid acid includes at least one of p-toluenesulfonic acid, ethylenediaminetetraacetic acid, and diatomaceous earth.

4. The preparation method according to claim 1, characterized in that, The scale inhibitor used is sodium hexamethylenediaminetetraphosphate.

5. The preparation method according to claim 1, characterized in that, Compound the solid acid and the scale inhibitor to obtain a compound product, specifically including: stirring the solid acid and the scale inhibitor to obtain a compound product.

6. The preparation method according to claim 1, characterized in that, Prepare the compound product into micron particles, specifically including: preparing the compound product into micron particles through a pneumatic ultrafine grinder.

7. The preparation method according to claim 1, characterized in that The micron particles are 325 mesh to 40 mesh.

8. The preparation method according to claim 1, characterized in that, Spraying the photocurable acrylic resin on the surface of the micron particles specifically includes: spraying the photocurable acrylic resin on the surface of the micron particles through an atomization device.

9. A slow-release acid for acidizing and plugging removal in deep coalbed methane wells prepared by using the preparation method according to any one of claims 1 to 8.

10. Application of the slow-release acid for acidizing and plugging removal in deep coalbed methane wells according to claim 9 in acidizing and plugging removal in deep coalbed methane wells.

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