Novel rubber combined sleeve and application thereof

Abstract

The invention relates to the technical field of petroleum and natural gas extraction, in particular to a casing pipe for well cementation of an oil-gas well, in particular to a novel rubber combined casing pipe for well cementation of a shale oil-gas well and a horizontal well and application of the novel rubber combined casing pipe. The novel rubber combined casing pipe comprises a steel casing pipe, the two end rings are fixedly connected to the outer surfaces of the two ends of the steel sleeve in a sleeving manner; the water absorption rubber layer is arranged on the outer surface of the steel sleeve in a sleeving mode and located between the two end rings; and the soluble organic layer is sleeved on the outer surface of the water absorption rubber layer, and the end faces of the two ends of the soluble organic layer are respectively and tightly connected with the corresponding end faces of the two end rings. By arranging the soluble organic layer, the water-absorbing rubber layer can be protected in the casing lowering process, and the situation that the water-absorbing rubber layer absorbs water too early and expands is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of oil and natural gas exploitation, and in particular to a casing for oil and gas well cementing, in particular to a new type of rubber combined casing for shale oil and gas well horizontal well cementing and application thereof. Background Art

[0002] Casing cementing is a routine operation in oil and gas field drilling. It is to lower a steel pipe with a certain wall thickness to the predetermined depth of the newly drilled open hole section, and then inject cement slurry into the annulus between the casing and the well wall. The casing and the formation are consolidated by the solidification of the cement slurry, thereby preventing the well wall from collapsing and isolating the drilled oil, gas and water layers. After the cementing is completed, the casing will be subjected to stress from the formation. Therefore, before casing cementing, the designer needs to perform theoretical calculations and select a steel pipe with appropriate mechanical strength to prevent the casing from deformation and failure after entering the well.

[0003] However, the problem of casing deformation and failure in oil and gas wells continues to occur. Part of the reason is that the underground salt-gypsum layer will creep after drilling. The force is large, which produces a strong squeezing force on the casing, causing the casing to yield and fail. To address this problem, the method of increasing the casing steel grade and wall thickness to improve the mechanical strength of the casing is generally adopted. However, this method is not effective in solving the deformation of the casing in the horizontal section of shale gas wells in Sichuan and Chongqing. Some scholars analyzed that the reason for the deformation of the casing in the horizontal section of shale gas wells is not the all-round creeping squeezing of the salt-gypsum layer, but the activation of small faults near the casing, which produces a shearing effect on the casing similar to a scissors action, causing the casing to shift. Based on this discovery, some technicians have proposed an idea to prevent casing deformation, that is, to bond an elastic rubber layer to the outside of the conventional steel casing, and use the elastic deformation of the rubber layer to greatly reduce or eliminate the shear displacement deformation of the steel casing by small faults.

[0004] In response to this technical idea, patent CN212671582U designed a combined casing that wraps the expansion rubber outside the steel casing. The rubber expands during the cementing process and is consolidated with the reservoir through cement slurry. The patent has a simple structure, but does not take into account the cementing process. First, the casing may expand during the lowering process, increasing the lowering resistance of the casing. In extreme cases, the casing may get stuck in the well wall, causing an underground accident. Second, the mechanical strength of the expansion rubber casing is not high, and it may be damaged by the rock in the open hole section during the lowering process, resulting in poor actual effect of the casing. Summary of the invention

[0005] In order to solve the deficiencies of the prior art, the present invention provides a novel rubber composite casing and its application. The present invention can protect the water-absorbing rubber layer during the casing lowering process by providing a soluble organic layer and prevent the water-absorbing rubber layer from absorbing water and swelling prematurely.

[0006] The technical solution provided by the present invention is as follows:

[0007] A novel rubber combined casing, comprising:

[0008] Steel casing;

[0009] Two end rings fixedly sleeved on the outer surfaces of both ends of the steel casing;

[0010] A water-absorbing rubber layer sleeved on the outer surface of the steel sleeve, which is located between the two end rings;

[0011] And the soluble organic layer is sleeved on the outer surface of the water-absorbing rubber layer, and the end faces of both ends of the soluble organic layer are tightly connected with the corresponding end faces of the two end rings respectively.

[0012] In the above technical solution:

[0013] The end ring is fixed on the outer surface of the steel casing, in close contact with the end surfaces of the water-absorbing rubber layer and the soluble organic layer, and is used to fix the water-absorbing rubber layer and the soluble organic layer;

[0014] The function of the soluble organic layer is to protect the water-absorbing rubber layer from being damaged by the well wall rock and to prevent the water-absorbing rubber layer from expanding prematurely;

[0015] The function of the water-absorbing rubber layer is that when the soluble organic layer dissolves, the water-absorbing rubber layer contacts the wellbore fluid and absorbs water molecules to expand. After a certain period of expansion, cement slurry is injected into the steel casing, and the cement slurry is filled between the water-absorbing rubber layer and the well wall rock, consolidating the water-absorbing rubber layer and the reservoir, thus achieving the purpose of cementing.

[0016] The working principle of the above technical solution is as follows:

[0017] Since the soluble organic layer can protect the water-absorbing rubber layer from being damaged by the wellbore rock and prevent the water-absorbing rubber layer from expanding prematurely, during the process of the combined casing entering the well, the soluble organic layer is located on the water-absorbing rubber, so that the water-absorbing rubber layer and the wellbore rock do not contact each other, and uses its own strength and wear resistance to prevent the wellbore rock from invading the water-absorbing rubber layer, thereby ensuring the integrity of the water-absorbing rubber layer; the soluble organic layer also isolates the fluid in the wellbore from the water-absorbing rubber layer, so that the water-absorbing rubber layer cannot absorb water molecules in the wellbore fluid, and thus does not expand. When the combined casing is lowered to a predetermined depth, the soluble organic layer gradually dissolves under the action of the wellbore fluid, exposing the water-absorbing rubber layer located below to the wellbore fluid, thereby causing the water-absorbing rubber layer to expand.

[0018] Under the protection of the soluble organic layer, the water-absorbing rubber layer maintains its integrity and does not expand for a certain period of time after the combined casing enters the well and reaches the predetermined depth. When the soluble organic layer dissolves, the water-absorbing rubber layer contacts the wellbore fluid and absorbs water molecules to expand. After a certain period of expansion, cement slurry is injected into the steel casing, and the cement slurry is filled between the water-absorbing rubber layer and the well wall rock, consolidating the water-absorbing rubber layer and the reservoir, achieving the purpose of cementing. The expansion rate of the water-absorbing rubber layer can be controlled by structural design and material selection.

[0019] The material of the soluble organic layer can be selected from the prior art, for example, Lubrizol Corporation of the United States TPU soluble rubber, Zeon Corporation of Japan NBR soluble rubber, American Trinseo Company SBS soluble rubber, etc. Similar materials are soluble in water at low, medium or high temperatures, and have certain strength and wear resistance.

[0020] The material of the water-absorbing rubber layer can be selected from the prior art, for example, DOWSIL TM Waterborne Silicone Rubber, Wacker Chemie AG, Germany LR water-absorbing rubber, etc.

[0021] Specifically, the end surfaces at both ends of the water-absorbing rubber layer are tightly connected to the corresponding end surfaces of the two end rings respectively.

[0022] Specifically, the inner wall of the water-absorbing rubber layer is pressed or adhered to the outer surface of the steel casing.

[0023] Based on the above technical solution, the water-absorbing rubber layer and the steel casing do not need to be glued, which can avoid occupying the water absorption function of the inner surface of the water-absorbing rubber layer, thereby not affecting the water absorption and expansion function of the water-absorbing rubber layer.

[0024] Specifically, the outer diameter of the water-absorbing rubber layer before expansion is smaller than the outer diameter of the end ring; and the outer diameter of the water-absorbing rubber layer after expansion is larger than the outer diameter of the end ring.

[0025] Specifically, the outer diameter of the soluble organic layer is less than or equal to the outer diameter of the end ring.

[0026] Specifically, the thickness of the soluble organic layer is 2 mm-10 mm.

[0027] Based on the above technical solution, the dissolution time of the entire soluble organic layer can be controlled by setting the thickness of the soluble organic layer, thereby meeting different operation requirements.

[0028] Specifically, the time range for the soluble organic layer to dissolve is 12h-96h.

[0029] Based on the above technical solution, sufficient operation time can be ensured, so as to achieve the purpose of safely lowering the casing into place in a horizontal well at a depth of more than 2,000 meters. Among them, the time to dissolve can be conveniently controlled by only setting the thickness of the soluble organic layer. For example, when the thickness is 2mm-10mm, the dissolution time can reach 12h-96h.

[0030] Furthermore, the cross section of the end ring and the water-absorbing rubber layer, and the cross section of the end ring and the soluble organic layer are sealed by an adhesive.

[0031] Based on this technical solution, the water-isolating effect on the water-absorbing rubber layer can be increased.

[0032] Specifically, the steel casing is a steel casing for horizontal well cementing.

[0033] The invention also provides application of a novel rubber combination casing for horizontal well cementing.

[0034] The new rubber combination casing provided by the present invention has a water-absorbing rubber layer wrapped with a soluble organic layer. During the lowering process of the combination casing, the soluble organic layer uses its own strength and wear resistance to prevent the well wall rock and wellbore debris from invading the water-absorbing rubber layer, thereby ensuring the integrity of the water-absorbing rubber layer; the soluble organic layer also isolates the water-absorbing rubber layer from the wellbore fluid to prevent the water-absorbing rubber layer from expanding prematurely. After the combination casing is lowered to a predetermined depth, the soluble organic layer dissolves under the action of the wellbore fluid, and the water-absorbing rubber layer begins to absorb water molecules from the wellbore fluid, thereby achieving the purpose of expansion. After the water-absorbing rubber layer expands for a certain period of time, the cement slurry injected through the steel pipe enters between the expanded water-absorbing rubber layer and the well wall rock, and solidifies the two after solidification, thereby achieving the purpose of cementing. When the fault near the combination casing slips and then produces a shearing effect, the expanded water-absorbing rubber layer undergoes shear dislocation deformation, which greatly reduces or even eliminates the shear deformation of the steel casing caused by the fault slip, thereby protecting the steel casing, providing a good space for subsequent operations, and forming a good oil and gas flow channel. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a structural schematic diagram of the novel rubber combined sleeve provided by the present invention before use.

[0036] Figure 2 It is a schematic diagram of the lowering process of the new rubber combination casing provided by the present invention.

[0037] Figure 3It is a schematic diagram of lowering the new rubber combination casing provided by the present invention to a predetermined depth.

[0038] Figure 4 It is a schematic diagram of a new type of rubber combination sleeve and a reservoir provided by the cement slurry consolidation invention.

[0039] Attached Figure 1 , 2 , 3, and 4, the structures represented by each number are listed as follows:

[0040] 100. combined casing, 10. steel casing, 20. water-absorbent rubber layer, 21. expanded water-absorbent rubber layer, 30. soluble organic layer, 40. end ring, 50. fluid, 60. wellbore rock, 70. cement slurry, 80. reservoir. DETAILED DESCRIPTION

[0041] The principles and features of the present invention are described below. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0042] In a specific embodiment, Figure 1 As shown, the novel rubber composite casing is composed of a steel casing 10, a water-absorbing rubber layer 20, a soluble organic layer 30 and two end rings 40.

[0043] The water-absorbing rubber layer 20 wraps the steel casing 10; the soluble organic layer 30 wraps the water-absorbing rubber layer 20; two end rings 40 are fixed to the outer surfaces of both ends of the steel casing 10, and are in close contact with the end surfaces of the water-absorbing rubber layer 20 and the soluble organic layer 30, and are used to fix the water-absorbing rubber layer 20 and the soluble organic layer 30. The end rings 40 and the soluble organic layer 30 together isolate the water-absorbing rubber layer 20 from water.

[0044] In a preferred solution, the cross section of the end ring 40 and the water-absorbing rubber layer 20, as well as the cross section of the end ring 40 and the soluble organic layer 30 are sealed with an adhesive to improve the water-isolating ability. At the same time, the fixing ability of the end ring 40 to the water-absorbing rubber layer 20 and the soluble organic layer 30 can also be increased. The adhesive can be from existing technology, such as Loctite adhesive, or potting glue, etc.

[0045] like Figure 2 As shown, during the process of the combined casing 100 entering the well, the soluble organic layer 30 is located outside the water-absorbing rubber layer 20, so that the water-absorbing rubber layer 20 and the well wall rock 60 do not contact each other, and use its own strength and wear resistance to prevent the well wall rock 60 from invading the water-absorbing rubber layer 20, thereby ensuring the integrity of the water-absorbing rubber layer 20; the soluble organic layer 30 also isolates the fluid 50 in the wellbore from the water-absorbing rubber layer 20, so that the water-absorbing rubber layer 20 cannot absorb water molecules in the wellbore fluid 50, and thus will not swell prematurely.

[0046] like Figure 3 As shown, when the combined casing 100 is lowered to a predetermined depth, the soluble organic layer 30 is gradually dissolved under the action of the wellbore fluid 50 , exposing the water-absorbing rubber layer 20 located therebelow to the wellbore fluid 50 , thereby forming an expanded water-absorbing rubber layer 21 .

[0047] After a certain period of expansion, cement slurry 70 is injected into the steel casing 10, and the cement slurry is filled between the expanded water-absorbing rubber layer 21 and the well wall rock 60, and the expanded water-absorbing rubber layer 21 is consolidated with the reservoir 80, thereby achieving the purpose of cementing. Figure 4 shown.

[0048] When the fault near the combined casing 100 slips and produces a shearing effect, the expanded water-absorbing rubber layer 21 undergoes shear displacement deformation, which greatly reduces or even eliminates the shear deformation of the steel casing 10 caused by the fault slip, thereby protecting the steel casing 10, providing a good space for subsequent operations, and forming a good oil and gas flow channel.

[0049] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A new type of rubber combined casing, characterized in that: include: Steel casing (10); Two end rings (40) fixedly sleeved on the outer surfaces of both ends of the steel sleeve (10); A water-absorbing rubber layer (20) sleeved on the outer surface of the steel sleeve (10) and located between the two end rings (40); And a soluble organic layer (30) sleeved on the outer surface of the water-absorbing rubber layer (20), the end surfaces of the two ends of the soluble organic layer (30) being tightly connected to the corresponding end surfaces of the two end rings (40) respectively.

2. The new rubber combined sleeve according to claim 1 is characterized in that: The end surfaces at both ends of the water-absorbing rubber layer (20) are tightly connected to the corresponding end surfaces of the two end rings (40).

3. The new rubber combined sleeve according to claim 1 is characterized in that: The inner wall of the water-absorbing rubber layer (20) is pressed or adhered to the outer surface of the steel casing (10).

4. The new rubber combined sleeve according to claim 1 is characterized in that: The outer diameter of the water-absorbing rubber layer (20) before expansion is smaller than the outer diameter of the end ring (40); and the outer diameter of the water-absorbing rubber layer (20) after expansion is larger than the outer diameter of the end ring (40).

5. The new rubber combined sleeve according to claim 1 is characterized in that: The outer diameter of the soluble organic layer (30) is less than or equal to the outer diameter of the end ring (40).

6. The new rubber combined sleeve according to claim 1 is characterized in that: The thickness of the soluble organic layer (30) is 2 mm to 10 mm.

7. The new rubber combined sleeve according to claim 6 is characterized in that: The time range for the soluble organic layer (30) to dissolve is 12h-96h.

8. The new rubber combined sleeve according to claim 1 is characterized in that: The steel casing (10) is a steel casing (10) for horizontal well cementing.

9. The new rubber combined sleeve according to any one of claims 1 to 8, characterized in that: The cross section of the end ring (40) and the water-absorbing rubber layer (20), and the cross section of the end ring (40) and the soluble organic layer (30) are sealed by an adhesive.

10. An application of the new rubber combined casing according to any one of claims 1 to 8, characterized in that: Used for horizontal well cementing.

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