Forward and reverse bidirectional flow rate metering method for underwater chemical agent injection device

Abstract

A forward and reverse bidirectional flow rate metering method for an underwater chemical agent injection device. The underwater chemical agent injection device comprises a device body, wherein the device body comprises an agent input joint (1), a pressure reduction member (2), a needle valve assembly (5) and an agent output joint (3), which are sequentially in communication by means of a flow channel. The method comprises: first, respectively performing forward calibration and reverse calibration by means of an agent at different opening degrees and different flow rates, during which a differential pressure is synchronously acquired before and after the agent flows through a needle valve assembly (5); then, fitting relationships between flow rates and differential pressures under different opening degrees of the needle valve assembly (5), so as to obtain several opening degree-flow coefficient arrays; and then fitting relationships between flow coefficients and the opening degrees, and establishing equations for the flow rate, opening degree and differential pressure.

Description

Method for measuring forward and reverse bidirectional flow rate of underwater chemical injection equipment Technical Field

[0001] The present invention relates to the field of petroleum engineering, and in particular to a method for controlling the injection of a chemical into an underwater Christmas tree pipe network. Background Art

[0002] [Corrected 26.12.2024 according to Rule 91] In order to ensure the normal operation of underwater oil pipelines and improve their service life and production efficiency, various reagents need to be regularly introduced into the pipelines through underwater injection equipment. Regarding underwater injection equipment, the applicant's earlier Chinese patent application (application number: CN202110934610.9) records the structure of an underwater reagent injection device, which shows that the orifice plate and flow channel groove can reduce the pressure of the high-pressure reagent flow passing through. In subsequent practice, the following problems were found:

[0003] [Corrected 26.12.2024 according to Rule 91] (1) Due to the original pipeline installation error on the underwater oil production tree, the inlet of the underwater chemical injection equipment was connected to the corresponding outlet on the oil production tree, and the outlet of the underwater chemical injection equipment was connected to the corresponding inlet on the oil production tree; because the relevant parameters of the underwater chemical injection equipment were calibrated in advance based on the default state of the chemical flowing in the forward direction in the underwater chemical injection equipment, the chemical flow rate would not be accurately measured if the chemical flow rate was reversed due to the original pipeline installation error. The injection would need to be stopped and the underwater chemical injection equipment would need to be re-installed in a reverse direction, which would increase the installation cost and affect the operation and maintenance of the pipeline network. In order to prevent similar situations from occurring in the future, it is necessary to calibrate the relevant parameters of the chemical flow in the forward and reverse directions in the underwater chemical injection equipment so that the chemical flow rate can be accurately measured in the forward and reverse directions.

[0004] (2) Based on the consideration of control stability, designers introduced a needle valve to control the flow rate. However, when the needle valve opening is different, the relevant flow parameters will also change, and it is impossible to measure the flow rate with fixed parameters. Therefore, it is necessary to establish a relationship between the flow rate and the valve opening to accurately and in real time measure the flow rate.

[0005] Summary of the Invention

[0006] In order to solve the above technical problems, the main technical solutions adopted by the present invention are as follows:

[0007] A method for measuring the forward and reverse bidirectional flow of underwater chemical injection equipment includes an equipment body, wherein the equipment body includes a chemical input connector, a pressure reducing member, a needle valve assembly, and a chemical output connector sequentially connected through a flow channel. The key to the method is to perform the following steps:

[0008] Step 1: Keeping the opening V of the needle valve assembly fixed, inject reagents of different calibration flow rates Q into the device body through the reagent input connector and the reagent output connector as inlets, respectively, to perform forward and reverse bidirectional calibration, and synchronously obtain a first differential pressure DP1 before and after the reagent flows through the pressure reducing component, and a second differential pressure DP2 before and after the reagent flows through the needle valve assembly;

[0009] Obtain the forward calibration array and reverse calibration array under the same opening V;

[0010] Step 2: According to formula ①, fit the flow-differential pressure relationship in both forward and reverse directions under the same opening V;

[0011] in:

[0012] Q A is the forward flow; K A is the forward flow coefficient; C A is the forward calibration coefficient; DPn A Or DP1 A , or DP2 A , DP1 A is the first positive differential pressure, DP2 A is the positive second differential pressure;

[0013] Q B is the reverse flow, K B is the reverse flow coefficient, C B is the reverse calibration coefficient; DPn B Or DP1 B , or DP2 B , DP1 B DP2 is the reverse first differential pressure B is the reverse second differential pressure;

[0014] Step 3: Adjust the needle valve assembly (5) to different openings V, repeat steps 1 and 2, and obtain the forward and reverse flow coefficients and the forward and reverse calibration coefficients at different openings respectively;

[0015] Forward opening V A , forward flow coefficient K A , forward calibration coefficient C A correspond to each other and form a forward fitting array;

[0016] Reverse opening V B , reverse flow coefficient K B , reverse calibration coefficient C B correspond to each other and form a reverse fitting array;

[0017] Step 4: Fit the relationship between flow coefficient and needle valve opening according to formula ②;

[0018] Step 5. Establish the flow rate, opening, and differential pressure formula according to formula ③;

[0019] in:

[0020] is some forward calibration coefficient C A The mean of

[0021] is some reverse calibration coefficient C B The mean of

[0022] Step 6: Connect the device to the production system and introduce the reagent;

[0023] [Corrected 26.12.2024 according to Rule 91] When the pressure of the agent shows a downward trend from the pressure reducing member to the needle valve assembly, it is determined that the agent is flowing in the forward direction; the forward real-time opening V of the needle valve assembly is controlled. A `, obtain the first positive real-time differential pressure DP1 A `, and the positive real-time second differential pressure DP2 A `, calculate the forward real-time flow Q according to formula ④ A `;

[0024] Where: DPn A Or DP1 A `, or DP2 A `;

[0025] [Corrected 26.12.2024 according to Rule 91] When the pressure of the agent increases from the pressure reducing member to the needle valve assembly, it is determined that the agent is flowing in the reverse direction; the reverse real-time opening V of the needle valve assembly is controlled. B `, obtain the reverse real-time first differential pressure DP1 B `, and reverse real-time second differential pressure DP2 B `, calculate the reverse real-time traffic Q according to formula ⑤ B `;

[0026] Using the above technical solution, the reagent input connector and the reagent output connector are used as inlets to introduce the reagent, simulating the forward and reverse flow of the reagent in the device body. The correlation coefficients / parameters are calibrated separately to obtain the forward and reverse flow calculation formulas. Later, the corresponding calculation formula is selected according to the forward and reverse flow conditions of the reagent to obtain the real-time flow rate, thus solving the problem of inaccurate measurement caused by the inappropriate parameters of the one-way calibration. In addition, the above method directly fits the relationship between flow rate, differential pressure, and opening degree. In actual use, the real-time flow rate can be obtained based on the real-time opening degree and real-time differential pressure, thus solving the problem of insufficiently fast and accurate measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] FIG1 is a schematic structural diagram of an underwater agent injection device;

[0028] Figure 2 shows the forward Q at different openings A -sqrt(DP2 A ) fitting curve;

[0029] Figure 3 shows the reverse Q at different openings B -sqrt(DP2 B ) fitting curve;

[0030] Figure 4 shows the flow coefficient K of the forward calibration A -Opening V A Fitting curves;

[0031] [Corrected 26.12.2024 according to Article 91] Figure 5 shows the reverse calibration flow coefficient K B -Opening V B Fitting curves;

[0032] Figure 6 shows the use of DP1 A `Distribution diagram of the percentage error of the calculated flow rate and the actual flow rate;

[0033] Figure 7 shows the use of DP2 A `Distribution diagram of the percentage error of the calculated flow and the actual flow. DETAILED DESCRIPTION

[0034] The present invention will be further described below with reference to the embodiments and accompanying drawings.

[0035] Example 1:

[0036] A method for measuring the forward and reverse bidirectional flow of underwater chemical injection equipment includes a device body, as shown in FIG1 , wherein a flow channel is configured inside the device body. The device body includes a chemical input connector 1, a pressure reducing member 2, a needle valve assembly 5, and a chemical output connector 3, which are sequentially connected through the flow channel.

[0037] [Corrected 26.12.2024 in accordance with Rule 91] The device body further comprises a first pressure sensor 61, a second pressure sensor 62, and a third pressure sensor 63;

[0038] The pressure detection end of the first pressure sensor 61 is connected to the flow channel at the upstream end of the pressure reducing member 2 to measure the front fluid pressure P1 before the medicine flows through the pressure reducing member 2;

[0039] The pressure detection end of the second pressure sensor 62 is in communication with the flow passage between the pressure reducing member 2 and the needle valve assembly 5 to measure the fluid pressure P2 of the middle section of the agent after it flows through the pressure reducing member 2 and before it flows through the needle valve assembly 5;

[0040] [Corrected 26.12.2024 according to Rule 91] The pressure detection end of the third pressure sensor 63 is connected to the flow channel of the downstream section of the needle valve assembly 5 to measure the rear fluid pressure P3 after the agent flows through the needle valve assembly 5.

[0041] The output ends of the first pressure sensor 61 , the second pressure sensor 62 and the third pressure sensor 63 are respectively connected to the signal processing and transmission module through signal harnesses.

[0042] The device body also includes a linear displacement sensor and a rotational displacement sensor, the sensing ends of which are respectively connected to the opening and closing function portion of the needle valve assembly 5. The linear displacement sensor and the rotational displacement sensor are mutually redundant, so that when one position sensing method fails or becomes inaccurate, an effective and reliable replacement solution can still be provided.

[0043] The linear displacement sensor and the rotational displacement sensor are both used to measure the position of the opening and closing function part (eg, valve needle / valve stem) of the needle valve assembly 5 , thereby obtaining the opening degree of the needle valve.

[0044] The calculation of the opening of the needle valve is well documented in the prior art and will not be described in detail here.

[0045] The method is carried out according to the following steps:

[0046] Step 1: First, keep the opening V of the needle valve assembly 5 fixed, and then use the medicine input connector 1 and the medicine output connector 3 as inlets to inject medicine with different calibration flow rates Q into the device body for forward and reverse bidirectional calibration. During this process, the first differential pressure DP1 before and after the medicine flows through the pressure reducing component 2, and the second differential pressure DP2 before and after the medicine flows through the needle valve assembly 5 are simultaneously obtained;

[0047] DP1 = |P1-P2|;

[0048] DP2 = |P2-P3|;

[0049] Thus, a forward calibration array and a reverse calibration array are obtained under the same opening V; the forward calibration array includes a number of corresponding forward calibration flow rates, forward first differential pressures, and forward second differential pressures; the reverse calibration array includes a number of corresponding reverse calibration flow rates, reverse first differential pressures, and reverse second differential pressures.

[0050] Step 2: Based on the forward calibration array and the reverse calibration array, the forward and reverse bidirectional flow-differential pressure relationships under the same opening V are fitted according to formula ①;

[0051] in:

[0052] Q A is the forward flow; K A is the forward flow coefficient; C A is the forward calibration coefficient; DPn A Or DP1 A , or DP2 A , DP1 A is the first positive differential pressure, DP2 A is the positive second differential pressure;

[0053] Q B is the reverse flow, K B is the reverse flow coefficient, C B is the reverse calibration coefficient; DPn B Or DP1 B , or DP2 B , DP1 B DP2 is the reverse first differential pressure B is the reverse second differential pressure;

[0054] Step 3: Adjust the needle valve assembly 5 to different openings V, repeat steps 1 and 2, and obtain the forward and reverse flow coefficients, as well as the forward and reverse calibration coefficients, at different openings.

[0055] Forward opening V A , forward flow coefficient K A , forward calibration coefficient C A correspond to each other and form a forward fitting array;

[0056] Reverse opening V B , reverse flow coefficient K B , reverse calibration coefficient C B correspond to each other and form a reverse fitting array;

[0057] Combining the above steps 2 and 3, we can also use the following formula to directly express it:

[0058] in:

[0059] Q Ai is the flow rate when performing forward calibration at the i-th opening;

[0060] K Ai is the flow coefficient when performing positive calibration at the i-th opening;

[0061] DPn Ai For DP1 Ai or DP2 Ai ;

[0062] DP1 Ai is the first differential pressure when performing positive calibration at the i-th opening;

[0063] DP2 Ai is the second differential pressure when performing positive calibration at the i-th opening;

[0064] C Ai is the calibration coefficient when performing forward calibration at the i-th opening;

[0065] V Ai is the i-th positive opening;

[0066] i=1,2,…,j; j is the total number of openings during forward calibration;

[0067] Q Br is the flow rate when reverse calibration is performed at the rth opening;

[0068] K Br is the flow coefficient when reverse calibration is performed at the rth opening;

[0069] DPn Br For DP1 Br or DP2 Br ;

[0070] DP1 Br is the first differential pressure when reverse calibration is performed at the rth opening;

[0071] DP2 Br is the second differential pressure when reverse calibration is performed at the rth opening;

[0072] C Br is the calibration coefficient when performing reverse calibration at the rth opening;

[0073] V Br is the rth positive opening;

[0074] r=1,2,…,k; k is the total number of openings during reverse calibration.

[0075] Step 4: Fit the relationship between flow coefficient and needle valve opening according to formula ②;

[0076] A number of K Ai 、V Ai , and several K Br 、V Br Substitute into formula ② to fit the relationship between the forward flow coefficient and the forward opening, and the relationship between the reverse flow coefficient and the reverse opening.

[0077] A specific fitting formula for flow coefficient and needle valve opening can be:

[0078] Among them: A A 、D A is the forward opening fitting parameter, A B 、D B is the reverse opening fitting parameter;

[0079] Step 5. Establish the flow rate, opening, and differential pressure formula according to formula ③;

[0080] in:

[0081] is some forward calibration coefficient C A The mean of

[0082] is some reverse calibration coefficient C B The mean of

[0083] Step 6: Connect the device to the production system and introduce the reagent;

[0084] When the pressure of the agent shows a downward trend from the pressure reducing component 2 to the needle valve assembly 5, that is, when the front fluid pressure P1 is greater than the rear fluid pressure P3, the agent is determined to be flowing in the forward direction; the forward real-time opening V of the needle valve assembly 5 is controlled. A `, obtain the first positive real-time differential pressure DP1 A `, with the positive real-time second differential pressure DP2 A `, calculate the forward real-time flow Q according to formula ④ A `;

[0085] Where: DPn A Or DP1 A `, or DP2 A `;

[0086] [Corrected 26.12.2024 according to Rule 91] When the pressure of the agent increases from the pressure reducing member 2 to the needle valve assembly 5, that is, when the pressure of the rear fluid section P3 is greater than the pressure of the front fluid section P1, it is determined that the agent is flowing in the reverse direction; the reverse real-time opening V of the needle valve assembly 5 is controlled. B `, obtain the reverse real-time first differential pressure DP1 B `, with the reverse real-time second differential pressure DP2 B `, calculate the reverse real-time traffic Q according to formula ⑤ B `;

[0087] Example 2:

[0088] A forward and reverse bidirectional flow measurement method for underwater chemical injection equipment.

[0089] The only difference between this embodiment and embodiment 1 is that:

[0090] In step 2, set the segmented flow rate value Q f ;

[0091] In step 6, the target flow rate Q is set m , control the opening of the needle valve assembly 5 so that Q A `=Q m or Q B `=Q m ;

[0092] When Q m >Q f hour:

[0093] DPn in step 2 A Take DP1 A , and in step 6 DPn A `Take DP1 A `;

[0094] DPn in step 2 B Take DP1 B , and in step six DPn B `Take DP1 B `;

[0095] When Q m ≤Q f hour:

[0096] DPn in step 2 A Take DP2 A , and in step 6 DPn A `Take DP2 A `;

[0097] DPn in step 2B Take DP2 B , and in step six DPn B `Take DP2 B `.

[0098] That is: DP1 A `With DP1 A There is a corresponding relationship between the front and back formulas. When the differential pressure between the positive front fluid pressure P1 and the positive middle fluid pressure P2 is used for fitting in step 2, the differential pressure between the positive front fluid pressure P1 and the positive middle fluid pressure P2 should also be used for real-time measurement in step 6.

[0099] Similarly, DP1 B `With DP1 B Between, DP2 A `With DP2 A Between, DP2 B `With DP2 B There is a corresponding relationship between them.

[0100] The effect of adopting segmented metering is that it can reduce the relative error of flow measurement and further improve the measurement accuracy.

[0101] Example 3:

[0102] [Corrected 26.12.2024 in accordance with Rule 91] A method for measuring the forward and reverse bidirectional flow rate of an underwater chemical injection device, comprising the underwater chemical injection device of Example 1, is performed according to the following steps:

[0103] Step 1: Bidirectional calibration

[0104] Step 1.1, forward calibration:

[0105] Adjust the needle valve assembly 5 to a plurality of different forward openings V A The drug input connector 1 is used as the inlet to inject different forward flow rates Q into the device body. A Calibration of the pharmaceutical agent;

[0106] At each positive opening V A Under these conditions, sufficient forward flow Q of different sizes should be introduced. A , preferably 10 times or more, each time the forward flow Q A Different in size; during the period, the forward front section fluid pressure P1, the forward middle section fluid pressure P2, the forward rear section fluid pressure P3 when the agent flows through the device body are obtained synchronously; the forward first differential pressure DP1 A =P1-P2; positive second differential pressure DP2 A =P2-P3;

[0107] VA , Q A DP1 A DP2 A Correspond to each other and form a forward calibration array; extract part of the forward calibration V A , Q A DP1 A DP2 A The data are shown in Table 1;

[0108] Step 1.2, reverse calibration:

[0109] Adjust the needle valve assembly 5 to a plurality of different reverse openings V B The medicine output connector 3 is used as the inlet to inject different reverse flow rates Q into the device body. B Calibration of the pharmaceutical agent;

[0110] At each reverse opening V B Under these conditions, sufficient reverse flow Q of different sizes should be introduced. B , preferably 10 times or more, each time the reverse flow Q B Different sizes; during the period, the reverse front section fluid pressure P1, reverse middle section fluid pressure P2, reverse rear section fluid pressure P3 when the medicine flows through the device body are obtained simultaneously; the reverse first differential pressure DP1 B =P2-P1; reverse second differential pressure DP2 B =P3-P2;

[0111] V B , Q B DP1 B DP2 B Correspond to each other and form a forward calibration array; extract some reverse calibration V B , Q B DP1 B DP2 B The data are shown in Table 2;

[0112] Step 2: Fit the relationship between flow rate and differential pressure under different openings according to the following formula ①;

[0113] in:

[0114] Q A By j Q Ai constitute;

[0115] Q Ai is the flow rate when performing forward calibration at the i-th opening;

[0116] K A is the forward flow coefficient, which is composed of j K Ai constitute;

[0117] K Ai is the flow coefficient when performing positive calibration at the i-th opening; C A is the forward calibration coefficient, which is composed of j C Ai constitute;

[0118] C Ai DPn is the calibration coefficient when performing forward calibration at the i-th opening; A By j DPn Ai constitute;

[0119] DPn A Or DP1 A , or DP2 A ;

[0120] DPn Ai Or DP1 Ai , or DP2 Ai ;

[0121] DP1 A By j DP1 Ai constitute;

[0122] DP1 Ai DP2 is the first differential pressure when performing positive calibration at the i-th opening; A By j DP2 Ai constitute;

[0123] DP2 Ai is the second differential pressure when performing positive calibration at the i-th opening; V A By j V Ai constitute;

[0124] V Ai is the i-th positive opening;

[0125] i=1,2,…,j; j is the total number of openings during forward calibration;

[0126] Q B By k Q Br constitute;

[0127] Q Br is the flow rate when reverse calibration is performed at the rth opening;

[0128] K B is the reverse flow coefficient, which is composed of k K Br constitute;

[0129] K Br is the flow coefficient when reverse calibration is performed at the rth opening; C B is the reverse calibration coefficient, which is composed of k CBr constitute;

[0130] C Br DPn is the calibration coefficient when reverse calibration is performed at the rth opening; B By k DPn Br constitute;

[0131] DPn B Or DP1 B , or DP2 B ;

[0132] DPn Br Or DP1 Br , or DP2 Br ;

[0133] DP1 B By k DP1 Br constitute;

[0134] DP1 Br DP2 is the first differential pressure when reverse calibration is performed at the rth opening; B By k DP2 Br constitute;

[0135] DP2 Br is the second differential pressure when reverse calibration is performed at the rth opening;

[0136] V B By k V Br constitute;

[0137] V Br is the rth reverse opening;

[0138] r=1,2,…,k; k is the total number of openings during reverse calibration;

[0139] After the above fitting, the calibration array of the same opening is fitted to obtain a flow coefficient and a calibration coefficient, namely:

[0140] Several positive openings V A , forward flow coefficient K A , forward calibration coefficient C A correspond to each other and form a forward fitting array;

[0141] Several reverse openings V B , reverse flow coefficient K B , reverse calibration coefficient C B correspond to each other and form a reverse fitting array;

[0142] DPn A For DP2 A , DPn BFor DP2 B For example: the forward flow coefficient K obtained by fitting A and the forward calibration coefficient C A The results are shown in Table 1; the fitted reverse flow coefficient K B and the reverse calibration coefficient C B The results are shown in Table 2;

[0143] In order to see the linear relationship between flow and differential pressure more intuitively, the forward and reverse bidirectional flow Q under different openings V are plotted. A -sqrt(DP2 A ) curve and Q B -sqrt(DP2 B ) curve, and the results are shown in Figures 2 and 3 respectively. It can be seen from Figures 2 and 3 that: no matter the agent flows forward or reverse, its flow rate has a good linear relationship with sqrt(DP2).

[0144] Step 3: Based on the forward fitting array and the reverse fitting array, the relationship between the flow coefficient and the needle valve opening is fitted according to formula ②;

[0145] A number of K Ai 、V Ai , and several K Br 、V Br Substitute into formula ② and fit separately to get the forward opening fitting parameter A A 、D A ; Reverse opening fitting parameter A B 、D B . A A 、D A 、A B 、D B The fitting results are shown in Table 1 and Table 2 respectively:

[0146] In order to more intuitively see the linear relationship between the flow coefficient and the opening, the KV curves of the forward and reverse flow coefficients and the opening V are drawn. The results are shown in Figures 4 and 5 respectively. It can be seen from Figures 4 and 5 that there is a good linear relationship between the flow coefficient and the opening when the agent flows in both forward and reverse directions.

[0147] From this, the relationship between flow rate, opening and differential pressure is obtained, as shown in formula ③:

[0148] is some forward calibration coefficient C A The mean of

[0149] is some reverse calibration coefficient C B The mean of .

[0150] Table 1. Statistics of forward calibration array, fitting array and some opening fitting parameters

[0151] Table 2. Statistics of reverse calibration array, fitting array and some opening fitting parameters

[0152] Step 5: For a more intuitive comparison, the first positive differential pressure DP1 in Table 1 A , positive second differential pressure DP2 A Equivalent to the first positive real-time differential pressure DP1 A `, forward real-time second differential pressure DP2 A `, and then respectively into the corresponding formula to obtain the corresponding real-time flow Q1 A `、Q2 A `;Q1 A To adopt DP1 A `Calculated forward real-time traffic, Q2 A To adopt DP2 A `Calculate the forward real-time flow rate. Take the calibrated flow rate Q as the actual flow rate and calculate the percentage error between the two real-time flow rates and the actual flow rate.

[0153] The results show:

[0154] Calculated real-time traffic Q1 A `The percentage error from the actual traffic is (-6.67%)-(+5.19%);

[0155] Calculated real-time traffic Q2 A `The percentage error from the actual traffic is (-7.49%)-(+5.84%);

[0156] [Corrected 26.12.2024 according to Rule 91] Overall, adopting DP1 A DP2 A DP1 A `、DP2 A `To fit and calculate real-time traffic, there is a small error range and relatively accurate results can be obtained.

[0157] [Corrected 26.12.2024 according to Article 91] A 、Q2 A The relationship between the corresponding percentage errors and the actual flow rate is plotted in the coordinate system, and the results are shown in Figures 6 and 7 respectively. Combining Figures 6 and 7, it can be seen that:

[0158] When the flow rate is large, use DP1 A / DP1 A`The percentage error obtained by fitting and calculating is relatively more concentrated, and the error range is relatively smaller. Using DP2 A / DP2 A The percentage errors obtained by fitting and calculating are relatively more dispersed, and the error range is relatively larger;

[0159] When the flow rate is small, use DP2 A / DP2 A `The percentage error obtained by fitting and calculating is relatively more concentrated, and the error range is relatively smaller. Using DP1 A / DP1 A The percentage errors obtained by fitting and calculating are relatively more dispersed, and the error range is relatively larger.

[0160] Therefore, it is possible to consider using different fitting and / or calculation methods to segment the real-time flow according to the size of the target flow: the key to segmentation is to find the dividing point between large and small flows; and the dividing point between large and small flows is generally set artificially based on the calibration results. The above dividing point is the segmented flow value Q f .

[0161] Therefore, when measuring and controlling real-time flow, the target flow Q m And the segmented metering flow value Q f The size of the differential pressure and the corresponding flow formula are selected to calculate the real-time flow rate to obtain a relatively more accurate result, that is, to perform segmented control as described in Example 2.

[0162] Beneficial effects: The technical solution of the present invention can detect the installation direction of the underwater injection equipment and accurately measure the flow rate for both the forward and reverse bidirectional installation conditions, thereby avoiding inaccurate flow measurement results due to inverted installation direction; and subsequently, only the differential pressure and needle valve opening need to be obtained to obtain the real-time flow rate, thereby simplifying the real-time flow rate measurement process.

[0163] Finally, it should be noted that the above description is only a preferred embodiment of the present invention. Under the guidance of the present invention, ordinary technicians in this field can make various similar expressions without violating the purpose and claims of the present invention. Such changes fall within the scope of protection of the present invention.

Claims

1. A method for measuring the forward and reverse bidirectional flow of an underwater chemical injection device, comprising a device body, wherein the device body comprises a chemical input connector (1), a pressure reducing member (2), a needle valve assembly (5) and a chemical output connector (3) which are sequentially connected through a flow channel, characterized in that Follow these steps: Step 1: Keep the opening V of the needle valve assembly (5) fixed, use the medicine input connector (1) and the medicine output connector (3) as inlets, inject medicines with different calibration flow rates Q into the device body for forward and reverse bidirectional calibration, and synchronously obtain a first differential pressure DP1 before and after the medicine flows through the pressure reducing component (2), and a second differential pressure DP2 before and after the medicine flows through the needle valve assembly (5); Obtain the forward calibration array and the reverse calibration array under the same opening V; Step 2: According to formula ①, fit the flow-differential pressure relationship in both positive and negative directions under the same opening V; in: Q A is the forward flow; K A is the forward flow coefficient; C A is the positive calibration coefficient; DPn A Or DP1 A , or DP2 A , DP1 A is the first positive differential pressure, DP2 A is the positive second differential pressure; Q B is the reverse flow, K B is the reverse flow coefficient, C B is the reverse calibration coefficient; DPn B Or DP1 B , or DP2 B , DP1 B DP2 is the reverse first differential pressure B is the reverse second differential pressure; Step 3, adjusting the needle valve assembly (5) to different openings V, repeating steps 1 and 2, and obtaining the forward and reverse flow coefficients at different openings, as well as the forward and reverse calibration coefficients; Positive opening V A , forward flow coefficient K A , forward calibration coefficient C A correspond to each other and form a forward fitting array; Reverse opening V B , reverse flow coefficient K B , reverse calibration coefficient C B correspond to each other and form a reverse fitting array; Step 4: Fit the relationship between flow coefficient and needle valve opening according to formula ②; Step 5: Establish the flow rate, opening, and differential pressure calculation formula according to formula ③; in: is some positive calibration coefficient C A The mean of is some reverse calibration coefficient C B The mean of Step 6: Connect the equipment body to the production system and introduce the medicine; When the pressure of the medicine shows a downward trend from the pressure reducing component (2) toward the needle valve assembly (5), it is determined that the medicine is flowing in the forward direction; and the forward real-time opening V of the needle valve assembly (5) is controlled. A `, obtain the first positive real-time differential pressure DP1 A `, with the positive real-time second differential pressure DP2 A `, calculate the forward real-time flow Q according to formula ④ A `; Where: DPn A Or DP1 A `, or DP2 A `; When the pressure of the medicine shows an upward trend from the pressure reducing component (2) toward the needle valve assembly (5), it is determined that the medicine is flowing in the reverse direction; and the reverse real-time opening V of the needle valve assembly (5) is controlled. B `, obtain the reverse real-time first differential pressure DP1 B `, with reverse real-time second differential pressure DP2 B `, calculate the reverse real-time flow Q according to formula ⑤ B `; 2. The method for measuring the forward and reverse bidirectional flow of underwater chemical injection equipment according to claim 1 is characterized in that In the step 4: Among them: A A , D A is the forward opening fitting parameter, A B , D B is the reverse opening fitting parameter.

3. The method for measuring the forward and reverse bidirectional flow rate of underwater chemical injection equipment according to claim 1 or 2, characterized in that: In step 2, set the segmented metering flow value Q f ; In step 6, the target flow rate Q is set m , control the opening of the needle valve assembly (5) so that Q A `=Q m or Q B `=Q m ; When Q m >Q f hour: DPn in step 2 A Take DP1 A , and in step 6, DPn A `Get DP1 A `; DPn in step 2 B Take DP1 B , and in step 6, DPn B `Get DP1 B `; When Q m ≤Q f hour: DPn in step 2 A Take DP2 A , and in step 6, DPn A `Get DP2 A `; DPn in step 2 B Take DP2 B , and in step 6, DPn B `Get DP2 B `.

4. The forward and reverse bidirectional flow metering method of underwater chemical injection equipment according to claim 1 or 2: the equipment body further comprises a first pressure sensor (61), a second pressure sensor (62), and a third pressure sensor; The first pressure sensor (61) is connected to the flow channel at the upstream end of the pressure reducing member (2) to measure the front fluid pressure P1 before the medicine flows through the pressure reducing member (2); The second pressure sensor (62) is connected to the flow passage between the pressure reducing component (2) and the needle valve assembly (5) to measure the fluid pressure P2 in the middle section after the medicine flows through the pressure reducing component (2) and before the needle valve assembly (5); The third pressure sensor is connected to the flow channel of the downstream section of the needle valve assembly (5) to measure the rear section fluid pressure P3 after the medicine flows through the needle valve assembly (5).

5. According to the forward and reverse bidirectional flow metering method of underwater chemical injection equipment in claim 5: in the step six, when the front-end fluid pressure P1 is greater than the rear-end fluid pressure P3, the agent is determined to be flowing in the forward direction; when the rear-end fluid pressure P3 is greater than the front-end fluid pressure P1, the agent is determined to be flowing in the reverse direction.

6. The method for measuring forward and reverse bidirectional flow of underwater chemical injection equipment according to claim 1, characterized in that: The device body also includes a linear displacement sensor and a rotational displacement sensor; The sensing end of the linear displacement sensor and the sensing end of the rotational displacement sensor are respectively connected to the opening and closing function part of the needle valve assembly (5).

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