Plugging agent for drilling fluid as well as preparation method and application of plugging agent

Abstract

The invention provides a plugging agent for drilling fluid as well as a preparation method and application thereof, and belongs to the technical field of drilling fluid, the plugging agent for drilling fluid comprises the following components: a main body material which is selected from one or more of sepiolite, apricot shell, coconut fiber, walnut shell and peanut shell; the coating material is coated on the surface of the main body material to form a coating layer and comprises epoxy resin and polyacrylamide; wherein the diameter of the main body material ranges from 0.005 mm to 0.03 mm. After being prepared into plugging drilling fluid to be pumped into a well bottom, the plugging drilling fluid easily enters formation cracks under the action of pressure difference, plugging agent particles are mutually filled to achieve a certain temporary plugging effect, and are mutually cemented and solidified under the action of formation temperature, and after 3-5 hours, solidified blocks are formed to achieve the effects of plugging a leakage layer and preventing the leakage layer from being blocked. And the loading capacity of the stratum is improved.

Description

Technical Field

[0001] The invention relates to the technical field of drilling fluid, in particular to a plugging agent for drilling fluid and a preparation method and application thereof. Background Art

[0002] Well leakage is one of the common complex situations in the drilling process. It refers to the leakage of drilling fluid, workover fluid, cementing water, etc. during drilling and workover operations in oil and gas exploration and development. It not only consumes drilling time and causes mud loss, but also may cause a series of complex situations such as drill sticking, blowout, well collapse, and even lead to the scrapping of the wellbore, resulting in significant economic losses. With the expansion of the field of oil and gas exploration and development, the formations encountered are becoming more and more complex, with low-pressure oil and gas reservoirs and formations with severe leakage in fractures and caves; in oil fields that have entered the middle and late stages of exploration and development, there are large pores and severe formation deficits in the formations to varying degrees, and there are many well leakage problems during drilling construction.

[0003] At present, the commonly used bridge plugging method is to mix plugging materials such as sepiolite, cottonseed, walnut shell and apricot shell in the drilling fluid to form plugging drilling fluid for plugging. The plugging drilling fluid is just a simple physical accumulation of materials such as sepiolite, cottonseed, walnut shell and apricot shell in the well to plug the leakage layer. The circulating drilling fluid will wash away the accumulated plugging agent, and the drill bit and drilling tools used in drilling will also scratch and damage the plugging layer, resulting in plugging failure. Summary of the invention

[0004] One of the purposes of the present invention is to provide a plugging agent for drilling fluid, with a particle diameter of 0.005mm-0.03mm, which is not easy to block downhole equipment such as instruments and drill bit water holes, is easy to use and simple to prepare; the plugging agent particles are configured so that after the plugging drilling fluid is pumped into the bottom of the well, the plugging agent enters the formation cracks under the action of the pressure difference, and at the same time, the plugging agent particles fill each other to play a certain temporary plugging role, and are mutually bonded and consolidated under the action of the formation temperature. After 3-5 hours, a solidified block is formed, which plays a role in sealing the leakage layer and improving the pressure bearing capacity of the formation.

[0005] The second object of the present invention is to provide a method for preparing the plugging agent for drilling fluid. The preparation method is relatively simple, has low equipment requirements, low cost, controllable product quality, and is conducive to promotion and application.

[0006] The third object of the present invention is to provide an application of the plugging agent for drilling fluid.

[0007] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0008] In a first aspect, the present invention provides a plugging agent for drilling fluid, the composition of which comprises:

[0009] The main material is one or more selected from the group consisting of sepiolite, apricot shell, coconut shell fiber, walnut shell and peanut shell; and,

[0010] The coating material is coated on the surface of the main material to form a coating layer, comprising epoxy resin and polyacrylamide;

[0011] Among them, the diameter of the main material is 0.005mm-0.03mm.

[0012] The following is a detailed description of each part:

[0013] Main material

[0014] The main material of the present invention is selected from one or more of sepiolite, apricot shell, coconut shell fiber, walnut shell and peanut shell. For example, it can be a combination of sepiolite and apricot shell, a combination of sepiolite and coconut shell fiber, a combination of sepiolite and walnut shell, a combination of sepiolite and peanut shell, a combination of coconut shell fiber and apricot shell, a combination of apricot shell and walnut shell, a combination of apricot shell and peanut shell, a combination of sepiolite, apricot shell and coconut shell fiber, a combination of sepiolite, walnut shell and peanut shell, a combination of apricot shell, coconut shell fiber and walnut shell, a combination of coconut shell fiber, walnut shell and peanut shell, a combination of sepiolite, apricot shell, coconut shell fiber, walnut shell and peanut shell, but is not limited to this.

[0015] Preferably, the main body material is a combination of sepiolite, apricot shell, coconut shell fiber, walnut shell and peanut shell.

[0016] The diameter of the main body material is 0.005mm-0.03mm, such as 0.005-0.01mm, 0.005-0.02mm, 0.008-0.03mm, 0.01-0.02mm, 0.02-0.03mm, etc., but not limited thereto.

[0017] Here, the diameter refers to the straight-line distance between the two farthest points of the main material particle, that is, the maximum size of the particle.

[0018] The plugging agent of the present invention has a particle diameter of 0.005mm-0.03mm, can be used while drilling, is not easy to block downhole equipment such as instruments and drill bit water holes, and can fill each other when entering cracks under the temperature and pressure of the bottom hole.

[0019] Coating materials

[0020] The coating material of the present invention is epoxy resin and polyacrylamide, and the main material is coated with the coating material to form a coating layer.

[0021] In some embodiments, the weight parts of each component of the plugging agent for drilling fluid are: 18-22 parts of sepiolite, for example, 18 parts, 19 parts, 20 parts, 21 parts, and 22 parts; 20-22 parts of apricot shells, for example, 20 parts, 21 parts, and 22 parts; 18-20 parts of coconut shell fibers, for example, 18 parts, 19 parts, and 20 parts; 19-21 parts of walnut shells, for example, 19 parts, 20 parts, and 21 parts; 18-20 parts of peanut shells, for example, 18 parts, 19 parts, and 20 parts; 0.2-0.3 parts of epoxy resin, for example, 0.2 parts, 0.25 parts, and 0.3 parts; 0.3-0.5 parts of polyacrylamide, for example, 0.3 parts, 0.4 parts, and 0.5 parts.

[0022] Preferably, the thickness of the coating layer is 10-20 μm.

[0023] The present invention uses epoxy resin and polyacrylamide as the outer self-consolidation material, so that the plugging particles are consolidated in the cracks, achieving the effect of "entering and standing", and finally achieving the plugging effect.

[0024] In a second aspect, the present invention provides a method for preparing the above-mentioned plugging agent for drilling fluid, comprising the following steps:

[0025] The coating material is evenly sprayed on the main material to obtain a plugging agent for drilling fluid.

[0026] The main material is one or more selected from sepiolite, apricot shell, coconut shell fiber, walnut shell and peanut shell; the diameter of the main material is 0.005mm-0.03mm;

[0027] The coating material contains epoxy resin and polyacrylamide.

[0028] In some embodiments, the weight proportions of each raw material are: 18-22 parts of sepiolite, 20-22 parts of apricot shells, 18-20 parts of coconut shell fibers, 19-21 parts of walnut shells, 18-20 parts of peanut shells, 0.2-0.3 parts of epoxy resin, and 0.3-0.5 parts of polyacrylamide.

[0029] In some embodiments, the method for preparing a plugging agent for drilling fluid comprises the following steps:

[0030] The sepiolite, apricot shell, coconut shell fiber, walnut shell and peanut shell are crushed to make their diameters 0.005mm-0.03mm respectively, and then dried. The dried particles are mixed in proportion. Finally, epoxy resin and polyacrylamide are mixed in proportion and evenly sprayed on the sepiolite, apricot shell, coconut shell fiber, walnut shell and peanut shell. After cooling, they are taken out and stored in bags.

[0031] Preferably, the crushing can be carried out by an ultra-fine grinder, and the operation method is as follows: sepiolite, apricot shell, coconut shell fiber, walnut shell, and peanut shell with a diameter of 2-3 mm are respectively fed into the crushing chamber between the machine body and the guide ring through the spiral feed port of the ultra-fine grinder, and are impacted by the high-speed rotating blade in the crushing chamber, so that they are thrown to the gear ring fixed on the machine body, causing collision and shearing, and the mutual collision, friction, and shearing between the material and the blade and the gear ring for alternating crushing. After crushing, under the pulling force of the negative pressure airflow, the small powder particles overcome their own weight, pass through the guide ring with the airflow, and enter the classification chamber. The grading impeller is composed of blades. The high-speed rotating blades generate a centrifugal force opposite to the negative pressure. The powder particles that sink into the blade channel are simultaneously affected by the centripetal force of the negative pressure airflow, the weight of the powder particles and the centrifugal force generated by the impeller. The particles larger than the critical diameter are thrown back to the crushing chamber for further crushing due to their large mass, and the particles smaller than the critical diameter enter the cyclone collector through the powder discharge pipe and are discharged through the discharge valve (the equipment controls the centrifugal force and the particle size selection. The large particles settle and the particles of the required size are centrifuged out and collected). The obtained particles are 0.005mm-0.03mm in diameter, including sepiolite, apricot shell, coconut shell fiber, walnut shell and peanut shell.

[0032] Preferably, the mixing can be carried out by a conical mixer, as follows:

[0033] The sepiolite, apricot shell, coconut shell fiber, walnut shell and peanut shell are mixed uniformly in a conical mixer according to proportion to obtain a main material.

[0034] Preferably, spray coating can be performed by a fluidized coating machine, as follows:

[0035] The main material is fluidized in a fluidized coating machine (reverse mixed flow fluidized bed), and polyacrylamide and epoxy resin mixed in proportion at a temperature of 85°C-95°C are evenly sprayed on the main material by tangential spraying. After the coating is completed, the target product is obtained after cooling and drying.

[0036] Preferably, the spraying thickness is 10-20 μm.

[0037] In a third aspect, the present invention provides a use of the plugging agent for drilling fluid in preparing drilling fluid.

[0038] Beneficial Effects

[0039] The plugging agent of the invention has a particle diameter of 0.005mm-0.03mm, is easy to use and simple to prepare; the plugging agent is used to prepare plugging drilling fluid, which is simple and convenient and is not easy to clog the drill bit and the instrument.

[0040] After the plugging agent particles are configured into plugging drilling fluid and pumped into the bottom of the well, the plugging agent enters the formation cracks under the action of pressure difference. At the same time, the plugging agent particles fill each other, playing a certain temporary plugging role. Under the action of formation temperature, they are bonded and consolidated to each other. After 3-5 hours, solidified blocks are formed, which play a role in sealing the leakage layer and improving the pressure bearing capacity of the formation.

[0041] The plugging agent has the advantages of wide raw material sources, environmental friendliness, excellent performance, and safe use. The preparation method is relatively simple, the equipment requirements are low, and the product quality is controllable.

[0042] The present invention has been described in detail above, but the above embodiments are only illustrative in nature and are not intended to limit the present invention. In addition, this article is not limited by any theory described in the above prior art or invention content or the following examples. DETAILED DESCRIPTION

[0043] The present invention is further described below in conjunction with examples. It should be noted that the following examples are provided for illustrative purposes only and do not constitute a limitation on the scope of protection claimed for the present invention.

[0044] Unless otherwise specified, the raw materials, reagents, methods, etc. used in the examples are conventional raw materials, reagents, methods in the art.

[0045] The raw materials involved in the embodiments and comparative examples are as follows:

[0046] Sepiolite was purchased from Panjin Petrochemical Company.

[0047] Apricot shells were purchased from Panjin Petrochemical Company.

[0048] Coconut shell fiber was purchased from Panjin Petrochemical Company.

[0049] Walnut shells were purchased from Panjin Petrochemical Company.

[0050] Peanut shells were purchased from Panjin Petrochemical Company.

[0051] Epoxy resin was purchased from Liaoning Quanrui Reagent Co., Ltd.

[0052] Polyacrylamide was purchased from Liaoning Quanrui Reagent Co., Ltd.

[0053] The conical mixer is from Beijing Huitianfeng Petroleum Machinery Co., Ltd.

[0054] The back-mixed flow fluidized bed is from Beijing Tongzhuang Boda Technology Co., Ltd.

[0055] Before use, sepiolite, apricot shell, coconut shell fiber, walnut shell and peanut shell were crushed into 0.005 mm-0.03 mm size by ultrafine grinder (Beijing Huitianfeng Petroleum Machinery Co., Ltd.).

[0056] Example 1

[0057] 1. Put 22 parts of sepiolite, 20 parts of apricot shells, 18 parts of coconut shell fibers, 19 parts of walnut shells, and 18 parts of peanut shells into a conical mixer and mix them evenly to obtain the main material.

[0058] 2. Mix 0.27 parts of epoxy resin and 0.3 parts of polyacrylamide evenly, put them into a back-mixed fluidized bed tangential spray device, and heat them to 85°C.

[0059] 3. The obtained main material is placed in a back-mixed flow fluidized bed for fluidized spraying. After the main material is completely wrapped, it is cooled and dried to obtain a plugging agent 1.

[0060] Example 2

[0061] 1. Put 22 parts of sepiolite, 20 parts of apricot shells, 18 parts of coconut shell fibers, 19 parts of walnut shells, and 18 parts of peanut shells into a conical mixer and mix them evenly to obtain the main material.

[0062] 2. Mix 0.27 parts of epoxy resin and 0.3 parts of polyacrylamide evenly, put them into a back-mixed fluidized bed tangential spray device, and heat them to 90°C.

[0063] 3. The obtained main material is placed in a back-mixed flow fluidized bed for fluidized spraying. After the main material is completely wrapped, it is cooled and dried to obtain a plugging agent 2.

[0064] Example 3

[0065] 1. Put 21 parts of sepiolite, 21 parts of apricot shells, 18 parts of coconut shell fibers, 19 parts of walnut shells, and 18 parts of peanut shells into a conical mixer and mix them evenly to obtain the main material.

[0066] 2. Mix 0.27 parts of epoxy resin and 0.3 parts of polyacrylamide evenly, put them into a back-mixed fluidized bed tangential spray device, and heat them to 85°C.

[0067] 3. The obtained main material is placed in a back-mixed flow fluidized bed for fluidized spraying. After the main material is completely wrapped, it is cooled and dried to obtain a plugging agent 3.

[0068] Example 4

[0069] 1. Put 20 parts of sepiolite, 20 parts of apricot shells, 19 parts of coconut shell fibers, 20 parts of walnut shells, and 18 parts of peanut shells into a conical mixer and mix them evenly to obtain the main material.

[0070] 2. Mix 0.25 parts of epoxy resin and 0.5 parts of polyacrylamide evenly, put them into a back-mixed fluidized bed tangential spray device, and heat them to 85°C.

[0071] 3. The obtained main material is placed in a back-mixed flow fluidized bed for fluidized spraying. After the main material is completely wrapped, it is cooled and dried to obtain a plugging agent 4.

[0072] Test Case

[0073] The drilling fluid used in the test example is a drilling fluid base slurry, and the formula is distilled water + 5% sodium bentonite + 0.4% Na2CO3.

[0074] Determination of drilling fluid properties:

[0075] According to SY / T5840-2007 “Test Methods for Bridge Plugging Materials for Drilling”, the plugging ability of the plugging agent was tested using the QD-2 plugging material experimental evaluation device.

[0076] 3%, 5% and 8% of plugging agent were added to the drilling fluid base slurry to carry out compatibility test and high temperature and high pressure plugging test (PPA plugging test) for plugging test.

[0077] Test Example 01: Drilling fluid base slurry;

[0078] Test Example 02: Drilling fluid base slurry + 3% plugging agent 1;

[0079] Test Example 03: Drilling fluid base slurry + 5% plugging agent 1;

[0080] Test Example 04: Drilling fluid base slurry + 8% plugging agent 1;

[0081] Test Example 05: Drilling fluid base slurry + 3% plugging agent 2;

[0082] Test Example 06: Drilling fluid base slurry + 5% plugging agent 2;

[0083] Test Example 07: Drilling fluid base slurry + 8% plugging agent 2;

[0084] Test Example 08: Drilling fluid base slurry + 3% plugging agent 3;

[0085] Test Example 09: Drilling fluid base slurry + 5% plugging agent 3;

[0086] Test Example 10: Drilling fluid base slurry + 8% plugging agent 3;

[0087] Test Example 11: Drilling fluid base slurry + 3% plugging agent 4;

[0088] Test Example 12: Drilling fluid base slurry + 5% plugging agent 4;

[0089] Test Example 13: Drilling fluid base slurry + 8% plugging agent 4;

[0090] Table 1 Performance evaluation data of plugging agent

[0091]

[0092]

[0093] Core filter disc specifications: 10-80μm.

[0094] It can be seen from Table 1 that the plugging agent has a good plugging ability for cracks of 10-80 μm, and has little effect on the rheological properties of the drilling fluid.

[0095] The plugging agent enters the cracks, and the plugging agent particles fill, cement and consolidate with each other, thereby sealing the leaking layer and improving the pressure-bearing capacity of the formation.

[0096] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments may be modified, or some or all of the technical features thereof may be replaced by equivalents, without departing from the spirit and essence of the claims of the present invention; and these modifications or replacements are still within the scope defined by the claims of the present invention.

Claims

1. A plugging agent for drilling fluid, characterized in that: Its composition includes: The main material is one or more selected from the group consisting of sepiolite, apricot shell, coconut shell fiber, walnut shell and peanut shell; and, The coating material is coated on the surface of the main material to form a coating layer, comprising epoxy resin and polyacrylamide; Among them, the diameter of the main material is 0.005mm-0.03mm.

2. The plugging agent for drilling fluid according to claim 1, characterized in that: The main material is a combination of sepiolite, apricot shell, coconut shell fiber, walnut shell and peanut shell.

3. The plugging agent for drilling fluid according to claim 2, characterized in that: The weight proportions of the components of the plugging agent for drilling fluid are: 18-22 parts of sepiolite, 20-22 parts of apricot shells, 18-20 parts of coconut shell fibers, 19-21 parts of walnut shells, 18-20 parts of peanut shells, 0.2-0.3 parts of epoxy resin and 0.3-0.5 parts of polyacrylamide.

4. The plugging agent for drilling fluid according to claim 1, characterized in that: The coating layer has a thickness of 10-20 μm.

5. The method for preparing a plugging agent for drilling fluid according to any one of claims 1 to 4, characterized in that: The following steps are involved: The coating material is evenly sprayed on the main material to obtain a plugging agent for drilling fluid. The main material is one or more selected from sepiolite, apricot shell, coconut shell fiber, walnut shell and peanut shell; the diameter of the main material is 0.005mm-0.03mm; The coating material contains epoxy resin and polyacrylamide.

6. The preparation method according to claim 5, characterized in that: The main material is a combination of sepiolite, apricot shell, coconut shell fiber, walnut shell and peanut shell.

7. The preparation method according to claim 6, characterized in that: The weight proportions of the raw materials are as follows: 18-22 parts of sepiolite, 20-22 parts of apricot shells, 18-20 parts of coconut shell fibers, 19-21 parts of walnut shells, 18-20 parts of peanut shells, 0.2-0.3 parts of epoxy resin and 0.3-0.5 parts of polyacrylamide.

8. The preparation method according to claim 5, characterized in that: The preparation method of the plugging agent for drilling fluid comprises the following steps: The sepiolite, apricot shell, coconut shell fiber, walnut shell and peanut shell are crushed to make their diameters 0.005mm-0.03mm respectively, and then dried. The dried particles are mixed in proportion. Finally, epoxy resin and polyacrylamide are mixed in proportion and evenly sprayed on the sepiolite, apricot shell, coconut shell fiber, walnut shell and peanut shell. After cooling, they are taken out and stored in bags.

9. The preparation method according to claim 8, characterized in that: The pulverization is carried out by means of an ultra-fine pulverizer; Preferably, mixing is performed by a conical mixer, as follows: The sepiolite, apricot shell, coconut shell fiber, walnut shell and peanut shell are mixed uniformly in a conical mixer according to a certain proportion to obtain a main material; Preferably, spraying is carried out by a fluidized coater, as follows: The main material is fluidized in a fluidized coating machine, and polyacrylamide and epoxy resin mixed in proportion at a temperature of 85°C-95°C are evenly sprayed on the main material by tangential spraying. After the coating is completed, the target product is obtained after cooling and drying; Preferably, the spraying thickness is 10-20 μm.

10. Use of the plugging agent for drilling fluid according to any one of claims 1 to 4 in preparing drilling fluid.

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