A control method for understanding the stratification of oil wells

Abstract

This invention relates to a control method for well stratification, belonging to the field of oilfield production tools technology. The method controls the opening and closing of switches according to a pre-set timed stratification status schedule. During stratification, if the current stratum is identified before the scheduled time for the next stratum, a stratification adjustment pulse signal is emitted at the wellhead by changing the wellhead pressure. Upon detecting the adjustment pulse signal, the open switch closes, and the switch corresponding to the next stratum in the schedule opens. If the current stratum is not identified by the scheduled time for the next stratum, a delayed pulse signal is emitted at the wellhead. Upon detecting the delayed pulse signal, all switches do not perform any switching actions. This solution addresses the problem in existing technologies that cannot adjust the single-layer water-finding cycle in real time according to the production status of each oil layer.

Description

Technical Field

[0001] This invention relates to a control method for understanding the stratification of oil wells, belonging to the technical field of oilfield production tools. Background Technology

[0002] In the later stages of oil well production, due to the decrease in oil content, water displacement is necessary, which increases the water content of the oil layer. To improve production, enhance recovery rate, and achieve water control and oil stabilization, a clear understanding of the water content of each oil layer in the well is required. Mechanical water-finding devices are typically used to perform stratified water-finding for each oil layer. These devices involve lowering a multi-stage stationary tubing string into the well, placing slip packers and water-finding switches inside the string. The slip packers seal off other oil layers, maintaining normal production in individual oil layers. The water content of each layer is determined by analyzing the produced fluid during normal production, thus providing a clear understanding of the water content of each oil layer.

[0003] The publication document of Chinese utility model patent with publication number CN202348249U discloses a downhole stratified oil production control device. The principle of this utility model is to use packers to isolate each layer downhole. A set of intelligent switches is installed on the tubing string for each target layer. During the water-finding and plugging process, the switches can automatically open or close the oil layer according to the set time sequence. Without the need for complicated surface operations, water-finding and water-plugging measures can be achieved in oil wells, so as to achieve arbitrary layer selection for mining and the purpose of reducing water and increasing oil production.

[0004] Although the aforementioned downhole stratified oil production control device can solve the problem of water injection wells taking turns to find water in each single layer of the oil well, the program of the switch during the water finding process is already set and cannot be changed. Therefore, there is a problem that the single-layer water finding cycle cannot be adjusted in real time according to the production status of each oil layer. Summary of the Invention

[0005] The purpose of this invention is to provide a control method for understanding the stratification of oil wells, in order to solve the problem in the prior art that the water-finding cycle of a single layer cannot be adjusted in real time according to the production status of each oil layer.

[0006] To achieve the above objectives, the present invention includes:

[0007] A control method for oil well stratification involves controlling the opening or closing of switches and performing stratification based on a pre-set switch timed stratification status schedule.

[0008] During the layer recognition process, if the recognition of the current layer is completed before the recognition time of the next layer in the timetable, a fixed layer adjustment pulse signal is emitted at the wellhead by changing the wellhead pressure. After the switch detects the layer adjustment pulse signal, the switch in the open state closes, and the switch corresponding to the recognition of the next layer in the timetable opens.

[0009] If the next layer recognition action time in the aforementioned timetable is reached and the current layer is still not clearly recognized, a delayed pulse signal is emitted at the wellhead by changing the wellhead pressure. After all switches detect the delayed pulse signal, no switching action is performed.

[0010] The switch is located between two packers, which are respectively used to seal the corresponding oil layers above and below the casing. The switch has an execution schedule and includes a pressure monitoring device for receiving wellhead pressure signals.

[0011] This invention controls the well stratification process through two methods: pre-programmed control and wellhead pressure pulse signal transmission. Pre-programmed control involves writing a timed stratification status schedule into the intelligent switch before the well stratification device is lowered. The stratification process then sequentially identifies each stratum according to the schedule. Wellhead pressure pulse signal transmission control involves manually manipulating a pressure tanker to change the wellhead pressure, ensuring the pressure changes conform to a pre-designed pressure pulse sequence. The pressure changes at the wellhead are transmitted downhole via water. The pressure pulse sequence is monitored by a pressure monitoring module, which converts the pressure pulse signals into digital signals and transmits them to a microcontroller control module. The microcontroller control module, based on pre-set control rules, transmits control information to a motor drive module, thereby controlling the motor drive module to perform corresponding actions to identify each stratum. This method allows for real-time adjustment of the well stratification stratification layer, solving the problem that the switch program is pre-set and cannot be changed during the stratification process, which prevents real-time adjustment of the single-layer water-finding cycle based on the production status of each oil layer.

[0012] Furthermore, after the switch detects the layer adjustment pulse signal, the switch corresponding to the layer that has not been identified determines which layer is the next layer to be identified based on the identification action time of each layer in the timetable.

[0013] By using a schedule, the switch can determine itself whether it is the switch to be turned on in the next layer. No external operation is required. The judgment logic is simple and the purpose of layer adjustment can be achieved without additional auxiliary operations.

[0014] Furthermore, after all switches detect the delay pulse signal, all switches perform a corresponding delay operation on their recognition action time in the timetable.

[0015] All switches will have their recognition time in the schedule delayed accordingly, so that other operations can be performed later according to the schedule.

[0016] Furthermore, the layer adjustment pulse signal is activated several times within a preset time period, and then does not activate again for a continuous preset time period after the last activation and depressurization is completed.

[0017] Furthermore, the delayed pulse signal is activated several times within a preset time period, and then continuously activated again for several minutes within a consecutive preset time period after the last activation and depressurization is completed.

[0018] Furthermore, the "several minutes" represents a preset time period for the delay.

[0019] Furthermore, the change of wellhead pressure is achieved by manually operating a pressure tanker truck at the wellhead.

[0020] Changing the pressure at the wellhead is a simple and easy-to-operate method that involves manually manipulating a pressure tanker truck at the wellhead. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the oil well stratification recognition device of the present invention;

[0022] Figure 2 This is a schematic diagram of the pressure detection principle structure of the intelligent switch of the present invention;

[0023] Figure 3 This is a schematic diagram of the pulse control for the layer adjustment control scheme and the delay control scheme of the present invention;

[0024] Figure 4 This is a schematic diagram of the liquid volume and moisture content monitoring principle of the intelligent switch of the present invention;

[0025] In the diagram: 1. Oil pipe; 2. Pump; 3. Screen pipe; 4. Tailpipe; 5. Drop string; 511. Packer; 521. Smart switch; 512. Packer; 522. Smart switch; 6. Plug. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0027] An embodiment of a control method for oil well stratification:

[0028] The embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0029] like Figure 1The oil well stratification recognition device of the present invention shown includes an oil tubing 1, a pump 2, a screen pipe 3, and a tailpipe 4 connected in sequence by threads; it also includes a drop string 5, which includes several stages of water-blocking packers 511, 512...51n and several stages of intelligent switches 521, 522...52n, and a plug 6, with each oil layer corresponding to one packer and one intelligent switch. The packers isolate each oil layer.

[0030] like Figure 2 The intelligent switch shown consists of a power supply module, a pressure monitoring module, a microcontroller control module, a motor drive module, and a storage module.

[0031] The power module consists of a high-temperature battery pack and a power circuit, providing a stable power supply for each level of intelligent switches 521, 522...52n.

[0032] The microcontroller control module processes the pressure signal and sends control signals to control the motor drive module.

[0033] The pressure monitoring module includes a pressure sensor and a pressure signal acquisition circuit, which is used for real-time monitoring of pressure signals.

[0034] The motor drive module includes a miniature DC motor and a motor control circuit. It receives control signals from the microcontroller control module to realize the forward and reverse rotation of the motor and for protection.

[0035] The storage module is a power-loss protected memory, which mainly stores information such as pressure and switching action commands.

[0036] The principle of oil well stratification recognition and control in this invention is as follows:

[0037] The well-level stratification process is controlled through two methods: pre-programmed control and wellhead pressure pulse signal transmission. Pre-programmed control involves writing a timed stratification status schedule into the intelligent switch before the well stratification device is lowered. The stratification process then proceeds sequentially according to this schedule. Wellhead pressure pulse signal transmission control involves manually manipulating a pressure tanker to change the wellhead pressure, ensuring the pressure changes conform to a pre-designed pressure pulse sequence. Pressure changes at the wellhead are transmitted downhole via water. The pressure pulse sequence is monitored by a pressure monitoring module, which converts the pressure pulse signals into digital signals and transmits them to a microcontroller control module. The microcontroller control module, based on pre-set control rules, transmits control information to a motor drive module, which then performs corresponding actions to stratify each layer.

[0038] This embodiment takes three layers as an example, and the specific control method is as follows:

[0039] 1) Before the well stratification detection device is lowered into the formation, the control method must be preset. Before lowering the well stratification detection device into the well, a timed stratification detection status schedule for the intelligent switch is set. The schedule mainly includes the start-up delay time, the first stratification detection action time, the second stratification detection action time, and the third stratification detection action time.

[0040] 2) After being powered on, the intelligent switch enters a start-up delay phase. During this period, the control circuit is in a dormant state, consuming very little power. Simultaneously, the well stratification detection device will be lowered into the oil layer during this time.

[0041] 3) After the start-up delay phase ends, the first layer recognition action time will begin according to the schedule. During this phase, the first layer intelligent switch 521 will be turned on, and the first layer intelligent switch 522 and the third layer intelligent switch 523 will be turned off. After a period of time, the oil well will enter the stable production phase. At this time, the staff will take samples at the wellhead for testing to understand the water content and production volume of the formation.

[0042] 4) If the level can be clearly understood within the time limit for recognizing the first level, then proceed to the recognition stage of the second level according to the preset time schedule.

[0043] 5) If the first layer is identified before the second layer identification action time, the well stratification identification device will adopt a layer adjustment control scheme, as follows: Figure 3 As shown, at the wellhead, the pressure value at the wellhead is changed by manually operating a pressure tanker truck to transmit a layer adjustment pulse signal according to the second layer. That is, the pressure is raised n times within the time period t1, and no more pressure is raised within the time period t2. After the pressure monitoring module in each layer's intelligent switch 521, 522...52n in the oil well layer recognition device detects the pulse signal, the open switch is closed. The switch corresponding to the layer that has not been recognized determines which layer is the switch corresponding to the next layer recognition according to the recognition action time of each layer in the timetable. The switch corresponding to the layer closest to the current time is opened. Specifically, the first layer intelligent switch 521 is closed. If the second layer intelligent switch 522 determines that it is the switch corresponding to the next layer recognition in the timetable, it executes a series of actions: the second layer intelligent switch 522 is opened, the third layer intelligent switch 523 is closed, and then the staff takes samples at the wellhead to enter the second layer recognition stage.

[0044] 6) If the first layer is still not clearly identified before the second layer recognition action time, a delay control scheme can be implemented, as follows: A delayed pulse signal is emitted in advance by manually operating a pressure tanker truck to change the pressure value at the wellhead. That is, the pressure is increased n times within time period t1, and then increased again for m minutes within time period t2, where m minutes represents the delay time period m. Each layer of the well layer recognition device uses an intelligent switch 521...

[0045] After the pressure monitoring module 52b in 522…52n detects the pulse signal, all smart switches will not perform any switching actions and will maintain their current switching state. However, each layer of smart switches will modify the recognition action time in the timed hierarchical recognition state timetable. All smart switches will delay the recognition action time of each layer in the timed hierarchical recognition state timetable by a time period m. Specifically, after all smart switches delay the recognition action time of each layer in the timed hierarchical recognition state timetable by a time period m, smart switch 521 will remain in the first layer recognition stage until the first layer is clearly recognized. The other layers of smart switches will then perform relevant actions according to the current delayed timed hierarchical recognition state timetable and enter the second layer recognition stage.

[0046] 7) Similarly, if the first and second layer recognition stages of the oil well stratification recognition smart switch are executed in the timetable order, and the second layer is clearly recognized within the preset time, then the third layer recognition stage will still be executed in the timetable order.

[0047] 8) If the third layer recognition stage is advanced or delayed, the control plan will be executed according to step 5, entering the third layer recognition stage, and finally all layers will be clearly understood to complete the water search work.

[0048] like Figure 4 As shown, a liquid volume monitoring module and a water cut monitoring module can be installed downhole. The monitoring module imports the monitoring data into the control module for analysis and judgment to determine whether to end the current layer recognition early or extend the current layer recognition time.

Claims

1. A control method for understanding the stratification of oil wells, characterized in that, The system controls the opening or closing of the switch and performs layer recognition according to a pre-set timetable for the switch to recognize the status of each layer. The timetable includes the action time for each layer recognition. During the layer recognition process, if the current layer is clearly recognized within the current layer recognition action time, the recognition stage of the next layer will proceed according to the preset timetable. If the recognition of the current layer is completed before the next layer recognition action time in the timetable, a layer adjustment control scheme will be adopted: a fixed layer adjustment pulse signal will be emitted at the wellhead by changing the wellhead pressure. After the switch detects the layer adjustment pulse signal, the switch in the open state will be closed, and the switch corresponding to the next layer recognition in the timetable will be opened. If the current level is still not clearly understood when the next level of recognition action time in the timetable is reached, a delay control scheme is executed: a delay pulse signal is emitted at the wellhead by changing the wellhead pressure. After all switches detect the delay pulse signal, they do not perform any switching action and perform corresponding delay operations on their respective recognition action time in the timetable. The switch is located between two packers, which are respectively used to seal the corresponding oil layers above and below the casing. The switch has an execution schedule and includes a pressure monitoring device for receiving wellhead pressure signals.

2. The control method for oil well stratification according to claim 1, characterized in that, After the switch detects the adjustment pulse signal, the switch corresponding to the layer that has not been identified determines which layer is the next layer to be identified based on the identification action time of each layer in the timetable.

3. The control method for oil well stratification according to claim 1, characterized in that, A liquid volume monitoring module and a water cut monitoring module are installed downhole. Each monitoring module imports the monitoring data into the control module for analysis and judgment to determine whether to end the current layer recognition early or extend the current layer recognition time.

4. The control method for oil well stratification according to claim 1, characterized in that, The layer adjustment pulse signal is activated several times within a preset time period, and then does not activate again within a continuous preset time period after the last activation and depressurization is completed.

5. The control method for oil well stratification according to claim 1, characterized in that, The delayed pulse signal is activated several times within a preset time period, and then continuously activated again for several minutes within a consecutive preset time period after the last activation and depressurization is completed.

6. The control method for oil well stratification according to claim 5, characterized in that, The number of minutes represents a preset time period for the delay.

7. The control method for oil well stratification according to claim 1, characterized in that, The method of changing the pressure at the wellhead involves manually operating a pressure tanker truck to change the pressure at the wellhead.

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