Underground sand bailing pipe string

Abstract

The utility model discloses an underground sand bailing pipe string which comprises a gas injection short section, a gas passing short section and a pen point which are connected in sequence. The gas injection short section comprises a gas injection joint, a gas injection inner pipe, a gas injection outer cylinder and a connecting joint; a gas injection hole is formed in the gas injection outer cylinder, the gas injection inner pipe is installed in the gas injection outer cylinder, and the upper end and the lower end of the gas injection outer cylinder and the upper end and the lower end of the gas injection inner pipe are connected with the gas injection connector and the lower gas passing connector I correspondingly; the gas passing short section comprises an upper gas passing joint, a gas passing inner pipe, a gas passing outer cylinder and a lower gas passing joint II; the air passing inner pipe is mounted in the air passing outer cylinder, and the upper and lower ends of the air passing outer cylinder and the air passing inner pipe are connected with the upper air passing joint and the lower air passing joint II respectively; the lower air passing joint I is connected with the upper air passing joint; the pen point is connected with the lower air passing connector II. Gas is injected from the ground, then liquid is carried upwards from the inner cylinder, and well bottom accumulated liquid, silt and the like are carried to the ground; the problem that silt is flushed back to the stratum during conventional sand flushing is solved, and silt at the well bottom is really fished to the ground.

Description

Technical Field

[0001] This utility model relates to a downhole sand retrieval pipe string, belonging to the field of oilfield oil production technology. Background Technology

[0002] Some oil and gas fields have shallow producing layers with low formation pressure coefficients, such as approximately 0.7. These layers are often composed of silt-rich water-flooded wells. Currently, CT (cutting and flushing) is commonly used to clean the wellbore and restore production. However, the following problems exist:

[0003] 1. In order to establish a sand flushing cycle, the flushing fluid inevitably enters the formation, affecting formation productivity; even with a density of 0.7 g / cm³... 3 Even with foam liquid, the sand flushing process may still increase water pressure by several megawatts;

[0004] 2. When silt enters the producing formation and production continues for a certain period, it is followed by another round of sand plugging at the bottom of the well due to formation fluids. This fails to truly achieve the goal of cleaning the well and producing sand, thus failing to achieve stable production. Utility Model Content

[0005] The purpose of this invention is to address the problems existing in the prior art by providing a downhole sand retrieval string. This string utilizes a surface gas injector or a gas source provided by the well itself or a neighboring well. The sand retrieval tool is lowered to the production formation using coiled tubing. By injecting gas into the annulus and circulating it through the designed downhole sand retrieval string, the sand at the bottom of the well is retrieved to the surface. The sand retrieval process does not generate additional bottom hole pressure, thus solving the problem of sand re-entering the production formation during conventional coiled tubing sand flushing processes.

[0006] The technical solution provided by this utility model to solve the above-mentioned technical problems is: a downhole sand retrieval pipe string, comprising an injection short section, an air passage short section, and a pen tip connected in sequence; the injection short section includes an injection connector, an inner injection tube, an outer injection cylinder, and a connecting connector; the outer injection cylinder is provided with an injection hole, the inner injection tube is installed inside the outer injection cylinder, and the upper and lower ends of the outer injection cylinder and the inner injection tube are respectively connected to the injection connector and the lower air passage connector I;

[0007] The air passage section includes an upper air passage connector, an inner air passage tube, an outer air passage cylinder, and a lower air passage connector II; the inner air passage tube is installed inside the outer air passage cylinder, and the upper and lower ends of the outer air passage cylinder and the inner air passage tube are respectively connected to the upper air passage connector and the lower air passage connector II.

[0008] The lower vent connector I is connected to the upper vent connector; the pen tip is connected to the lower vent connector II.

[0009] A further technical solution is that the lower air-passing connector I includes a connector housing I and a lower air-passing core I; the lower air-passing core I is installed inside the connector housing I, and the connector housing I and the lower air-passing core I are respectively connected to the air-injection outer cylinder and the air-injection inner pipe.

[0010] A further technical solution is that the lower end of the gas injection connector is connected to the gas injection outer cylinder via a thread.

[0011] A further technical solution is that the upper air-passing connector includes a connector housing and an upper air-passing core. The upper air-passing core is installed inside the connector housing. The upper and lower ends of the connector housing are respectively connected to the connector housing I and the air-passing outer cylinder. The upper and lower ends of the upper air-passing core are respectively connected to the lower air-passing connector I and the air-passing inner pipe.

[0012] A further technical solution is that the lower air-passing connector II includes a connector housing II and a lower air-passing core II. The lower air-passing core II is installed inside the connector housing II. The upper and lower ends of the connector housing II are respectively connected to the air-passing outer cylinder and the pen tip. The upper and lower ends of the lower air-passing core II are respectively connected to the air-passing inner tube and the pen tip.

[0013] A further technical solution is that the lower air passage core I, the upper air passage core, and the lower air passage core II are all fixedly installed in the connector housing I, the connector housing, and the connector housing II respectively by means of pins.

[0014] A further technical solution is to install gaskets at the connections between the inner gas injection tube, the outer gas injection cylinder and the gas injection connector, the lower gas inlet connector I, and the inner gas inlet tube, the outer gas inlet cylinder and the upper gas inlet connector, the lower gas inlet connector II.

[0015] This invention has the following advantages: It can inject gas from the surface or use pneumatic methods to drive the downhole device to rotate, further increasing the breaking up of sand clumps. This solves the problem of sand being flushed back into the formation during conventional sand flushing, and then entering the bottom of the well after a period of time, causing the bottom of the well to be buried. It truly achieves the goal of bringing sand from the bottom of the well to the surface. At the same time, when injecting gas and carrying liquid from the surface, the injection pressure is generally 2-3 MPa, which is much lower than the increase in annular pressure caused by sand flushing, reducing or avoiding leakage. When injecting gas and carrying liquid, the liquid level at the bottom of the well becomes lower and lower, thus the bottom pressure becomes lower and lower, which is conducive to achieving negative pressure sand retrieval. Attached Figure Description

[0016] Figure 1 A three-dimensional schematic diagram of a downhole sand retrieval string;

[0017] Figure 2 This is a schematic diagram of the structure of the air-injection sub.

[0018] Figure 3 This is a schematic diagram of the structure of the short section of air;

[0019] Figure 4 This is a schematic diagram of the pen tip structure;

[0020] Figure 5 This is a schematic diagram of the air injection connector.

[0021] Figure 6 This is a schematic diagram of the structure of the air injection outer cylinder;

[0022] Figure 7 This is a schematic diagram of the gas injection inner tube;

[0023] Figure 8 This is a schematic diagram of the connector housing.

[0024] Figure 9 This is a schematic diagram of the lower air passage core.

[0025] Figure 10 This is a schematic diagram of the upper air passage core. Detailed Implementation

[0026] The technical solution of this utility model will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0027] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0028] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can also refer to a mechanical connection. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0029] Furthermore, the technical features involved in the different embodiments of this utility model described below can be combined with each other as long as they do not conflict with each other.

[0030] like Figures 1-10As shown, this utility model provides a downhole sand retrieval pipe string, including an injection short section, an air passage short section (multiple air passage short sections can be combined as needed), and a pen tip connected in sequence; the injection short section includes an injection connector 1, an inner injection tube 3, an outer injection cylinder 2, and a lower air passage connector I; the outer injection cylinder 2 is provided with an injection hole 4, the inner injection tube 3 is installed inside the outer injection cylinder 2, and the upper and lower ends of the outer injection cylinder 2 and the inner injection tube 3 are respectively connected to the injection connector 1 and the lower air passage connector I;

[0031] The air passage section includes an upper air passage connector, an inner air passage tube 10, an outer air passage cylinder 9, and a lower air passage connector II; the inner air passage tube 10 is installed inside the outer air passage cylinder 9, and the upper and lower ends of the outer air passage cylinder 9 and the inner air passage tube 10 are respectively connected to the upper air passage connector and the lower air passage connector II; the lower air passage connector I is connected to the upper air passage connector; the pen tip is connected to the lower air passage connector II.

[0032] In this embodiment, the upper part of the gas injection connector 1 is connected to the continuous oil pipe. Ground gas injection descends from the annulus between the continuous oil pipe and the production oil pipe to the gas injection connector, and then gas is injected from the gas injection port 4 of the gas injection connector. The gas descends through the annulus between the gas injection inner pipe 3 and the gas injection outer cylinder 2, as well as the annulus 11 between the gas passage inner pipe 10 and the gas passage outer cylinder 9. After reaching the lowest lower gas passage connector II, it ascends in the pipe, carrying the liquid (including powder and sand) that enters from the pen tip hole. It ascends through the inner pipe and the continuous oil pipe to the ground, where it is separated by the sand settling device and the gas-liquid separator.

[0033] Injecting air from the surface in this way can also be used to drive the downhole equipment to rotate via pneumatic means, further increasing the breaking up of sand clumps.

[0034] like Figure 2 As shown, in this embodiment, the lower air-passing connector I includes a connector housing I5 and a lower air-passing core I6; the lower air-passing core I6 is installed inside the connector housing I5, and the connector housing I5 and the lower air-passing core I6 are respectively connected to the air-injection outer cylinder 2 and the air-injection inner pipe 3.

[0035] like Figure 3As shown, in this embodiment, the upper vent connector includes a connector housing 7 and an upper vent core 8. The upper vent core 8 is installed inside the connector housing 7. The upper and lower ends of the connector housing 7 are respectively connected to the connector housing I5 and the vent outer cylinder 9. The upper and lower ends of the upper vent core 8 are respectively connected to the lower vent connector I6 and the vent inner tube 10. The lower vent connector II includes a connector housing II12 and a lower vent core II13. The lower vent core II13 is installed inside the connector housing II12. The upper and lower ends of the connector housing II12 are respectively connected to the vent outer cylinder 9 and the pen tip. The upper and lower ends of the lower vent core II13 are respectively connected to the vent inner tube 10 and the pen tip. The structures of the lower vent core I6 and the lower vent core II13 are as follows: Figure 10 As shown, the structure of the upper air passage core 8 is as follows: Figure 9 As shown.

[0036] In this way, the gas injection connector 1, the gas injection inner tube 3, the lower gas passage core I 6, the upper gas passage core 8, the gas passage inner tube 10, and the lower gas passage core II 13 are connected in sequence to form an inner cylinder for gas to carry liquid upward; at the same time, the gas injection outer cylinder 2, the connector outer shell I 5, the connector outer shell 7, the gas passage outer cylinder 9, and the connector outer shell II 12 are also connected in sequence to provide a flow channel for the injected gas;

[0037] In this embodiment, for ease of installation, the preferred implementation is that the lower air passage core I6, the upper air passage core 8, and the lower air passage core II13 are all fixedly installed in the connector housing I5, connector housing 7, and connector housing II12 respectively by pins.

[0038] In this embodiment, to facilitate fine-tuning of the length and ensure installation, a preferred implementation is to install gaskets at the connections between the inner gas injection tube 10, the outer gas injection cylinder 2 and the gas injection connector, the lower gas inlet connector I, and the inner gas inlet tube 10, the outer gas inlet cylinder 9 and the upper gas inlet connector, the lower gas inlet connector II.

[0039] In this embodiment, the lower end of the gas injection connector 1 is connected to the gas injection outer cylinder 2 via threads. Other connections between the outer cylinder and the outer shell also use threaded connections.

[0040] This invention uses coiled tubing to lower a downhole sand-removal string to the designed position. Gas is injected from the surface, flowing downwards between the coiled tubing and the production tubing. The gas enters the double-walled interior of the sand-removal string through the injection port of the injection connector and continues downwards to the bottom of the string. Then, carrying fluid, it rises from the inner cylinder, bringing the accumulated fluid and fine sand from the bottom of the well to the surface. Alternatively, a pneumatic method can be used to drive the downhole device to rotate, further breaking up the clumps of fine sand. This solves the problem of fine sand being flushed back into the formation during conventional sand flushing, truly achieving the goal of bringing fine sand from the bottom of the well to the surface.

[0041] The above description is not intended to limit the present invention in any way. Although the present invention has been disclosed through the above embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A sand bailer string downhole, characterized by, It includes an air-injection section, an air-passing section, and a pen tip connected in sequence; the air-injection section includes an air-injection connector, an air-injection inner tube, an air-injection outer cylinder, and a connecting connector; the air-injection outer cylinder is provided with an air-injection hole, the air-injection inner tube is installed inside the air-injection outer cylinder, and the upper and lower ends of the air-injection outer cylinder and the air-injection inner tube are respectively connected to the air-injection connector and the lower air-passing connector I; The air passage section includes an upper air passage connector, an inner air passage tube, an outer air passage cylinder, and a lower air passage connector II; the inner air passage tube is installed inside the outer air passage cylinder, and the upper and lower ends of the outer air passage cylinder and the inner air passage tube are respectively connected to the upper air passage connector and the lower air passage connector II. The lower vent connector I is connected to the upper vent connector; the pen tip is connected to the lower vent connector II.

2. A sand bailer string as claimed in claim 1, wherein, The lower air-passing connector I includes a connector housing I and a lower air-passing core I; the lower air-passing core I is installed inside the connector housing I, and the connector housing I and the lower air-passing core I are respectively connected to the air-injection outer cylinder and the air-injection inner pipe.

3. A sand bailer string as defined in claim 1, wherein, The lower end of the gas injection connector is connected to the gas injection outer cylinder via threads.

4. A sand bailer string as defined in claim 2, wherein, The upper air-passing connector includes a connector housing and an upper air-passing core. The upper air-passing core is installed inside the connector housing. The upper and lower ends of the connector housing are respectively connected to the connector housing I and the air-passing outer cylinder. The upper and lower ends of the upper air-passing core are respectively connected to the lower air-passing connector I and the air-passing inner tube.

5. A sand bailer string as claimed in claim 4, wherein, The lower air-passing connector II includes a connector housing II and a lower air-passing core II. The lower air-passing core II is installed inside the connector housing II. The upper and lower ends of the connector housing II are respectively connected to the outer air-passing cylinder and the pen tip. The upper and lower ends of the lower air-passing core II are respectively connected to the inner air-passing tube and the pen tip.

6. A sand bailer string as claimed in claim 5, wherein, The lower air passage core I, the upper air passage core, and the lower air passage core II are all fixedly installed inside the connector housing I, the connector housing, and the connector housing II respectively by pins.

7. A sand bailer string as defined in claim 5, wherein, Gaskets are installed at the connections between the inner gas injection tube, the outer gas injection cylinder and the gas injection connector, the lower gas inlet connector I, and the inner gas inlet tube, the outer gas inlet cylinder and the upper gas inlet connector, the lower gas inlet connector II.

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