Separate injection tubular column suitable for separate injection well and online detection and allocation method of separate injection tubular column

Abstract

The invention relates to the technical field of separated layer water injection of oil fields, in particular to a separated layer water injection tubular column suitable for a separated layer water injection well and an online detection and allocation method thereof.The separated layer water injection tubular column comprises a sleeve arranged in the separated layer water injection well, and the sleeve divides an inner cavity into an upper water injection layer and a lower water injection layer through a packer arranged in the inner cavity; the water injection pipe is arranged in the inner cavity of the sleeve, and a water distributor switch, an upper water distributor, a lower water distributor and a screwed plug are sequentially arranged in the water injection pipe from top to bottom; the conveying pipe is arranged at the top of the water injection pipe, and a paraffin removal valve, a main valve and a wellhead self-control valve are arranged on the conveying pipe; according to the on-line monitoring and allocation method for the separate injection well, real-time monitoring of the separate injection pressure and the injection amount can be achieved on the basis of an existing bridge type separate injection pipe column, long-term qualified water injection of all layers of water distributors is guaranteed, the separate layer water injection development effect is further improved, meanwhile, the cost of a bridge type separate injection technology measuring and adjusting instrument can be reduced, and the production efficiency is improved. And the influence on normal production caused by frequent calibration of the flowmeter of the measuring and adjusting instrument is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of oilfield stratified water injection, and in particular to an injection column suitable for an injection well and an online detection and deployment method thereof. Background Art

[0002] Layered water injection is an effective technical means to stabilize oil production, control water and improve the utilization rate of oil strata in oil fields. After nearly 60 years of development, Dagang Oilfield has gone through three generations of injection technologies, including fixed stratified water injection, wire casting and measurement stratified water injection, and cable measurement and adjustment stratified water injection. At present, the main injection process is based on the third generation of injection technology, including bridge concentric injection technology and bridge eccentric injection technology, with supporting cable measurement and adjustment linkage technology, which has the advantages of mature supporting facilities, low cost and wide application. However, as the oilfield enters the ultra-high water cut period, the remaining oil is highly dispersed, the oil-water relationship is complex, the water injection qualification rate decreases rapidly, and the difficulty of stabilizing oil and controlling water increases. The third generation of injection technology uses instruments for regular and fixed-point measurement and adjustment, and only monitors 4 instantaneous injection volumes each year. It is impossible to continuously monitor the changes in stratified water injection volume and injection pressure, and dynamic analysis becomes "a pot without rice". In addition, the cost of conventional measurement and adjustment instruments is high. Once the well is dropped, the loss is large. The flow meter data is easy to drift, and frequent flow calibration is required, which delays normal production. The measurement and adjustment results table needs to be manually recorded and uploaded to the system. The degree of informatization is not high, and it cannot adapt to the construction of digital oilfields. Summary of the invention

[0003] The purpose of the present invention is to provide an injection string suitable for injection wells, which is used to solve the problems that the current bridge-type injection technology cannot continuously monitor the changes in stratified water injection volume and injection pressure, the cost of measurement and adjustment instruments is high, and the measurement and adjustment data need to be manually reported, the degree of informatization is not high, and it cannot adapt to the development of digital oil fields.

[0004] The technical solution of the present invention is achieved in this way:

[0005] On the one hand, an embodiment of the present invention provides an injection string suitable for an injection well, comprising:

[0006] A casing arranged in the sub-injection well, wherein the casing isolates the inner cavity into an upper water injection layer and a lower water injection layer through a packer arranged in the inner cavity;

[0007] A water injection pipe is arranged in the inner cavity of the casing, wherein a water distributor switch, an upper water distributor, a lower water distributor and a screw plug are arranged in sequence from top to bottom, wherein the upper water distributor is located at the upper water injection layer, and the lower water distributor is located at the lower water injection layer;

[0008] A water injection pipeline is arranged at the top of the water injection pipe, and a wax cleaning valve, a main valve and a wellhead automatic control valve are arranged on the water injection pipeline.

[0009] In a second aspect, an embodiment of the present application provides an online detection and deployment method for an injection string suitable for an injection well, the method comprising:

[0010] This embodiment will take two-stage injection as an example. The method determines the high-pressure injection layer and the low-pressure injection layer through trial injection. First, the low-pressure injection layer water distributor is closed by using the water distributor switch. Then, the opening of the water nozzle of the high-pressure injection layer water distributor is adjusted. During the adjustment process, the flow of this layer is observed in real time. After the injection requirements are met, the adjustment is stopped. The injection flow value and pressure value at this time are recorded. The automatic control valve is set to the constant pressure mode under this pressure value. Next, the opening of the water nozzle of the low-pressure injection layer water distributor is opened and adjusted. During the adjustment process, the flow of this layer is observed in real time until the injection requirements are met. After the injection requirements are met, stop adjusting and record the injection flow and pressure values ​​at this time, so that each layer can be injected at a certain injection pressure. After the ground calibration is completed, set the automatic control valve to the constant flow mode at this flow value. If the number of injection layers is greater than two, the injection pressure of each injection layer can be determined by trial injection. The injection layer with the largest injection pressure is still used for injection. By analogy, the multi-layer injection allocation of the whole well is finally completed. After the injection pressure and flow of each injection layer are calibrated, they can be monitored in real time through the remote transmission function.

[0011] The two-stage injection pipe string structure in the implementation process of the method mainly includes: (1) wellhead automatic control valve; (2) water distributor switch; (3) packer; (4) upper water distributor; (5) lower water distributor; (6) screw plug; (7) wax cleaning gate; (8) main gate; (9) casing; (10) upper water injection layer; (11) lower water injection layer; (12) artificial well bottom, wherein: the wellhead automatic control valve (1) has constant pressure and constant flow control functions, and also has data remote transmission function, and is welded on the water injection pipeline. The water distributor switch is a specific device for adjusting the size of the water nozzle of the water distributor. It is connected to the ground test vehicle through an armored cable. There is no need to lower the device during normal water injection. The packer and water distributor are downhole supporting tools for the bridge-type injection technology. They are connected to the oil pipe thread and lowered into the wellbore casing. After the packer is sealed, the upper water injection layer and the lower water injection layer are separated. The water injection of the upper water distributor corresponds to the upper water injection layer, and the water injection of the lower water distributor corresponds to the lower water injection layer. The bottom of this set of injection pipe string is sealed by a threaded plug, and the bottom of the wellbore is an artificial well bottom.

[0012] Step S1, determine the injection pressure relationship between the upper water injection layer and the lower water injection layer through trial injection, lower the water distributor switch from the wellhead, pass through the wax cleaning gate and the main gate respectively, and finally connect with the low-pressure layer water distributor through the packer. If the low-pressure layer is the upper water injection layer, after docking, control the water distributor switch on the ground through the armored cable, and then adjust the opening of the upper water distributor nozzle to completely close the upper water distributor nozzle. At this time, the bridge-type injection process pipe string is set in the wellbore formed by the casing and the artificial well bottom, and the bottom of the pipe string is blocked with a wire plug, wherein the injected water enters the water injection layer from the upper water distributor and the lower water injection layer;

[0013] Step S2, taking the lower water injection layer as the research object, when the flow rate of the lower water injection layer is equal to the flow rate displayed by the wellhead automatic control valve, connect the water distributor switch with the lower water distributor, and gradually close the water nozzle Z1 of the lower water distributor. When the injection amount is reached at a certain moment, the flow rate Q1 displayed by the wellhead automatic control valve is the actual injection amount of the lower water injection layer, and record the injection pressure P1 displayed by the automatic control valve at this time;

[0014] Step S3, the wellhead automatic control valve is kept at the injection pressure P1 for observation for 15 minutes, and then the wellhead automatic control valve is set to the constant pressure P1 injection mode. In this mode, the water distributor switch is lifted to the position of the upper water distributor. After successful docking, the water nozzle Z2 of the upper water distributor begins to be opened step by step. During the process of adjusting the water nozzle Z2 of the upper water distributor, at a certain moment, the total flow Q of the ground automatic control valve is equal to the sum of the injection amounts of the upper water injection layer and the lower water injection layer;

[0015] Step S4, calibrate the upper water injection layer and the lower water injection layer step by step in sequence. After the calibration is completed, set the wellhead automatic control valve to inject in a constant flow rate Q mode.

[0016] In some embodiments, the lower water injection layer is a high-pressure water injection layer.

[0017] In some embodiments, in the constant pressure P1 injection mode, when the water nozzle Z1 of the lower water distributor remains unchanged, the real-time injection volume of the lower water injection layer remains unchanged.

[0018] In some embodiments, the step of calibrating the upper water injection layer and the lower water injection layer step by step, after the calibration is completed, setting the wellhead automatic control valve to inject at a constant flow rate Q, further includes:

[0019] The injection pressure and injection volume of each layer are monitored in real time through the remote transmission function.

[0020] In some embodiments, after setting the wellhead automatic control valve to inject in a constant flow rate Q mode in step S4, the method further includes:

[0021] Step S5, if the bridge type injection process is three stages or more, the water nozzle Z3 of the third low-pressure layer water distributor can be opened step by step on the basis of step S3, and at a certain moment the total flow rate of the ground automatic control valve Q = Q1 + Q2 + Q3, ..., and then the water nozzle Zn of the Nth low-pressure layer water distributor is opened step by step, and at a certain moment the total flow rate of the ground automatic control valve Q = Q1 + Q2 + Q3 + ... Qn;

[0022] Step S6, complete the calibration of each injection layer step by step, set the wellhead automatic control valve to inject in a constant flow rate Q mode, that is, complete the deployment of N-segment bridge injection, and the calibrated injection pressure and injection volume of each layer segment are monitored in real time through the remote transmission function.

[0023] The beneficial effects of the present invention are:

[0024] The online monitoring and adjustment method of injection wells provided by the present invention can realize real-time monitoring of stratified injection pressure and injection volume on the basis of the existing bridge-type injection string, ensure long-term qualified water injection of each layer of water distributor, further improve the stratified water injection development effect, and at the same time reduce the cost of bridge-type injection technology measurement and adjustment instruments, avoiding the impact on normal production due to frequent calibration of the flow meter of the measurement and adjustment instrument. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 A schematic diagram of an injection string suitable for injection wells.

[0027] Figure Number:

[0028] 1-wellhead automatic control valve; 2-water distributor switch; 3-packer; 4-upper water distributor; 5-lower water distributor; 6-thread plug; 7-wax cleaning gate; 8-main gate; 9-casing; 10-upper water injection layer; 11-lower water injection layer; 12-artificial well bottom. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0030] In the description of the present invention, it is necessary to understand that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0031] Example 1

[0032] like Figure 1 As described above, this embodiment provides an injection string suitable for an injection well, comprising:

[0033] A casing 9 is arranged in the sub-injection well, wherein the casing 9 isolates the inner cavity into an upper water injection layer 10 and a lower water injection layer 11 through a packer 3 arranged in the inner cavity;

[0034] A water injection pipe is arranged in the inner cavity of the casing 9, and a water distributor switch 2, an upper water distributor 4, a lower water distributor 5 and a screw plug 6 are arranged in the water injection pipe from top to bottom, wherein the upper water distributor 4 is located at the upper water injection layer 10, and the lower water distributor 5 is located at the lower water injection layer 11;

[0035] A water injection pipeline is arranged at the top of the water injection pipe, and a wax removal valve 7, a main valve 8 and a wellhead automatic control valve 1 are arranged on the water injection pipeline.

[0036] Among them: the wellhead automatic control valve 1 has constant pressure and constant flow control functions, and also has data remote transmission function, which is welded on the water injection pipeline. The water distributor switch 2 is a specific device for adjusting the size of the water distributor nozzle, which is connected to the ground test vehicle through an armored cable. There is no need to lower the device during normal water injection. The packer 3 and the water distributor are downhole supporting tools for the bridge-type injection technology, which are connected to the oil pipe thread and lowered into the wellbore casing. After the packer 3 is sealed, the upper injection layer and the lower injection layer are separated. The upper water distributor 4 injects water corresponding to the upper injection layer, and the lower water distributor 5 injects water corresponding to the lower injection layer. The bottom of this set of injection pipe string is sealed by the threaded plug 6, and the bottom of the wellbore is an artificial well bottom.

[0037] Example 2

[0038] This embodiment is based on Embodiment 1 and is used to describe an online detection and deployment method based on an injection string suitable for an injection well, the method comprising:

[0039] This embodiment takes two-stage injection as an example. The method determines the high-pressure injection layer and the low-pressure injection layer through trial injection. First, the low-pressure injection layer water distributor is closed by using the water distributor switch. Then, the opening of the water nozzle of the high-pressure injection layer water distributor is adjusted. During the adjustment process, the flow rate of the layer is observed in real time. After the injection requirements are met, the adjustment is stopped. The injection flow rate value and pressure value at this time are recorded. The automatic control valve is set to the constant pressure mode under this pressure value. Next, the opening of the water nozzle of the low-pressure injection layer water distributor is opened and adjusted. During the adjustment process, the flow rate of the layer is observed in real time. After the injection requirements are met, the adjustment is stopped. The injection flow rate value and pressure value at this time are recorded. The injection of each layer section under a certain water injection pressure is achieved. Finally, after the ground calibration is completed, the automatic control valve is set to the constant flow mode under this flow value. If the number of injection layers is greater than two, the injection pressure of each injection layer section can be determined by trial injection. The injection pressure is still adjusted from the injection layer with the largest injection pressure. By analogy, the multi-segment injection adjustment of the whole well is finally completed. After the injection pressure and flow of each injection layer section are calibrated, they are monitored in real time through the remote transmission function.

[0040] Step S1, determine the injection pressure relationship between the upper water injection layer 10 and the lower water injection layer 11 through trial injection, lower the water distributor switch 2 from the wellhead, pass through the wax cleaning gate 7 and the main gate 8 respectively, and finally dock with the low-pressure layer water distributor through the packer 3. If the low-pressure layer is the upper water injection layer 10, after docking, control the water distributor switch 2 on the ground through the armored cable, and then adjust the opening of the water nozzle of the upper water distributor 4, and completely close the water nozzle of the upper water distributor 4. At this time, the bridge-type injection process pipe string is set in the wellbore formed by the casing 9 and the artificial well bottom 12, and the bottom of the pipe string is blocked with a wire plug 6, wherein the injected water enters the water injection layer from the upper water distributor 10 and the lower water injection layer 11;

[0041] Step S2, taking the lower water injection layer 11 as the research object, when the flow rate of the lower water injection layer 11 is equal to the flow rate displayed by the wellhead automatic control valve 1, the water distributor switch 2 is connected to the lower water distributor 5, and the water nozzle Z1 of the lower water distributor 5 is gradually closed. When the injection amount is reached at a certain moment, the flow rate Q1 displayed by the wellhead automatic control valve 1 is the actual injection amount of the lower water injection layer 11, and the injection pressure P1 displayed by the automatic control valve 1 at this time is recorded;

[0042] Step S3, the wellhead automatic control valve 1 is kept at the injection pressure P1 for a preset time (for example, 15 minutes), and then the wellhead automatic control valve 1 is set to the constant pressure P1 injection mode. In this mode, the water distributor switch 2 is lifted to the position of the upper water distributor 4. After successful docking, the water nozzle Z2 of the upper water distributor 4 begins to be opened step by step. During the process of adjusting the water nozzle Z2 of the upper water distributor 4, at a certain moment, the total flow Q of the ground automatic control valve 1 is equal to the sum of the injection amounts of the upper water injection layer 10 and the lower water injection layer 11, that is: Q2 = Q-Q1. In the constant pressure P1 injection mode, when the water nozzle Z1 of the lower water distributor 5 remains unchanged, the real-time injection amount of the lower water injection layer 11 will never change;

[0043] Step S4, calibrate the upper water injection layer 10 and the lower water injection layer 11 step by step in sequence. After the calibration is completed, set the wellhead automatic control valve 1 to inject in a constant flow mode of Q. At this time, the deployment of the two-stage bridge injection is completed, and the calibrated injection pressure and injection volume of each layer are monitored in real time through the remote transmission function.

[0044] Step S5, if the bridge type injection process is three stages or more, the water nozzle Z3 of the third low-pressure layer water distributor can be opened step by step on the basis of step S3, and at a certain moment the total flow Q of the ground automatic control valve 1 is Q=Q1+Q2+Q3, ..., and then the water nozzle Zn of the Nth low-pressure layer water distributor is opened step by step, and at a certain moment the total flow Q of the ground automatic control valve 1 is Q=Q1+Q2+Q3+...Qn;

[0045] Step S6, complete the calibration of each injection layer step by step, set the wellhead automatic control valve 1 to inject in a constant flow rate Q, that is, complete the deployment of N-segment bridge injection, and the calibrated injection pressure and injection volume of each layer segment are monitored in real time through the remote transmission function.

[0046] Secondly, in step S2 of this embodiment, the lower water injection layer 11 is a high-pressure water injection layer.

[0047] The online monitoring and adjustment method described in this embodiment can realize real-time monitoring of stratified injection pressure and injection volume on the basis of the existing bridge-type injection string, ensure long-term qualified water injection of each layer of water distributor, further improve the stratified water injection development effect, and at the same time reduce the cost of bridge-type injection technology measurement and adjustment instruments, avoiding the impact on normal production due to frequent calibration of the flow meter of the measurement and adjustment instrument.

[0048] It is mainly aimed at solving the problems that the current bridge-type injection technology cannot continuously monitor the changes in stratified water injection volume and injection pressure, the cost of measuring and adjusting instruments is high, the measuring and adjusting data need to be manually reported, the degree of informatization is not high, and it cannot adapt to the development of digital oil fields. Through the ground calibration technology of downhole flow in multi-segment injection wells, the implementation monitoring of stratified flow and pressure is realized, and a large torque adjustment instrument is used to adjust the injection volume, which not only saves the instrument cost but also improves the success rate of adjustment. The original measuring and adjusting instruments are mainly ultrasonic flow meters with high costs. At the same time, the network informatization of measuring and adjusting data is realized through a wireless remote transmission system.

[0049] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. An injection string suitable for injection wells, It is characterized in that include: A casing (9) arranged in a sub-injection well, wherein the casing (9) isolates the inner cavity into an upper water injection layer (10) and a lower water injection layer (11) through a packer (3) arranged in the inner cavity; A water injection pipe is arranged in the inner cavity of the casing (9), wherein the water distributor switch (2), the upper water distributor (4), the lower water distributor (5) and the screw plug (6) are arranged in sequence from top to bottom, wherein the upper water distributor (4) is located at the upper water injection layer (10), and the lower water distributor (5) is located at the lower water injection layer (11); A water injection pipeline is arranged at the top of the water injection pipe, and a wax removal valve (7), a main valve (8) and a wellhead automatic control valve (1) are arranged on the water injection pipeline.

2. An online detection and deployment method for an injection string suitable for an injection well according to claim 1, It is characterized in that The method comprises: Step S1, determine the injection pressure relationship between the upper water injection layer (10) and the lower water injection layer (11) through trial injection, lower the water distributor switch (2) from the wellhead, pass through the wax cleaning gate (7) and the main gate (8), and finally connect with the low-pressure layer water distributor through the packer (3). If the low-pressure layer is the upper water injection layer (10), after connection, control the water distributor switch (2) on the ground through the armored cable, and then adjust the opening of the water nozzle of the upper water distributor (4), and completely close the water nozzle of the upper water distributor (4). At this time, the bridge-type injection process pipe column is set in the wellbore formed by the casing (9) and the artificial well bottom (12), and the bottom of the pipe column is blocked with a wire plug (6), wherein the injected water enters the water injection layer from the upper water distributor (10) and the lower water injection layer (11); Step S2, taking the lower water injection layer (11) as the research object, when the flow rate of the lower water injection layer (11) is equal to the flow rate displayed by the wellhead automatic control valve (1), the water distributor switch (2) is connected to the lower water distributor (5), and the water nozzle Z1 of the lower water distributor (5) is gradually closed. When the injection amount is reached at a certain moment, the flow rate Q1 displayed by the wellhead automatic control valve (1) is the actual injection amount of the lower water injection layer (11), and the injection pressure P1 displayed by the automatic control valve (1) at this time is recorded; Step S3, the wellhead automatic control valve (1) is kept at the injection pressure P1 for a preset time, and then the wellhead automatic control valve (1) is set to a constant pressure P1 injection mode. In this mode, the water distributor switch (2) is lifted to the position of the upper water distributor (4). After successful docking, the water nozzle Z2 of the upper water distributor (4) begins to be opened step by step. During the process of adjusting the water nozzle Z2 of the upper water distributor (4), at a certain moment, the total flow Q of the ground automatic control valve (1) is equal to the sum of the injection amounts of the upper water injection layer (10) and the lower water injection layer (11); Step S4, calibrate the upper water injection layer (10) and the lower water injection layer (11) step by step in sequence. After the calibration is completed, set the wellhead automatic control valve (1) to inject in a constant flow rate Q mode.

3. The online detection and preparation method according to claim 2, It is characterized in that The lower water injection layer (11) is a high-pressure water injection layer.

4. The online detection scheduling method according to claim 2, It is characterized in that In the constant pressure P1 injection mode, when the water nozzle Z1 of the lower water distributor (5) remains unchanged, the real-time injection volume of the lower water injection layer (11) remains unchanged.

5. The online detection scheduling method according to claim 2, It is characterized in that The upper water injection layer (10) and the lower water injection layer (11) are calibrated step by step in sequence. After the calibration is completed, the wellhead automatic control valve (1) is set to inject in a constant flow rate Q mode, and further comprises: The injection pressure and injection volume of each layer are monitored in real time through the remote transmission function.

6. The online detection scheduling method according to claim 2, It is characterized in that After setting the wellhead automatic control valve (1) to inject in a constant flow rate Q mode in step S4, the method further includes: Step S5, if the bridge type injection process is three or more stages, the water nozzle Z3 of the third low-pressure layer water distributor can be opened step by step on the basis of step S3, and at a certain moment, the total flow rate Q of the ground automatic control valve (1) is Q1+Q2+Q3, and then the water nozzle Zn of the Nth low-pressure layer water distributor is opened step by step, and at a certain moment, the total flow rate Q of the ground automatic control valve (1) is Q1+Q2+Q3+...Qn; Step S6, complete the calibration of each injection layer step by step, set the wellhead automatic control valve (1) to inject in a constant flow rate Q, that is, complete the deployment of N-stage bridge injection, and the calibrated injection pressure and injection volume of each layer segment are monitored in real time through the remote transmission function.

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