Plugging agent

Abstract

The utility model discloses a plugging agent and belongs to the technical field of chemical materials. The plugging agent is prepared from flaky polyethylene glycol terephthalate and at least one anchor type material compounded in the flaky polyethylene glycol terephthalate. The plugging agent facilitates delivery of a rigid anchor material to a leak passage without plugging a pipeline. Due to the fact that the strength of the sheet-shaped polyethylene glycol terephthalate is far smaller than that of the anchor type material, after the sheet-shaped polyethylene glycol terephthalate is conveyed to the leakage layer channel, the sheet-shaped polyethylene glycol terephthalate can be partially or completely broken due to pressure difference, or the sheet-shaped polyethylene glycol terephthalate is subjected to degradation reaction under the action of high-temperature and strong-alkalinity drilling fluid in the leakage layer channel, and therefore the anchor type material is partially or completely released. And the released anchor-type material is hung on the wall of the channel through an anchor hook in the leakage layer channel, so that the aim of leaking stoppage is fulfilled. According to the utility model, the plugging agent can smoothly reach a leakage layer channel and is subjected to physical separation or in-situ degradation, so that the anchor-type material is released for plugging.

Description

Technical Field

[0001] The utility model relates to the technical field of chemical materials, in particular to a plugging agent. Background Art

[0002] During oil drilling operations, lost circulation often occurs due to the presence of cracks or pores in the formation, low formation pressure coefficient, etc. Lost circulation is a global problem, especially the vicious loss in fractured formations, which not only loses drilling time, consumes a large amount of plugging and drilling fluid materials, damages oil and gas layers, affects geological logging, but also causes well collapse, drill stuck, and even wellbore scrapping and other engineering accidents, and may also lead to uncontrolled blowouts, thus causing safety and environmental accidents.

[0003] At present, the main plugging technology is bridging plugging technology, in which the bridging plugging material is mainly a mixture of conventional material particles such as walnut shells, fibers, and mica in a certain proportion. Due to the insufficient strength of plugging materials such as walnut shells, fibers, and mica, the particle size of these materials is difficult to match the width of the cracks and holes in the formation. If the particle size of the plugging material is too large, it cannot enter the crack. If the particle size of the plugging material is too small, it will completely leak with the fluid and cannot fundamentally solve the problem of plugging the leak. For severe leakage, the width of the crack is often greater than 3mm. Due to the insufficient strength of the plugging material, the plugging material will break under the pressure difference between the wellbore fluid column and the formation (usually greater than 1MPa), which will also cause plugging failure.

[0004] How to solve the problem that when there is serious leakage, the plugging material will flow out from the hole due to low friction, or the plugging material is weak and easy to break, is an important direction in the research and development of plugging materials.

[0005] CN112940694A discloses an environmentally friendly composite plugging liquid for water-based drilling fluid and a preparation method thereof, which comprises, by weight ratio: 20% to 30% of regular tetrahedral rigid material, 2% to 5% of hydrophobic associating polymer, 10% to 20% of water-swelling material, 10% to 20% of fiber material, and the balance is water. The regular tetrahedral rigid material is a rigid material of regular tetrahedral structure formed by limestone powder through compression molding. The plugging liquid has a good plugging effect. The regular tetrahedral rigid material can form a plugging layer with very low permeability in a simulated fracture of the formation in a short time and under the condition of small leakage, and the formed plugging layer can withstand a pressure of more than 10MPa. This verifies that the rigid material can achieve plugging and improve the pressure bearing capacity of the formation. However, the disadvantage is that the gaps between the regular tetrahedral rigid materials are large, resulting in poor bridging ability.

[0006] "Research Progress of Modified Thermosetting Resins and Their Application Prospects in the Field of Drilling Fluids", "Journal of China University of Petroleum: Natural Science Edition" 2022 Issue 2 discloses a plugging agent in which unsaturated polyester modified by nitrile rubber is mixed with rigid aggregate in a certain proportion. The plugging agent UPC enters the cracks under the action of the formation pressure difference, and the cured unsaturated polyester plays a "hanging resistance" role under the action of the formation temperature, making the rigid aggregate more likely to be retained and form a bridge, and the unsaturated polyester modified by nitrile rubber is squeezed into the small channel between the crack space and the rigid aggregate bridge through "heating deformation + extrusion filling". After a period of time, a plugged leakage channel of the overall concrete structure is formed, which improves the pressure-bearing capacity of the fractured formation. However, the friction between the rigid aggregate and the crack is small, which makes it easy for the plugging agent to be lost in large quantities.

[0007] Therefore, researching and developing a new type of plugging agent with less loss and less rupture is of great significance for oil drilling operations. Utility Model Content

[0008] In view of this, the technical problem to be solved by the utility model is to provide a plugging agent, wherein the plugging agent transports a rigid anchor material to the leaking layer channel to achieve plugging.

[0009] In order to achieve the above purpose, the technical solution adopted by the utility model is as follows:

[0010] The utility model provides a leak-proofing agent, which is composed of sheet-shaped polyethylene terephthalate and at least one anchor-type material compounded in the sheet-shaped polyethylene terephthalate.

[0011] The above-mentioned composite includes but is not limited to at least one anchor-type material being completely embedded in the sheet-shaped polyethylene terephthalate, at least one anchor-type material being half-embedded in the sheet-shaped polyethylene terephthalate, at least one anchor-type material being wrapped in the sheet-shaped polyethylene terephthalate, etc.

[0012] The sheet-like polyethylene terephthalate is obtained by heating and melting amorphous polyethylene terephthalate and then reshaping it.

[0013] During the use of the plugging agent, the anchor material is released and the anchor hook is hung on the wall of the leaking layer channel to achieve a plugging effect.

[0014] The sheet-like polyethylene terephthalate and the anchor material can be physically separated by pressure difference, or can be separated by chemical degradation in a high temperature and strong alkaline environment of the leaky layer, such as adding strong alkaline drilling fluid during drilling.

[0015] Preferably, the anchor material of the utility model is selected from a material having an anchor hook at one end or having anchor hooks at both ends.

[0016] The above anchor materials can be divided into:

[0017] There are n anchor hooks at only one end;

[0018] The n is ≥ 1 and is an integer;

[0019] There are m anchor hooks at each end;

[0020] The m is ≥ 1 and is an integer.

[0021] The anchor material in the plugging agent of the utility model is at least one of the above specific situations.

[0022] The length of the anchor material in the plugging agent of the utility model is adjusted according to the diameter of the pores of different leaking layers.

[0023] Preferably, the length of the anchor material is greater than 3 mm. In some specific embodiments of the present invention, the length is 10 mm.

[0024] Preferably, the thickness of the sheet of polyethylene terephthalate is 0.3 to 10 mm, more preferably 0.5 to 6 mm, and even more preferably 0.5 to 2 mm. In some specific embodiments of the present invention, the thickness of the sheet of polyethylene terephthalate is 1 mm.

[0025] Preferably, the volume ratio of the anchor material to the sheet-like polyethylene terephthalate is 5% to 30%.

[0026] The thickness of the anchor material is preferably 0.3 to 2 mm.

[0027] The thickness refers to the vertical height of the anchor material when it is laid flat.

[0028] Preferably, in the utility model, the anchor material is selected from one or more of iron wire, carbon steel and ceramics; more preferably, the anchor material is selected from iron wire.

[0029] Preferably, in the present invention, the sheet-like polyethylene terephthalate is selected from one or more of circular polyethylene terephthalate, elliptical polyethylene terephthalate, polygonal polyethylene terephthalate, and irregular polyethylene terephthalate; more preferably, the sheet-like polyethylene terephthalate is selected from elliptical polyethylene terephthalate.

[0030] Preferably, the thickness of the sheet of polyethylene terephthalate is 0.3 to 10 mm, more preferably 0.5 to 6 mm, and even more preferably 0.5 to 2 mm. In some specific embodiments of the present invention, the thickness of the sheet of polyethylene terephthalate is 1 mm.

[0031] The utility model provides a method for preparing a plugging agent, comprising the following steps:

[0032] The amorphous polyethylene terephthalate slice and the anchor material are mixed, and then the mixture is heated and pressurized to shape, so that the anchor material is compounded in the sheet-like amorphous polyethylene terephthalate to prepare a plugging agent. The mixing is preferably to place the amorphous polyethylene terephthalate slice on the surface of the anchor material.

[0033] The plugging agent of the utility model is compositely formed by flaky polyethylene terephthalate and anchor-type material.

[0034] The anchor material is bonded and fixed by a sheet of hot-melt plastic polyethylene terephthalate, so it is not easy to loosen at normal temperature and pressure, which is conducive to the storage and use of the plugging agent.

[0035] The amorphous polyethylene terephthalate slices in the above preparation method refer to the flake particles of the processed amorphous polyethylene terephthalate.

[0036] The amorphous polyethylene terephthalate slice in the utility model is a common commercial product. The size of the amorphous polyethylene terephthalate slice is 4mm×4mm×2.5mm. It is purchased from Sinopec Corporation and is a fiber-grade polyester, a bright polyester slice BRN-204 model.

[0037] Preferably, in the preparation method, the heating is performed by placing the mixture between two metal plates, and only one metal plate is used to heat the mixture.

[0038] The above-mentioned heating adopts only one metal plate to heat the mixture, the purpose of which is to prevent the amorphous polyethylene terephthalate slices from adhering to the metal plate after being heated, resulting in the inability to remove the plugging agent.

[0039] Preferably, the heating temperature is 120°C to 200°C; more preferably 140°C to 180°C.

[0040] The heating and pressurizing shaping method in the above preparation method is preferably:

[0041] The mixture of the amorphous polyethylene terephthalate slice and the anchor material is heated and pressurized to shape by using upper and lower metal plates.

[0042] The temperature of the upper metal plate is preferably 120°C to 200°C, more preferably 140°C to 180°C, and further preferably 150°C to 170°C. In some specific embodiments of the present invention, 170°C is preferred.

[0043] The temperature of the lower metal plate is preferably room temperature.

[0044] The normal temperature is preferably 10°C to 30°C.

[0045] The mixture of the amorphous polyethylene terephthalate slice and the anchor material is placed between the upper and lower metal plates.

[0046] The heating and pressurizing shaping method prevents the polyethylene terephthalate and the metal plate from adhering to each other, making it easy to remove after shaping.

[0047] The metal plate is preferably an iron plate.

[0048] The smooth surface of the iron plate is preferably a polished carbon steel surface.

[0049] Through the shaping method, a leak-proofing agent sheet with a thickness of 0.3 to 10 mm is obtained under the condition of being lower than the melting point of polyethylene terephthalate, and the sheet can be taken out smoothly without adhesion.

[0050] The utility model also provides the use of the plugging agent or the plugging agent prepared by the preparation method in oil drilling, bridge construction and reservoir dam construction.

[0051] The plugging agent of the utility model is used in oil drilling. After the plugging material is delivered to the leaking layer at the bottom of the well, the plugging agent enters the holes or cracks under the pressure difference between the wellbore liquid column and the leaking layer.

[0052] The size of the anchor material can be adjusted according to the size of the hole or crack, so that the size of the anchor material matches the size of the hole or crack.

[0053] Then, under the pressure difference between the wellbore and the leaking layer, the sheet-like polyethylene terephthalate in the plugging agent is partially or completely broken due to its low strength, thereby releasing the anchor material.

[0054] Then, the released anchor material moves in the leakage layer channel until the anchor hook of the anchor material is hung on the wall of the leakage layer channel.

[0055] The above-mentioned anchor hook is similar to the barb principle of a fishhook and can firmly block the leakage layer channel.

[0056] The polyethylene terephthalate is easily hydrolyzed in an alkaline environment at a temperature above 100°C.

[0057] In oil drilling operations, the downhole temperature at depths of more than 1,000 meters is usually over 100°C, which is conducive to the in-situ degradation of polyethylene terephthalate to release the anchor material.

[0058] Finally, the anchor material that has lost its restraint can effectively plug the underground leaks.

[0059] The utility model also provides a composite plugging agent, wherein the composite plugging agent is one or more of walnut shell particles, cotton seed particles, sawdust, calcium carbonate particles, rubber particles, and mica compounded in the above plugging agent.

[0060] The compounding includes but is not limited to encapsulation, complete embedding or partial embedding, etc.

[0061] Preferably, the wrapping is completely or partially wrapped on the surface of the above-mentioned plugging agent.

[0062] Preferably, the entire wrapping is wrapping the entire surface of the plugging agent.

[0063] Preferably, the partial wrapping is wrapping a part of the surface of the flaky polyethylene terephthalate in the plugging agent. Preferably, the complete embedding is that one or more of the walnut shell particles, cotton seed particles, sawdust, calcium carbonate particles, rubber particles, and mica are completely embedded in the flaky polyethylene terephthalate.

[0064] Preferably, the partial embedding is one or more of the above-mentioned walnut shell particles, cotton seed particles, sawdust, calcium carbonate particles, rubber particles, and mica partially embedded in the flaky polyethylene terephthalate.

[0065] One or more of the walnut shell particles, cotton seed particles, sawdust, calcium carbonate particles, rubber particles and mica in the composite plugging agent are fixed together by bonding with hot-melt plastic polyethylene terephthalate.

[0066] The composite plugging agent is delivered to the leaking layer at the bottom of the well, and its working principle is the same as that of the above-mentioned plugging agent.

[0067] Under the pressure difference between the wellbore and the leaking layer, the flaky polyethylene terephthalate in the composite plugging agent and one or more of the walnut shell particles, cotton seed particles, sawdust, calcium carbonate particles, rubber particles, and mica composited on its surface are partially or completely broken due to low strength, thereby releasing the anchor material.

[0068] Then, the released anchor material moves in the leaking layer channel until the anchor hook of the anchor material is hung on the wall of the leaking layer channel, thereby achieving the plugging purpose of the composite plugging agent.

[0069] The combination of the above materials and the plugging agent described in the utility model can significantly improve the plugging effect.

[0070] Compared with the prior art, the plugging agent provided by the utility model is composed of a sheet of polyethylene terephthalate and at least one anchor material compounded in the sheet of polyethylene terephthalate. The plugging agent is conducive to transporting the rigid anchor material to the leaking layer channel without blocking the pipeline. Since the strength of the sheet of polyethylene terephthalate is much smaller than that of the anchor material, after being transported to the leaking layer channel, the sheet of polyethylene terephthalate will be partially or completely broken due to the pressure difference, or will undergo a degradation reaction under the action of the high temperature and strong alkaline drilling fluid in the leaking layer channel, thereby partially or completely releasing the anchor material. The released anchor material is in the leaking layer channel and is hung on the channel wall by an anchor hook to achieve the purpose of plugging. The utility model achieves the purpose of the plugging agent smoothly reaching the leaking layer channel, and releasing the anchor material for plugging through physical separation or in-situ degradation. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] Figure 1 The figure is a diagram of the preparation process of the plugging agent of Example 1, wherein 1 is an upper heated iron plate, 2 is an amorphous polyethylene terephthalate slice, 3 is an anchor material containing an anchor hook, and 4 is a lower normal temperature iron plate;

[0072] Figure 2 It is a top view of the structure of the plugging agent prepared in Example 1, wherein 5 is an anchor material containing an anchor hook, and 6 is an oval polyethylene terephthalate;

[0073] Figure 3 This is a diagram of an anchor material with two anchor hooks in Example 2. DETAILED DESCRIPTION

[0074] In order to further illustrate the utility model, the plugging agent provided by the utility model and its preparation method and application are described in detail below in conjunction with embodiments.

[0075] Production method Figure 1 As shown, the anchor material and the amorphous polyethylene terephthalate slices are placed together, and two metal plates at a certain temperature are used to flatten the slices and the anchor material. The appropriate temperature selection prevents the plates and the plugging agent from sticking together, making it easy to remove the plugging agent from between the two plates.

[0076] Example 1

[0077] The anchor material is a 10mm long, 1mm diameter wire. There is a 2mm long protruding hook at one end of the wire, similar to the principle of a fishhook barb. Figure 1As shown, put the 4mm×4mm×2.5mm amorphous PET slice and anchor material together, then press the upper iron plate heated to 170℃, and the lower iron plate is at room temperature. Press for 1 second to form a thin sheet, white and translucent plugging bridge agent. After the PET resin is flattened, a sheet with a thickness of about 1mm is obtained. The anchor material and the PET resin sheet are compounded together without looseness to prepare the plugging agent of the present invention, with a structure as shown Figure 2 As shown, the plugging agent structure is an anchor material with an anchor hook at one end compounded in an oval polyethylene terephthalate (PET). The volume ratio of the anchor material to the oval polyethylene terephthalate is 20:100.

[0078] Example 2

[0079] The anchor material is a 10mm long, 1mm diameter iron wire. There is a 2mm long protruding hook at each end of the iron wire. Figure 3 The manufacturing process of the product of the present invention is as shown in Figure 1 As shown, put the 4mm×4mm×2.5mm amorphous PET slices and anchor materials together, and then press down the upper iron plate heated to 170°C, while the lower iron plate is at room temperature. Press it once and it will become a thin sheet in 1 second, white and translucent. After the resin is flattened, a sheet with a thickness of about 1mm is obtained. The composite sheet will not stick to the iron plate and can be easily removed. The anchor material and the resin are compounded together without looseness to prepare the plugging agent of the present invention, wherein the plugging agent has a structure in which an anchor material with an anchor hook at each end is compounded in an elliptical polyethylene terephthalate. The volume ratio of the anchor material to the elliptical polyethylene terephthalate is 15:100. The anchor structure in the plugging agent is as follows Figure 3 shown.

[0080] Comparative Example 1

[0081] Stack amorphous polyethylene terephthalate resin slices and a wire anchor material containing an anchor hook between two iron plates. The lower iron plate is 170°C and the upper iron plate is 170°C. Press them and they will become thin sheets in 1 second. They are white and translucent, but they stick to the iron plates and are difficult to separate physically.

[0082] The above embodiments are only used to help understand the method and core idea of ​​the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A plugging agent, characterized in that: The invention is composed of a sheet of polyethylene terephthalate and at least one anchor-type material compounded in the sheet of polyethylene terephthalate.

2. The plugging agent according to claim 1, characterized in that: The anchor material is selected from a material having an anchor hook at one end or having anchor hooks at both ends.

3. The plugging agent according to claim 1, characterized in that: The length of the anchor material is greater than 3 mm; The thickness of the sheet-like polyethylene terephthalate is 0.3-10 mm.

4. The plugging agent according to claim 1, characterized in that: The volume ratio of the anchor material to the sheet-shaped polyethylene terephthalate is 5% to 30%.

5. The plugging agent according to claim 1, characterized in that: The anchor material is selected from iron wire, carbon steel or ceramics.

6. The plugging agent according to claim 1, characterized in that: The sheet-shaped polyethylene terephthalate is selected from circular polyethylene terephthalate, elliptical polyethylene terephthalate, polygonal polyethylene terephthalate or irregular polyethylene terephthalate.

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