CN110564383A - Rigid plugging agent for drilling fluid and preparation method thereof - Google Patents

Abstract

The invention discloses a rigid plugging agent for drilling fluid and a preparation method thereof, wherein the rigid plugging agent comprises the following components in parts by weight: 2-6 parts of walnut shells, 2-7 parts of calcite, 0.8-2.4 parts of sawdust, 1-2 parts of polypropylene fibers and 1.2-2.7 parts of elastic particles. The invention also provides a preparation method of the rigid plugging agent. The invention effectively solves the problems of poor bearing capacity and plugging effect of the plugging agent, easy leakage, high production cost and low cost performance.

Description

Rigid plugging agent for drilling fluid and preparation method thereof

Technical Field

The invention relates to the technical field of plugging agents, and particularly relates to a rigid plugging agent for drilling fluid and a preparation method thereof.

Background

Downhole loss is the phenomenon that during the operation of an oil and gas well, working fluids such as drilling fluid, cement slurry, workover fluid and the like in a shaft enter an underground high permeability zone, a hole stratum and a natural or induced stratum fracture. Downhole loss can result in: blowout caused by the reduction of the liquid column pressure; causing downhole stuck drill; reservoir damage is aggravated, and well cementation quality is affected; the well drilling period is prolonged, the cost is increased, and the oil well is scrapped if the oil well is serious. The annual global cost for leak protection and plugging of wells is as high as $ 8 billion, and no other cost for dealing with other downhole accidents caused by lost circulation is included. The complex drilling leakage phenomenon is more and more prominent along with the trend of the exhaustion of oil and gas fields in part of old areas at home and abroad.

downhole loss, whether in land or marine drilling environments, has long been a common problem with oil drilling, particularly for lost circulation complex well conditions. At present, the problem of underground leakage is solved by using a common plugging agent, the types of the conventional plugging agents are few, the conventional plugging agents can be divided into single agents and complexing agents according to the composition types of the plugging agents, and when the single agents are used for plugging, the bearing capacity and the plugging effect are poor and need to be improved. Particularly for the leakage of complex lost circulation, the existing plugging agent is difficult to meet the plugging requirement, so that the improvement of the complex treatment efficiency of the lost circulation is restricted, and the plugging agent becomes one of the main technical bottlenecks restricting the oil and gas exploration and development speed. Meanwhile, the production cost is high, so that the cost performance is reduced, and the wide use of the plugging agent is limited.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides a rigid plugging agent for drilling fluid and a preparation method thereof, which effectively solve the problems of poor bearing capacity and plugging effect, easy leakage, high production cost and low cost performance of the plugging agent.

In order to achieve the purpose, the technical scheme adopted by the invention for solving the technical problems is as follows: the rigid plugging agent for the drilling fluid comprises the following components in parts by weight: 2-6 parts of walnut shells, 2-7 parts of calcite, 0.8-2.4 parts of sawdust, 1-2 parts of polypropylene fibers and 1.2-2.7 parts of elastic particles.

Further, the plugging agent comprises the following components in parts by weight: 4 parts of walnut shells, 5 parts of calcite, 1.6 parts of sawdust, 1.5 parts of polypropylene fibers and 2 parts of elastic particles.

further, the rigid plugging agent also comprises 1-5 parts of an adsorbent.

further, the adsorbent is 20-40 mesh diatomite.

Furthermore, the mesh number of the walnut shells is 20-60 meshes, the mesh number of the calcite is 40-80 meshes, and the mesh number of the elastic particles is 20-40 meshes.

Further, the elastic particles are polyurethane particles, polyvinyl chloride particles or a mixture of the polyurethane particles and the polyvinyl chloride particles.

Further, the mixture is formed by mixing polyurethane particles and polyvinyl chloride particles according to the mass ratio of 1: 1.

Furthermore, the diameter of the polypropylene fiber is 0.4-0.8 mm, and the length is 2-7 mm.

the preparation method of the rigid plugging agent for the drilling fluid comprises the following steps:

(1) sequentially stirring and uniformly mixing walnut shells, calcite, sawdust and polypropylene fibers at the rotating speed of 100-300 r/min to obtain a mixture;

(2) And (2) adding the elastic particles into the mixture obtained in the step (1), and uniformly stirring at the rotating speed of 60-90 r/min to obtain the rigid plugging agent.

In summary, the invention has the following advantages:

1. The leak stopping agent is prepared from walnut shells, calcite, sawdust, polypropylene fibers and elastic particles, has good pressure resistance and temperature resistance, can reduce leakage loss and plugging times, has large pressure bearing capacity, can enlarge a safe density window, can reduce loss of well cementing liquid, and can ensure the well cementing construction quality to the greatest extent; meanwhile, all the raw materials are easily available, the production cost can be reduced, the cost performance is improved, and the problems of poor bearing capacity and plugging effect of the plugging agent, easiness in leakage, high production cost and low cost performance are effectively solved.

2. When the plugging agent is used, the plugging agent can be used for bridging and filling in a crack in a short time to form a low-permeability and high-strength plugging layer, the plugging layer enables drilling fluid to be prevented from being percolated out and cannot be completely supplemented, the crack induction effect disappears, the crack is not expanded, the plugging layer can bear larger fluid pressure and rock closing stress effect, the pressure-bearing and leakage-proof effects are guaranteed, and the using effect is better.

3. When the walnut shells and the acid-soluble calcite are used, cracks are plugged, particles bridge at the narrow part of the cracks, the following particles stop moving when meeting the front particles, and the cracks are stacked to complete plugging of the cracks; sawdust can be filled between walnut shells and the like to finish the plugging of cracks, so that the cracks are not expanded any more, and the plugging effect is enhanced; the polypropylene fiber is easy to form a bridge at a crack by matching the length of the polypropylene fiber, and other fibers are mutually dragged to form a net rack structure with a compact structure, so that the stability of the plugging layer is enhanced, and meanwhile, the filling of materials such as sawdust and the like is facilitated, and the plugging is completed; the elastic particles enter the crack after deformation, and because the deformed elastic particles generate friction force at the crack, the stability of the blocking layer can be enhanced, the blocking layer is prevented from wholly sliding along with the increase of pressure, and blocking is difficult to form at the crack. The adsorbent diatomite can enhance the adsorption capacity during bridging, so that all plugging components are quickly accumulated at the cracks to form plugging layers at the cracks, and the plugging work is completed.

Detailed Description

example 1

A rigid plugging agent for drilling fluid comprises the following components in parts by weight: 2 parts of walnut shells of 20 meshes, 2 parts of calcite of 40 meshes, 0.8 part of sawdust, 1 part of polypropylene fiber with the diameter of 0.4mm and the length of 2mm and 1.2 parts of polyurethane particles of 20 meshes.

The preparation method of the rigid plugging agent for the drilling fluid comprises the following steps:

(1) Sequentially stirring and uniformly mixing walnut shells, calcite, sawdust and polypropylene fibers at the rotating speed of 100r/min to obtain a mixture;

(2) And (2) adding polyurethane particles into the mixture obtained in the step (1), and uniformly stirring at the rotating speed of 60r/min to obtain the rigid plugging agent.

Example 2

A rigid plugging agent for drilling fluid comprises the following components in parts by weight: 4 parts of walnut shells of 40 meshes, 5 parts of calcite of 60 meshes, 1.6 parts of sawdust, 1.5 parts of polypropylene fibers with the diameter of 0.6mm and the length of 5mm and 2 parts of polyvinyl chloride particles of 30 meshes.

The preparation method of the rigid plugging agent for the drilling fluid comprises the following steps:

(1) sequentially stirring and uniformly mixing walnut shells, calcite, sawdust and polypropylene fibers at the rotating speed of 200r/min to obtain a mixture;

(2) And (2) adding the polyvinyl chloride particles into the mixture obtained in the step (1), and uniformly stirring at the rotating speed of 70r/min to obtain the rigid plugging agent.

example 3

A rigid plugging agent for drilling fluid comprises the following components in parts by weight: 4 parts of walnut shells of 40 meshes, 5 parts of calcite of 60 meshes, 1.6 parts of sawdust, 1.5 parts of polypropylene fibers with the diameter of 0.6mm and the length of 5mm, 2 parts of polyurethane particles of 30 meshes and 3 parts of diatomite of 30 meshes.

the preparation method of the rigid plugging agent for the drilling fluid comprises the following steps:

(1) Sequentially stirring and uniformly mixing walnut shells, calcite, sawdust, polypropylene fibers and diatomite at the rotating speed of 200r/min to obtain a mixture;

(2) And (2) adding polyurethane particles into the mixture obtained in the step (1), and uniformly stirring at the rotating speed of 70r/min to obtain the rigid plugging agent.

Example 4

A rigid plugging agent for drilling fluid comprises the following components in parts by weight: 4 parts of walnut shells of 40 meshes, 5 parts of calcite of 60 meshes, 1.6 parts of sawdust, 1.5 parts of polypropylene fibers with the diameter of 0.6mm and the length of 5mm and 2 parts of elastic particles of 30 meshes. The elastic particles are a mixture formed by mixing polyurethane particles and polyvinyl chloride particles according to the mass ratio of 1: 1.

the preparation method of the rigid plugging agent for the drilling fluid comprises the following steps:

(1) Sequentially stirring and uniformly mixing walnut shells, calcite, sawdust and polypropylene fibers at the rotating speed of 200r/min to obtain a mixture;

(2) And (2) adding the elastic particles into the mixture obtained in the step (1), and uniformly stirring at the rotating speed of 70r/min to obtain the rigid plugging agent.

Example 5

A rigid plugging agent for drilling fluid comprises the following components in parts by weight: 6 parts of walnut shells of 60 meshes, 7 parts of calcite of 80 meshes, 2.4 parts of sawdust, 2 parts of polypropylene fibers with the diameter of 0.8mm and the length of 7mm and 2.7 parts of polyurethane particles of 40 meshes.

The preparation method of the rigid plugging agent for the drilling fluid comprises the following steps:

(1) Sequentially stirring and uniformly mixing walnut shells, calcite, sawdust and polypropylene fibers at the rotating speed of 300r/min to obtain a mixture;

(2) and (2) adding polyurethane particles into the mixture obtained in the step (1), and uniformly stirring at the rotating speed of 90r/min to obtain the rigid plugging agent.

Example 6

A rigid plugging agent for drilling fluid comprises the following components in parts by weight: 4 parts of walnut shells of 40 meshes, 5 parts of calcite of 60 meshes, 1.6 parts of sawdust, 1.5 parts of polypropylene fibers with the diameter of 0.6mm and the length of 5mm, 2 parts of elastic particles of 30 meshes and 3 parts of diatomite of 30 meshes. The elastic particles are a mixture formed by mixing polyurethane particles and polyvinyl chloride particles according to the mass ratio of 1: 1.

The preparation method of the rigid plugging agent for the drilling fluid comprises the following steps:

(1) Sequentially stirring and uniformly mixing walnut shells, calcite, sawdust, polypropylene fibers and diatomite at the rotating speed of 200r/min to obtain a mixture;

(2) and (2) adding the elastic particles into the mixture obtained in the step (1), and uniformly stirring at the rotating speed of 70r/min to obtain the rigid plugging agent.

The pressure-bearing values and the leakage amounts of the rigid plugging agents obtained in examples 1 to 6 were measured, and the results are shown in table 1.

TABLE 1 statistical table of pressure-bearing value and leakage quantity of rigid plugging agent

	bearing pressure/MPa	leakage/mL
			Example 1	6	280
Example 2	11	215
			Example 3	17	110
example 4	18	100
			Example 5	13	170
Example 6	19	80

As can be seen from Table 1, the rigid plugging agents provided in the embodiments 1 to 6 have good pressure resistance, can bear 6 to 19MPa of pressure, have good leakage-proof effect, and effectively reduce the leakage amount due to pressure resistance; meanwhile, all the raw materials of the rigid plugging agent are easy to obtain, so that the production cost can be reduced, the cost performance is improved, and the problems of poor bearing capacity and plugging effect, easiness in leakage, high production cost and low cost performance of the plugging agent are effectively solved.

Comparative example

a lipophilic rigid particle plugging agent comprises the following components: high-pressure polyethylene, polyvinyl acetate, asphalt, marble, limestone and ceramsite. The preparation method comprises the following steps: firstly, heating a reaction kettle to 70 ℃, and removing air in the reaction kettle by using nitrogen; secondly, sequentially adding the required amounts of high-pressure polyethylene, polyvinyl acetate and asphalt under stirring, heating to 150-180 ℃, and stirring at constant temperature for 30-120 min; then sequentially adding marble, limestone, asphalt and ceramsite in required amount under stirring, cooling to 120 ℃, adding chlorine dioxide, stirring at constant temperature for 30-120 min, cooling to 90 ℃, discharging, and finally sieving to obtain the lipophilic rigid particle plugging agent.

The rigid plugging agent obtained by the comparative example has the characteristic of lipophilicity, but has more components and higher relative cost, increases the production cost to a certain extent, and reduces the cost performance; meanwhile, the plugging agent of the comparative example is lack of elastic particle components, a plugging layer formed at a crack is easy to slip along with the increase of pressure, plugging is difficult to form, and the plugging effect is influenced. The invention introduces elastic particles to increase the friction force between the plugging layer and the crack after deformation, and the plugging effect is better without slippage.

While the present invention has been described in detail with reference to the specific embodiments thereof, it should not be construed as limited by the scope of the present patent. Various modifications and changes may be made by those skilled in the art without inventive step within the scope of the appended claims.

Claims (9)

1. The rigid plugging agent for the drilling fluid is characterized by comprising the following components in parts by weight: 2-6 parts of walnut shells, 2-7 parts of calcite, 0.8-2.4 parts of sawdust, 1-2 parts of polypropylene fibers and 1.2-2.7 parts of elastic particles.

2. The rigid plugging agent for drilling fluid as claimed in claim 1, which comprises the following components in parts by weight: 4 parts of walnut shells, 5 parts of calcite, 1.6 parts of sawdust, 1.5 parts of polypropylene fibers and 2 parts of elastic particles.

3. the rigid plugging agent for drilling fluid as claimed in claim 1 or 2, wherein the rigid plugging agent further comprises 1-5 parts of an adsorbent.

4. The rigid plugging agent for drilling fluid as claimed in claim 3, wherein the adsorbent is 20-40 mesh diatomite.

5. The rigid plugging agent for drilling fluid as claimed in claim 1 or 2, wherein the walnut shell mesh number is 20-60 meshes, the calcite mesh number is 40-80 meshes, and the elastic particle mesh number is 20-40 meshes.

6. The rigid plugging agent for drilling fluid according to claim 1, 2 or 5, wherein the elastic particles are polyurethane particles, polyvinyl chloride particles or a mixture of the polyurethane particles and the polyvinyl chloride particles.

7. The rigid plugging agent for drilling fluid as claimed in claim 6, wherein the mixture is a mixture of polyurethane particles and polyvinyl chloride particles mixed according to a mass ratio of 1: 1.

8. The rigid plugging agent for drilling fluid as claimed in claim 1 or 2, wherein the diameter of the polypropylene fiber is 0.4-0.8 mm, and the length is 2-7 mm.

9. The preparation method of the rigid plugging agent for the drilling fluid, which is characterized by comprising the following steps of:

(1) Sequentially stirring and uniformly mixing walnut shells, calcite, sawdust and polypropylene fibers at the rotating speed of 100-300 r/min to obtain a mixture;

(2) And (2) adding the elastic particles into the mixture obtained in the step (1), and uniformly stirring at the rotating speed of 60-90 r/min to obtain the rigid plugging agent.