A venturi flow measurement device for gas injection wells

Abstract

The present invention relates to an underground venturi flow measurement device for gas injection wells, including a venturi, a pressure collection device and a flow-blocking structure. The venturi is provided with a plurality of pressure-conducting holes, and each pressure-conducting hole is provided with a pressure collection device, so that the pressure collection device can measure the pressure of each pressure-conducting hole when the fluid flows through the venturi, so as to obtain the pressure difference between each pressure-conducting hole. The venturi is arranged in a working cylinder, and a gap is left between the venturi and the working cylinder, and a flow-blocking structure is arranged in the gap. The present application measures the pressure upstream, throat and downstream of the venturi through a pressure sensor. Due to the narrow working space underground, the pressure sensor is smaller in size compared with the differential pressure sensor, so that under the premise of a certain available space, the overall design of the device can take more into account the requirements of pressure bearing, sealing and wiring, and the accuracy of the differential pressure calculated by the pressure meets the requirements of flow measurement. In addition, the device has no movable parts, so that the device as a whole has a higher reliability.

Description

Technical Field

[0001] The invention relates to the technical field of oilfield development and production, in particular to a wellbore venturi flow measurement device for a gas injection well. Background Art

[0002] Oil is one of the most important energy resources in the world. However, as time goes by, the production capacity of oil fields gradually decreases. As a production increase technology, oil well gas injection has been widely used in the oil industry.

[0003] The principle of oil well gas injection is to inject gas into the oil well to change the pressure and temperature conditions inside the oil well, thereby improving the physical properties of the reservoir, increasing the fluidity and recovery rate of crude oil, and reducing environmental pollution and energy waste. However, the high temperature and high pressure environment downhole makes the injected medium in a multiphase flow or supercritical state, which brings great challenges to the design of flow measurement devices. Therefore, the gas injection flow rate is usually measured on land. When the downhole stratified gas injection technology is used, the flow rate of each layer is measured by a single-phase flow meter or allocated according to experience, and the accurate flow rate of each layer cannot be obtained. It is also possible to inject only one layer at a time, but the work efficiency is low.

[0004] Due to the small working space underground, the design of the measuring device needs to consider the requirements of pressure bearing, sealing and wiring. The current measurement design scheme that can simultaneously measure the accurate flow of each layer is large in size and is not suitable for the small working space underground.

[0005] Therefore, there is an urgent need for a well venturi flow measurement device for gas injection wells. Summary of the invention

[0006] The invention provides a well venturi flow measurement device for a gas injection well, so as to solve the problem that the flow of each layer in the prior art is measured by a single-phase flow meter or distributed according to experience, and the accurate flow of each layer cannot be obtained.

[0007] The present invention discloses an underground venturi flow measurement device for a gas injection well, comprising a venturi, a pressure collection device and a flow-blocking structure. The venturi is provided with a plurality of pressure-conducting holes, and each of the pressure-conducting holes is provided with the pressure collection device, so that the pressure collection device can measure the pressure of each of the pressure-conducting holes when the fluid flows through the venturi, so as to obtain the pressure difference between each of the pressure-conducting holes. The venturi is arranged in a working cylinder, and a gap is left between the venturi and the working cylinder, and the flow-blocking structure is provided in the gap.

[0008] The underground Venturi flow measuring device for gas injection wells is preferably such that the main body of the Venturi is provided with a front straight pipe section, a contraction section, a throat, an expansion section and a rear straight pipe section in sequence, the front straight pipe section is provided with a collecting port, the rear straight pipe section is provided with a discharge port, and the front straight pipe section, the throat and the rear straight pipe section are respectively provided with the pressure conducting holes.

[0009] The underground Venturi flow measurement device for gas injection wells, preferably, the pressure acquisition device includes multiple pressure sensors and ground instruments, the pressure sensors are arranged at the pressure guide holes, and the ground instruments are electrically connected to the pressure sensors to realize signal processing and output to the ground instruments.

[0010] In the underground Venturi flow measurement device for a gas injection well, preferably, the flow-blocking structure is a baffle ring, and the baffle ring is arranged between the collecting port and the discharge port.

[0011] The underground Venturi flow measurement device for gas injection wells, preferably, the Venturi also includes an upstream interface and a downstream interface, the upstream interface is located at the upstream end of the Venturi body, and the downstream interface is located at the downstream end of the Venturi body.

[0012] In the underground Venturi flow measurement device for a gas injection well, preferably, the diameter of the pressure-conducting hole is 3-4 mm.

[0013] The underground venturi flow measurement device for gas injection wells is preferably configured such that the diameter of the venturi is 15-16 mm.

[0014] The underground venturi flow measurement device for gas injection wells preferably has a throat diameter of 6-7 mm.

[0015] The beneficial effects are:

[0016] The present application measures the pressure upstream, throat and downstream of the Venturi by means of a pressure sensor. Due to the narrow working space underground, the pressure sensor is smaller in size compared with the differential pressure sensor. Therefore, under the premise of a certain available space, the overall design of the device can take more consideration of the pressure bearing, sealing and wiring requirements, and the accuracy of the differential pressure calculated by the pressure meets the requirements of flow measurement. In addition, the device has no moving parts, so that the device as a whole has a higher reliability.

[0017] The implementation of underground wet gas flow measurement in the present application can timely understand the gas injection flow of each layer when injecting gas in layers simultaneously, which is convenient for guiding the gas injection operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the device structure of the present invention.

[0019] In the figure:

[0020] 1. Upstream interface; 3. Collecting port; 4. Venturi;

[0021] 5. Upstream pressure sensor; 6. Throat pressure sensor; 7. Downstream pressure sensor; 8. Discharge port;

[0022] 9. Downstream interface; 10. Working cylinder wall; 11. Retaining ring. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0024] The present invention provides a downhole venturi flow measurement device for gas injection wells, comprising a venturi, a pressure collection device and a flow-blocking structure. The venturi is provided with a plurality of pressure-conducting holes, and each of the pressure-conducting holes is provided with the pressure collection device, so that the pressure collection device measures the pressure of each of the pressure-conducting holes when the fluid flows through the venturi, so as to obtain the pressure difference between each of the pressure-conducting holes. The venturi is arranged in a working cylinder, and a gap is left between the venturi and the working cylinder, and the flow-blocking structure is provided in the gap. The present invention generates a pressure difference between the pressure-conducting holes by contracting the flow channel first and then expanding when the fluid flows through the venturi. Three pressure sensors collect pressure signals at three locations respectively, and realize the measurement of two-phase flow according to the difference in the differential pressure before and after the venturi.

[0025] The whole technical process is described in detail below using a wellbore venturi flow measurement device for gas injection wells as an example.

[0026] Reference Figure 1A downhole venturi flow measurement device for a gas injection well is shown, comprising a venturi, a pressure collection device and a flow-blocking structure. The venturi body is provided with a front straight pipe section, a contraction section, a throat, an expansion section and a rear straight pipe section in sequence. The front straight pipe section is provided with a collecting port 3, and the rear straight pipe section is provided with a discharge port 8. The collecting port 3 is used to introduce fluid into the venturi 4, and the discharge port 8 is used to discharge the fluid in the venturi 4. The front straight pipe section, the throat and the rear straight pipe section are respectively provided with an upstream pressure-guiding hole, a throat pressure-guiding hole and a downstream pressure-guiding hole. The upstream pressure-guiding hole, the throat pressure-guiding hole and the downstream pressure-guiding hole are respectively provided with the pressure collection device, so that the pressure collection device measures the pressure of each of the pressure-guiding holes when the fluid flows through the venturi, so as to obtain the pressure difference between the upstream pressure-guiding hole, the throat pressure-guiding hole and the downstream pressure-guiding hole. The venturi is arranged in a working cylinder, and a gap is left between the venturi and the working cylinder 10 for medium flow, and the flow-blocking structure is arranged in the gap.

[0027] Among them, the pressure collection device includes an upstream pressure sensor 5, a throat pressure sensor 6, a downstream pressure sensor 7, and a ground instrument. The upstream pressure sensor 5 is arranged on the upstream pressure conducting hole, the throat pressure sensor 6 is arranged on the throat pressure conducting hole, and the downstream pressure sensor 7 is arranged on the downstream pressure conducting hole. The ground instrument is electrically connected to the upstream pressure sensor 5, the throat pressure sensor 6, and the downstream pressure sensor 7 respectively to realize signal processing and output to the ground instrument.

[0028] When the fluid flows through the Venturi, the flow channel first contracts and then expands, thereby generating a pressure difference between the pressure guide holes. The three pressure sensors collect pressure signals at three locations respectively, and the two-phase flow measurement is achieved based on the difference in differential pressure before and after the Venturi.

[0029] Continue to refer to Figure 1 As shown, the flow-blocking structure is a baffle ring 11 , and the baffle ring 11 is arranged between the manifold 3 and the discharge port 8 .

[0030] Continue to refer to Figure 1 As shown, the Venturi also includes an upstream interface 1 and a downstream interface 9. The upstream interface 1 is located at the upstream end of the Venturi body and is used to achieve mechanical and electrical connection with upstream equipment. The downstream interface 9 is located at the downstream end of the Venturi body and is used to achieve mechanical and electrical connection with downstream equipment.

[0031] The diameter of the pressure-conducting hole is 3-4 mm, the diameter of the venturi is 15-16 mm, and the diameter of the throat is 6-7 mm. Preferably, the diameter of the pressure-conducting hole is 3 mm, the diameter of the venturi is 15 mm, and the diameter of the throat is 6 mm.

[0032] The present invention can realize the integration of the venturi and the pressure sensor into the device housing, the outer diameter of the device housing is 42mm, so as to form a venturi flow measurement device and meet the requirements of adapting to the pressure of 60MPa. The venturi is arranged eccentrically in the cavity of the device housing.

[0033] Example 1

[0034] Selection of the diameter of the Venturi 4: According to the flow range to be measured, the diameter of the Venturi 4 of the present embodiment 1 is 15 mm, the diameter of the throat is 6 mm, and the diameter of the pressure-conducting hole is 3 mm.

[0035] Selection and wiring of upstream pressure sensor 5, throat pressure sensor 6, and downstream pressure sensor 7:

[0036] In this embodiment 1, the upstream pressure sensor 5, the throat pressure sensor 6 and the downstream pressure sensor 7 are 6LHP pressure sensors of KELLER Company. The lead wires of the upstream pressure sensor 5, the throat pressure sensor 6 and the downstream pressure sensor 7 are led to the ground instrument through the threading holes arranged inside the device.

[0037] Selection of device material: This embodiment 1 uses a precipitation-hardened stainless steel as the main material of the device, and the material has the characteristics of high strength and corrosion resistance.

[0038] The manifold 3 and the discharge port 8: In the present embodiment 1, the manifold 3 and the discharge port 8 both include upper and lower double ports, and their total flow areas are both larger than the maximum flow area of ​​the Venturi to reduce unnecessary pressure loss.

[0039] Interface connection mode: In Example 1, the upstream interface 1 and the downstream interface 9 are both internal thread interfaces.

[0040] Sealing method: The sealing elements between the parts in Example 1 are fluororubber O-rings.

[0041] Temperature and pressure resistance test:

[0042] The embodiment passed the 150°C, 60MPa temperature and pressure resistance test. The test results are shown in Table 1.

[0043] Table 1 150℃, 60MPa temperature and pressure resistance test

[0044]

[0045] The Venturi flow measurement device as a whole was subjected to a high-temperature and high-pressure static sealing test with a pressure resistance of 60MPa and a temperature resistance of 150℃. The test was conducted for 15 minutes, with the temperature reaching a maximum of 150.2℃, the pressure being stable at 60MPa, and the pressure drop being 0MPa. The high-pressure sealing test of the Venturi flow measurement device passed.

[0046] The actual use effect test of this embodiment, the test data is shown in Table 2.

[0047] Table 2 Actual use effect test

[0048]

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A venturi flow measurement device for a gas injection well, characterized in that: It includes a Venturi, a pressure collection device and a flow-blocking structure. The Venturi is provided with a plurality of pressure-conducting holes, and each of the pressure-conducting holes is provided with the pressure collection device, so that the pressure collection device can measure the pressure of each of the pressure-conducting holes when the fluid flows through the Venturi, so as to obtain the pressure difference between each of the pressure-conducting holes. The Venturi is arranged in a working cylinder, and a gap is left between the Venturi and the working cylinder, and the flow-blocking structure is arranged in the gap.

2. The underground Venturi flow measurement device for gas injection wells according to claim 1, characterized in that: The main body of the Venturi is provided with a front straight pipe section, a contraction section, a throat, an expansion section and a rear straight pipe section in sequence; the front straight pipe section is provided with a collecting port, the rear straight pipe section is provided with a discharge port, and the front straight pipe section, the throat and the rear straight pipe section are respectively provided with the pressure guide holes.

3. The underground Venturi flow measurement device for gas injection wells according to claim 2, characterized in that: The pressure acquisition device includes a plurality of pressure sensors and a ground instrument. The pressure sensor is arranged at the pressure conducting hole. The ground instrument is electrically connected to the pressure sensor to realize signal processing and output to the ground instrument.

4. The underground Venturi flow measurement device for gas injection wells according to claim 3, characterized in that: The flow-blocking structure is a baffle ring, and the baffle ring is arranged between the collecting port and the discharge port.

5. The underground Venturi flow measurement device for gas injection wells according to claim 4, characterized in that: The venturi further comprises an upstream interface and a downstream interface, wherein the upstream interface is located at the upstream end of the body of the venturi, and the downstream interface is located at the downstream end of the body of the venturi.

6. The underground Venturi flow measurement device for a gas injection well according to any one of claims 2 to 5, characterized in that: The diameter of the pressure-conducting hole is 3-4 mm.

7. The underground Venturi flow measurement device for gas injection wells according to claim 6, characterized in that: The diameter of the venturi is 15-16 mm.

8. The underground Venturi flow measurement device for gas injection wells according to claim 7, characterized in that: The diameter of the throat is 6-7 mm.

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