Underground data acquisition unit and method with flow, pressure and temperature monitoring functions

Abstract

The invention relates to the technical field of oil field oil production engineering, in particular to an underground data acquisition unit with flow, pressure and temperature monitoring functions and a method. The method is suitable for underground working condition monitoring of submersible motor type lifting equipment such as submersible screw pumps, submersible plunger pumps and submersible centrifugal pumps. The unit comprises a pressure-resistant shell, wherein a central pipe, an electromagnetic flowmeter, two pressure and temperature sensors and an underground parameter collector are integrated in the pressure-resistant shell; the two sensors are used for measuring the temperature and pressure of liquid flow of the central pipe and the temperature and pressure of an oil casing annulus respectively; the electromagnetic flowmeter measures the flow, and real-time temperature and pressure data are used for compensation to improve the precision. The unit is further provided with a collecting pipe, an upper end, a lower end, a connecting sliding ring, an annulus / oil pipe inner testing channel, a sealing rubber ring and the like. Through the integrated design, synchronous high-precision in-situ monitoring of underground key parameters is achieved, the problem that underground data of multiple instruments are not synchronous is solved, and a reliable data terminal is provided for an intelligent oil field.

Description

Technical Field

[0001] This invention relates to the field of oilfield production equipment technology, and particularly to a multifunctional data acquisition unit and monitoring method capable of simultaneously, in real-time, and accurately monitoring downhole fluid flow rate, tubing internal pressure and temperature, and external annular pressure and temperature. It is applicable to downhole condition monitoring of submersible motor-type lifting equipment, including submersible screw pumps, submersible plunger pumps, and submersible centrifugal pumps. Background Technology

[0002] Modern intelligent oilfield development requires comprehensive and high-precision sensing of downhole production status. Flow rate, pressure, and temperature are the three most critical parameters characterizing oil well production dynamics. Currently, most downhole monitoring instruments are single-function or combinations of limited functions, which present the following problems: 1) Multiple instruments need to be installed, resulting in high costs and complex operations; 2) Parameter measurements are not synchronized, making correlation analysis difficult; 3) Flow rate measurement is easily affected by changes in fluid properties (such as density and viscosity under the influence of temperature and pressure), leading to decreased accuracy. Therefore, developing a highly integrated data acquisition unit capable of simultaneously measuring flow rate, pressure, and temperature and performing compensation calculations is of great significance. Summary of the Invention

[0003] (a) Technical problems to be solved

[0004] 1. Solving the problem of "fragmented and asynchronous" monitoring data: Traditional solutions require the installation of multiple single-function instruments (such as independent flow meters, pressure gauges, and thermometers) to obtain complete data, resulting in data being asynchronous in time and space, making it difficult to conduct effective correlation analysis; The patented solution uses a highly integrated "multi-parameter monitoring system" to simultaneously collect key parameters such as flow rate, internal static pressure, internal temperature, annular pressure, and annular temperature within a single unit, providing a "panoramic view" of the downhole production status at the same time and geographical location.

[0005] 2. Solving the problem of inaccurate downhole flow measurement: First, surface metering suffers from lag and distortion. Second, downhole flow measurement is easily affected by changes in fluid properties (density, viscosity), which in turn vary with temperature and pressure, causing traditional fixed-model flowmeters to experience a sharp drop in accuracy under varying operating conditions. The patented solution uses the main control circuit to dynamically compensate for the fluid's density and viscosity using real-time measured product fluid temperature and external annular temperature, thereby correcting the flow calculation results and achieving high-precision measurement under complex operating conditions.

[0006] 3. Addressing the issue of insufficient "survivability and reliability" of instruments downhole: The harsh environment of high temperature, high pressure, and vibration downhole poses a severe challenge to the mechanical structure sealing and electrical connection stability of instruments, making them prone to failure. The patented solution involves two aspects: First, at the mechanical level, using a high-strength precipitation-hardened stainless steel shell and central tube; multiple high-precision sealing designs (such as at least two O-rings at the ends, with a key sealing surface roughness ≤1.6μm) ensure structural strength and sealing integrity. Second, at the electrical level, employing redundant slip ring connections (four sets of connection points evenly distributed 360°) ensures uninterrupted power and signal connections under harsh operating conditions.

[0007] 4. Addressing the issue of "significant interference with production" in monitoring systems: Some insertion-type or channel-occupying flow meters can cause significant permanent pressure loss or pose a risk of clogging, affecting normal well production. The patented solution involves two main approaches: First, directly integrating the monitoring unit into the production tubing, making it part of the process. Second, applying a low-resistance coating to the inner wall of the central tube, with the pressure tapping holes flush with the inner wall, minimizing interference with the production fluid flow and reducing the risk of clogging.

[0008] (II) Technical Solution

[0009] To address the aforementioned problems, this invention provides a downhole data acquisition unit and method that integrates flow, pressure, and temperature monitoring functions. The main components include a pressure-resistant housing, a central tube, a multi-parameter monitoring system, and connecting slip rings.

[0010] Preferably, the integrated pressure-resistant seal and flow channel design forms the structural foundation of the entire solution, ensuring the equipment can survive long-term in harsh downhole environments, including:

[0011] (1) Robust carrier: The pressure-resistant shell and central tube are made of high-strength precipitation hardening stainless steel, providing protection for the core structure.

[0012] (2) Multiple sealing: At least two O-ring seals are used at the connection between the end and the housing, and the surface roughness (Ra≤1.6μm) of all key sealing surfaces (sealing groove, sensor mounting hole) is precisely machined to achieve ultimate sealing.

[0013] (3) Low-resistance flow channel: The central tube serves as the only liquid production channel, and the inner wall is coated with a low-resistance coating using resin spraying or ion sputtering technology to minimize flow resistance and the risk of blockage.

[0014] (4) Reliable connection: The connection slip ring is made of copper and polytetrafluoroethylene / polyetheretherketone and has four sets of connection points evenly distributed in 360° to achieve high redundancy and high reliability of power supply and signal transmission.

[0015] Preferably, the three monitoring modules (pressure, temperature, and flow rate) enable simultaneous sensing of multi-functional parameters, which is the core module for realizing monitoring functions on the hardware basis.

[0016] (1) Dual Temperature and Pressure Monitoring Module: Two temperature and pressure sensors are installed. One directly contacts the product fluid to measure the fluid temperature and pressure, while the other monitors the ambient temperature and pressure of the annulus. Dynamic compensation is performed on the fluid density and viscosity to correct the flow rate calculation results, achieving high-precision measurement under complex operating conditions.

[0017] (2) Non-contact high-precision flow module: The central tube is no longer just a flow channel; part of it is given the function of an electromagnetic flowmeter measuring tube. Through the insulating lining on the inner wall, the external excitation coil, and the measuring electrode that penetrates the tube wall, non-contact, high-precision, and low-resistance measurement of fluid velocity (flow rate) is achieved.

[0018] (III) Beneficial Effects

[0019] Compared with existing technologies, the downhole data acquisition unit and method provided by this invention, which integrates flow rate, pressure, and temperature monitoring functions, has the following significant advantages:

[0020] (1) High integration and comprehensive perception: A set of equipment simultaneously acquires five key parameters: flow rate, internal pressure, external pressure, internal temperature and external temperature, providing an unprecedented dynamic panoramic view of downhole production.

[0021] (2) High measurement accuracy: Real-time compensation for flow measurement by temperature and pressure overcomes the measurement error caused by changes in fluid properties, making the flow data more accurate and reliable.

[0022] (3) Strong data synchronization and correlation: All parameters are collected synchronously, providing a perfect data foundation for analyzing the coupling relationship between flow rate, pressure and temperature and diagnosing well conditions (such as wax deposition, motor overload, etc.).

[0023] (4) Economy and reliability: It avoids multiple well runs and the use of multiple instruments, reducing operating costs and potential failure points. It inherits the original high-strength sealing and redundant electrical design to ensure long-term stable operation. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of a downhole data acquisition unit and method that integrates flow, pressure and temperature monitoring functions according to the present invention.

[0025] The components are as follows: 1. Manifold; 2. Upper end; 3. Connecting slip ring; 4. Electromagnetic flowmeter; 5. Pressure-resistant housing; 6. Central tube; 7. Annular pressure and temperature sensor; 8. Annular test channel; 9. Lower end; 10. Manifold; 11. Upper end sealing ring; 12. Downhole parameter collector; 13. Tubing internal pressure and temperature sensor; 14. Tubing internal test channel; 15. Lower end sealing ring. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] In the description of this invention, it is necessary to understand that the orientation or positional relationship indicated by terms such as "upper", "lower", "inner", "outer", "top", and "bottom" are based on the orientation or positional relationship shown in the accompanying drawings. The purpose is only to facilitate the description of this invention and to simplify the description. It is not intended to indicate or imply that the component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this invention.

[0028] The preferred embodiments of a downhole data acquisition unit and method integrating flow, pressure, and temperature monitoring functions provided by the present invention will now be described in detail with reference to the accompanying drawings. Those skilled in the art will understand that the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0029] refer to Figure 1 This invention provides a downhole data acquisition unit and method that integrates flow, pressure, and temperature monitoring functions. It is connected in series within the tubing as part of a production string and lowered to a predetermined depth in the well. Structurally, the unit forms a pressure-bearing, sealed whole, providing a flow channel for the produced fluid, and integrates multiple sensors to achieve synchronous data acquisition.

[0030] 1. Overall structure and mechanical seal design

[0031] The core mechanical structure of the data acquisition unit includes:

[0032] ① Pressure-resistant shell (5): As the main pressure-bearing and structural component, this embodiment preferably uses high-strength precipitation-hardening stainless steel (such as 0Cr17Ni4Cu4Nb) integral forging or seamless tube processing, which has excellent mechanical strength and corrosion resistance, and is used to protect internal electronic components and sensors from damage by the downhole high-pressure environment.

[0033] ② Upper end (2) and lower end (9): Both are screwed into the upper and lower ends of the pressure-resistant housing (5) respectively by means of threaded connection. In order to achieve absolute sealing, an upper end sealing ring (11) is provided at the connection between the upper end (2) and the pressure-resistant housing (5), and a lower end sealing ring (15) is provided at the connection between the lower end (9) and the pressure-resistant housing (5). Preferably, the sealing ring is a fluororubber or perfluoroether rubber O-ring, and at least one is provided before and after the sealing groove to form multiple sealing barriers.

[0034] ③ Central tube (6): It is installed through the center of the interior of the pressure-resistant housing (5), and its two ends are respectively connected to the inner holes of the upper end (2) and the lower end (9) to form a smooth liquid flow channel that runs through the entire unit. In order to reduce flow resistance and prevent scaling, the inner wall of the central tube (6) is treated with a low-resistance coating, for example, by resin spraying or ion sputtering technology to form a smooth, wear-resistant, and corrosion-resistant insulating coating.

[0035] 2. Electrical Interface Design

[0036] Connection slip ring (3): Located inside the pressure-resistant housing (5) near the upper end (2). This slip ring is composed of a copper conductive ring and a polytetrafluoroethylene (PTFE) or polyetheretherketone (PEEK) insulator. Its key feature is that it forms four sets of connection points evenly distributed in a 360° space with the external mating connector (connected to the downhole cable). This redundant design ensures that even when severe downhole vibration causes slight rotation of the unit, the power and signal transmission connections remain stable and reliable without interruption.

[0037] 3. Integration of multi-parameter monitoring systems

[0038] The unit integrates three major monitoring modules, which are controlled, powered, and have their data acquired by the downhole parameter collector (12) (main control circuit).

[0039] 3.1 Electromagnetic Flowmeter (4)

[0040] This module transforms a section of the central tube (6) into the measuring tube of an electromagnetic flowmeter, with the following specific structure:

[0041] ① Insulating lining: The aforementioned low-resistance insulating coating is pre-attached to the inner wall of a specific section of the central tube (6). This coating also serves as the insulating lining required by the electromagnetic flowmeter to prevent short circuits in the electrical signals of the fluid.

[0042] ② Excitation coils: A pair of excitation coils are symmetrically installed and fixed on the outer wall of a specific section of the central tube (6). The coils are sealed and encapsulated in a pressure-resistant housing (5). When an excitation current supplied by the downhole parameter collector (12) is passed through the coils, a stable or alternating magnetic field perpendicular to the fluid flow direction is generated inside the tube.

[0043] ③ Measuring electrodes: A pair of measuring electrodes pass through the wall of the central tube (6) in the radial direction, with their inner ends in direct contact with the fluid and their outer ends connected to the signal processing circuit. According to Faraday's law of electromagnetic induction, when the conductive fluid (product fluid) flows through the magnetic field, an induced electromotive force proportional to the average flow velocity is generated. This electromotive force is picked up by the measuring electrodes and transmitted to the downhole parameter collector (12) for calculation, ultimately obtaining the instantaneous flow rate of the fluid.

[0044] 3.2 Dual Pressure and Temperature Monitoring Module

[0045] This module includes two independent sensors for simultaneously measuring physical parameters at different locations:

[0046] ① Oil pipe pressure and temperature sensor (13): Its pressure-sensing end and temperature-sensing end are in direct contact with the product fluid inside the central tube (6) through the oil pipe test channel (14). The oil pipe test channel (14) is a through hole machined on the lower end (9), and its inlet is flush with the inner wall of the central tube (6) to avoid eddy currents and scale buildup. This sensor is used to directly measure the temperature and pressure of the product fluid.

[0047] ② Annular pressure and temperature sensor (7): Its pressure-sensing end and temperature-sensing end are in contact with the annular fluid between the tubing and the casing through the annular test channel (8). The annular test channel (8) is also a through hole machined on the lower end (9). This sensor is used to measure the temperature and pressure of the external environment of the unit.

[0048] To ensure the sealing reliability of the sensor mounting points, the surface roughness of the inner wall sealing surface of all pressure sensor mounting holes is precision machined to control its arithmetic mean deviation (Ra) to be no greater than 1.6μm.

[0049] 4. Data Acquisition, Compensation, and Transmission Process

[0050] The monitoring method of the present invention is implemented through the following steps:

[0051] Step 1: Synchronous data acquisition: The downhole parameter collector (12) synchronously triggers and acquires the raw flow signal from the electromagnetic flowmeter (4), the production pressure and temperature signal from the tubing pressure and temperature sensor (13), and the annular pressure and temperature signal from the annular pressure and temperature sensor (7) according to the preset sampling cycle.

[0052] Step 2, Data Packaging and Preliminary Processing: The downhole parameter collector (12) digitizes, filters and performs preliminary calculations on the collected multi-channel data (such as converting the electromotive force signal into a flow velocity value), and packages it into a predetermined data frame format.

[0053] Step 3, downhole data transmission: The packaged data is transmitted to the ground receiving system in real time or intermittently via the connecting slip ring (3) and downhole cable.

[0054] Step 4: Ground Data Compensation and Precise Calculation: After the ground receiving system obtains the raw data, it performs crucial dynamic compensation calculations for fluid properties.

[0055] Based on the measured temperature and pressure of the produced liquid, the system dynamically calculates the density (ρ) and viscosity (μ) of the produced liquid under the current operating conditions using built-in fluid property models (such as equations of state and empirical formula libraries).

[0056] Subsequently, the calculated (ρ) and (μ) are used to correct and compensate the original flow rate value measured by the electromagnetic flowmeter, eliminating the influence of fluid property changes on measurement accuracy, and finally outputting a high-precision compensated product flow rate value.

[0057] 5. Work Process Summary

[0058] During oilfield production, the produced fluid flows upward through the central pipe (6) of this unit. During this time, the electromagnetic flowmeter (4) measures its flow rate without obstruction; the in-pipe sensor (13) and the annulus sensor (7) simultaneously capture the internal and external pressure and temperature. All data is uploaded to the ground in real time. Utilizing these synchronous and homogeneous parameters, the ground system can not only directly monitor the production status but also obtain extremely accurate flow data through advanced compensation algorithms, providing a solid and reliable data foundation for oil well production analysis (such as operating condition diagnosis, production capacity assessment, and optimization of lift parameters).

[0059] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A downhole data acquisition unit and method that integrates flow rate, pressure, and temperature monitoring functions, characterized in that, include: (a) Pressure-resistant shell (5) for bearing downhole pressure; (b) The upper end (2) and the lower end (9) are respectively sealed to both ends of the pressure-resistant housing (5); (c) A central tube (6) is installed inside the pressure-resistant shell (3) to form a liquid flow channel; (d) A multi-parameter monitoring system, integrated within the pressure-resistant housing (3), includes: annular pressure and temperature sensor (7), oil pipe pressure and temperature sensor (13), and electromagnetic flow meter (4); (e) Downhole parameter collector (12) for collecting and packaging the flow, pressure and temperature data; (f) Connecting slip ring (3), which is set inside the pressure-resistant housing (5), is used to electrically connect the main control circuit with external equipment to realize power supply and data transmission.

2. The downhole data acquisition unit and method with combined flow, pressure and temperature monitoring functions according to claim 1, characterized in that, The electromagnetic flowmeter (4) assembly includes: an insulating liner attached to the inner wall of a specific section of the central tube (6); a pair of excitation coils symmetrically mounted on the outer wall of the specific section of the central tube (6) for generating a magnetic field perpendicular to the fluid flow direction; and a pair of measuring electrodes passing through the tube wall of the central tube (6), with their ends in contact with the fluid for sensing the electromotive force generated by the fluid cutting magnetic field lines.

3. The downhole data acquisition unit and method with combined flow, pressure and temperature monitoring functions according to claim 1, characterized in that: The annular pressure and temperature sensor (7) and the tubing pressure and temperature sensor (13) are used to measure both internal and external static pressure and to calculate flow correction compensation.

4. A downhole data acquisition unit and method with combined flow, pressure, and temperature monitoring functions according to claim 1 or 3, characterized in that, The temperature monitoring module includes: (a) The temperature sensing end of the pressure and temperature sensor (13) inside the oil pipe is set inside the pressure-resistant housing (3). The lower end (9) is in thermal contact with the product liquid inside the central tube (6) through the test channel (14) inside the oil pipe, and is used to measure the product liquid temperature. (b) The temperature sensing end of the annular pressure and temperature sensor (7) is located inside the pressure-resistant housing (3) or on the lower end (9) and is in thermal contact with the annular liquid through the annular test channel (8) to measure the ambient temperature outside the unit.

5. A downhole data acquisition unit and method with combined flow, pressure and temperature monitoring functions according to claim 4, characterized in that, The downhole parameter collector (12) collects the parameters measured by the tubing pressure and temperature sensor (13), the annular pressure and temperature sensor (7), and the electromagnetic flowmeter (4), and transmits them to the ground receiving system. The ground receiving system compensates for the measured production flow rate by fluid properties (density and viscosity under the influence of temperature and pressure) to improve the flow rate measurement accuracy.

6. The downhole data acquisition unit and method with combined flow, pressure and temperature monitoring functions according to claim 1, characterized in that, The upper end (2) and lower end (9) are provided with an upper sealing ring (11) and a lower sealing ring (15) at the connection between them and the pressure-resistant housing (5). The surface roughness of the mounting sealing surface of the mounting hole of all pressure sensors is no greater than 1.6μm, ensuring the absolute sealing of the pressure-resistant housing (5).

7. The downhole data acquisition unit and method with combined flow, pressure and temperature monitoring functions according to claim 1, characterized in that, The connecting slip ring (3) is composed of a copper conductive ring and a polytetrafluoroethylene or polyetheretherketone insulator, and forms four sets of connection points evenly distributed in a 360° space with the external mating connector.

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