Oil reservoir heating system based on photovoltaic power generation

Abstract

The invention belongs to the technical field of oil reservoir heating, and discloses an oil reservoir heating system based on photovoltaic power generation, which comprises a photovoltaic module, a power supply control system, a submersible motor, a submersible centrifugal pump, an oil-gas separator with a suction inlet, a cable and a hollow pipe electric heating system, the power supply control system is connected with the hollow pipe electric heating system through a cable. The method for heating the oil reservoir through photovoltaic power generation has the advantages of being low in cost, high in efficiency, environmentally friendly, capable of saving energy, sustainable, wide in application range and the like, and is a novel oil reservoir heating technology with development prospects.

Description

Technical Field

[0001] This invention relates to the field of reservoir heating technology, and in particular to a reservoir heating system based on photovoltaic power generation. Background Technology

[0002] Photovoltaic power generation:

[0003] Photovoltaic power generation is a technology that directly converts light energy into electrical energy using the photovoltaic effect at semiconductor interfaces. The key component of this technology is the solar cell. Solar cells are connected in series and then encapsulated for protection to form a large-area solar cell module. Combined with components such as a power controller, this forms a photovoltaic power generation device.

[0004] Photovoltaic power generation is simple in principle, requires no mechanical movement, consumes no fuel, and emits no substances, including greenhouse gases. It is also noiseless and pollution-free. As long as there is solar energy, it can generate electricity through photovoltaic conversion, and solar energy is inexhaustible. Compared to traditional energy sources, solar energy can be considered the cleanest and most sustainable energy type.

[0005] Analysis of the characteristics of photovoltaic (PV) power generation reveals that the impact of PV power generation systems on the power grid is mainly due to the instability of PV power sources. From the perspective of power grid safety, stability, and economic operation, grid-connected PV power generation systems without energy storage will adversely affect line power flow, system protection, economic operation of the power grid, power quality, and dispatching. The impact of grid-connected PV power plants, especially large-scale PV power plants, on the power grid cannot be ignored.

[0006] Oil reservoir heating:

[0007] As an important component of petroleum resources, heavy oil has substantial reserves in my country. Effective utilization of this oil would greatly benefit the country's petroleum industry. Due to its high density, viscosity, and poor fluidity, heavy oil requires a series of auxiliary extraction measures to effectively increase production, with thermal recovery technology being the most common. Currently, the most widely used thermal recovery technologies are reservoir combustion and steam injection, with steam injection technology further divided into steam drive and steam huff and puff techniques.

[0008] Burning oil reservoirs has the following disadvantages: ① The heat generated by underground combustion is used not only to heat crude oil, but also partly to heat bedrock and caprock; ② The formation of emulsions in production wells reduces oil well productivity; ③ Acidic gases in the produced fluids accelerate the corrosion of production well tubing and surface facilities; ④ Sand production and wellbore collapse in production wells cause damage to the oil wells; ⑤ Thermal cracking and crude oil evaporation cause wax and asphalt precipitation in the area near the production wellbore, clogging the formation and wellbore; ⑥ The high temperature of the production well causes damage to the production tubing; ⑦ Burning oil reservoirs burns away a portion of the crude oil, approximately 10%-15% of the crude oil reserves.

[0009] Steam injection for thermal oil recovery has the following disadvantages: ① Thermal oil recovery requires a large amount of energy to heat underground oil reservoirs, which consumes a large amount of natural gas or coal, resulting in energy waste and environmental pollution; ② Thermal oil recovery technology requires advanced technology and equipment, including high-temperature and high-pressure equipment, geological exploration technology, thermodynamic calculations, etc., which are technically difficult and costly; ③ The equipment, labor, operation and maintenance costs required for thermal oil recovery are relatively high, and the economic benefits are greatly affected by the fluctuation of crude oil prices, resulting in unstable benefits. Summary of the Invention

[0010] To overcome the shortcomings of existing technologies, the present invention aims to combine photovoltaic power generation technology with thermal oil recovery technology, using solar energy to heat oil reservoirs and improve crude oil recovery rate.

[0011] A reservoir heating system based on photovoltaic power generation mainly consists of the following parts:

[0012] 1. Photovoltaic modules: Photovoltaic modules are the core component of the entire power generation system. By connecting photovoltaic modules in series and parallel, a photovoltaic module array is formed, also known as a photovoltaic array.

[0013] Working principle: Sunlight shines on a semiconductor PN junction, forming new electron-hole pairs. Under the influence of the PN junction's electric field, holes flow from the P-region to the N-region, and electrons flow from the N-region to the P-region, forming a current when the circuit is connected. Its function is to convert solar energy into electrical energy, which is then stored in a battery or used to power a load.

[0014] 2. Power supply control system: The power supply control system mainly consists of three parts: inverter, controller, and battery.

[0015] An inverter is a device that converts direct current (DC) generated by photovoltaic (PV) power generation into alternating current (AC). PV inverters are a crucial component for system balancing in PV array systems and can be used in conjunction with general AC power supply equipment. Solar inverters have special functions tailored to PV arrays, such as maximum power point tracking and islanding protection.

[0016] The controller is an automatic control device that can prevent overcharging and over-discharging of the battery while delivering stable power to downstream loads. Employing a high-speed CPU microprocessor and a high-precision A / D converter, it is a microcomputer-based data acquisition and monitoring control system that can quickly and in real-time acquire the current operating status of the photovoltaic system and ensure the stable operation of the electrical equipment.

[0017] Batteries store excess electrical energy in a photovoltaic power generation system by converting electrical energy into chemical energy, and then convert the chemical energy back into electrical energy to power downstream equipment.

[0018] 3. Submersible Electric Motor: A submersible electric motor is an electric motor that can operate while submerged in an oil well at a specified depth. It is generally a vertical three-phase squirrel-cage induction motor, which, together with a multi-stage centrifugal pump, forms a submersible electric pump that can be submerged in oil wells at depths of several hundred meters to 3000 meters to continuously and reliably extract crude oil or well fluid from the well.

[0019] Submersible motors are three-phase AC squirrel-cage asynchronous motors. Their working principle is as follows: When the three-phase stator windings are connected to a three-phase AC power supply, a rotating magnetic field with a rotational speed of 60 f / p is generated inside the stator. Its direction of rotation depends on the current phase sequence. Because this rotating magnetic field cuts the rotor bars, an induced current is generated in the closed rotor circuit according to the law of electromagnetic induction. Furthermore, due to the laws of motors, this induced current experiences a force in the rotating magnetic field, thus generating electromagnetic torque that causes the rotor to drive the load to rotate asynchronously along the direction of the rotating magnetic field.

[0020] 4. Submersible Centrifugal Pump: A submersible electric pump is a multi-stage centrifugal pump, mainly composed of multi-stage impellers, guide casing, pump shaft, pump housing, and upper and lower joints. Multi-section pumps can be connected in series using connecting flanges and spline sleeves to meet the required head.

[0021] Submersible electric pumps (SAPs) can adapt to different types of oil well conditions. Nickel-cast iron impellers and guide casings, along with K-500 Monel alloy pump shafts, ensure satisfactory service life under maximum strength and load. To adapt to oil well conditions, reduce component load, and simplify assembly, multi-stage SSPs are available in three assembly types: fully floating, fully compressed, or semi-floating. Structurally, they are divided into radial flow and mixed flow types, and in application, they are classified as standard pumps, sand control pumps, and corrosion-resistant pumps.

[0022] 5. Oil-gas separator (suction inlet): When free gas enters a centrifugal pump, it will reduce the pump's displacement, head, and efficiency, causing unstable operation and making it prone to cavitation damage to the blades. Therefore, a gas separator is commonly used as the pump's suction inlet to separate the gas.

[0023] 6. Protector: The protector is an essential component for the normal operation of the electric pump unit. Based on different structures and operating principles, it can be divided into three types: continuous type, settling type, and bladder type. The function of the protector:

[0024] 1) Seal the power output end of the motor shaft to prevent well fluid from entering the motor.

[0025] 2) During the start-up and shutdown of the electric pump unit, it provides a storage space to compensate for the thermal expansion and contraction of the motor oil.

[0026] 3) It plays a role in transmitting torque by connecting the motor drive shaft and the pump shaft.

[0027] 4) The thrust bearing inside the protector can withstand the axial force of the pump.

[0028] 7. Submersible Pump Cable: As the channel for transmitting electrical energy to the electric pump unit, it operates for extended periods in environments with high temperature, high pressure, and corrosive fluids. Therefore, submersible pump cables are required to possess high core wire electrical properties, dielectric properties of the insulation layer, and good overall corrosion resistance, wear resistance, and stable physical and chemical properties such as high-temperature resistance. Submersible pump cables include submersible power cables and submersible motor lead wires. Power cables are available in two types: round cables and flat cables, while motor lead wires are only available in flat cables. Round cables are used for wells with larger diameters, while flat cables can be used for wells with smaller diameters.

[0029] 8. Hollow Tube Electric Heating System. The hollow tube electric heating system is an integrated device consisting of hollow tubes, heating cables, etc. It utilizes the heat energy generated by electric heating to heat the crude oil throughout the oil pipe, thereby increasing the crude oil temperature, reducing its viscosity, and improving its fluidity. This effectively allows for the extraction of high-viscosity, high-pour-point, and high-wax crude oil, achieving the goal of increasing production and efficiency.

[0030] Compared with the prior art, the advantages of the present invention are mainly as follows:

[0031] 1. Low cost: Compared with traditional oil reservoir heating methods, photovoltaic power generation for oil reservoir heating is less expensive because it uses solar energy to generate electricity, does not consume fossil fuels, and does not require combustion or emissions, thus reducing environmental pollution.

[0032] 2. High efficiency: Photovoltaic power generation is highly efficient in heating oil reservoirs because it can use the electricity generated by solar energy to heat the reservoir, thereby improving oil flow and increasing recovery rate.

[0033] 3. Environmental protection and energy saving: Photovoltaic power generation to heat oil reservoirs is an environmentally friendly and energy-saving oil extraction method because it does not require the consumption of fossil fuels, nor does it require combustion and emissions, thus reducing environmental pollution.

[0034] 4. Sustainability: Photovoltaic power generation for heating oil reservoirs is sustainable because solar energy is a renewable energy source that will not be depleted like fossil fuels and can be used for a long time.

[0035] 5. Wide range of applications: Photovoltaic power generation for heating oil reservoirs is applicable to various types of oil reservoirs, including shallow, medium and deep reservoirs, and can meet the oil production needs of different regions and types.

[0036] In summary, heating oil reservoirs using photovoltaic power generation has advantages such as low cost, high efficiency, environmental friendliness and energy saving, sustainability and wide applicability, making it a promising new oil reservoir heating technology. Attached Figure Description

[0037] Appendix Figure 1 This is a simplified diagram of an oil reservoir heating device based on photovoltaic power generation.

[0038] 1-Photovoltaic module, 2-Cable, 3-Power supply control system, 4-Wellhead plugging device, 5-Well wall, 6-Tubing, 7-Upper shut-off valve, 8-Perforation, 9-Crude oil heating pipe, 10-Casing, 11-Lower check valve, 12-Oil delivery pipe, 13-Submersible centrifugal pump, 14-Suction port, 15-Submersible motor. Detailed Implementation

[0039] The present invention will now be described in detail through specific embodiments.

[0040] Example 1

[0041] like Figure 1 As shown, photovoltaic module 1 converts solar energy into electrical energy.

[0042] Cable 2 transmits the electrical energy generated by the photovoltaic module to the power supply control system 3.

[0043] The power supply control system 3 mainly consists of three parts: an inverter, a controller, and a battery. The inverter is a device that converts the direct current (DC) generated by photovoltaic power generation into the required alternating current (AC). The controller is an automatic control device that prevents overcharging and over-discharging of the battery while simultaneously delivering stable power to downstream loads. The battery stores excess electrical energy in the photovoltaic power generation system by converting electrical energy into chemical energy, and then converts the chemical energy back into electrical energy to power downstream equipment.

[0044] The wellhead sealing device 4 is installed at the wellhead to suspend the casing and tubing, and to seal the annular space between the tubing and the casing and each layer of casing. It is generally composed of a casing head, a tubing head, and a blowout preventer assembly.

[0045] A casing 10 is installed between the wellbore 5 and the tubing 6. The tubing 6 is the pipe run into the well casing during normal production. The casing 10 is the pipe run downhole after drilling is completed. The casing 10 is cemented to the wellbore. Then, a perforating gun is used to perforate the target layer, allowing heated oil to flow through the perforation 8, through the crude oil heating pipe 9, tubing 6, casing 10, cement sheath, and rock formation into the upper oil layer. Its main functions are: ① to reinforce the wellbore and prevent formation collapse; ② to isolate different oil and water layers, enabling stratified production; ③ to facilitate fracturing, acidizing, and other maintenance operations; and ④ to form an oil flow channel.

[0046] The crude oil heating tube 9 has a built-in electric heating device that transfers heat energy to the crude oil flowing inside, heating it. The upper part of the crude oil heating tube 9 has an upper shut-off valve 7, which acts as a seal to prevent crude oil from overflowing from the top. The lower part of the crude oil heating tube 9 has a lower check valve 11, ensuring that crude oil enters from the bottom and preventing crude oil from flowing back from the top to the bottom.

[0047] The submersible motor 15 drives the submersible centrifugal pump 13 to rotate, generating centrifugal force to drive crude oil into the suction port 14 and out through the oil delivery pipe 12.

[0048] Main process:

[0049] The device mainly consists of seven parts: a photovoltaic module 1, a power supply control system 3, a submersible motor 15, a submersible centrifugal pump 13, an oil-gas separator with an intake port 14, a cable 2, and a hollow tube electric heating system. The photovoltaic module 1 generates electrical energy, which is transmitted to the power supply control system 3 through the cable 2. The power supply control system 3 then transmits the electrical energy to the crude oil heating pipe 9 and the submersible motor 15 in the well through the cable 2. The rotation of the submersible motor 15 drives the submersible centrifugal pump 13 to generate centrifugal force, which drives the crude oil to enter through the intake port 14, exit through the oil delivery pipe 12, enter the crude oil heating pipe 9 for heating, and then enter the upper oil layer through the perforation 8, thus realizing the function of heating and circulating the crude oil in the reservoir.

[0050] This device combines photovoltaic power generation technology with thermal oil recovery technology, using solar energy to heat the oil reservoir, thereby improving the utilization efficiency of photovoltaic power generation, reducing the cost of oil reservoir heating, and increasing the crude oil recovery rate.

[0051] The embodiments described above are merely preferred embodiments of the present invention, and not all feasible embodiments of the present invention. Any obvious modifications made by those skilled in the art without departing from the principles and spirit of the present invention should be considered to be included within the scope of protection of the claims of the present invention.

Claims

1. A reservoir heating system based on photovoltaic power generation, characterized in that, The system includes a photovoltaic module (1), a power supply control system (3), a submersible motor (15), a submersible centrifugal pump (13), an oil-gas separator with a suction port (14), a cable (2), and a hollow tube electric heating system. The photovoltaic module (1) is connected to the power supply control system (3) via the cable (2), and the power supply control system (3) is connected to the hollow tube electric heating system via the cable (2).

2. The reservoir heating system based on photovoltaic power generation according to claim 1, characterized in that, The hollow tube electric heating system includes a wellhead sealing device (4). The wellhead sealing device (4) is installed at the wellhead and is used to suspend the casing (10) and tubing (6) and seal the annular space between the tubing (6) and the casing (10) and each layer of casing. The casing (10) is installed between the well wall (5) and the tubing (6).

3. The reservoir heating system based on photovoltaic power generation according to claim 1, characterized in that, The hollow tube electric heating system includes a crude oil heating tube (9), which has a built-in electric heating device. The upper part of the crude oil heating tube (9) is a top shut-off valve (7), which acts as a seal to prevent the crude oil inside the crude oil heating tube (9) from overflowing from the top. The lower part of the crude oil heating tube (9) is a bottom flow valve (11), which ensures that the crude oil enters from the bottom and prevents the crude oil from flowing back from the top to the bottom.

4. The reservoir heating system based on photovoltaic power generation according to claim 1, characterized in that, The hollow tube electric heating system includes a submersible motor (15). The submersible motor (15) drives the submersible centrifugal pump (13) to rotate, generating centrifugal force to drive crude oil into the suction port (14) and out through the oil delivery pipe (12).

5. The reservoir heating system based on photovoltaic power generation according to claim 1, characterized in that, The power supply control system (3) consists of three parts: inverter, controller and battery.

6. The reservoir heating system based on photovoltaic power generation according to claim 5, characterized in that, The controller uses a high-speed CPU microprocessor and a high-precision A / D analog-to-digital converter.

7. The reservoir heating system based on photovoltaic power generation according to claim 1, characterized in that, The submersible motor (15) is a vertical three-phase squirrel-cage induction motor.

8. The reservoir heating system based on photovoltaic power generation according to claim 1, characterized in that, The submersible centrifugal pump (13) is a multi-stage centrifugal pump.

9. The reservoir heating system based on photovoltaic power generation according to claim 1, characterized in that, A multistage centrifugal pump consists of multistage impellers, guide casing, pump shaft, pump housing, and upper and lower joints.

10. The reservoir heating system based on photovoltaic power generation according to claim 1, characterized in that, When working, the photovoltaic module (1) generates electrical energy and transmits the electrical energy to the power supply control system (3) through the cable (2). The power supply control system (3) transmits the electrical energy to the crude oil heating pipe (9) and the submersible motor (15) in the well through the cable (2). The submersible motor (15) rotates and drives the submersible centrifugal pump (13) to operate and generate centrifugal force, which drives the crude oil to enter from the suction port (14), exit from the oil pipeline (12), enter the crude oil heating pipe (9) for heating, and then enter the upper oil layer through the perforation (8), realizing the function of heating and circulating crude oil in the reservoir.

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