阅读说明：本技术 页岩解卡液及其制备方法和页岩钻井的溶蚀解卡方法 (Shale stuck-releasing liquid, preparation method thereof and shale drilling corrosion stuck-releasing method ) 是由 刘伟 陆灯云 吴正良 袁志平 欧翔 彭陶钧 景岷嘉 王棋 朱思远 向朝纲 曾婷 于 2020-04-03 设计创作，主要内容包括：本发明公开了一种页岩解卡液及其制备方法和页岩钻井的溶蚀解卡方法,所述页岩解卡液由按重量计100份的水、10～15份的页岩主溶蚀分散剂、5～10份的页岩辅溶蚀分散剂、1～3份的页岩渗透分散剂、1～3份的缓蚀剂构成。本发明的优点包括：浸泡时间短,配制施工工艺简单,解卡综合成本相对较低；客服了传统及国外现有的常规油基解卡液浸泡时间长的缺陷,并且解卡效率高；与水基钻井液和油基钻井液的配伍性均较好,对井下钻井性能不造成污染；解卡液对石英含量为35％以上、层理发育且脆性系数为0.2以上的页岩地层(例如,龙马溪页岩)的大掉块48h的溶蚀率可达55％以上；且对定向仪器各个配件的腐蚀率很低。(The invention discloses a shale stuck freeing liquid, a preparation method thereof and an erosion stuck freeing method for shale drilling, wherein the shale stuck freeing liquid comprises 100 parts of water, 10-15 parts of shale main erosion dispersing agent, 5-10 parts of shale auxiliary erosion dispersing agent, 1-3 parts of shale penetrating dispersing agent and 1-3 parts of corrosion inhibitor by weight. The advantages of the invention include: the soaking time is short, the preparation and construction process is simple, and the comprehensive cost of releasing the stuck is relatively low; the defect of long soaking time of the conventional and foreign conventional oil-based stuck freeing liquid is overcome, and the stuck freeing efficiency is high; the compatibility with water-based drilling fluid and oil-based drilling fluid is better, and the pollution to the underground drilling performance is avoided; the dissolution rate of the stuck freeing solution to large fallen blocks of a shale stratum (such as the Longmaxi shale) with the quartz content of more than 35 percent, the bedding development and the brittleness coefficient of more than 0.2 can reach more than 55 percent after 48 hours; and the corrosion rate to various fittings of the orientation instrument is low.)

1. The shale stuck freeing fluid is characterized by comprising 100 parts of water, 10-15 parts of shale main dissolution dispersing agent, 5-10 parts of shale auxiliary dissolution dispersing agent, 1-3 parts of shale permeation dispersing agent and 1-3 parts of corrosion inhibitor by weight.

2. The shale stuck freeing fluid of claim 1, wherein the shale stuck freeing fluid is used in shale formations with high quartz content, developed bedding and high brittleness.

3. The shale unfreezing liquid as claimed in claim 1, wherein the shale main corrosion dispersing agent is obtained by uniformly mixing a corrosion material, a surfactant carrier material and a catalyst adsorbing material, wherein the corrosion material is prepared by uniformly mixing 28-35 parts by weight of sodium polyepoxysuccinate, 15-25 parts by weight of sodium gluconate, 4-6 parts by weight of dimethylethanolamine and 8-10 parts by weight of ethyl polylactic acid ester, grinding, crushing, sieving and stirring; the surfactant carrier material is prepared by uniformly mixing 5-8 parts by weight of sodium fatty alcohol-polyoxypropylene ether sulfate, 6-9 parts by weight of magnesium amino acid and 3-4 parts by weight of a complexing agent, and sieving; the catalyst adsorption material is prepared by uniformly mixing 8-12 parts by weight of catalytic lipase, 12-17 parts by weight of sodium p-hydroxysulfonate and 2-6 parts by weight of hydroxybutylate amine and sieving.

4. The shale stuck freeing fluid according to claim 1, wherein the shale auxiliary corrosion dispersant is obtained by uniformly mixing a first powder, a second powder and a third powder, wherein the first powder is obtained by uniformly mixing 20-25 parts by weight of epoxy succinic acid amine, 9-20 parts by weight of magnesium hydroxy butylene phosphate and 12-15 parts by weight of ethylene triamine pentaacetic acid amine, grinding, crushing, sieving and stirring; the second powder is prepared by uniformly mixing 8-12 parts by weight of active attapulgite, 8-12 parts by weight of ammonium persulfate and 12-17 parts by weight of sulfosuccinate and sieving; the third powder is prepared by uniformly mixing 7-13 parts by weight of butyl propionate, 8-14 parts by weight of sodium dodecyl benzene sulfonate and 3-9 parts by weight of an organic complexing agent and sieving the mixture.

5. The preparation method of the shale unfreezing liquid is characterized by comprising the following steps:

under the condition of stirring, adding 10-15 parts by weight of shale main corrosion dispersing agent into 100 parts by weight of clear water to obtain a first mixed solution;

continuously stirring, and adding 5-10 parts by weight of shale auxiliary corrosion dispersing agent into the first mixed solution to obtain a second mixed solution;

continuously stirring, and adding 1-3 parts by weight of shale penetrating dispersant into the second mixed solution to obtain a third mixed solution;

and continuously stirring, adding 1-3 parts of corrosion inhibitor into the third mixed solution, and uniformly stirring to obtain the shale unfreezing liquid.

6. The preparation method of the shale unfreezing liquid as claimed in claim 5, wherein the shale main corrosion dispersing agent is obtained by uniformly mixing a corrosion material, a surfactant carrier material and a catalyst adsorbing material, wherein the corrosion material is prepared by uniformly mixing 28-35 parts by weight of sodium polyepoxysuccinate, 15-25 parts by weight of sodium gluconate, 4-6 parts by weight of dimethylethanolamine and 8-10 parts by weight of ethyl polylactic acid ester, grinding, crushing, sieving and stirring; the surfactant carrier material is prepared by uniformly mixing 5-8 parts by weight of sodium fatty alcohol-polyoxypropylene ether sulfate, 6-9 parts by weight of magnesium amino acid and 3-4 parts by weight of a complexing agent, and sieving; the catalyst adsorption material is prepared by uniformly mixing 8-12 parts by weight of catalytic lipase, 12-17 parts by weight of sodium p-hydroxysulfonate and 2-6 parts by weight of hydroxybutylate amine and sieving.

7. The preparation method of the shale unfreezing liquid as claimed in claim 5, wherein the shale auxiliary corrosion dispersant is obtained by uniformly mixing a first powder, a second powder and a third powder, wherein the first powder is prepared by uniformly mixing 20-25 parts by weight of epoxy succinic acid amine, 9-20 parts by weight of hydroxyl butylidene magnesium phosphate and 12-15 parts by weight of ethylene triamine pentaacetic acid amine, grinding, crushing, sieving and stirring; the second powder is prepared by uniformly mixing 8-12 parts by weight of active attapulgite, 8-12 parts by weight of ammonium persulfate and 12-17 parts by weight of sulfosuccinate and sieving; the third powder is prepared by uniformly mixing 7-13 parts by weight of butyl propionate, 8-14 parts by weight of sodium dodecyl benzene sulfonate and 3-9 parts by weight of an organic complexing agent and sieving the mixture.

8. The method for preparing the shale-etching stuck fluid according to claim 5, wherein the stirring speed is 100-1400 r/min.

9. An erosion stuck method of shale drilling, characterized in that the method pumps the shale-freeing fluid as claimed in any one of claims 1 to 4 into a shale formation stuck drilling section to erode shale chippings or cuttings in the shale formation drilling.

Technical Field

The invention relates to the technical field of shale gas drilling stuck releasing agents developed in oil fields, in particular to a shale gas drilling stuck releasing liquid for shale gas drilling stuck drilling, a preparation method of the shale gas drilling stuck releasing liquid and an erosion stuck releasing method of shale drilling.

Background

At present, in the drilling process of the shale gas horizontal well in China (for example, the drilling process of the shale gas horizontal well in Longmaxi), multiple accidents such as instability of the well wall, block falling, blockage, drill sticking and the like exist. According to statistics, in 2014 to date, the rotary guide tool in Chongqing areas is buried in 45 sleeves of wells, so that economic loss is serious. In 2016, oil-based mud is used in a large area, 41 sets of wells are buried, the well burying rate is as high as 7.75%, and blocks such as Changning-Zhaotong, Weiyuan and Yonggong are distributed in the buried well area. In a rotary guide complex well buried in a well, drilling blocking accidents all occur in a horizontal section, and shale blocks fall and are blocked mainly.

At present, shale block falling and drill blocking accidents are large in processing difficulty, few in processing means, long in time consumption due to the fact that a mechanical method is used for shocking, reversing and the like, high in operation cost and low in success rate, and the shale block falling and drill blocking accidents cannot be relieved by using common stuck releasing agents, conventional hydrochloric acid, earth acid and oil foam. In particular, the shale stratum with the characteristics of high quartz content, bedding development, high brittleness and the like is not suitable.

The spotting fluid comprises the following components: 1) soaking oil; 2) oil-in-water type spotting fluid; 3) inorganic salt stuck freeing fluid; 4) and pickle acids, and these methods are collectively called spotting fluid methods. They are simple and effective methods for handling various types of stuck bits. The method is to pump the stuck freeing liquid into the well, return the stuck freeing liquid to the stuck point part for soaking, reduce the friction coefficient of the filter cake, and free the drilling tool while soaking to free the stuck freeing liquid. However, the above stuck freeing solutions have limitations due to their advantages and disadvantages. The oil is easy to upward flee due to the fact that oil is lighter, the stuck point cannot be effectively soaked, the stuck releasing effect is relatively low, oil can damage mud cakes, the unfavorable well wall is stable, and complex sleeves can be caused due to improper treatment. The oil-in-water stuck freeing fluid has much poorer effect than oil soaking, but has low cost and is not easy to pollute the environment. The inorganic salt stuck freeing fluid can only be applied to a salt water drilling fluid system. The acid is only used for sticking the drill in the carbonate stratum, and the acid liquor has the corrosion effect on the drilling tool.

In summary, there is a need for a novel spotting fluid suitable for shale gas development (particularly, shale strata with high quartz content, high bedding development, high brittleness, etc.).

Disclosure of Invention

In view of the above deficiencies, it is an object of the present invention to address one or more of the problems in the prior art described above. For example, an object of the present invention is to provide a novel stuck freeing fluid suitable for the development of shale gas and a preparation method thereof, and particularly, a novel stuck freeing fluid suitable for the stuck shale freeing or stuck sand setting freeing of a drilled shale formation with a quartz content of 35% or more, a bedding development and a brittleness coefficient of 0.2 or more, and a preparation method thereof.

In order to achieve the above purpose, one aspect of the present invention provides a shale unfreezing liquid, which is composed of, by weight, 100 parts of water, 10-15 parts of a shale main corrosion dispersant, 5-10 parts of a shale auxiliary corrosion dispersant, 1-3 parts of a shale permeation dispersant, and 1-3 parts of a corrosion inhibitor.

The invention provides a preparation method of a shale unfreezing liquid, which comprises the following steps: under the condition of continuous stirring, adding 10-15 parts by weight of shale main corrosion dispersing agent into 100 parts by weight of clear water to obtain a first mixed solution; adding 5-10 parts by weight of shale auxiliary corrosion dispersant into the first mixed solution to obtain a second mixed solution; adding 1-3 parts by weight of shale penetrating dispersant into the second mixed solution to obtain a third mixed solution; and adding 1-3 parts of a corrosion inhibitor into the third mixed solution, and uniformly stirring to obtain the shale unfreezing liquid.

In still another aspect of the present invention, there is provided a method for dissolving stuck shale in shale drilling, which comprises the steps of adding the shale dissolving stuck fluid into a water-based or oil-based drilling fluid, and pumping the shale dissolving stuck fluid into a shale formation drilling section to dissolve the shale chippings or cuttings in the shale formation drilling.

Compared with the prior art, the beneficial effects of the invention comprise at least one of the following:

1. the soaking time is short, the preparation and construction process is simple, and the comprehensive cost of releasing the stuck is relatively low;

2. the soaking time for shale chipping or sand setting is shorter, the defect of long soaking time of the conventional and foreign conventional oil-based stuck freeing solution is overcome, the stuck freeing efficiency is high, and the accidents of shale chipping and stuck drill or shale well section stuck drill in drilling can be solved more quickly and effectively;

3. the compatibility with water-based drilling fluid and oil-based drilling fluid is better, and the pollution to the underground drilling performance is avoided;

4. the dissolution rate of the stuck freeing solution to large fallen blocks of a shale stratum (such as the Longmaxi shale) with the quartz content of more than 35 percent, the bedding development and the brittleness coefficient of more than 0.2 can reach more than 55 percent after 48 hours;

5. the corrosion rate of each part of the standard N80 steel sheet, the 45# steel sheet and the orientation instrument is lower than 6 g/(m) specified by the national standard²·h)。

Drawings

The above and other objects and features of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings, in which:

FIGS. 1a to 1d show photographs of the rock core fragments before immersion, without rinsing after immersion, after rinsing with 6 mesh screen cloth, and after drying of the rock core fragments remaining after passing through 6 mesh screen cloth, respectively;

FIG. 2 shows a corresponding core fragment erosion rate curve of FIG. 1;

FIG. 3 shows corrosion rate test curves for N80 steel sheets;

FIGS. 4a and 4b show pictures of 45# crude steel sheets before and after soaking in the spotting fluid, respectively.

Detailed Description

Hereinafter, the shale-unfreezing fluid, the preparation method thereof and the corrosion-unfreezing method of shale drilling will be described in detail with reference to the accompanying drawings and exemplary embodiments.

Through research, the inventor provides a shale stuck freeing fluid suitable for shale drilling, a preparation method thereof and a shale drilling corrosion stuck freeing method. The stuck freeing solution is particularly suitable for shale strata (such as a Longmaxi shale stratum) with the quartz content of more than 35 percent, the bedding development and the brittleness coefficient of more than 0.2, and the aim of freeing the shale stuck drillings caused by the shale chipping is fulfilled by leading the shale to be chipped or the rock debris to be converted into water-soluble salt through chemical permeation, solubilization, oxidation, chain scission and conversion. Here, the term "bedding development" means that the natural bedding surface of the shale is flat or substantially flat, exfoliation along the bedding surface is significant, and a small amount of microporosities develop. For example, the opening of the micro-cracks in a natural state is 5 to 10 μm.

In an exemplary embodiment of the invention, the shale unfreezing liquid may be composed of, by weight, 100 parts of water, 10-15 parts of a shale primary eroding dispersant (which may be simply referred to as a primary eroding agent), 5-10 parts of a shale secondary eroding dispersant (which may be simply referred to as a secondary eroding agent), 1-3 parts of a shale penetrating dispersant, and 1-3 parts of a corrosion inhibitor. The shale penetrating and dispersing agent can be one or more of dioctyl sodium sulfosuccinate, alcohol amine and ether. The corrosion inhibitor can be an organic amine corrosion inhibitor.

Specifically, the preparation method of the shale drilling main corrosion remover can be used for preparing the expected shale drilling main corrosion remover by uniformly mixing the corrosion material, the surfactant carrier material and the catalyst adsorbent material according to the weight ratio of 1:1: 1.

Specifically, the corrosion inhibitor is prepared by uniformly mixing 28-35 parts by weight of sodium polyepoxysuccinate, 15-25 parts by weight of sodium gluconate, 4-6 parts by weight of dimethylethanolamine and 8-10 parts by weight of ethyl polylactic acid, grinding, crushing, sieving and stirring. Preferably, the sodium polyepoxysuccinate may be 30 to 32 parts, and the sodium gluconate may be 18 to 22 parts.

The surfactant carrier material is prepared by uniformly mixing 5-8 parts by weight of fatty alcohol-polyoxypropylene ether sodium sulfate, 6-9 parts by weight of magnesium amino acid and 3-4 parts by weight of a complexing agent, and sieving. Here, the complexing agent may be a carboxylic acid.

The catalyst adsorption material is prepared by uniformly mixing 8-12 parts by weight of catalytic lipase, 12-17 parts by weight of sodium p-hydroxysulfonate and 2-6 parts by weight of hydroxybutylate amine and sieving. Preferably, the catalytic lipase is 9-10 parts, and the p-hydroxysulfonic acid sodium salt is 14-16 parts.

Further, the particle size of the erosion material is controlled to pass through a 20 mesh sieve, the particle size of the surfactant carrier material is controlled to pass through a 20 mesh sieve, and the catalyst adsorption material is controlled to pass through a 40 mesh sieve. The corrosion material and the surfactant carrier material are mixed and react to form a product with certain viscosity and larger particle size, the product can be effectively screened out by sieving with a 20-mesh sieve, and if the product is sieved with a sieve with smaller size, part of the product with larger particle size can be screened out, so that waste is caused. The resultant third powder was collected well by passing through a 40 mesh screen.

The preparation method of the shale drilling main corrosive agent can be realized by the following steps:

A. 28-35 parts of polyepoxy succinic acid, 15-25 parts of sodium gluconate, 4-6 parts of dimethylethanolamine and 8-10 parts of poly ethyl lactate are weighed and uniformly mixed according to parts by weight, crushed by a grinding machine, sieved by a 20-mesh sieve to enable the particle size of the mixture to be smaller than 20 meshes, and stirred for more than 30 minutes to obtain the corrosion-resistant material.

B. 5-8 parts of sodium fatty alcohol-polyoxypropylene ether sulfate, 6-9 parts of magnesium amino acid and 3-4 parts of a complexing agent are weighed according to parts by weight, mixed by a conical mixing stirrer and stirred uniformly, and the stirring time can be more than 1 hour; then sieving the mixture by a 20-mesh sieve to obtain the uniform complex surfactant carrier material.

C. Weighing 8-12 parts of catalytic lipase, 12-17 parts of sodium p-hydroxysulfonate and 2-6 parts of hydroxybutyl diamine according to parts by weight, stirring for more than 40 minutes by using a conical mixer-stirrer, and sieving by using a 40-mesh sieve to obtain the catalyst adsorbent.

D. And uniformly stirring the prepared erosion material, the surfactant carrier material and the catalyst adsorbent material to prepare the shale drilling well main erosion agent.

It should be noted that item A, B, C in the above exemplary embodiment does not have a strict sequence, and may be performed sequentially or simultaneously.

The preparation method of the shale drilling dissolution agent can be used for preparing the expected shale drilling dissolution agent by uniformly mixing the first powder, the second powder and the third powder according to the weight ratio of 1:1: 1.

Specifically, the first powder is prepared by uniformly mixing 20-25 parts by weight of epoxy succinic acid amine, 9-20 parts by weight of magnesium hydroxy butylene phosphate and 12-15 parts by weight of ethylene triamine pentaacetic acid amine, grinding, crushing, sieving and stirring. Preferably, the epoxy succinic acid amine may be 22 to 24 parts, and the magnesium hydroxy butylene phosphate may be 14 to 18 parts.

The second powder is prepared by uniformly mixing 8-12 parts by weight of active attapulgite, 8-12 parts by weight of ammonium persulfate and 12-17 parts by weight of sulfosuccinate and sieving.

The third powder is prepared by uniformly mixing 7-13 parts by weight of butyl propionate, 8-14 parts by weight of sodium dodecyl benzene sulfonate and 3-9 parts by weight of an organic complexing agent and sieving the mixture. Here, the organic complexing agent may be diethylenetriaminepentaacetic acid, nitrilotriacetic acid and carboxylic acids.

Further, the particle size of the first powder is controlled to pass a 20 mesh sieve, the particle size of the second powder is controlled to pass a 20 mesh sieve, and the third powder is controlled to pass a 40 mesh sieve. The first powder and the second powder have certain viscosity after being mixed and reacted, the particle size is larger, the product can be effectively screened out after passing through a 20-mesh sieve, and if the product passes through a sieve with smaller size, part of the product with larger particle size can be screened out, so that waste is caused. The resultant third powder was collected well by passing through a 40 mesh screen.

In another exemplary embodiment of the present invention, the preparation method of the shale drilling co-etchant can be realized by the following steps:

(1) 20-25 parts of epoxy succinic acid amine, 9-20 parts of hydroxyl butylidene magnesium phosphate and 12-15 parts of ethylene triamine pentaacetic acid amine are weighed and uniformly mixed according to parts by weight, a grinding machine is used for crushing, the crushed mixture is sieved by a 20-mesh sieve, the granularity of the sieved mixture is smaller than 20 meshes, and the sieved mixture is stirred for more than 30 minutes to obtain first powder with the functions of unblocking and the like.

(2) Weighing 8-12 parts of active attapulgite, 8-12 parts of ammonium persulfate and 12-17 parts of sulfonated succinate according to parts by weight, mixing by using a conical mixing stirrer, and stirring uniformly for more than 1 hour; sieving with 20 mesh sieve to obtain second powder with surface activity.

(3) Weighing 7-13 parts of butyl propionate, 8-14 parts of sodium dodecyl benzene sulfonate and 3-9 parts of organic complexing agent according to parts by weight, stirring for more than 40 minutes by using a conical mixer, and sieving by using a 40-mesh sieve to obtain third powder with the functions of adsorption and the like.

(4) And uniformly mixing and stirring the prepared first powder, second powder and third powder according to the weight ratio of 1:1:1 to obtain the shale drilling auxiliary solvent.

It should be noted that items (1), (2) and (3) in the above exemplary embodiments do not have a strict sequence, and may be performed sequentially or simultaneously.

In another exemplary embodiment of the present invention, the preparation method of the shale unfreezing liquid can be realized by the following steps:

firstly, under the condition of stirring, adding 10-15 parts by weight of shale main corrosion dispersing agent into 100 parts by weight of clear water to obtain a first mixed solution; then, continuously stirring, and adding 5-10 parts by weight of shale auxiliary corrosion dispersing agent into the first mixed solution to obtain a second mixed solution; then, continuously stirring, and adding 1-3 parts by weight of shale penetrating dispersant into the second mixed solution to obtain a third mixed solution; and continuously stirring, adding 1-3 parts of corrosion inhibitor into the third mixed solution, and uniformly stirring to obtain the shale unfreezing liquid. Here, the stirring speed may be 100 to 1400r/min, and in the step of adding 1 to 3 parts of the corrosion inhibitor to the third mixed solution, the stirring speed is preferably increased.

In order that the above-described exemplary embodiments of the invention may be better understood, further description thereof with reference to specific examples is provided below.

Example 1

In this example, the shale spotting fluid may be prepared using the following method:

filling 100 parts by weight of clear water into a container, adding 10 parts by weight of shale main corrosion dispersant under the condition of continuous low-speed electric stirring at 800r/min, stirring for 15min, adding 5 parts by weight of shale auxiliary corrosion dispersant, stirring for 10min, adding 3 parts by weight of dioctyl sodium sulfosuccinate, and stirring for 10 min; subsequently, under the condition of continuous high-speed stirring at 1200r/min, 3 parts by weight of organic amine corrosion inhibitor is added and stirred for 10min, and after uniform mixing, the shale stuck freeing fluid (which may be referred to as stuck freeing fluid for short) of the example is prepared.

In this example, the main etchant was prepared as follows:

a. forming an erosion material: 30Kg of polyepoxy succinic acid, 18Kg of sodium gluconate, 5Kg of dimethylethanolamine and 8Kg of poly ethyl lactate are weighed and mixed evenly according to the parts by weight, crushed by a grinder, sieved by a 20-mesh sieve to ensure that the granularity is smaller than 20 meshes, and stirred for 30 minutes to obtain the polyepoxy succinic acid-sodium salt-water-soluble polymer.

b. Forming a surfactant carrier material: weighing 6Kg of fatty alcohol-polyoxypropylene ether sodium sulfate, 7Kg of magnesium amino acid and 3Kg of nitrilotriacetic acid according to parts by weight, mixing by using a conical mixer, and stirring uniformly for 1 hour; and then the mixture is sieved by a 20-mesh sieve to obtain the product.

c. Forming a catalyst adsorbent: 10Kg of catalytic lipase, 14Kg of sodium p-hydroxysulfonate and 4Kg of hydroxybutyl diamine are weighed according to parts by weight, stirred for 40 minutes by a conical mixer-blender and sieved by a 40-mesh sieve to obtain the finished product.

And then, mixing the erosion material prepared in the items a, b and c, a surfactant carrier material and a catalyst adsorbent material according to the proportion of 1:1:1, and uniformly stirring to prepare the shale drilling well main erosion agent.

The preparation process of the dissolution assisting agent is as follows:

(i) 22Kg of epoxy succinic acid amine, 18Kg of hydroxyl butylidene magnesium phosphate and 15Kg of ethylene triamine pentaacetic acid amine are weighed and uniformly mixed according to the parts by weight, crushed by a grinder, sieved by a 20-mesh sieve to ensure that the granularity is smaller than 20 meshes, and stirred for 25 minutes to obtain first uniform powder.

(ii) Weighing 10Kg of active attapulgite, 9Kg of ammonium persulfate and 16Kg of sulfonated succinate according to parts by weight, mixing by using a conical mixer, and uniformly stirring for 50 minutes. And sieved again through a 20 mesh sieve to obtain a second uniform powder.

(iii) Weighing 12Kg of butyl propionate, 13Kg of sodium dodecyl benzene sulfonate and 8Kg of organic complexing agent according to parts by weight, stirring for 30 minutes by a conical mixer, and sieving by a 40-mesh sieve to obtain third powder.

And (3) mixing the first powder, the second powder and the third powder prepared in the (i), (ii) and (iii) according to the proportion of 1:1:1, and uniformly stirring to prepare the shale drilling corrosion inhibitor.

Example 2

In this example, the shale spotting fluid may be prepared using the following method:

filling 100 parts by weight of clear water into a container, adding 13 parts by weight of shale main corrosion dispersant under the condition of 200r/min of continuous low-speed electric stirring, stirring for 18min, adding 8 parts by weight of shale auxiliary corrosion dispersant, stirring for 12min, adding 2 parts by weight of alcohol amine, and stirring for 10 min; and then adding 3 parts by weight of organic amine corrosion inhibitor under the continuous high-speed stirring condition of 900r/min, stirring for 15min, and obtaining the shale stuck freeing fluid of the example after uniform stirring.

In this example, the main etchant was prepared as follows:

a. forming an erosion material: 32Kg of polyepoxy succinic acid, 16Kg of sodium gluconate, 6Kg of dimethylethanolamine and 9Kg of poly ethyl lactate are weighed and mixed evenly according to the parts by weight, crushed by a grinder, sieved by a 20-mesh sieve to ensure that the granularity is smaller than 20 meshes, and stirred for 35 minutes to prepare the polyepoxy succinic acid.

b. Forming a surfactant carrier material: weighing 7Kg of fatty alcohol-polyoxypropylene ether sodium sulfate, 6Kg of magnesium amino acid and 3Kg of nitrilotriacetic acid according to parts by weight, mixing by using a conical mixer, and uniformly stirring; and then the mixture is sieved by a 20-mesh sieve to obtain the product.

c. Forming a catalyst adsorbent: weighing 8Kg of catalytic lipase, 15Kg of sodium p-hydroxysulfonate and 3Kg of hydroxybutyl diamine according to parts by weight, stirring for 35 minutes by using a conical mixer-blender, and sieving by using a 40-mesh sieve to obtain the finished product.

And then, mixing the erosion material prepared in the items a, b and c, a surfactant carrier material and a catalyst adsorbent material according to the proportion of 1:1:1, and uniformly stirring to prepare the shale drilling well main erosion agent.

The preparation process of the dissolution assisting agent is as follows:

(i) uniformly mixing the epoxy succinic acid amine, the hydroxyl butylene magnesium phosphate and the ethylene triamine pentaacetic acid amine according to the parts by weight, crushing by using a grinding machine, sieving by using a 20-mesh sieve to ensure that the granularity is smaller than 20 meshes, and stirring for 30 minutes to obtain first uniform powder.

(ii) Mixing the active attapulgite, the ammonium persulfate and the sulfosuccinate according to the parts by weight by using a conical mixing stirrer, and uniformly stirring for 1 hour. And sieved again through a 20 mesh sieve to obtain a second uniform powder.

(iii) And (3) stirring the butyl propionate, the sodium dodecyl benzene sulfonate and the diethylenetriamine pentaacetic acid in the parts by weight for 40 minutes by using a conical mixing stirrer, and sieving by using a 40-mesh sieve to obtain third powder.

And (3) mixing the first powder, the second powder and the third powder prepared in the (i), (ii) and (iii) according to the proportion of 1:1:1, and uniformly stirring to prepare the shale drilling corrosion inhibitor.

In the following, different tests are performed to compare and evaluate the shale agglomerated core corrosion rate performance of the shale unfreezing liquid of example 1 and example 2, analyze and evaluate the corrosion condition, and analyze and evaluate the compatibility of the unfreezing liquid and the drilling fluid.

Test one: the rock core of the rock shale block (the mass of a single rock is about 60 g) is respectively soaked in clear water, earth acid and the shale unfreezing liquid of the example 1 and the example 2, the rock core and the earth acid are respectively put into an aging tank, the temperature is kept at 100 ℃ for 48 hours, the rock core is taken out and the tank is opened, the rock core and the earth acid are sieved by 6-mesh sieve cloth and then dried at 80 ℃, weighed, and the dissolution rate of the shale is calculated, and the result is shown in the table 1.

Table 1 results comparing corrosion rate performance of shale-unfreezing fluids of examples 1, 2

Item	Corrosion rate of × 48h at 100 ℃%
		Clean water	0.56
Earth acid	4.79
		Shale stuck freeing fluid of example 1	61.60
Shale stuck freeing fluid of example 2	62.80

By analyzing the comparison results of table 1, it can be seen that: the stuck freeing fluids of examples 1 and 2 have high corrosion rate and have good corrosion action on the falling shale blocks.

And (2) test II: the shale core fragments (10 pieces in size and 65.30g in total as shown in figure 1 a) of Showa 104 well are taken and soaked in the shale unfreezing liquid of example 1, the shale core fragments are placed in an aging tank and are respectively kept at a constant temperature of 100 ℃ for 2h, 4h, 8h, 24h and 48h, then the shale core fragments are taken out and opened, and are screened by 6-mesh clean water, dried (80 ℃), weighed, the corrosion rate of the shale core fragments at different times is calculated, and a corrosion curve is drawn, and the results are shown in figures 1 a-1 d and figure 2. The weight of the remaining crushed stone in fig. 1d was 29.50g and the size of the block diameter was significantly reduced.

As can be seen from fig. 2: the shale core fragments increase in corrosion rate along with the increase of time, and the corrosion rate is about 55% and more than 50% in 48h, which indicates that the stuck freeing solution has higher corrosion rate. Similarly, the shale-based stuck freeing fluid of example 2 has a dissolution rate of greater than 60% at 48h, after similar tests.

And (3) test III: evaluation of corrosion of shale stuck freeing fluid of example 1 and example 2 on N80 standard steel sheets.

Taking 4 hanging pieces of N80 steel sheets, respectively putting the hanging pieces into a curing tank filled with the shale unfreezing liquid of the example 1, keeping the temperature at 100 ℃ for 8 hours, 16 hours, 24 hours and 48 hours respectively, then opening the curing tank, taking out the curing tank, drying the curing tank (80 ℃), weighing the curing tank, calculating the corrosion rate, and drawing a corrosion rate curve, which is shown in figure 3.

As can be seen from fig. 3: the corrosion rates of the N80 standard steel sheets at different times are all less than 6 g/(m) specified by the national standard²H). The corrosion rate of the shale stuck freeing fluid of the example 1 on the N80 steel sheet is shown to meet the requirements specified by the national standard. Similarly, the corrosion rates of the shale stuck freeing fluid of the example 2 to the N80 standard steel sheet at different times are all less than 6 g/(m) specified by the national standard after similar tests²H) meets the requirements specified by the national standard.

And (4) testing: evaluation of corrosion of 45# base steel sheet by shale unfreezing liquid of example 1 and example 2.

And (3) putting the 45# original steel sheet hanging piece into a curing tank filled with dissolved and corroded solution, keeping the temperature of the curing tank constant at 100 ℃ for 48 hours, then opening the curing tank, taking out the curing tank, drying the curing tank (80 ℃), weighing the curing tank, and calculating the corrosion rate, wherein the corrosion rate is shown in a figure 4a and a figure 4 b.

From fig. 4, it is calculated: the corrosion rate of the 45# steel sheet after being soaked in the stuck freeing solution for 48 hours is 4.226 g/(m)²H) less than 6 g/(m) specified by the national standard²H), indicating that the corrosion rate of the dissolved stuck solution on the 45# steel sheet meets the requirement specified by the national standard. Similarly, the corrosion rates of the shale stuck freeing fluid of the example 2 to the 45# steel sheet at different times are all less than 6 g/(m) specified by the national standard after similar tests²H) meets the requirements specified by the national standard.

And (5) testing: evaluation of corrosion of shale spotting fluid of examples 1 and 2 on directional instrument fittings.

The method comprises the steps of respectively taking an iron sheet cylinder (APS instrument), a Hainan instrument (APS instrument), an anti-pressure cylinder (APS instrument), a non-magnetic drilling tool, an anti-pressure block (Hainan instrument) and an anti-pressure block (APS instrument) of different accessories of a directional instrument, putting the devices into a maintenance tank filled with the shale unfreezing liquid of example 1, keeping the devices at a constant temperature for 48 hours at 100 ℃, then opening the tank and taking out the devices, drying the devices (80 ℃) and weighing the devices, calculating the corrosion rate of the unfreezing liquid to each accessory to be 0, and indicating that the unfreezing liquid does not.

And (6) test six: evaluation of the compatibility of the shale-deblocking fluid of example 1 with water-based drilling fluids.

Table 2 shale-unfreezing fluid and water-based drilling fluid (sulfonated system) compatibility experiment of example 1

Note that the rolling temperature of ① experimental conditions is 100 ℃ × 16h, the rheological property measuring temperature is 55 ℃, the high-temperature and high-pressure fluid loss measuring temperature of ② is 100 ℃, the drilling fluid + 5% of unfreezing fluid and the drilling fluid + 10% of unfreezing fluid in table 2 of ③ mean that 5 and 10 parts of unfreezing fluid are respectively added into 100 parts of water-based drilling fluid, the volume ratio can be called as follows, ④ AV is the apparent viscosity, PV is the plastic viscosity, YP is the dynamic shear force, G10'/G10 is the static shear force, F L is the medium-pressure water loss, and HTHP is the high-temperature and high-pressure water loss.

As can be seen from table 2: after the stuck freeing fluid with the volume ratio of 5-10% is added to pollute the drilling fluid, the drilling fluid still has excellent rheological property and better filtration wall forming property, and the stuck freeing fluid and the water-based drilling fluid system have good compatibility.

Test seven: evaluation of compatibility of shale-unfreezing fluid and oil-based drilling fluid of example 1.

Table 3 shale unfreezing fluid and oil-based drilling fluid compatibility experiment of example 1

Note that ① experiment conditions are that the rolling temperature is 100 ℃ and × 16h, the rheological property measurement temperature is 55 ℃, the high-temperature and high-pressure fluid loss measurement temperature is ② and is 100 ℃, ③ in Table 2, the drilling fluid + 5% of unfreezing fluid and the drilling fluid + 10% of unfreezing fluid are respectively added into 100 parts of oil-based drilling fluid, the components are called volume ratio, ④ AV is apparent viscosity, PV is plastic viscosity, YP is dynamic shear force, G10'/G10 is static shear force, F L is medium-pressure water loss, and HTHP is high-temperature and high-pressure water loss.

As can be seen from table 3: after 5% of unfreezing liquid is added to pollute the drilling fluid, the drilling fluid still has excellent rheological property and better filtration wall building property, and after 10% of unfreezing liquid is added to dissolve pollution, the apparent viscosity of the drilling fluid is increased, but the shearing force and other properties are similar to the properties of the drilling fluid, which indicates that the unfreezing liquid and an oil-based drilling fluid system have good compatibility.

In conclusion, the shale unfreezing liquid can be used for shale strata which has the quartz content of more than 35%, the bedding development and the brittleness coefficient of more than 0.2, and has the following excellent technical effects:

1. compared with the conventional oil-based stuck freeing solution, the oil-based stuck freeing solution has the advantages of environmental protection, short soaking time, simple preparation and construction process and relatively low stuck freeing comprehensive cost;

2. the soaking time for shale chipping or sand setting is shorter, the defect of long soaking time of the conventional and foreign conventional oil-based stuck freeing solution is overcome, the stuck freeing efficiency is high, and the accidents of shale chipping and stuck drilling or shale well section sand setting and stuck drilling in the drilling process can be more quickly and effectively eliminated;

3. the temperature resistance is more than or equal to 140 ℃, the transportation is convenient, the prepared stuck freeing solution is nontoxic, tasteless, non-combustible, non-explosive, neutral and easy to degrade, and the residual stuck freeing solution which is returned after stuck freeing does not need special treatment and can be automatically degraded;

4. the compatibility with water-based drilling fluid and oil-based drilling fluid is better, and the pollution to the underground drilling performance is avoided; the dissolution rate of the stuck freeing solution on large dropping blocks of a shale stratum (such as Longmaxi shale) with the quartz content of more than 35 percent, the bedding development and the brittleness of more than 0.2 can reach 55 percent and even more than 60 percent after 48 hours; the corrosion rate of each part of the standard N80 steel sheet, the 45# steel sheet and the orientation instrument is lower than 6 g/(m) specified by the national standard²·h)。

Although the present invention has been described above in connection with exemplary embodiments, it will be apparent to those skilled in the art that various modifications and changes may be made to the exemplary embodiments of the present invention without departing from the spirit and scope of the invention as defined in the appended claims.