A low-viscosity polymer fluid loss reducer for drilling fluid and preparation method thereof

Abstract

The invention discloses a low-viscosity polymer fluid loss reducer for drilling fluid and a preparation method thereof, wherein the fluid loss reducer is composed of the following components in parts by weight: 25-35 parts of polyacrylic acid salt polymer, 20-30 parts of acrylic acid ester copolymer, 25-35 parts of polyacrylamide, 5-15 parts of sulfonated styrene-maleic anhydride copolymer, 1-3 parts of wood fiber, and 2-4 parts of a temporary plugging agent with multiple particle size distributions; wherein the polyacrylic acid salt polymer is copolymerized with acrylic acid, acrylamide, acrylonitrile and sodium propylene sulfonate; the acrylic acid ester copolymer is polymerized with methyl methacrylate, butyl acrylate, N-acetoxymethyl acrylamide and hydroxyethyl methacrylate; the sulfonated styrene-maleic anhydride copolymer is sulfonated with styrene-maleic anhydride; and the temporary plugging agent with multiple particle size distributions is a calcium salt. The purpose of the invention is to solve the problem that the fluid loss reducer used in drilling in the prior art has a great influence on the rheology of the drilling fluid and has a more obvious viscosity increase.

Description

Technical Field

[0001] The invention relates to the technical field of drilling, and in particular to a low-viscosity polymer fluid loss reducer for drilling fluid and a preparation method thereof. Background Art

[0002] Filtrate reducer is the largest and most important type of treatment agent used in oil drilling. It plays an important role in maintaining stable performance of drilling fluid and ensuring safe and efficient drilling.

[0003] As the field of drilling exploration gradually expands to harsh areas, the drilling areas become increasingly complex, and the phenomenon of reduced drilling speed and increased drilling costs caused by wellbore instability is common. At the same time, new drilling technologies such as horizontal wells, directional wells, and large-reach wells developed in the same period have put forward higher requirements on the viscosity and shear force of the drilling fluid system, its anti-pollution ability, and its ability to cope with the complexity and diversity of the formation.

[0004] There are many types of fluid loss reducers in the prior art, among which cellulose-based fluid loss reducers are cheap and of high quality, but have the problem of having a great influence on the rheological properties of the drilling fluid and causing a significant increase in viscosity. Summary of the invention

[0005] The invention provides a low-viscosity polymer fluid loss reducer for drilling fluid and a preparation method thereof, aiming to solve the problem that the fluid loss reducer used in drilling in the prior art has a great influence on the rheology of the drilling fluid and increases viscosity significantly.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0007] A low-viscosity polymer fluid loss reducer for drilling fluid, comprising the following components in parts by weight:

[0008] 25-35 parts of polyacrylic acid salt polymer, 20-30 parts of acrylic acid ester copolymer, 25-35 parts of polyacrylamide, 5-15 parts of sulfonated styrene-maleic anhydride copolymer, 1-3 parts of wood fiber, 2-4 parts of multi-particle size distribution temporary plugging agent;

[0009] in,

[0010] Polyacrylate polymer is made by copolymerization of acrylic acid, acrylamide, acrylonitrile and sodium propylene sulfonate;

[0011] Acrylate copolymer is prepared by polymerization of methyl methacrylate, butyl acrylate, N-acetoxymethyl acrylamide, and hydroxyethyl methacrylate;

[0012] The sulfonated styrene-maleic anhydride copolymer is formed by sulfonating styrene-maleic anhydride;

[0013] The temporary plugging agent with multiple particle size distribution is calcium salt.

[0014] Further, styrene-maleic anhydride is polymerized using benzene as a solution and azobisisobutylcyanide as an initiator;

[0015] Further, 30 parts of polyacrylic acid salt polymer, 25 parts of acrylic acid ester copolymer, 30 parts of polyacrylamide, 10 parts of sulfonated styrene-maleic anhydride copolymer, 2 parts of wood fiber, and 3 parts of multi-particle size distribution temporary plugging agent;

[0016] Furthermore, the calcium salt is at least one of calcium carbonate, calcium silicate or calcium dolomite.

[0017] Furthermore, the calcium salt is a mixture of any two of calcium carbonate, calcium silicate and calcium dolomite.

[0018] Furthermore, calcium carbonate, calcium silicate or calcium dolomite is compounded in a ratio of 2:1 with 400 mesh and 2000 mesh.

[0019] Furthermore, the fiber length of the wood fiber is 0.03-0.05 mm.

[0020] A method for preparing a low-viscosity polymer fluid loss reducer for drilling fluid comprises the following steps:

[0021] S1: Add 25-35 parts of polyacrylic acid salt polymer, 20-30 parts of acrylic acid ester copolymer, 25-35 parts of polyacrylamide, 5-15 parts of sulfonated styrene-maleic anhydride copolymer, 1-3 parts of wood fiber, and 2-4 parts of multi-particle size distribution temporary plugging agent into a stirrer;

[0022] S2: Start the stirrer and take out after stirring for 14-16 minutes.

[0023] Further, in S1, 30 parts of polyacrylic acid salt polymer, 25 parts of acrylic acid ester copolymer, 30 parts of polyacrylamide, 10 parts of sulfonated styrene-maleic anhydride copolymer, 2 parts of wood fiber, and 3 parts of multi-particle size distribution temporary plugging agent are added into the stirrer;

[0024] Furthermore, in S2, the stirring time of the stirrer is 15 minutes.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The invention mainly comprises polyacrylic acid salt polymer, acrylic acid ester copolymer, polyacrylamide, sulfonated styrene-maleic anhydride copolymer, wood fiber and multi-particle size distribution temporary plugging agent. In actual use, staff put 25-35 parts of polyacrylic acid salt polymer, 20-30 parts of acrylic acid ester copolymer, 25-35 parts of polyacrylamide, 5-15 parts of sulfonated styrene-maleic anhydride copolymer, 1-3 parts of wood fiber and 2-4 parts of multi-particle size distribution temporary plugging agent into a stirrer for stirring. After stirring for 30-35 seconds, a powdery fluid loss reducing agent is formed. Finally, the powdery fluid loss reducing agent is taken out for collection. The raw materials of polyacrylic acid salt polymer, acrylic acid ester copolymer, polyacrylamide, sulfonated styrene-maleic anhydride copolymer, wood fiber and multi-particle size distribution temporary plugging agent have low viscosity. When drilling, the fluid loss reducing agent made of the raw materials is added, which has low viscosity and can achieve the effect of fluid loss reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 It is a structural schematic diagram of the agitator in the present invention.

[0029] Figure 2 It is a cross-sectional view of the agitator in the present invention.

[0030] In the figure, 101-support frame, 102-mixing box, 103-screw feeder, 104-partition, 105-coarse mixing area, 106-fine mixing area, 107-dropping hole, 108-valve, 109-first rotating shaft, 110-mixing rod, 111-first motor, 112-second rotating shaft, 113-mixing blade, 114-second motor. DETAILED DESCRIPTION

[0031] The present invention is further described below in conjunction with embodiments, which are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, other embodiments obtained by ordinary technicians in the field without creative work are all within the scope of protection of the present invention.

[0032] Embodiment 1

[0033] This embodiment discloses a low-viscosity polymer fluid loss reducer for drilling fluid, which is composed of the following components in parts by weight:

[0034] 25-35 parts of polyacrylic acid salt polymer, 20-30 parts of acrylic acid ester copolymer, 25-35 parts of polyacrylamide, 5-15 parts of sulfonated styrene-maleic anhydride copolymer, 1-3 parts of wood fiber, 2-4 parts of multi-particle size distribution temporary plugging agent;

[0035] Among them, polyacrylate polymer is copolymerized by acrylic acid, acrylamide, acrylonitrile and sodium propylene sulfonate;

[0036] Acrylate copolymer is prepared by polymerization of methyl methacrylate, butyl acrylate, N-acetoxymethyl acrylamide, and hydroxyethyl methacrylate;

[0037] The sulfonated styrene-maleic anhydride copolymer is formed by sulfonating styrene-maleic anhydride;

[0038] The temporary plugging agent with multiple particle size distribution is calcium salt;

[0039] The invention mainly comprises polyacrylic acid salt polymer, acrylic acid ester copolymer, polyacrylamide, sulfonated styrene-maleic anhydride copolymer, wood fiber and multi-particle size distribution temporary plugging agent. In actual use, staff put 25-35 parts of polyacrylic acid salt polymer, 20-30 parts of acrylic acid ester copolymer, 25-35 parts of polyacrylamide, 5-15 parts of sulfonated styrene-maleic anhydride copolymer, 1-3 parts of wood fiber and 2-4 parts of multi-particle size distribution temporary plugging agent into a stirrer for stirring. After stirring for 30-35 seconds, a powdery fluid loss reducing agent is formed. Finally, the powdery fluid loss reducing agent is taken out for collection. The raw materials of polyacrylic acid salt polymer, acrylic acid ester copolymer, polyacrylamide, sulfonated styrene-maleic anhydride copolymer, wood fiber and multi-particle size distribution temporary plugging agent have low viscosity. When drilling, the fluid loss reducing agent made of the raw materials is added, which has low viscosity and can achieve the effect of fluid loss reduction.

[0040] In some embodiments, styrene-maleic anhydride is polymerized using benzene as a solution and azobisisobutylcyanide as an initiator;

[0041] In this embodiment, 30 parts of polyacrylic acid salt polymer, 25 parts of acrylic acid ester copolymer, 30 parts of polyacrylamide, 10 parts of sulfonated styrene-maleic anhydride copolymer, 2 parts of wood fiber, and 3 parts of multi-particle size distribution temporary plugging agent;

[0042] In some embodiments, the calcium salt is at least one of calcium carbonate, calcium silicate or calcium dolomite. In this embodiment, the calcium salt is calcium carbonate.

[0043] In this embodiment, calcium carbonate, calcium silicate or calcium dolomite is compounded in a ratio of 2:1 with 400 mesh and 2000 mesh.

[0044] In some embodiments, the fiber length of the wood fiber is 0.03-0.05 mm. In this embodiment, the fiber length of the wood fiber is 0.04 mm.

[0045] A method for preparing a low-viscosity polymer fluid loss reducer for drilling fluid comprises the following steps:

[0046] S1: Add 25-35 parts of polyacrylic acid salt polymer, 20-30 parts of acrylic acid ester copolymer, 25-35 parts of polyacrylamide, 5-15 parts of sulfonated styrene-maleic anhydride copolymer, 1-3 parts of wood fiber, and 2-4 parts of multi-particle size distribution temporary plugging agent into a stirrer;

[0047] S2: Start the stirrer and take it out after stirring for 30-40 seconds.

[0048] Further, in S1, 30 parts of polyacrylic acid salt polymer, 25 parts of acrylic acid ester copolymer, 30 parts of polyacrylamide, 10 parts of sulfonated styrene-maleic anhydride copolymer, 2 parts of wood fiber, and 3 parts of multi-particle size distribution temporary plugging agent are added into the stirrer;

[0049] Furthermore, in S2, the stirring time of the stirrer is 35S.

[0050] Embodiment 2

[0051] See also Figure 1 as well as Figure 2 As shown, this embodiment specifically describes the structure of the agitator in the first embodiment. In this embodiment, the agitator includes a support frame 101, a mixing box 102 and a screw feeder 103;

[0052] The mixing box 102 is installed above the support frame 101, and a partition 104 is arranged inside the mixing box 102. The partition 104 divides the installation line into a coarse mixing area 105 and a fine mixing area 106. A material drop hole 107 is arranged on the partition 104, and a valve 108 is arranged on the material drop hole 107. The coarse mixing area 105 is located above the fine mixing area 106. A first rotating shaft 109 is arranged in the coarse mixing area 105. A plurality of stirring rods 110 are arranged in an array on the first rotating shaft 109, and adjacent stirring rods 110 are arranged alternately. One end of the first rotating shaft 109 is rotatably connected to the mixing box 102, and the other end extends out of the mixing box 102 and is connected to a first motor 111. The first motor 111 is installed on the top of the mixing box 102.

[0053] A second rotating shaft 112 is arranged in the fine stirring area 106, and a plurality of stirring blades 113 are arranged on the second rotating shaft 112. The interval between adjacent stirring blades 113 is much smaller than the distance between adjacent stirring rods 110. One end of the second rotating shaft 112 is rotatably connected to the stirring box 102, and the other end extends out of the stirring box 102 and is connected to a second motor 114. The second motor 114 is installed on the support frame 101.

[0054] A discharge port is provided at the bottom of the mixing box 102, and a discharge pipe is connected to the discharge port.

[0055] In actual use, the staff poured 30 parts of polyacrylate polymer, 25 parts of acrylate copolymer, 30 parts of polyacrylamide, 10 parts of sulfonated styrene-maleic anhydride copolymer, 2 parts of wood fiber, and 3 parts of multi-particle size distribution temporary plugging agent into the screw feeder 103, and the screw feeder 103 transported the above materials to the mixing box 102. The materials first need to be roughly stirred in the rough stirring area 105, and then the valve 108 is opened to enter the fine stirring area 106 for fine mixing and stirring. After the stirring is completed, the materials will be discharged through the discharge pipe for collection;

[0056] The advantage of this setting is that the material can be stirred more evenly through two stirrings of coarse stirring and fine stirring.

[0057] Embodiment 3

[0058] In this example, the low-viscosity polymer fluid loss reducer in Example 1 is subjected to comparative experiments indoors and outdoors. In this example, the calcium salt in the fluid loss reducer is calcium carbonate;

[0059] In this example, the low-viscosity polymer fluid loss reducer was tested in an indoor laboratory. The staff conducted a comparative experiment on the use effect of the low-viscosity polymer fluid loss reducer in bentonite slurry and composite salt water slurry. The experimental method is as follows:

[0060] 1. Experimental method for verification test of low viscosity polymer fluid loss reducer in bentonite slurry:

[0061] 1% and 2% low-viscosity polymer fluid loss reducer were added to 4% bentonite slurry, stirred at high speed for 10 minutes, and sealed and cured at room temperature for 16 hours. After stirring at high speed for 10 minutes, the API fluid loss of the base slurry and the sample slurry was tested. The experimental results are shown in Table 1.

[0062] Table 1 API water loss test data in bentonite slurry

[0063]

[0064] 2. Experimental method for verification experiment of low viscosity polymer fluid loss reducer in composite salt water slurry:

[0065] Take 350mL of 4% sodium chloride solution, add 35g potassium chloride and 1.00g sodium bicarbonate in turn. After high-speed stirring for 3 minutes, add 28.00g evaluation soil and stir at high speed for 10 minutes. Add the sample slowly and evenly while stirring on the stirrer. The sample addition time should last for about 1 minute. After adding the sample (the sample amount is 0g, 2g, and 4g respectively), stir at high speed for a total of 20 minutes. During this period, stop at least twice to scrape off the adhesion on the wall of the cup. Seal and cure at room temperature for 16 hours. After curing, stir at high speed for 5 minutes and measure the API filtration loss of the sample slurry. The experimental results are shown in Table 2.

[0066] Table 2 API water loss test data in composite brine slurry

[0067]

[0068] From the experimental data in Table 1 and Table 2, it can be seen that after adding the low-viscosity polymer fluid loss reducer, the API fluid loss of soil slurry and composite salt water slurry is significantly reduced, proving that the low-viscosity polymer fluid loss reducer has fluid loss reduction performance and good salt resistance.

[0069] Then the staff continued to conduct comparative experiments. They added PAC-LV and low-viscosity polymer fluid loss reducer into the well slurry for comparative tests. The specific test steps are as follows:

[0070] The test method is as follows;

[0071] 35g KCL was added to 358g 4.2% sea salt solution, and then 5g low viscosity polymer fluid loss reducer or PAC-LV was added, stirred and cured at room temperature for 16h. API and apparent viscosity were tested at 25℃, and the experimental results are shown in Table 3.

[0072] Table 3 Comparison with PAC-LV data

[0073]

[0074]

[0075] Finally, the staff conducted outdoor comparative experiments on whether or not low-viscosity polymer fluid loss reducer was added to the well slurry used in the drilling process in the Y101 H12-2 well with a depth of 596m and the Y101 H12-3 well with depths of 626m and 704m respectively.

[0076] (1) When used on site at the Y101 H12-2 well, the well depth of the Y101 H12-2 well is 596 m, the drilling fluid density is 1.27 g / cm3, FV: 36 s, and the experimental data when the well slurry is used during drilling and 0.2% polymer fluid loss reducer is added to the well slurry are shown in Table 4.

[0077] Table 4 Comparison before and after adding low viscosity polymer fluid loss reducer

[0078]

[0079] (2) When used on the Y101H12-3 well site, the Y101H12-3 well is located in Group 9, Baixiang Village, Desheng Town, Lu County, Luzhou City, Sichuan Province. The second opening of this well is a 406.4mm borehole, with a well section of 84-1028.51m. The strata are Shaximiao Formation, Lianggaoshan Formation, Ziliujing Formation, Xujiahe Formation, and the lithology is a large section of purple-red mudstone, gray mudstone, shale, and sandstone. The drilling fluid system is a KCL high-performance water-based drilling fluid system. During the drilling of this well section, a drilling fluid with a density of 1.48g / cm3 was used. In the upper well section of 84-700m, high water loss drilling fluid was used to prevent drill bit balling and fast drilling, and the filtration loss was 33mL. The actual drilling performance of Well Y101H12-3 is shown in Table 5. The experimental data of using well slurry and adding 0.3% polymer filtration reducer to the well slurry when drilling in Well Y101H12-3 at 626m are shown in Table 6, and the experimental data of using well slurry and adding 0.3% polymer filtration reducer to the well slurry when drilling in Well Y101H12-3 at 704m are shown in Table 7.

[0080] Table 5 Actual drilling performance of Well Y101H12-3

[0081]

[0082] Table 6 Comparison data of Y101H12-3 well slurry before and after adding low viscosity fluid loss reducer

[0083]

[0084] Table 7 Data of Y101H12-3 well slurry after adding low viscosity fluid loss reducer

[0085] <![CDATA[ρ,g / cm 3 ]]> FV, S PV, mPa·s Y.P., Pa. Gel,Pa / Pa FLAPI,ml pH 1.36 35 12 3 0.5 / 4 13 8

[0086] Conclusion: The experimental data in Tables 1 to 7 show that the actual performance of the low-viscosity polymer fluid loss reducer after entering the well is better than expected in the indoor experiment.

[0087] In the description of the present invention, it is necessary to understand that the terms "coaxial", "bottom", "one end", "top", "middle", "the other end", "upper", "one side", "top", "inside", "front", "center", "both ends" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0088] In addition, the terms "first", "second", "third" and "fourth" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first", "second", "third" and "fourth" may explicitly or implicitly include at least one of such features.

[0089] In the present invention, unless otherwise clearly stipulated and limited, the terms such as "installation", "setting", "connection", "fixation" and "screw-on" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal connection of two elements or the interaction relationship between two elements. Unless otherwise clearly defined, ordinary technicians in this field can understand the specific meanings of the above terms in the present invention according to the specific circumstances.

[0090] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A low-viscosity polymer fluid loss reducer for drilling fluid, characterized in that: It is composed of the following components in parts by weight: 25-35 parts of polyacrylic acid salt polymer, 20-30 parts of acrylic acid ester copolymer, 25-35 parts of polyacrylamide, 5-15 parts of sulfonated styrene-maleic anhydride copolymer, 1-3 parts of wood fiber, 2-4 parts of multi-particle size distribution temporary plugging agent; Among them, polyacrylate polymer is copolymerized by acrylic acid, acrylamide, acrylonitrile and sodium propylene sulfonate; Acrylate copolymer is prepared by polymerization of methyl methacrylate, butyl acrylate, N-acetoxymethyl acrylamide, and hydroxyethyl methacrylate; The sulfonated styrene-maleic anhydride copolymer is formed by sulfonating styrene-maleic anhydride; The temporary plugging agent with multiple particle size distribution is calcium salt.

2. The low-viscosity polymer fluid loss reducer for drilling fluid according to claim 1, characterized in that: Styrene-maleic anhydride is polymerized using benzene as a solution and azobisisobutylcyanide as an initiator.

3. The low-viscosity polymer fluid loss reducer for drilling fluid according to claim 1, characterized in that: 30 parts of polyacrylic acid salt polymer, 25 parts of acrylic acid ester copolymer, 30 parts of polyacrylamide, 10 parts of sulfonated styrene-maleic anhydride copolymer, 2 parts of wood fiber, and 3 parts of multi-particle size distribution temporary plugging agent.

4. The low-viscosity polymer fluid loss reducer for drilling fluid according to claim 1, characterized in that: The calcium salt is at least one of calcium carbonate, calcium silicate or calcium dolomite.

5. The low-viscosity polymer fluid loss reducer for drilling fluid according to claim 4, characterized in that: Calcium carbonate, calcium silicate or calcium dolomite is mixed and used in a ratio of 2:1 with 400 mesh and 2000 mesh.

6. The low-viscosity polymer fluid loss reducer for drilling fluid according to claim 1, characterized in that: The fiber length of the wood fiber is 0.03-0.05 mm.

7. A method for preparing a low-viscosity polymer fluid loss reducer for drilling fluid, characterized in that: The low-viscosity polymer fluid loss reducer is a low-viscosity polymer fluid loss reducer for drilling fluid as described in claim 1; The preparation method comprises the following steps: S1: Add 25-35 parts of polyacrylic acid salt polymer, 20-30 parts of acrylic acid ester copolymer, 25-35 parts of polyacrylamide, 5-15 parts of sulfonated styrene-maleic anhydride copolymer, 1-3 parts of wood fiber, and 2-4 parts of multi-particle size distribution temporary plugging agent into a stirrer; S2: Start the stirrer and take out after stirring for 14-16 minutes.

8. The method for preparing a low-viscosity polymer fluid loss reducer for drilling fluid according to claim 7, characterized in that: In S1, 30 parts of polyacrylic acid salt polymer, 25 parts of acrylic acid ester copolymer, 30 parts of polyacrylamide, 10 parts of sulfonated styrene-maleic anhydride copolymer, 2 parts of wood fiber, and 3 parts of multi-particle size distribution temporary plugging agent are added into the stirrer.

9. The method for preparing a low-viscosity polymer fluid loss reducer for drilling fluid according to claim 7, characterized in that: In S2, the stirring time of the stirrer is 15 min.

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