Layered steam injection tubular column with simultaneous injection function

Abstract

The utility model discloses a steam injection tubular column, namely a layered steam injection tubular column with a simultaneous injection function, which comprises a steam distribution valve consisting of a valve body, a valve seat, a valve ball and the like, and is characterized in that a simultaneous injection support body is arranged in a valve body cavity of the steam distribution valve, and the simultaneous injection support body and the steam distribution valve are combined into a steam injection valve. The co-injection supporting body is matched with the valve seat and the valve ball which move downwards to the final position for use to form a downward movement stopping block of the valve seat, and an upper body of the co-injection supporting body can be in top contact with the valve ball, so that a steam injection gap is formed between the lower spherical surface of the valve ball and a lower port of an inner cavity of the valve seat. Compared with an existing layered steam injection tubular column, the layered steam injection tubular column has the outstanding advantages that the soaking time of an upper oil layer and the soaking time of a lower oil layer are guaranteed to be consistent, the steam huff and puff effect of a heavy oil well is enhanced, and the crude oil recovery rate is improved.

Description

Technical Field

[0001] This utility model relates to a steam injection string for steam-blowing wells, specifically a layered steam injection string that also has the function of simultaneous injection. Technical Background

[0002] In the oilfield field, steam injection wells are a common type of heavy oil thermal recovery well. The working principle of this well is to inject high-temperature, high-humidity steam into the well using a steam injection device consisting of a downhole steam injection string, thereby increasing the reservoir temperature and formation pressure, reducing the viscosity of the crude oil, increasing its fluidity, and improving the oil recovery rate. Currently, the steam injection string used in steam injection wells consists of two parts: an uphole section and a downhole section. Among them, the more advanced steam injection string is the layered steam injection string. The technical feature of this string is its ability to perform directional and quantitative steam injection into any layer of several oil reservoirs. A representative layered steam injection string is the utility model patent technology with patent number ZL201420473193.8, entitled "A Layered Steam Injection String". The construction form of this steam injection string, hereinafter referred to as the "existing string", is as follows: Figure 1 As shown in the figure, the tubing string consists of, from top to bottom, the following components connected in sequence: wellhead 1 (upper section), insulation pipe 2 (lower section), expansion joint 3, upper packer 4, tubing 5, steam distribution valve 6, expansion joint 7, lower packer 8, and connecting pipes. The steam distribution valve 6 is shown in the figure. Figure 3 As shown, it mainly consists of a valve body 11, a valve seat 12, and a valve ball 10. The tubular valve seat 12 is slidably inserted into the upper part of the cavity of the valve body 11, and the two are positioned by a shearable pin 13; the valve ball 10 is used to mate with the lower port of the inner cavity of the valve seat 12, and can form a sealing contact with it.

[0003] The existing tubing string consists of an upper packer 4, tubing 5, steam distribution valve 6, expansion joint 7, and lower packer 8, assembled into an independent component. When in use, follow... Figure 2 Connection method.

[0004] In practical applications, assuming there are two oil reservoirs to be developed (hereinafter referred to as "oil layers"), one located below the lower packer 8 (hereinafter referred to as the "lower oil layer") and the other located above the lower packer 8 and below the upper packer 4 (hereinafter referred to as the "upper oil layer"), the main steps for implementing steam injection operations on the upper and lower oil layers using the existing tubing string are as follows: First, inject steam into the lower oil layer; after reaching the set steam injection volume, insert the valve ball 10 into the tubing string, causing the positioning pin 13 between the valve seat 12 and the valve body 11 to be sheared by the gravity of the valve ball 10, so that the valve ball 10 and the valve seat 12 move down together to the set final position, which is the bottom of the inner cavity of the valve body 11. During this process, the valve ball 10 seals the lower port of the valve seat 12's inner cavity, stopping steam injection into the lower oil layer. Simultaneously, the radial through-hole 14 on the valve body 11 wall, i.e., the upper oil layer steam injection channel, is unsealed, allowing steam injection into the upper oil layer to begin. Once the upper oil layer reaches the set steam injection volume, steam injection stops, and the well-closing operation proceeds as usual. Years of practical application have shown that while this patented technology has positive effects on improving steam utilization, it also has some shortcomings under certain operating conditions. For example, when the required steam injection volume for the upper oil layer is more than twice that for the lower oil layer, if the steam injection time for the lower oil layer is 2-3 days, the steam injection time for the upper oil layer is approximately 4-6 days. If the well-closing time after the upper oil layer steam injection is completed is conventionally set at 4 days, the well-closing time for the lower oil layer is at least 8 days. In other words, the well-closing time for the lower oil layer is at least twice that for the upper oil layer. If the lower oil layer is kept in the well for too long, the heat injected into it will inevitably diffuse to the caprock, causing the thinning heat energy of the lower oil layer to be lost. Therefore, compared with the upper oil layer, it inevitably has the prominent problems of poor steam injection effect and low crude oil recovery rate. Summary of the Invention

[0005] The purpose of this invention is to provide a downhole stratified steam injection string that also has the function of simultaneous injection, so that when using the string to carry out steam injection operations, the simmering time of each oil layer to be produced can be kept consistent, thereby improving the overall steam injection effect of heavy oil wells and thus increasing the recovery rate of crude oil.

[0006] The purpose of this utility model is achieved as follows: it includes a steam distribution valve 6 composed of a valve body 11, a valve seat 12, and a valve ball 10. Its structural feature is that a co-injection support 15 with an axial through hole is provided in the lower part of the valve body 11 cavity. The two are combined to form a steam injection valve 9. The upper body of the co-injection support 15 mates with the valve seat 12 and valve ball 10 when they are lowered to their final position. The upper end of the support 15 extends from the lower port of the valve seat 12 cavity and forms a top-mounted contact with the valve ball 10, creating a predetermined steam injection gap between the lower spherical surface of the valve ball 10 and the lower port of the valve seat 12 cavity. The key to this technology is that the size of the valve seat 12 cavity must be larger than the diameter of the valve ball 10.

[0007] The upper packer 4, oil pipe 5, steam injection valve 9, telescopic short connector 7 and lower packer 8 of this utility model are assembled into independent components.

[0008] After this invention is implemented, when the valve ball and valve seat of the steam injection valve move down to their final positions together and begin steam injection into the upper oil layer, the lower oil layer will also be injected with appropriate amount of steam through the steam injection gap formed between the lower spherical surface of the valve ball and the lower port of the valve seat cavity via the axial through hole on the same injection support body. This ensures that the steam injection time of the upper and lower oil layers is consistent, and the well enters a shut-in state, effectively maintaining the oil layer temperature field, thereby enhancing the steam injection effect of the heavy oil well and improving the crude oil recovery rate. Attached Figure Description

[0009] Figure 1 This is a schematic diagram of the existing tubular column structure.

[0010] Figure 2 This is an assembly diagram of the existing tubing string, including the upper packer, tubing, steam distribution valve, expansion joint, and lower packer.

[0011] Figure 3 This is a schematic diagram of the structural form of the steam distribution valve in an existing tubing column.

[0012] Figure 4 This is a schematic diagram of the structural form of this utility model.

[0013] Figure 5 This is a diagram showing the assembly components of the upper packer, oil pipe, steam injection valve, telescopic connector, and lower packer of this utility model.

[0014] Figure 6 This is a schematic diagram of the structure of the steam injection valve of this utility model. Detailed Implementation

[0015] Depend on Figure 4 As can be seen, this utility model consists of, from top to bottom, a wellhead 1, a heat insulation pipe 2, a telescopic pipe 3, an upper packer 4, an oil pipe 5, a steam injection valve 9, a telescopic short connector 7, a lower packer 8, and a connecting pipe. The connection method between the components of this utility model is the same as that of the prior art; except for the steam injection valve 9, the structural form of the other components is also the same as that of the prior art.

[0016] The difference between this utility model and the prior art lies in the structural form of its steam injection valve 9, which is different from that of the prior art. For example... Figure 6As shown, the steam injection valve 9 of this utility model includes all the components of the existing steam distribution valve 6, including a valve ball 10, a valve body 11, a valve seat 12, and a shearable positioning pin 13. The innovative aspect of this utility model lies in the installation of a co-injection support 15 with an axial through hole in the lower cavity of the valve body 11, which is positioned on a stop platform formed by a variable-diameter boss in the stepped inner cavity of the valve body 11. This allows the steam distribution valve 6 and the co-injection support 15 to combine into the steam injection valve 9. In application, the upper body of the co-injection support 15 mates with the valve seat 12 and valve ball 10 when they are lowered to their final position. Simultaneously, the co-injection support 15 forms a downward movement stop for the valve seat 12. The upper end of its body can extend from the lower port of the inner cavity of the valve seat 12 and form a top-mounted contact with the valve ball 10, creating a predetermined steam injection gap between the lower spherical surface of the valve ball 10 and the lower port of the inner cavity of the valve seat 12.

[0017] It should be noted that:

[0018] 1. The size of the inner cavity of the valve seat 12 must be larger than the diameter of the valve ball 10, so that a sufficient gap is formed between the two to connect the steam injection gap formed between the lower spherical surface of the valve ball 10 and the lower port of the inner cavity of the valve seat 12, and to communicate with the axial through hole on the same injection support body 15.

[0019] 2. In this embodiment, the injection support 15 is located below the valve seat 12 and is freely situated at the bottom of the inner cavity of the valve body 11. The injection support 15 can also be fixedly situated at the bottom of the inner cavity of the valve body 11.

[0020] 3. In this embodiment, the upper body of the injection holder 15 is made into a cone shape. However, in practical applications, this invention can also be implemented when the upper body of the injection holder 15 is made into a cylindrical shape.

[0021] To facilitate the storage, safekeeping, transportation, and on-site installation of the components of this utility model, the upper packer 4, oil pipe 5, steam injection valve 6, telescopic short joint 7, and lower packer 8 can be assembled into relatively independent components before leaving the factory.

[0022] The operation method of this utility model:

[0023] Figure 4 One usage configuration of this utility model is given. As shown in the figure, in this configuration, there are two oil reservoirs to be extracted: one located below the lower packer 8, hereinafter referred to as the "lower oil layer," and the other located above the lower packer 8 and below the upper packer 4, hereinafter referred to as the "upper oil layer." The steps for implementing steam injection operations on the upper and lower oil layers using this utility model, hereinafter referred to as the "string," are as follows:

[0024] First, steam is injected into the lower oil layer through the tubing string. After the set steam injection volume is reached, the valve ball 10 is inserted into the tubing string through the wellhead 1. When the valve ball 10 falls to the moment it contacts the lower end of the valve seat 12, the positioning pin 13 between the valve seat 12 and the valve body 11 will be sheared by the gravity of the valve ball 10, causing the valve ball 10 and the valve seat 12 to move down quickly together. During this process, the valve seat 12 releases the blockage of the radial through hole 14 on the wall of the valve body 11, i.e., the steam injection channel for the upper oil layer, allowing the upper oil layer to enter the steam injection state. When the valve ball 10 and the valve seat 12 move down to the set final position, i.e., the position where the lower end face of the valve seat 12 contacts the upper end face of the lower part of the same injection support body 15, the upper end of the upper part of the same injection support body 15 will extend from the lower port of the inner cavity of the valve seat 12 and form a top contact with the valve ball 10, so that a set steam injection gap is formed between the lower spherical surface of the valve ball 10 and the lower port of the valve seat, allowing the lower oil layer to continue to be injected with steam through the axial through hole on the same injection support body 15 through the gap. When the upper oil layer reaches the set steam injection amount, the upper and lower oil layers stop steam injection at the same time and enter the conventional well shut-in operation. Thus, this utility model fully ensures that the upper and lower oil layers obtain the same well shut-in time, injects steam into the oil layer with high quality and efficiency, and effectively guarantees the steam injection quality.

Claims

1. A layered steam injection string with simultaneous injection function, comprising a steam distribution valve (6), the steam distribution valve (6) including a valve body (11), a valve seat (12) and a valve ball (10), characterized in that... The steam distribution valve (6) is also provided with a co-injection support body (15) with an axial through hole, and it is placed on the bottom stop platform in the cavity of the valve body (11). The steam distribution valve (6) and the co-injection support body (15) are combined to form a steam injection valve (9). The co-injection support body (15) is used in conjunction with the valve seat (12) and valve ball (10) when it is moved down to the final position. At the same time, the co-injection support body (15) constitutes the downward movement stop of the valve seat (12). The upper end of its upper body can extend from the lower port of the inner cavity of the valve seat (12) and form a top contact with the valve ball (10), so that the lower spherical surface of the valve ball (10) and the lower port of the inner cavity of the valve seat (12) form a set steam injection gap.

2. A layered steam injection string with simultaneous injection function as described in claim 1, characterized in that... Its upper packer (4), oil pipe (5), steam injection valve (9), telescopic short joint (7) and lower packer (8) are assembled into independent components.

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