Liquid rubber plug and method for plugging underground annulus by using liquid rubber plug

Abstract

The invention discloses a liquid rubber plug which is characterized by comprising hard rubber and soft rubber, wherein the hard rubber is prepared from the following components in parts by weight: 25 to 30 parts of a base solution I, 5 to 10 parts of a base solution II, 1 to 10 parts of glass fibers, 0.15 to 0.5 part of a curing agent, 0.3 to 0.5 part of heptanal oxime and 0.01 to 0.05 part of an inhibitor; the flexible glue is prepared from the following components in parts by weight: 25 to 30 parts of base liquid I, 5 to 10 parts of base liquid II, 0.15 to 0.5 part of curing agent, 0.3 to 0.5 part of heptanal oxime and 0.01 to 0.05 part of inhibitor. The method for plugging the underground annulus through the liquid rubber plug comprises the following steps that 1, hard rubber slurry and soft rubber slurry are prepared; 2, the hard rubber slurry is pumped into the underground annulus, and a hard rubber supporting layer is formed in the underground annulus after the hard rubber slurry is solidified; and 3, the soft rubber slurry enters the underground annulus, so that a soft rubber sealing layer is formed above the hard rubber supporting layer. When the device is used, the limiting conditions of a shaft structure are few, and the device is generally suitable for casing pipe and oil pipe environments of various wells and can also be used in annuluses among various casing pipes no matter new wells or old wells.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of plugging materials, in particular to a liquid rubber plug and a method for plugging a downhole annulus using the liquid rubber plug. BACKGROUND

[0002] In the process of oil and gas exploitation and production, temporary isolation of the wellbore or production layer is often required for various reasons, and then these temporary isolations are conveniently removed in subsequent operations to restore the communication with the production layer and continue production. In addition, in some wells containing H2S or CO2, in order to protect the wellhead, a temporary barrier is sometimes established in the well during completion or workover operations, so that these harmful gases do not corrode and harm the wellhead or devices (such as hangers) on the wellhead.

[0003] The traditional method is to establish a downhole physical barrier, such as various cast iron, bridge plugs, packers, etc. These packers are lowered into the well through drill pipe, coiled tubing or wireline operations to a certain position, and the physical barriers are anchored by embedding metal teeth into the casing or tubing. With the development of technology, these physical barriers can also be recovered by special downhole tools, so that they can be removed from the well when needed. Although the technology of physical barriers is mature, there are still many limitations and disadvantages in use, as follows:

[0004] 1. The fixed size of the general casing is used, and many non-standard casings or small size oil casings cannot find related products.

[0005] 2. The requirements for the integrity and regularity of the wellbore are high. If the oil casing in the wellbore has slight deformation or there is some necking design above the lowered position, it cannot be lowered to the specified position. In addition, some well conditions, such as annulus, require to lower the screen packer to the annulus or high angle wells, etc. cannot be constructed.

[0006] 3. Lowering and taking out need to be brought in by wireline, coiled tubing or drill pipe, which requires the support of large equipment. Many production wells cannot install these equipment on the well due to site limitations. And the mobilization and installation of large equipment is time-consuming and laborious, and the construction cost is relatively high.

[0007] 4. Since it is mechanically lowered and taken out, it requires good well conditions. If the casing is corroded or scaled, or there are many residues in the wellbore, etc. mechanical problems such as sticking, failure to set, and failure to take out are easy to occur.

[0008] 5, Once the problem occurs, the subsequent processing is very troublesome and the downhole falling fish is easy to appear, thereby blocking the wellbore, and the subsequent drilling and grinding or fishing operations are required, which are high in technical difficulty, high in risk and high in cost. SUMMARY

[0009] The present application aims to solve the above problems and provide a liquid rubber plug and a method for sealing the downhole annulus by using the liquid rubber plug.

[0010] The present application is achieved by the following technical scheme: a liquid rubber plug, comprising hard glue and soft glue; wherein the hard glue comprises the following components by weight: base fluid one 25-30 parts, base fluid two 5-10 parts, glass fiber 1-10 parts, curing agent 0.15-0.5 parts, heptanal oxime 0.3-0.5 parts, inhibitor 0.01-0.05 parts;

[0011] The soft glue comprises the following components by weight: base fluid one 25-30 parts, base fluid two 5-10 parts, curing agent 0.15-0.5 parts, heptanal oxime 0.3-0.5 parts, inhibitor 0.01-0.05 parts.

[0012] The base fluid one comprises one or more of acrylamide and polyacrylamide fiber.

[0013] The base fluid two comprises one or more of polyacrylic acid-acrylamide and diacetone acrylamide.

[0014] The curing agent comprises one or more of sodium chloride and sodium hypochlorite.

[0015] The inhibitor comprises one or more of 2-ethyl-4-methoxyphenol and 2-iodo-4-methoxyphenol.

[0016] The present application also discloses a method for sealing the downhole annulus by using the above-mentioned liquid rubber plug, comprising the following steps:

[0017] Step 1: mix and stir 25-30 parts of base fluid one, 5-10 parts of base fluid two, 1-10 parts of glass fiber, 0.15-0.5 parts of curing agent, 0.3-0.5 parts of heptanal oxime and 0.01-0.05 parts of inhibitor and dissolve them in clean water to prepare a hard glue slurry; mix and stir 25-30 parts of base fluid one, 5-10 parts of base fluid two, 0.15-0.5 parts of curing agent, 0.3-0.5 parts of heptanal oxime and 0.01-0.05 parts of inhibitor and dissolve them in clean water to prepare a soft glue slurry;

[0018] Step 2: pump the hard glue slurry into the downhole annulus, and form a hard glue supporting layer in the downhole annulus after the hard glue slurry solidifies;

[0019] Step 3: pump the soft glue slurry into the downhole annulus, thereby forming a soft glue sealing layer above the hard glue supporting layer.

[0020] Compared with the prior art, the application has the following beneficial effects:

[0021] (1) The application has fewer restrictions on the wellbore structure when used, is universally applicable to casing and tubing environments of various types of wells, and can be used in annuli between various casings, whether in new wells or old wells.

[0022] (2) The application can be simply sent downhole without the assistance of large equipment, and the overall process is simple and easy to implement, especially for many small production well sites, which can still be smoothly implemented. BRIEF DESCRIPTION OF DRAWINGS

[0023] The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and serve to explain the principles of the application. In the drawings, the same reference symbols refer to the same components. Of the drawings,

[0024] Figure 1 The soft glue of the application has a gluing effect.

[0025] Figure 2 The hard glue of the application has a gluing effect.

[0026] Figure 3 The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and serve to explain the principles of the application. In the drawings, the same reference symbols refer to the same components. Of the drawings,

[0027] Figure 4 The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and serve to explain the principles of the application. In the drawings, the same reference symbols refer to the same components. Of the drawings, DETAILED DESCRIPTION

[0028] Embodiment 1

[0029] The liquid plug of the present embodiment comprises hard glue and soft glue; wherein the hard glue comprises the following components by weight: base fluid one 25 parts, base fluid two 10 parts, glass fiber 10 parts, curing agent 0.5 parts, heptanal oxime 0.5 parts, inhibitor 0.01 parts.

[0030] The soft glue comprises the following components by weight: base fluid one 25 parts, base fluid two 10 parts, curing agent 0.15 parts, heptanal oxime 0.3 parts, inhibitor 0.01 parts.

[0031] The base fluid one is acrylamide, the base fluid two is polyacrylic acid-acrylamide, the curing agent is sodium chloride, and the inhibitor is 2-ethyl-4-methoxyphenol.

[0032] The method for plugging the downhole annulus using the liquid plug described above comprises the following steps:

[0033] Step 1: Mix 25 parts of base liquid one, 10 parts of base liquid two, 10 parts of glass fiber, 0.5 parts of curing agent, 0.5 parts of heptanal oxime, and 0.01 parts of inhibitor, stir for 50 minutes, and dissolve in water to obtain a solution with a density of 1.3 kg / m³. 3 A rigid adhesive mortar was prepared; 25 parts of base liquid one, 10 parts of base liquid two, 0.15 parts of curing agent, 0.3 parts of heptanal oxime, and 0.01 parts of inhibitor were mixed and stirred to dissolve in water to obtain a mortar with a density of 1.1 kg / m³. 3 Soft rubber paste.

[0034] Step 2: Pump the rigid grout into the downhole annulus. After the rigid grout solidifies, a rigid grout support layer is formed in the downhole annulus.

[0035] Step 3: Inject the soft rubber slurry into the downhole annulus to form a soft rubber sealing layer above the hard rubber support layer.

[0036] The rigid adhesive mortar in this embodiment exhibits good toughness and anti-collapse properties after solidification, and it does not have independent flowability, such as... Figure 2 As shown, the hard rubber support layer formed after solidification in the downhole annulus can support the soft rubber sealing layer. The soft rubber slurry thickens into a viscous consistency and exhibits certain rheological properties, such as... Figure 1 As shown, after being pumped into the downhole annulus, it can fully fill the downhole annulus, providing a good sealing effect and effectively preventing H2S or CO2 gas from escaping upwards to the wellhead. Figure 3 As shown.

[0037] Injecting a breaker (such as hydrogen peroxide) into the well will degrade the hard rubber support layer and the soft rubber sealing layer after a certain period of time, without affecting subsequent well workover operations.

[0038] The rigid adhesive of this embodiment was tested, as follows:

[0039] Simulating the actual casing dimensions in a well, a 2-7 / 8” tubing was placed inside a 5.5” casing and centered. 10L of hardened grout was prepared as described above and slowly poured into the annulus between the 2-7 / 8” tubing and the 5.5” casing. After the grout completely solidified, it tightly enveloped the annulus between the inner and outer tubing strings, making it impossible to manually pull out the casing. Using tools with approximately 50-80 kg of force, the inner casing of the 2-7 / 8” tubing was pulled out of the 5.5” casing. A tough plug of approximately 1m was observed formed above the casing by the grout. Figure 4 As shown. In actual construction, the liquid plug is usually filled to a depth of 30-50 meters, which is sufficient to withstand downhole pressure.

[0040] Example 2

[0041] The liquid rubber plug of the embodiment comprises hard rubber and soft rubber; wherein the hard rubber comprises the following components by weight: base fluid one 30 parts, base fluid two 5 parts, glass fiber 5 parts, curing agent 0.15 parts, heptanal oxime 0.3 parts, inhibitor 0.05 parts.

[0042] The soft rubber comprises the following components by weight: base fluid one 30 parts, base fluid two 5 parts, curing agent 0.3 parts, heptanal oxime 0.5 parts, inhibitor 0.02 parts.

[0043] The base fluid one is acrylamide fiber, the base fluid two is diacetone acrylamide, the curing agent is sodium hypochlorite, and the inhibitor is 2-iodo-4-methoxyphenol.

[0044] The method for plugging the downhole annulus by using the liquid rubber plug of the embodiment is basically the same as that of embodiment 1, and the difference lies in that the components by weight of the embodiment are used to prepare the hard rubber slurry and the soft rubber slurry.

[0045] Embodiment 3

[0046] The liquid rubber plug of the embodiment comprises hard rubber and soft rubber; wherein the hard rubber comprises the following components by weight: base fluid one 30 parts, base fluid two 5 parts, glass fiber 5 parts, curing agent 0.15 parts, heptanal oxime 0.3 parts, inhibitor 0.05 parts.

[0047] The soft rubber comprises the following components by weight: base fluid one 30 parts, base fluid two 5 parts, curing agent 0.3 parts, heptanal oxime 0.5 parts, inhibitor 0.02 parts.

[0048] The base fluid one comprises acrylamide fiber and polyacrylamide fiber, the base fluid two comprises polyacrylic acid-acrylamide and diacetone acrylamide, the curing agent is sodium chloride and sodium hypochlorite, and the inhibitor is 2-ethyl-4-methoxyphenol and 2-iodo-4-methoxyphenol.

[0049] The method for plugging the downhole annulus by using the liquid rubber plug of the embodiment is basically the same as that of embodiment 1, and the difference lies in that the components by weight of the embodiment are used to prepare the hard rubber slurry and the soft rubber slurry.

[0050] It should be noted that all the features disclosed in the specification, or all the steps of the methods or processes disclosed, can be combined in any manner, except for the features and / or steps that are mutually exclusive.

[0051] In addition, the above specific embodiments are exemplary, and those skilled in the art can think of various solutions under the inspiration of the disclosure of the present application, and these solutions also belong to the disclosed range of the present application and fall within the protection scope of the present application. Those skilled in the art should understand that the specification and drawings of the present application are illustrative and do not constitute a limitation on the claims. The protection scope of the present application is defined by the claims and their equivalents.

Claims

1. A liquid rubber stopper, characterized in that, It includes rigid adhesives and flexible adhesives; wherein, the rigid adhesive comprises the following components in parts by weight: base liquid one 25-30 parts, base liquid two 5-10 parts, glass fiber 1-10 parts, curing agent 0.15-0.5 parts, heptanal oxime 0.3-0.5 parts, and inhibitor 0.01-0.05 parts; The soft adhesive comprises the following components in parts by weight: 25-30 parts of base liquid one, 5-10 parts of base liquid two, 0.15-0.5 parts of curing agent, 0.3-0.5 parts of heptanal oxime, and 0.01-0.05 parts of inhibitor.

2. The liquid stopper according to claim 1, characterized in that, The base liquid includes one or more of acrylamide and polyacrylamide fibers.

3. The liquid stopper according to claim 1, characterized in that, The base liquid 2 includes one or more of polyacrylic acid-acrylamide and diacetone-acrylamide.

4. The liquid stopper according to claim 1, characterized in that, The curing agent includes one or more of sodium chloride and sodium hypochlorite.

5. The liquid stopper according to claim 1, characterized in that, The inhibitors include one or more of 2-ethyl-4-methoxyphenol and 2-iodo-4-methoxyphenol.

6. A method for sealing downhole annulus using a liquid rubber plug as described in any one of claims 1-5, characterized in that, Includes the following steps: Step 1: Mix 25-30 parts of base liquid one, 5-10 parts of base liquid two, 1-10 parts of glass fiber, 0.15-0.5 parts of curing agent, 0.3-0.5 parts of heptanal oxime, and 0.01-0.05 parts of inhibitor and stir to dissolve in water to prepare a rigid adhesive slurry; Mix 25-30 parts of base liquid one, 5-10 parts of base liquid two, 0.15-0.5 parts of curing agent, 0.3-0.5 parts of heptanal oxime, and 0.01-0.05 parts of inhibitor and stir to dissolve in water to prepare a soft adhesive slurry; Step 2: Pump the rigid grout into the downhole annulus. After the rigid grout solidifies, a rigid grout support layer is formed in the downhole annulus. Step 3: Inject the soft rubber slurry into the downhole annulus to form a soft rubber sealing layer above the hard rubber support layer.

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