CN107060712B - A downhole electromagnetic induction heavy oil heating device and heating method - Google Patents

Abstract

The invention relates to a downhole electromagnetic induction heavy oil heating device and heating method, which includes a protective cover, a transformer, an excitation coil, a heating element, a partition, a snap ring A, a snap ring B, an inner core, a variable diameter nozzle and a water outlet pipe. The protective cover is installed inside the shaft, and a transformer is installed inside the protective cover. One end of the transformer is connected to the power supply equipment, and the other end is connected to the excitation coil. One end of the heating element is provided with a snap ring A, and the other end is provided with a snap ring B. The inner core is set inside the heating element and one end of the inner core passes through the snap ring A, and the other end is fixed on the snap ring B. The outlet pipe One end is connected to the end of the heating element, and the other end passes through the packer. The downhole heavy oil heating device of the present invention has long service life, high heating efficiency, compact structure, less heat energy loss, high heat energy utilization rate, fast heating rate, and can realize high-power dense heating.

Description

A downhole electromagnetic induction heavy oil heating device and heating method

technical field

The invention relates to a downhole oil layer heating device, in particular to a downhole electromagnetic induction heavy oil heating device and a heating method.

Background technique

With the rapid development of modern industry and the huge demand for energy in modern life, the demand for oil and natural gas resources continues to increase. With the increasing difficulty of oil and natural gas exploitation, and regional conflicts affecting energy transportation channels, the contradiction between supply and demand has become increasingly prominent. The tight supply of conventional crude oil and the fluctuation of crude oil price bring opportunities for the exploitation and development of heavy oil. Different from the exploitation of conventional crude oil, heavy oil is difficult to flow or cannot flow at all under reservoir conditions due to its high viscosity and high density. There are also some technical problems that need to be solved and overcome urgently in terms of technology, mining cost, and environmental protection.

At present, heavy oil recovery is mainly thermal recovery, and the thermal recovery methods mainly include steam huff and puff and steam drive. In steam injection for heavy oil development, steam generator is one of the essential equipment. Both of these two methods require the construction of steam station boilers on the ground, which are transported to various gas injection wells through pipelines under the control of the central system. Steam injection is almost in a monopoly position in the current heavy oil thermal recovery process, but with the development of thermal recovery process With the continuous improvement of demand and the increasing difficulty of well conditions, its shortcomings are increasingly exposed. Various factors such as the unequal transmission distance from the ground steam station to each gas injection well, different topographical conditions of oil wells, differences between different oil production wells, transmission pipelines, and difficulty in wellbore insulation make the dryness of the steam injected into the downhole low, which in turn leads to thickening. The oil recovery ratio decreases, and the comprehensive economic benefits decrease.

China National Petroleum Corporation published a patent in April 2014: downhole electric heating steam generator, the heating tube is a hollow cylinder, the number is multiple, and the hollow part is a through hole, and the fluid passes through the The electric heating element is a slender electric heating wire wound on the tube wall of the heating pipe. After the heating element is energized, the fluid in the heating tube is heated. In this heating method, the heat is generated by the electric heating wire, and then transferred to the heating pipe, and finally transferred to the water, involving three-stage heat transfer, which leads to low heat transfer efficiency, that is, low heating efficiency, and when the heating power is large, the electric heating The silk itself is easily burned.

China National Offshore Oil Corporation disclosed a patent in May 2013: a kind of equipment and method for steam thermal recovery of heavy oil, a kind of equipment for steam thermal recovery of heavy oil, including surface equipment and downhole equipment, the downhole equipment includes at least A steam generator; the steam generator is arranged above or in the oil layer. The steam generated by the steam generator directly heats the heavy oil, which can increase the temperature of the steam and greatly increase the recovery of the heavy oil.

The patent document whose publication number is CN106016221A discloses an electrothermal downhole steam generator. The electrothermal downhole steam generator comprises an inlet part, an electric heating part and an outlet part which are sequentially connected from top to bottom; Heating pipes; electric heating wires are installed in each heating pipe; spaces for water flow are formed between the heating pipes and between the heating pipes and the shell of the heating section; high-temperature steam is generated downhole and directly injected into the oil layer.

All the above-mentioned downhole electric heating methods are heated by electric heating wire. The disadvantage of this method is that the electric heating wire itself is seriously worn out and easily damaged, resulting in a short service life of the heater and a relatively complicated structure of the heater.

Contents of the invention

The object of the present invention is to overcome the shortcomings of the prior art, and provide a downhole electromagnetic induction heavy oil heating device and heating method.

The purpose of the present invention is achieved through the following technical solutions: a downhole electromagnetic induction heavy oil heating device, which includes a shaft, a water tank, a water pump, a water pipe, power supply equipment and a packer, the shaft is vertically installed underground, and the bottom of the shaft is installed with A packer, one end of the water pump is connected to the water tank, and the other end is connected to a water pipe. The water pipe is fixed inside the wellbore. It is characterized in that it also includes a heating device, which is placed in the wellbore. The heating device includes a protective cover, a transformer, and a variable diameter nozzle. And the induction heater, the transformer, the reducing nozzle and the induction heater are all installed inside the protective cover, and the induction heater includes an excitation coil, a heating element, an inner core, a compartment, an outlet pipe, a snap ring A and a snap ring B, The compartment is fixed on the inner wall of the protective cover, and the exciting coil is embedded in the wall of the compartment. The exciting coil is connected to one end of the transformer, and the other end of the transformer is connected to the power supply equipment. The compartment is equipped with a heating element, and one end of the heating element is installed with The other end of the variable-diameter nozzle is provided with a snap ring B, and the variable-diameter nozzle is connected to the water pipe. A snap ring A is provided between the snap ring B and the variable-diameter nozzle. One end passes through the snap ring A, the other end is fixed on the snap ring B, one end of the outlet pipe is connected to the end of the heating element, the other end passes through the packer and a check valve is installed on the outlet pipe.

The protective cover is made of corrosion-resistant stainless steel, and one end thereof is an arc-shaped structure with equal wall thickness.

The interlayer is an insulating and heat-insulating material.

The inner surface of the variable-diameter nozzle is provided with protrusions.

The excitation coil is a hollow copper tube, and a cooling water pipe joint is arranged on it.

The end of the inner core that passes through the snap ring A is an open structure, and the end that is fixed on the snap ring B is a sealed structure, and a plurality of through holes are evenly distributed on the circumference of the wall surface of the inner core.

The inner core can also be a shuttle-shaped entity, and the surface of the entity is provided with spirally distributed protrusions. The two ends of the heating element are fixed with snap rings B, and the two ends of the inner core are inserted into the snap ring B. .

The length and diameter of the inner core can be adjusted according to actual production needs.

A method for heating heavy oil with a downhole electromagnetic induction heavy oil heating device, comprising the following steps:

S1. Start the water pump, the water pump draws water from the water tank, the water enters the heating element through the water pipe through the variable diameter nozzle, and the variable diameter nozzle increases the disturbance of the water flow;

S2. Start the power supply equipment, and the power supply equipment sends the intermediate frequency alternating current to the transformer to reduce the voltage and increase the current, thereby supplying power to the excitation coil, and the excitation coil generates a corresponding alternating magnetic field under the action of the intermediate frequency alternating current;

S3, the heating element generates an induced current in an eddy current state in the alternating magnetic field in step S2, and the flowing induced current overcomes the resistance of the heating element to generate heat, so that the heating element generates heat;

S4. When the inner core inside the heating element has the structure described in claim 6, the water entering the heating element in step S1 first passes through the variable-diameter nozzle, and the variable-diameter nozzle will disturb the water, increasing the water and the wall surface of the heating element The water will be preheated at the entrance of the heating element, and the preheated water will enter the inner core of the heating element under pressure. After entering the inner core, the water will spray to the heating element through the through hole on the inner core. On the wall, the high-temperature heating element instantly vaporizes the water sprayed on it into water vapor;

S5. When the inner core inside the heating element has the structure described in claim 7, the water entering the heating element in step S1 first passes through the variable-diameter nozzle, and the variable-diameter nozzle will disturb the water, increasing the water and the wall surface of the heating element The water will be preheated at the entrance of the heating element, and the preheated water will enter between the heating element and the inner core through the small hole on the snap ring B installed at the entrance of the heating element under pressure. It will move forward along the spiral protrusion on the inner core to fully contact the wall surface of the high-temperature heating element, and the water will instantly vaporize into water vapor;

S6. The water vapor in step 4 or step 5 continuously gathers and expands, rushes out from the small hole on the snap ring B installed at the outlet of the heating element, passes through the outlet pipe and the one-way valve at the end of the heating element, and then passes through the packer It is pressed into the heavy oil layer to be heated, and after a period of heating, the heating of the downhole heavy oil is realized.

The present invention has the following advantages:

1. Long service life and high heating efficiency.

2. Compact structure, small volume, reduce handling cost.

3. Less heat energy loss and high heat energy utilization rate.

4. The system has better stability, and the heating temperature can be controlled according to the heating power.

5. The heating rate is fast, and high power intensive heating can be realized.

Description of drawings

Fig. 1 is the structural representation of the present invention;

Fig. 2 is a structural sectional view of the first embodiment of the present invention;

Fig. 3 is a structural sectional view of the second embodiment of the present invention;

In the figure: 1-well shaft, 2-water tank, 3-water pump, 4-water pipe, 5-power supply equipment, 6-packer, 7-heating device, 8-protective cover, 9-transformer, 10-variable nozzle, 11-induction heater, 11-1 excitation coil, 11-2 heating element, 11-3 inner core, 11-4 interlayer, 11-5 water outlet pipe, 11-6 snap ring A, 11-7 snap ring B.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings, but the protection scope of the present invention is not limited to the following description.

As shown in Figures 1 to 3, a downhole electromagnetic induction heavy oil heating device includes a wellbore 1, a water tank 2, a water pump 3, a water pipe 4, a power supply device 5, and a packer 6. The wellbore 1 is vertically installed underground, and the wellbore A packer 6 is installed at the bottom of 1. One end of the water pump 3 is connected to the water tank 2, and the other end is connected to the water pipe 4. The water pipe 4 is fixed inside the well shaft 1. It is characterized in that it also includes a heating device 7, which is placed in the well shaft 1, the heating device 7 includes a protective cover 8, a transformer 9, a variable diameter nozzle 10 and an induction heater 11, and the transformer 9, the variable diameter nozzle 10 and the induction heater 11 are all installed inside the protective cover 8, and the induction heater 11 Including excitation coil 11-1, heating element 11-2, inner core 11-3, interlayer 11-4, outlet pipe 11-5, snap ring A11-6 and snap ring B11-7, interlayer 11-4 is fixed On the inner wall of the protective cover 8, the exciting coil 11-1 is embedded in the wall of the interlayer 11-4, the exciting coil 11-1 is connected to one end of the transformer 9, and the other end of the transformer 9 is connected to the power supply device 5, and the interlayer 11- 4. The set is equipped with a heating element 11-2. One end of the heating element 11-2 is equipped with a variable-diameter nozzle 10, and the other end is provided with a snap ring B11-7. The variable-diameter nozzle 10 is connected to the water pipe 4, and the snap ring B11- A snap ring A11-6 is provided between 7 and the variable-diameter nozzle 10, the inner core 11-3 is set in the heating element 11-2, and one end of the inner core 11-3 passes through the snap ring A11-6, and the other end is fixed On the clasp B11-7, one end of the water outlet pipe 11-5 is connected to the end of the heating element 11-2, the other end passes through the packer 6 and a check valve is installed on the water outlet pipe 11-5.

The protective cover 7 is made of corrosion-resistant stainless steel, and one end thereof is an arc-shaped structure with equal wall thickness.

The interlayer 11-4 is an insulating and heat insulating material.

The inner surface of the variable-diameter nozzle 10 is provided with protrusions.

The excitation coil 11-1 is a hollow copper tube, and a cooling water pipe joint is arranged on it.

One end of the inner core 11-3 passing through the snap ring A11-6 is an open structure, and one end fixed on the snap ring B11-7 is a sealed structure, and the circumference of the wall surface of the inner core 11-3 is evenly distributed. through holes.

The inner core 11-3 can also be a shuttle-shaped entity, and the surface of the entity is provided with spirally distributed protrusions, and the two ends of the heating element 11-2 are fixed with snap rings B11-7, and the inner core 11- The two ends of 3 are inserted on the snap ring B11-7.

The length and diameter of the inner core 11-3 can be adjusted according to actual production requirements.

A method for heating heavy oil with a downhole electromagnetic induction heavy oil heating device, comprising the following steps:

S1, start the water pump 3, the water pump 3 extracts water from the water tank 2, the water enters the heating element 11-2 through the water pipe 4 through the variable diameter nozzle 10, and the variable diameter nozzle 10 increases the disturbance of the water flow;

S2, start the power supply device 5, the power supply device 5 sends the intermediate frequency alternating current to the transformer 9 to reduce the voltage and increase the current, thereby supplying power to the excitation coil 11-1, and the excitation coil 11-1 generates a corresponding alternating magnetic field under the action of the intermediate frequency alternating current;

S3, the heating element 11-2 generates an induced current in an eddy current state in the alternating magnetic field in step S2, and the flowing induced current overcomes the resistance of the heating element 11-2 to generate heat, so that the heating element 11-2 generates heat;

S4. When the inner core 11-3 inside the heating element 11-2 has the structure described in claim 6, the water entering the heating element 11-2 in step S1 first passes through the variable-diameter nozzle 10, and the variable-diameter nozzle 10 will meet the water Perform turbulence to increase the chance of contact between the water and the wall of the heating element 11-2, the water will be preheated at the entrance of the heating element 11-2, and the preheated water will enter the inside of the heating element 11-2 under pressure Inner core 11-3, after water enters the inner core 11-3, it sprays to the wall surface of the heating element 11-2 through the through hole on the inner core 11-3, and the high temperature heating element 11-2 instantly vaporizes the water sprayed on it become water vapor

S5. When the inner core 11-3 inside the heating element 11-2 has the structure described in claim 7, the water entering the heating element 11-2 in step S1 first passes through the variable-diameter nozzle 10, and the variable-diameter nozzle 10 will meet the water Perform turbulence to increase the chance of contact between the water and the wall of the heating element 11-2, the water will be preheated at the entrance of the heating element 11-2, and the preheated water will pass through the heating element 11-2 under pressure. The small hole on the snap ring B11-7 at the entrance enters between the heating element 11-2 and the inner core 11-3, and the water will move forward along the spiral protrusion on the inner core 11-3 to fully contact the heating element with high temperature 11-2 Wall contact, water vaporizes instantly into water vapor;

S6. The water vapor in step 4 or step 5 continuously gathers and expands, rushes out from the small hole on the snap ring B11-7 installed at the outlet of the heating element 11-2, and passes through the water outlet pipe 11 at the end of the heating element 11-2 -5 and the one-way valve are pressed into the heavy oil layer to be heated through the packer 6, and after a period of heating, the heating of the downhole heavy oil is realized.

The working process of the present invention is as follows: start the water pump 3, the water pump 3 draws water from the water tank 2, the water enters the heating device 7 installed inside the shaft 1 through the water pipe 4, starts the power supply equipment 5, and the power supply equipment 5 is an intermediate frequency power supply, and the power supply cable used adopts Core copper conductive wire-polypropylene insulation-bedding layer and double steel wire armored structure special cable for petroleum industry to reduce power loss and ensure power supply safety. The power supply equipment 5 is connected to the excitation coil after the voltage is reduced by the transformer 9 and the current is increased. 11-1, the excitation coil 11-1 is made of a hollow copper tube, and the whole is in a spiral shape. The excitation coil 11-1 is provided with a cooling water pipe joint, which can be connected to the cooling water so that the cooling water flows in the excitation coil 11. The internal flow of -1, the cooling water in the hollow copper tube of the exciting coil 11-1 can effectively reduce the overheating of the coil itself during the working process of the heater, prevent the heater from working due to overheating of the coil, and effectively prolong the life of the heater. The coil 11-1 is embedded in the wall of the interlayer 11-4, the interlayer 11-4 is an insulating material, and the exterior of the interlayer 11-4 is wrapped with a protective cover 8, and the protective cover 8 is made of corrosion-resistant stainless steel , the inner suit of compartment 11-4 has

The heating element 11-2, the heating element 11-2 is a hollow cylinder made of magnetically conductive stainless steel, and the excitation coil 11-1 will generate a corresponding alternating magnetic field under the action of the intermediate frequency alternating current provided by the power supply device 5, and the heating element 11- 2. Under the action of the alternating magnetic field, an eddy current is generated. When the induced current overcomes the resistance and flows, heat is generated to make the heating element 11-2 generate heat. One end of the heating element 11-2 is equipped with a variable-diameter nozzle 10, and the water pumped by the water pump 1 Through the water pipe 4, it enters the heating element 11-2 through the variable-diameter nozzle 10. At the same time, the inner surface of the variable-diameter nozzle 10 is provided with uniformly arranged protrusions. Part of the water flow hits the protrusions to change the flow direction, so that part of the water stays on the heating element. The time at the entrance of 11-2 becomes longer, and the preheating of water is completed. The inner core 11-3 is set inside the heating element 11-2. The inner core 11-3 has two kinds of embodiment structures. The first embodiment structure inner core 11-3 is a hollow tube structure with one end sealed, and a plurality of through holes are evenly distributed on the surface of the hollow tube, and the two ends of the inner core 11-3 respectively pass through the snap ring A11-6 installed at the entrance of the heating element 11-2 and the snap ring B11-7 at the outlet are fixed inside the heating element 11-2. The inner core 11-3 is a hollow tube structure with one end sealed, and a plurality of through holes are evenly distributed on the surface of the hollow tube. The heated water enters the inner core 11-3 and is sprayed to the high-temperature heating element 11-2 through the through hole on its surface. The small hole on the ring B11-7 is punched out, passes through the water outlet pipe 11-5 installed at one end of the heating element 11-2, the one-way valve and the packer 6 in sequence, and is pressed into the heavy oil layer to be heated. After a period of heating, the The purpose of heating thick oil. In the second embodiment, the inner core 11-3 is a solid shuttle-shaped body, and the two ends of the solid shuttle-shaped solid body are fixed on the clasp B11-7 at the two ends of the heating element 11-2. The helically wound protrusions can increase the contact time between the water flow and the heating element 11-2 to ensure that the water fully contacts the heating element 11-2 and increase the efficiency of water vaporization. The water pumped by the water pump 1 enters through the variable diameter nozzle 10 To the entrance of the heating element 11-2, complete the preheating at the entrance of the heating element 11-2, and then flow into the heating element 11-2 and the Between the inner core 11-3, the water flow will spiral forward along the spiral protrusion on the inner core 11-3 to the outlet of the heating element 11-2, and the water flow will fully contact the wall surface of the high-temperature heating element 11-2, and continuously vaporize and expand. The expanded water vapor rushes out from the small hole of the snap ring B11-7 at the outlet end of the heating element 11-2, passes through the water outlet pipe 11-5, the one-way valve and the packer 6 in sequence, and is pressed into the heavy oil layer to be heated. The heating of time completes the purpose of thick oil heating.

Claims (1)

1. A method for heating heavy oil with a downhole electromagnetic induction heavy oil heating device, the device includes a wellbore (1), a water tank (2), a water pump (3), a water pipe (4), power supply equipment (5) and a packer (6), the wellbore (1) is installed vertically underground, the bottom of the wellbore (1) is installed with a packer (6), one end of the water pump (3) is connected to the water tank (2), and the other end is connected to the water pipe (4), The water pipe (4) is fixed inside the shaft (1), and it also includes a heating device (7). The heating device (7) is placed in the shaft (1). The heating device (7) includes a protective cover (8), a transformer (9) , variable-diameter nozzle (10) and induction heater (11), transformer (9), variable-diameter nozzle (10) and induction heater (11) are all installed inside the protective cover (8), and the induction heater (11 ) including excitation coil (11-1), heating element (11-2), inner core (11-3), compartment (11-4), outlet pipe (11-5), snap ring A (11-6) and snap ring B (11-7), the compartment (11-4) is fixed on the inner wall of the protective cover (8), the excitation coil (11-1) is embedded in the wall of the compartment (11-4), and the excitation The coil (11-1) is connected to one end of the transformer (9), and the other end of the transformer (9) is connected to the power supply device (5). -2) One end is equipped with a variable diameter nozzle (10), and the other end is provided with a snap ring B (11-7). The variable diameter nozzle (10) is connected to the water pipe (4), and the snap ring B (11-7) 7) There is a clasp A (11-6) between the variable diameter nozzle (10), the inner core (11-3) is set in the heating element (11-2), and one end of the inner core (11-3) Through the snap ring A (11-6), the other end is fixed on the snap ring B (11-7), one end of the outlet pipe (11-5) is connected to the end of the heating element (11-2), and the other end Pass through the packer (6) and a one-way valve is installed on the outlet pipe (11-5). The protective cover (8) is made of corrosion-resistant stainless steel, and one end of it is an arc-shaped structure with equal wall thickness. The interlayer (11-4) is an insulating and heat-insulating material, the inner surface of the variable-diameter nozzle (10) is provided with protrusions, and the excitation coil (11-1) is a hollow copper tube, and there is a There is a cooling water pipe joint, the end of the inner core (11-3) passing through the snap ring A (11-6) is an open structure, and the end fixed on the snap ring B (11-7) is a sealed structure, and The inner core (11-3) has a plurality of through holes evenly distributed on the circumference of the wall surface, the length and diameter of the inner core (11-3) can be adjusted according to the actual production needs, and it is characterized in that: the method of heating heavy oil Include the following steps: S1. Start the water pump (3), the water pump (3) draws water from the water tank (2), the water enters the heating element (11-2) through the water pipe (4) through the variable diameter nozzle (10), and the variable diameter nozzle (10) Increased turbulence of water flow; S2. Start the power supply equipment (5). The power supply equipment (5) sends the intermediate frequency AC power to the transformer (9) to reduce the voltage and increase the current, thereby supplying power to the excitation coil (11-1). The excitation coil (11-1) is powered by the intermediate frequency AC power Under the action, a corresponding alternating magnetic field is generated; S3. The heating element (11-2) generates an induced current in an eddy current state in the alternating magnetic field in step S2, and the flowing induced current overcomes the resistance of the heating element (11-2) to generate heat, so that the heating element (11-2) )fever; S4. The water entering the heating element (11-2) in step S1 first passes through the variable-diameter nozzle (10), and the variable-diameter nozzle (10) will disturb the flow of water, increasing the distance between the water and the wall surface of the heating element (11-2) Contact opportunity, the water will be preheated at the entrance of the heating element (11-2), the preheated water enters the inner core (11-3) inside the heating element (11-2) under pressure, and the water enters the inner core (11-2) The core (11-3) then sprays to the wall surface of the heating element (11-2) through the through hole on the inner core (11-3), and the high temperature heating element (11-2) instantly vaporizes the water sprayed on it. for water vapor; S5. The water vapor in step 4 continuously accumulates and expands, rushes out from the small hole on the snap ring B (11-7) installed at the outlet of the heating element (11-2), and passes through the end of the heating element (11-2) The water outlet pipe (11-5) and the one-way valve are pressed into the heavy oil layer to be heated through the packer (6). After a period of heating, the downhole heavy oil is heated.