阅读说明：本技术 钻井液用纤维聚合物堵漏剂及其制备方法 (Fiber polymer plugging agent for drilling fluid and preparation method thereof ) 是由 张丽洋 于 2021-02-03 设计创作，主要内容包括：本发明为解决现有技术中堵漏剂与漏层裂缝尺寸匹配难度大的问题,公开了一种钻井液用纤维聚合物堵漏剂,包括以下原料,以质量份计,粉末状的聚合物40～50份；纤维10～15份；碳酸钙10～15份；降滤失剂1～5份；硅酸钠5～10份；氯化钙5～15份；分散剂0.5～1份。本发明还公开了一种钻井液用纤维聚合物堵漏剂的制备方法,聚合物、硅酸钠、氯化钙和分散剂先行混合,而后在与纤维、碳酸钙以及降滤失剂混合。本发明提供一种钻井液用纤维聚合物堵漏剂,该堵漏剂与漏层裂缝尺寸具有良好的配伍性,封堵效果良好。本发明还提供了一种钻井液用纤维聚合物堵漏剂的制备方法,先行在聚合物表面形成水化硅酸钙硬核层,改善不同裂缝尺寸下的作用效果。(The invention discloses a fiber polymer plugging agent for drilling fluid, aiming at solving the problem of large difficulty in matching the sizes of the plugging agent and a leak layer crack in the prior art, and the fiber polymer plugging agent comprises the following raw materials, by mass, 40-50 parts of powdery polymer; 10-15 parts of fibers; 10-15 parts of calcium carbonate; 1-5 parts of a filtrate reducer; 5-10 parts of sodium silicate; 5-15 parts of calcium chloride; 0.5-1 part of dispersing agent. The invention also discloses a preparation method of the fiber polymer plugging agent for the drilling fluid, wherein the polymer, sodium silicate, calcium chloride and the dispersing agent are mixed firstly and then are mixed with the fiber, calcium carbonate and the fluid loss additive. The invention provides a fiber polymer plugging agent for drilling fluid, which has good compatibility with the size of a leak layer crack and good plugging effect. The invention also provides a preparation method of the fiber polymer plugging agent for the drilling fluid, which is characterized in that a calcium silicate hydrate hard core layer is formed on the surface of the polymer in advance, so that the action effects under different crack sizes are improved.)

1. A fiber polymer plugging agent for drilling fluid is characterized by comprising the following raw materials in parts by mass,

40-50 parts of a powdery polymer;

10-15 parts of fibers;

10-15 parts of calcium carbonate;

1-5 parts of a filtrate reducer;

5-10 parts of sodium silicate;

5-15 parts of calcium chloride;

0.5-1 part of dispersing agent.

2. The fiber polymer plugging agent for drilling fluid as claimed in claim 1, wherein the polymer is one or more of polystyrene, polymethyl methacrylate, polyacrylamide, polyethylene vinyl acetate, acrylate copolymer, styrene and acrylate copolymer, and acrylamide and acrylate copolymer.

3. The fiber polymer plugging agent for drilling fluid as claimed in claim 1, wherein the polymer particle size is 0.1-1 mm.

4. A fibrous polymer plugging agent for drilling fluid according to claim 1, wherein the fiber is one or more of polyethylene fiber, polypropylene fiber, polyvinyl alcohol fiber, polyester fiber, polyacrylonitrile fiber, nylon fiber and lignin fiber.

5. The fiber polymer plugging agent for drilling fluid as claimed in claim 1, wherein the length of the fiber is 3-5 mm, and the diameter is 10-20 μm.

6. The fiber polymer plugging agent for drilling fluid as claimed in claim 1, wherein the particle size of the calcium carbonate is 200-300 meshes.

7. The fiber polymer plugging agent for drilling fluid as recited in claim 1, wherein the fluid loss additive is one or more of sodium carboxymethyl cellulose and polyanionic cellulose.

8. The fiber polymer plugging agent for drilling fluid as claimed in claim 1, wherein the dosage ratio of the sodium silicate to the calcium chloride is 1: 1 to 1.5.

9. The fibrous polymer plugging agent for drilling fluid according to claim 1, wherein the dispersant is one of naphthalene sulfonate formaldehyde condensate, polycarboxylic acid copolymer, lignosulfonate, or naphthalene sulfonate formaldehyde condensate.

10. The preparation of the fiber polymer plugging agent for drilling fluid according to any one of claims 1 to 9, which comprises the following steps,

step 1, adding a powdery polymer, sodium silicate, calcium chloride and a dispersing agent into a closed stirrer, continuously stirring for 5-10 min at a stirring speed of 100-200 rpm, and controlling the humidity in the stirrer to be below 10% and the temperature to be 50-60 ℃;

step 2, introducing atomized water into the closed stirrer, controlling the humidity in the stirrer to be 20-30%, controlling the temperature to be 50-60 ℃, intermittently stirring at the stirring speed of 100-200 rpm for 20-30 s, and stirring for 30-60 s each time;

step 3, stopping introducing atomized water after intermittent stirring for 10-15 min, continuing the intermittent stirring at a stirring speed of 100-200 rpm for 5-10 min, and controlling the temperature in the stirrer to be 50-60 ℃;

step 4, repeating the step 2 and the step 3 for 2-5 times, discharging, drying and crushing;

and 5, adding the calcium carbonate, the filtrate reducer, the fibers and the product obtained in the previous step into another stirrer, stirring at the speed of 200-300 rpm for 15-20 min, and discharging to obtain the fiber polymer plugging agent for the drilling fluid.

Technical Field

The invention relates to the technical field of petroleum drilling engineering plugging, in particular to a fiber polymer plugging agent for drilling fluid and a preparation method thereof.

Background

Lost circulation is one of the most serious complications affecting the safety of drilling operations. If the lost circulation is improperly controlled, well collapse, overflow, blowout and other downhole complications can be induced, and safety accidents are caused. How to effectively plug an underground leaking layer and ensure the normal operation of drilling construction is always the key point of research of scientific research and engineering personnel.

The most widely applied bridge plug plugging technology is currently used, and the used bridge plug plugging agent is mainly formed by mixing various mineral particles, shells, mica sheets, fibers and the like with different sizes. The bridge plug plugging technology has the characteristics of wide material source, low cost and simple construction process, and is favored by field personnel.

However, the bridge plug plugging technology needs to accurately master the size of the formation pore or the fracture, and the actual situation is that the underground situation is complicated and variable, and the size of the leaking layer cannot be accurately obtained, so that the matching difficulty of the conventional bridge plug plugging agent and the size of the leaking layer fracture is high.

Disclosure of Invention

The invention provides a fiber polymer plugging agent for drilling fluid, aiming at solving the problem of high difficulty in matching the size of the plugging agent and the size of a leak layer crack in the prior art, wherein the plugging agent has good compatibility with the size of the leak layer crack and good plugging effect.

The invention also provides a preparation method of the fiber polymer plugging agent for the drilling fluid, wherein a hydrated calcium silicate hard core layer is formed on the surface of the polymer in advance in the preparation method so as to improve the action effect under different fracture sizes.

The technical scheme adopted by the invention is as follows:

a fiber polymer plugging agent for drilling fluid comprises the following raw materials in parts by mass,

40-50 parts of a powdery polymer;

10-15 parts of fibers;

10-15 parts of calcium carbonate;

1-5 parts of a filtrate reducer;

5-10 parts of sodium silicate;

5-15 parts of calcium chloride;

0.5-1 part of dispersing agent.

Further, the polymer is one or more of polystyrene, polymethyl methacrylate, polyacrylamide, polyethylene vinyl acetate, acrylate copolymer, styrene and acrylate copolymer, and acrylamide and acrylate copolymer.

Further, the particle size of the polymer is 0.1-1 mm.

Further, the fiber is one or more of polyethylene fiber, polypropylene fiber, polyvinyl alcohol fiber, polyester fiber, polyacrylonitrile fiber, nylon fiber and lignin fiber.

Further, the length of the fiber is 3-5 mm, and the diameter of the fiber is 10-20 mu m.

Furthermore, the particle size of the calcium carbonate is 200-300 meshes.

Further, the fluid loss additive is one or more of sodium carboxymethyl cellulose and polyanionic cellulose.

Further, the dosage ratio of the sodium silicate to the calcium chloride is 1: 1 to 1.5.

Further, the dispersant is one of a naphthalene sulfonate formaldehyde condensate, a polycarboxylic acid copolymer, a lignosulfonate, or a naphthalene sulfonate formaldehyde condensate.

The preparation method of the fiber polymer plugging agent for the drilling fluid comprises the following steps,

step 1, adding a powdery polymer, sodium silicate, calcium chloride and a dispersing agent into a closed stirrer, continuously stirring for 5-10 min at a stirring speed of 100-200 rpm, and controlling the humidity in the stirrer to be below 10% and the temperature to be 50-60 ℃;

step 2, introducing atomized water into the closed stirrer, controlling the humidity in the stirrer to be 20-30%, controlling the temperature to be 50-60 ℃, intermittently stirring at the stirring speed of 100-200 rpm for 20-30 s, and stirring for 30-60 s each time;

step 3, stopping introducing atomized water after intermittent stirring for 10-15 min, continuing the intermittent stirring at a stirring speed of 100-200 rpm for 5-10 min, and controlling the temperature in the stirrer to be 50-60 ℃;

step 4, repeating the step 2 and the step 3 for 2-5 times, discharging, drying and crushing;

and 5, adding the calcium carbonate, the filtrate reducer, the fibers and the product obtained in the previous step into another stirrer, stirring at the speed of 200-300 rpm for 15-20 min, and discharging to obtain the fiber polymer plugging agent for the drilling fluid.

The invention has the beneficial effects that:

1. the invention provides a fiber polymer plugging agent for drilling fluid, which comprises powdery polymer, fiber, calcium carbonate, a filtrate reducer, sodium silicate, calcium chloride, a dispersing agent and the like. The plugging agent has good compatibility with the size of a leak layer crack, has strong bearing capacity, and can meet the plugging operation requirements of various stratum leakage cementing wells.

2. The invention provides a preparation method of a fiber polymer plugging agent for drilling fluid, which hydrates a calcium silicate hard shell layer on the surface of a polymer after sodium silicate and calcium chloride absorb water, wherein the surface of the hard shell layer is not smooth. When the crack size is larger, the polymer can form a stable bridge plug structure because the hard shell layers are mutually overlapped and reinforced by fibers, calcium carbonate and the like. The hard shell of the non-smooth surface also increases the friction between the polymers and the fracture wall, and can effectively reduce the scouring of the polymerization into the stratum. When the fracture size is small, the polymer itself is soft and does not adequately support the crust. Under the pressure, the hard shell layer is fractured, and the deformed polymer is pressed into the fracture to play a role in plugging. The disintegrated crust layer can also be used as a dispersing anchor point, and the stability of the polymer in cracks is increased. Meanwhile, the characteristic that sodium silicate is easy to absorb moisture is fully utilized, the humidity is controlled, and intermittent stirring is carried out, so that the forming process of hydrated calcium silicate is adjusted, and polymer agglomeration can be effectively reduced, and the use is influenced.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 is a schematic diagram of plugging principle of plugging agent.

Detailed Description

In the following, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.

Embodiments of the invention are described in detail below with reference to the accompanying drawings.

The preparation method of the fiber polymer plugging agent for the drilling fluid comprises the following steps,

step 1, adding a powdery polymer, sodium silicate, calcium chloride and a dispersing agent into a closed stirrer, continuously stirring for 5-10 min at a stirring speed of 100-200 rpm, and controlling the humidity in the stirrer to be below 10% and the temperature to be 50-60 ℃.

Wherein the polymer has a particle size of 0.1-1 mm and is one or more of polystyrene, polymethyl methacrylate, polyacrylamide, polyethylene vinyl acetate, acrylate copolymer, styrene and acrylate copolymer, and acrylamide and acrylate copolymer.

The fiber length is 3-5 mm, the diameter is 10-20 mu m, and the fiber is one or a combination of a plurality of polyethylene fibers, polypropylene fibers, polyvinyl alcohol fibers, polyester fibers, polyacrylonitrile fibers, nylon fibers and lignin fibers.

The dispersant is one of naphthalene sulfonate formaldehyde condensate, polycarboxylic acid copolymer, lignin sulfonate or naphthalene sulfonate formaldehyde condensate.

And 2, introducing atomized water into the closed stirrer, controlling the humidity in the stirrer to be 20-30%, controlling the temperature to be 50-60 ℃, intermittently stirring at the stirring speed of 100-200 rpm for 20-30 s, and stirring for 30-60 s each time.

And 3, stopping introducing the atomized water after intermittent stirring for 10-15 min, continuing the intermittent stirring at a stirring speed of 100-200 rpm for 5-10 min, and controlling the temperature in the stirrer to be 50-60 ℃.

And 4, repeating the step 2 and the step 3 for 2-5 times, discharging, drying and crushing.

And 5, adding the calcium carbonate, the filtrate reducer, the fibers and the product obtained in the previous step into another stirrer, stirring at the speed of 200-300 rpm for 15-20 min, and discharging to obtain the fiber polymer plugging agent for the drilling fluid.

Wherein the particle size of the calcium carbonate is 200-300 meshes.

The fluid loss additive is one or more of sodium carboxymethyl cellulose and polyanionic cellulose.

The plugging agents in examples 1 to 4 were prepared according to the above preparation method, and the raw material composition in each example is as shown in the following table.

Adding 3g of plugging agent into each 100ml of water-based drilling fluid, and adding the same amount of plugging agent in the embodiments 1-4 into the water-based drilling fluid retrieved on a certain site. The drilling fluid was tested for property changes and the results are shown in the table below.

From the comparative test results of the examples 1-4 and the blank group, it can be seen that the apparent viscosity, the dynamic shear force and the like are slightly increased after the plugging agent in the examples is added, which indicates that the addition of the plugging agent has little influence on the performance of the water-based drilling fluid, and the plugging agent has good compatibility with other additives and can meet the requirements of drilling operation.

Preparing six parts of base slurry, wherein three parts of base slurry are respectively added with the same amount of the plugging agent in the embodiment 3 and stirred for 20min to prepare the plugging slurry for later use.

And pouring 400mL of plugging slurry into a 20-40 mesh sand bed of an FA non-permeable filtration apparatus, slowly pressurizing to 0.7MPa, stabilizing the pressure for 30min, and immersing the filtrate to the depth of 5.0 cm.

And pouring 400mL of base slurry into a 20-40 mesh sand bed of an FA non-permeable filtration apparatus, slowly pressurizing to 0.7MPa, and stabilizing the pressure for 30min to completely filter.

2000mL of leaking stoppage slurry is added into a leaking stoppage simulation device, a 1mm crack template is used for a leaking stoppage module, nitrogen is used for slow pressurization, the pressure is increased to 7MPa, the pressure is stabilized for 30min, and the pressure drop is 1 MPa.

2000mL of leaking stoppage slurry is added into a leaking stoppage simulation device, a leaking stoppage module uses a 0.5mm crack template, nitrogen is used for slowly pressurizing to 7MPa, the pressure is stabilized for 30min, and the pressure drop is 0.3 MPa.

2000mL of base slurry is added into a plugging simulation device, a 1mm crack template is used for a plugging module, nitrogen is used for slow pressurization, the pressure is increased to 7MPa, the pressure cannot be stabilized, and the pressure is reduced to 0 MPa.

2000mL of base slurry is added into a plugging simulation device, a 0.5mm crack template is used for a plugging module, nitrogen is used for slow pressurization, the pressure is increased to 7MPa, the pressure cannot be stabilized, and the pressure is reduced to 0 MPa.

From the above detection results, the plugging agent in this embodiment has a good plugging effect on the uniformity of cracks with different sizes, and the plugging principle is as shown in fig. 1. After the sodium silicate and the calcium chloride absorb water, a calcium silicate hard shell layer is hydrated on the surface of the polymer, and the surface of the hard shell layer is not smooth. When the crack size is larger, the polymer can form a stable bridge plug structure because the hard shell layers are mutually overlapped and reinforced by fibers, calcium carbonate and the like. The hard shell of the non-smooth surface also increases the friction between the polymers and the fracture wall, and can effectively reduce the scouring of the polymerization into the stratum. When the fracture size is small, the polymer itself is soft and does not adequately support the crust. Under the pressure, the hard shell layer is fractured, and the deformed polymer is pressed into the fracture to play a role in plugging. The disintegrated crust layer can also be used as a dispersing anchor point, and the stability of the polymer in cracks is increased.