Method and system for quickly acquiring layered flow of wave code separate injection well

Abstract

The invention provides a method and a system for quickly acquiring the layered flow of a wave code separate injection well, and the method comprises the following steps: a ground controller controls underground water distributors to inject water in a constant-pressure mode, and the underground water distributors respectively record the opening degrees of water nozzles when the water is injected in a constant-flow mode; the ground controller controls the opening degree of the water nozzle of the underground water distributor of the measured oil layer to be kept unchanged, the opening degree of the water nozzle of the underground water distributor of the other layers is kept closed, and the ground controller reads the flow value at the moment as the water injection flow of the measured oil layer; according to the method, a traditional mode of indirectly reading the underground layered flow through layered coding is changed into a mode of directly and sequentially reading the flow of each underground layer on the ground through one-time coding, the flow reading efficiency is effectively improved, the reading time is effectively shortened, and the flow reading time is effectively shortened through the mode of directly and sequentially reading the flow of each underground layer on the ground.

Description

Technical Field

[0001] The present invention belongs to the technical field of stratified water injection and oil recovery in oil and gas wells, and particularly relates to a method and system for quickly acquiring stratified flow rates in wave code-based injection wells. Background Art

[0002] Currently used stratified water injection technologies are mainly divided into two types: cable communication and wave code communication. Cable communication is efficient, but it is difficult to install, cannot be operated under pressure, and has high maintenance costs. Wave code communication can be operated under pressure and is convenient to install, but the communication efficiency between the surface and the underground is relatively low.

[0003] The current method of wave code communication uses downhole instruments to measure and store the injection flow rate of each layer. When inquiries are made on the ground, the flow data of that layer is transmitted back to the surface in the form of return codes. Since the formation of a set of return code sequence waves requires the water nozzle of the downhole instrument to be opened and closed multiple times, it consumes a lot of electricity. While taking into account the battery life, the flow data can only be updated every 15 days, resulting in a relatively low frequency of data updates. At the same time, it takes about 120 minutes to complete a complete return code process underground, and the communication time is relatively long, which puts a heavy workload on data monitoring personnel. Summary of the Invention

[0004] In order to solve the above problems, the purpose of the present invention is to provide a method and system for quickly obtaining the stratified flow rate of wave code injection wells. Based on the theory of the orifice flow formula, the present invention can quickly and accurately obtain the downhole stratified water injection flow rate through the coordinated control of each layer of downhole water distributors.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0006] A method for quickly acquiring stratified flow rates in wave-code injection wells, the method comprising:

[0007] The surface controller controls the downhole water distributor to perform water injection in a constant pressure mode, and the downhole water distributor respectively records the opening of the water nozzle during the constant flow mode water injection;

[0008] The surface controller controls the water nozzle opening of the downhole water distributor of the measured oil layer to remain unchanged, and the water nozzles of the downhole water distributors of other layers remain closed. The surface controller reads the flow value at this time as the water injection flow of the measured oil layer.

[0009] Furthermore, the surface controller controls the downhole water distributor to perform water injection in a constant pressure mode, and the downhole water distributor records the water nozzle opening during the constant flow mode water injection, specifically:

[0010] The surface controller records the water injection pressure value of the downhole water distributor when injecting water in a constant flow mode;

[0011] The surface controller sends a quick flow reading instruction to the downhole water distributor and then performs water injection at a constant pressure according to the water injection pressure value;

[0012] After the downhole water distributor recognizes the quick flow reading instruction, the downhole water distributor of each layer records the opening of the water nozzle during the constant flow water injection.

[0013] Furthermore, before the surface controller controls the downhole water distributor to perform water injection in a constant pressure mode, the method further includes:

[0014] The surface controller determines whether a fast flow reading operation is required. If required, the surface controller controls the downhole water distributor to perform water injection in a constant pressure mode.

[0015] Furthermore, if it is not necessary, the surface controller controls the downhole water distributor to inject water in a constant flow manner.

[0016] Furthermore, after the surface controller reads the flow value at this time, the method further includes: the surface controller controls the water nozzle opening of the downhole water distributor of all oil layers to recover, and the downhole water distributor performs water injection in a constant flow mode.

[0017] Furthermore, the constant flow rate value read by the ground controller is used as the water injection flow rate of the measured oil layer.

[0018] Furthermore, the measured oil layers are arranged in sequence from top to bottom to read the flow values.

[0019] Furthermore, the flow value measurement formula is as follows:

[0020]

[0021] Where: Q is the flow rate of the nozzle; C d is the discharge coefficient of the faucet, C d Less than 1; A is the cross-sectional area of ​​the water nozzle; △P is the difference between the injection pressure and the formation pressure; ρ is the density of water.

[0022] Furthermore, the range of ΔP is -0.1 to +0.1 MPa.

[0023] The present invention also provides a system for quickly acquiring the stratified flow rate of wave-code injection wells, which is applied to the method for quickly acquiring the stratified flow rate of wave-code injection wells of the present invention. The system includes a ground controller and a downhole water distributor. Several layers of downhole water distributors connected in series are arranged in an injection well for injecting water into the corresponding oil layer. The ground controller is connected to the downhole water distributor by wave-code wireless communication, and is used to control the downhole water distributor to read the injection flow rate of the corresponding oil layer when injecting water in a constant pressure manner.

[0024] The present invention adopts the above technical solution, which has the following advantages and effects:

[0025] (1) The present invention provides a method and system for quickly acquiring layered flow in wave-coded injection wells. Based on the theoretical support of the orifice flow formula, the traditional method of indirectly reading the underground layered flow by coding the layers is changed to a method of coding once and directly reading the flow of each underground layer in sequence from the ground. The flow reading efficiency is effectively improved and the reading time is effectively shortened.

[0026] (2) The present invention provides a method and system for quickly acquiring the layered flow of wave-coded injection wells, which changes the returned downhole flow into a constant pressure mode of water injection and directly reads the flow of each layer from the ground. Through a pre-specified process, with the cooperation of the ground and the underground, the number of times the downhole motor operates is reduced, and the actual downhole flow can be read once every five days. The reading of the downhole water injection status is more timely, which can improve the efficiency and real-time performance of acquiring the downhole flow, and provide a strong basis for stratified and refined water injection. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a structural diagram of the system for quickly acquiring stratified flow rates of wave-coded injection wells according to the present invention.

[0028] Figure 2 The figure is a flow chart of the method for quickly obtaining the layered flow rate of the wave code injection well of the present invention.

[0029] The accompanying drawings are marked as follows: 101 - surface controller; 102 - Christmas tree; 103 - water injection pipe; 104 - downhole water distributor; 105 - main water injection pump station; 106 - water injection well. DETAILED DESCRIPTION

[0030] The following will be described in detail with reference to the accompanying drawings to provide a clearer understanding of the objectives, features and advantages of the present invention. It should be understood that the embodiments shown in the accompanying drawings are not intended to limit the scope of the present invention, but are only intended to illustrate the essential spirit of the technical solution of the present invention.

[0031] like Figure 1 The present invention provides a system for rapidly acquiring stratified flow rates in wave-code-based injection wells, comprising a surface controller 101 and a downhole water distributor 104. Several layers of downhole water distributors 104, connected in series, are disposed in an injection well 106 for injecting water into corresponding oil layers. The surface controller 101 is connected to the downhole water distributors 104 via wave-code wireless communication. The surface controller 101 is used to control the downhole water distributors 104 during constant pressure water injection to read the injection flow rate of the corresponding oil layer.

[0032] Specifically, each oil layer is equipped with a downhole water distributor 104. The downhole water distributor 104 of each layer is connected in series to the oil production tree 102 through the water injection pipe 103. One end of the oil production tree 102 is also connected to the ground controller 101. The ground controller 101 is connected to the main water injection pump station 105. The main water injection pump station 105 supplies water to the water injection well 106 and maintains the pressure of the entire water injection pipe 103 stable. The ground controller 101 controls the water injection flow of the water injection well 106 to ensure accurate water injection according to the injection design.

[0033] The surface controller 101 is used to routinely inject water into the injection well 106 at a constant flow rate. When downhole flow rates are needed, the actual downhole stratified flow rates can be obtained by coding the downhole water distributor 104. The Christmas tree 102, located at the wellhead of the injection well 106, is connected to the surface controller 101 at one end and to the injection pipe 103 at the other end, serving as a link between the upper and lower levels. The injection pipe 103 serves as a channel for injecting water into the injection well 106 and connects the downhole water distributors 104 at each layer in series. These distributors 104 at each layer are interconnected via the injection pipe 103 for wave-code-based, stratified, and refined water injection.

[0034] The downhole water distributor 104 and the surface controller 101 communicate wirelessly via pressure and flow codes. This wireless communication allows the surface controller 101 to control the motor of the downhole water distributor 104 and acquire downhole data. When the surface controller 101 performs coding operations, the downhole water distributor 104 recognizes the pressure code. When the surface controller 101 parses the return data from the downhole water distributor 104, it recognizes the flow code. Through a pre-specified process, and in cooperation with the downhole water distributor 104, the surface controller 101 replaces traditional pressure wave communication to transmit downhole flow with direct acquisition of flow rates from each reservoir during constant pressure water injection.

[0035] A method for quickly acquiring stratified flow rates of wave-code injection wells according to the present invention uses a system for quickly acquiring stratified flow rates of wave-code injection wells according to the present invention. The method comprises:

[0036] First, the surface controller 101 controls the downhole water distributor 104 to perform constant-pressure water injection. The downhole water distributor 104 records the nozzle openings during each constant-flow injection. Constant-pressure water injection uses a fixed injection pressure, which is regulated by controlling the opening and closing of the injection valves.

[0037] Specifically, the surface controller 101 first records the surface injection pressure during constant-flow injection by the downhole water distributor 104. Then, the surface controller 101 sends a quick flow read command to the downhole water distributor 104, and constant-flow injection is performed at the surface injection pressure during constant-flow injection. After the downhole water distributor 104 recognizes the quick flow read command, each downhole water distributor 104 records the nozzle opening during constant-flow injection. Constant-flow injection is an operating mode in which injection valves are controlled according to a pre-set daily injection volume, thereby controlling the instantaneous injection flow rate. Constant-flow injection is the daily operating mode of an injection well.

[0038] Second, the ground controller 101 controls the water nozzle opening of the downhole water distributor 104 of the measured oil layer to remain unchanged, and the water nozzles of the downhole water distributor 104 of the other layers remain closed. The flow value read by the ground controller 101 at this time is the water injection flow of the measured oil layer. When the ground controller 101 reads the flow value, it reads it after the flow value is constant. It can be understood that the constant flow value means that the fluctuation of the flow value within the preset time length is within the preset threshold, wherein the preset time length and the preset threshold can be set according to actual needs. It can also be understood that after obtaining the water injection flow of the measured oil layer, the water injection flow of the next oil layer can be obtained after the timing waiting time is reached.

[0039] Furthermore, before the ground controller 101 controls the downhole water distributor 104 to perform water injection in a constant pressure mode, it also includes: the ground controller 101 determines whether a quick flow reading operation is required; if not, the ground controller 101 controls the downhole water distributor 104 to continue to inject water in a constant flow mode; if required, the ground controller 101 controls the downhole water distributor 104 to inject water in a constant pressure mode.

[0040] Furthermore, after the surface controller 101 reads the flow value at this time, the process also includes: the surface controller 101 controls the water nozzle openings of the downhole water distributors 104 of all oil layers to recover, and the downhole water distributors 104 continue to inject water in a constant flow manner.

[0041] Furthermore, the ground controller 101 reads the flow rate values ​​of the measured oil layers in order from top to bottom. That is, the flow rate value of the first oil layer is read first as the water injection flow rate of the first oil layer, and then the flow rate value of the second oil layer is read as the water injection flow rate of the second oil layer, and so on until the flow rate value of the last oil layer is read as the water injection flow rate of the last oil layer.

[0042] Furthermore, when the ground controller 101 reads the flow value of the corresponding oil layer, the flow value measurement formula is as follows:

[0043]

[0044] (1) Where: Q is the flow rate of the faucet; C dis the discharge coefficient of the faucet, C d Less than 1; A is the cross-sectional area of ​​the water nozzle; △P is the pressure difference on both sides of the water nozzle, that is, the difference between the injection pressure and the formation pressure; ρ is the density of water, and the range of △P is -0.1—+0.1MPa.

[0045] In the actual stratified water injection system, when the water injection state is adjusted, the cross-sectional area A of the nozzle is fixed. At this time, the flow coefficient C of the nozzle is d When the water injection state stabilizes, the water injection pressure also remains stable. When the water injection pressure remains stable, the pressure difference △P on both sides of the nozzle will also remain stable. According to formula (1), when the pressure difference △P is controlled within the range of ±0.1MPa, the water injection flow rate of each oil layer measured is consistent with the water injection flow rate after the deployment is completed. Therefore, this application utilizes this characteristic to quickly obtain stratified flow.

[0046] Example

[0047] This embodiment is described by taking a three-layer downhole water distributor as an example. The surface controller controls the downhole water distributor to measure flow rate layer by layer to achieve rapid acquisition of layered flow rate.

[0048] like Figure 2 A method for quickly acquiring the stratified flow rate of a wave code injection well according to an embodiment specifically comprises the following steps:

[0049] In step S1, when the ground controller controls the downhole water distributor to inject water in a constant flow mode, the ground controller determines whether a quick flow reading operation is required; if not, the ground controller controls the downhole water distributor to continue injecting water into the injection well in a constant flow mode; if required, after the ground controller receives the remote "quick flow reading" instruction, the ground controller performs the corresponding quick flow reading operation and enters step 2.

[0050] Step S2: The ground controller records the water injection pressure value during constant flow water injection after the adjustment.

[0051] In step S3, the ground controller sends a quick flow rate code command to the downhole water distributors of all oil layers by sending a pressure wave code.

[0052] Step S4: After the ground controller completes coding and sending the fast flow rate reading code command, the ground controller controls all downhole water distributors to perform constant pressure water injection according to the water injection pressure value recorded in step S2.

[0053] Step S5: After the downhole water distributor recognizes the fast flow rate reading code command, the downhole water distributors of each oil layer respectively record the water nozzle opening during constant flow water injection after their respective deployment is completed.

[0054] Step S6: the surface controller controls the water nozzle opening of the downhole water distributor of the first oil layer to remain unchanged, and closes the water nozzles of the downhole water distributors of the second oil layer and the third oil layer.

[0055] In step S7, when the flow rate value read by the surface controller remains constant for at least three consecutive minutes, the flow rate value at that time is the water injection flow rate of the first oil layer. This embodiment ensures the accuracy of the flow rate value by reading a constant flow rate value for at least three consecutive minutes. Only through such long-term continuous monitoring can reliable flow rate data be obtained, thereby providing an accurate basis for subsequent determination of the water injection flow rate.

[0056] Step S8, the ground controller reads the flow rate quickly according to the preset timing sequence. After the timing waiting time is reached, the ground controller closes the water nozzle of the downhole water distributor of the first oil layer, and restores the water nozzle opening of the downhole water distributor of the second oil layer during constant flow water injection, and controls the water nozzle opening of the downhole water distributor of the third oil layer to remain unchanged.

[0057] Step S9: When the flow rate value read by the surface controller remains constant for at least 3 consecutive minutes, the flow rate value at this time is the water injection flow rate of the second oil layer.

[0058] Step S10, after the timing waiting time is reached, the ground controller closes the water nozzle of the downhole water distributor of the second oil layer, and restores the water nozzle opening of the downhole water distributor of the third oil layer during constant flow water injection, and controls the water nozzle opening of the downhole water distributor of the first oil layer to remain unchanged.

[0059] In step S11, when the flow rate value read by the surface controller remains constant for at least three consecutive minutes, the flow rate value at this time is the water injection flow rate of the third oil layer.

[0060] In step S12, after the surface controller completes the rapid flow reading in sequence, the surface controller restores the water nozzle opening of the downhole water distributor of the first oil layer and the second oil layer, and the surface controller changes the constant pressure water injection mode to the constant flow water injection mode to restore the normal water injection state.

[0061] The stratified flow acquisition of the three-layer downhole water distributor provided in this embodiment, if the downhole flow is obtained according to the traditional wave code method, the average time for sending and returning the code for one layer is about 120 minutes, and the total time required for the three layers is about 360 minutes. However, through the present invention, it takes about 20 minutes to obtain the flow of each layer of the downhole (reading the flow code), and the time for obtaining the flow of each layer is about 6 minutes, and the total time is about 38 minutes. Compared with the traditional method, the efficiency is improved by about 9.4 times, and as the number of oil layers increases, the efficiency improvement will be more obvious.

Claims

1. A method for quickly obtaining stratified flow rate of wave code injection wells, characterized in that: The method comprises: The surface controller (101) controls the downhole water distributor (104) to perform water injection in a constant pressure mode. The downhole water distributor (104) respectively records the opening of the water nozzle during the constant flow mode water injection, specifically: The surface controller (101) records the water injection pressure value of the downhole water distributor (104) in a constant flow mode; The surface controller (101) sends a quick flow reading instruction to the downhole water distributor (104), and then performs water injection at a constant pressure according to the water injection pressure value; After the downhole water distributor (104) recognizes the fast flow reading instruction, the downhole water distributor (104) of each layer records the opening of the water nozzle during the constant flow mode water injection; The surface controller (101) controls the water nozzle opening of the downhole water distributor (104) of the measured oil layer to remain unchanged, and the water nozzles of the downhole water distributors (104) of other layers to remain closed, and the flow value read by the surface controller (101) at this time is the water injection flow rate of the measured oil layer.

2. The method for rapidly acquiring stratified flow rate of wave code injection wells according to claim 1 is characterized in that: Before the surface controller (101) controls the downhole water distributor (104) to perform water injection in a constant pressure mode, the method further includes: The surface controller (101) determines whether a fast flow reading operation is required. If required, the surface controller (101) controls the downhole water distributor (104) to perform water injection in a constant pressure manner.

3. The method for rapidly acquiring stratified flow rate of wave code injection wells according to claim 2 is characterized in that: If not required, the surface controller (101) controls the downhole water distributor (104) to perform water injection in a constant flow manner.

4. The method for rapidly acquiring stratified flow rate of wave code injection wells according to claim 3 is characterized in that: After the ground controller (101) reads the flow value at this time, the method further includes: The surface controller (101) controls the water nozzle opening of the downhole water distributor (104) of all oil layers to recover, and the downhole water distributor (104) performs water injection in a constant flow mode.

5. The method for rapidly acquiring stratified flow rate of wave code injection wells according to claim 1 is characterized in that: The constant flow rate value read by the ground controller (101) is used as the water injection flow rate of the measured oil layer.

6. The method for rapidly acquiring stratified flow rate of wave code injection wells according to claim 5 is characterized in that: The measured oil layers are arranged in sequence from top to bottom to read the flow values.

7. The method for rapidly acquiring stratified flow rate of wave code injection wells according to claim 1 is characterized in that: The flow value measurement formula is as follows: Where: Q is the flow rate of the faucet; C d is the discharge coefficient of the faucet, C d Less than 1; A is the cross-sectional area of ​​the water nozzle; △P is the difference between the injection pressure and the formation pressure; ρ is the density of water.

8. The method for rapidly acquiring stratified flow rate of wave code injection wells according to claim 7 is characterized in that: The range of △P is -0.1—+0.1MPa.

9. A system for rapidly acquiring stratified flow rates of wave-code injection wells, applied to the method for rapidly acquiring stratified flow rates of wave-code injection wells according to any one of claims 1 to 8, characterized in that: The system comprises a surface controller (101) and a downhole water distributor (104). Several layers of the downhole water distributors (104) are serially connected and arranged in a water injection well (106) for injecting water into corresponding oil layers. The surface controller (101) is connected to the downhole water distributor (104) via wave code wireless communication and is used to control the downhole water distributor (104) to read the injection flow rate of the corresponding oil layer when injecting water in a constant pressure manner.

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