CN113236211B

CN113236211B - Device and method for removing water phase trapping damage through underground eddy heat shock of tight reservoir

Info

Publication number: CN113236211B
Application number: CN202110606828.1A
Authority: CN
Inventors: 游利军; 王阳; 康毅力; 陈一健; 唐际锐
Original assignee: Southwest Petroleum University
Current assignee: Southwest Petroleum University
Priority date: 2021-06-01
Filing date: 2021-06-01
Publication date: 2022-04-05
Anticipated expiration: 2041-06-01
Also published as: CN113236211A

Abstract

The invention discloses a device and a method for removing water phase trapping damage by underground eddy heat shock of a compact reservoir. The method is that the casing of the reservoir section generates induced current (eddy) through electromagnetic induction and is heated, the casing of the reservoir section heats a water phase in a shaft in a heat convection and heat radiation mode after being heated, the heat can be transferred to the reservoir near a well zone in a heat conduction mode through a cement sheath and a crack so as to heat the water phase, and the water phase is heated and then is discharged in a water vapor mode. By the device and the method, the water trap damage of the tight sandstone reservoir can be removed efficiently with low energy consumption, the permeability of the reservoir can be recovered, and meanwhile, the permeability of the reservoir can be improved to a certain extent by heat energy, and the recovery ratio of the tight sandstone gas is improved.

Description

Device and method for removing water phase trapping damage through underground eddy heat shock of tight reservoir

Technical Field

The invention relates to a device and a method for removing water phase trapping damage of a tight reservoir by underground eddy heat shock, which can economically and efficiently remove the water phase trapping damage of the tight sandstone reservoir and improve the recovery ratio of a tight sandstone gas reservoir.

Background

The unconventional natural gas resource amount in China is huge, wherein the compact sandstone gas has many years of mining experience and more profound technical strength compared with shale gas and coal bed gas, the compact sandstone gas resource is widely distributed in China, and the prospect resource amount cannot be estimated. Therefore, at the present stage, the compact sandstone gas is still unconventional natural gas which has the greatest significance in exploration and development in China. Because the tight sandstone gas reservoir has geological characteristics of low porosity and permeability, low reservoir pressure, high capillary force and the like, hydraulic fracturing is needed in the production stage to increase production and improve the yield, a large amount of fracturing fluid enters the reservoir, the flowback rate of the fracturing fluid is low, and finally serious water phase trap damage is caused, once the water phase trap damage occurs, the seepage capability of the tight sandstone reservoir is seriously influenced, so that the production reduction is caused.

Methods for the resolution of aqueous entrapment damage generally fall into two broad categories, one being physical, represented by high temperature thermal shock, and the other being chemical, based on chemical surfactants. The high-temperature heat shock can effectively relieve the damage of water phase trapping, the thermal fracture caused by the thermal stress can expand the primary cracks in the rock and generate secondary cracks, the cracks are communicated with each other to form a network, and the oil-gas mass transfer capacity is greatly improved. There is therefore a pressing need for an efficient, economical and environmentally friendly downhole heating apparatus and method to relieve aqueous entrapment damage.

Compared with the induction eddy current energy-saving heating device disclosed in the Chinese patent publication No. CN 202188648U, the device is mainly characterized in that a metal pipe to be heated is arranged in the device, and then the device enables the metal pipe to generate eddy current so as to heat the metal pipe.

Compared with the 'underground vortex heater' disclosed by the Chinese patent publication No. CN 208089276U, the device is mainly applied to pyrolysis of underground hydrocarbon resources and is not applied to removal of water phase trapping damage of a compact sandstone gas reservoir, in addition, the mode of exciting a metal pipeline by the device to generate vortex is different from that of the device, and the invention also provides a specific method for removing the water phase trapping damage by underground heat shock.

In addition, other downhole thermal stimulation devices and methods are used for removing water trapping damage at present, but other methods have certain limitations, some methods are difficult to implement, and some methods have low energy efficiency ratio and poor economical efficiency.

Disclosure of Invention

The invention aims to provide a device and a method for removing water phase trapping damage by underground eddy heat shock of a compact reservoir. The technical scheme adopted by the invention for solving the technical problems is as follows: the method comprises the steps of installing a vortex excitation device at the end of a continuous oil pipe section of a reservoir section, enabling a sleeve of the reservoir section to generate a vortex and then be heated.

Further, the method comprises the following steps: the eddy current excitation device is characterized in that the main body structure of the eddy current excitation device is a single copper pipe, the upper end and the lower end of the inside of the copper pipe are provided with the electric control electrode devices, the inside of the copper pipe is provided with the insulating layer, the outside of the insulating layer is covered with the cylindrical quartz glass cover, the quartz glass cover and the eddy current excitation device are arranged on the same fixing device, and the connection mode is screwing (the diameter of the copper pipe is larger than that of an oil pipe and smaller than that of a sleeve).

Further, the method comprises the following steps: the fixing device is made of ceramic, and the appearance of the fixing device is shown in detail in the attached figure 3.

Further, the method comprises the following steps: the reservoir section oil pipe is processed with screw threads, and the fixing device is installed on the reservoir section oil pipe in a screwing mode.

Further, the method comprises the following steps: all the devices also comprise a reservoir section oil pipe, a reservoir section sleeve, a wet and dry bulb thermometer and a power supply system.

Further, the method comprises the following steps: the power supply system comprises a ground power supply and a power supply cable, wherein the power supply cable is an armored cable, and the power supply cable is wired from the inside of the oil pipe and is respectively connected with the electricity control electrode devices at two ends of the inside of the copper pipe (the cable is wrapped inside by the copper pipe) to supply power to the copper pipe.

Further, the method comprises the following steps: the dry-wet bulb thermometer is installed at a wellhead through a fixed base, and the installation follows a fixed distance installation principle. The invention also provides a method for removing the water phase trapping damage through the device, in particular to a method for removing the water phase trapping damage through underground eddy heat excitation of a compact reservoir.

Further, the method comprises the following steps: the heating duration and the heating temperature of the casing pipe in the storage layer can be adjusted by changing the current of the vortex excitation device, so that the vortex size is changed, the temperature is adjusted, and the vortex disappears immediately after the power supply to the vortex excitation device is stopped (the casing pipe is generally made of API standard petroleum pipeline materials and can bear the temperature within 800 ℃).

Further, the method comprises the following steps: when the water phase in the reservoir is heated to steam, the pressure difference between the reservoir and the inside of the shaft can make the steam enter the casing through a perforation crack and the like and then return to the ground.

Further, the method comprises the following steps: when the mixed gas such as water vapor and the like returns to the ground, the dry-wet bulb thermometer can measure the relative humidity of the gas returning to the ground, and when the relative humidity is reduced to a certain level or does not change along with the change of time, the damage of water phase entrapment can be removed.

The invention has the advantages and beneficial effects that:

1. the method not only can release the water phase trapping damage and recover the permeability of the reservoir in an environment-friendly manner, but also can improve the permeability of a compact sandstone reservoir by utilizing high-temperature fracturing;

2. compared with the method for heating the metal pipeline by using the eddy current of other external equipment, the eddy current excitation device is arranged in the metal pipeline, so that the eddy current heating of the sleeve can be realized in a narrow space in the pit;

3. compared with other underground heating devices and methods which rely on electric energy for heating, the underground heating device and the underground heating method have the advantages that the sleeve directly heats, unnecessary heat transfer steps are omitted, so the energy efficiency ratio is extremely high, and the economy is good;

4. the eddy current is only generated in the casing of the reservoir section, so that the influence on the casing of the rest part is small and the heat energy utilization rate is high;

5. the reliability is high, the realization difficulty is small, the limitation is small, and long-time preheating is not needed;

6. the reservoir section sleeve is directly used as a heat source, and the characteristics of high heating efficiency and low energy consumption can not only remove the water phase trapping damage of a near-wellbore zone, but also solve the water phase trapping damage of a deep reservoir to a certain extent.

Drawings

FIG. 1 is a flow chart of the present invention in the well site construction process

In the figure: 1. the system comprises a ground power supply, 2 power supply cables, 3 wet and dry bulb thermometers, 4 oil pipes, 5 casings, 6 perforation cracks, 7 reservoir sections, 8 eddy current excitation devices, 9 cylindrical quartz glass covers and 10 fixing devices.

FIG. 2 is a schematic diagram and a left side view of the main structure of the eddy current excitation device

11. And (3) an electric control electrode device, 12. an insulating and heat-insulating layer.

FIG. 3 is a schematic view of a fixing device

13. External thread, 14 internal thread.

Detailed Description

The invention will be further explained with reference to the drawings.

See fig. 1, fig. 2, fig. 3.

Install vortex excitation device 8 on fixing device 10, install fixing device 10 at oil pipe 4 tip again to transfer it to the position of placing reservoir section 7, ground power supply 1 supplies power to vortex excitation device 8 through supply cable 2, and supply cable 2 walks that mainly inside oil pipe 4.

After the eddy current excitation device 8 is electrified with alternating current, the eddy current excitation device is arranged inside the casing 5 and is equivalent to a section of single-phase conducting device, so that an electromagnetic field generated by the eddy current excitation device can collide with the metal casing 5 to enable the casing 5 of the reservoir section to generate eddy current and generate heat, and the average power and the heating temperature of the casing 5 of the reservoir section are controlled by adopting an interval electrifying method for the eddy current excitation device 8.

After a casing 5 of the reservoir section heats, heat enters the reservoir in a heat transfer mode mainly based on heat conduction and heats water phase in the reservoir into steam, the steam enters the inside of the shaft along a perforation crack 6 due to pressure difference between the reservoir and the inside of the shaft and then returns to the ground, a dry-wet bulb thermometer 3 on the ground can measure the relative humidity of the returned gas, and when the humidity is lower than a preset standard or is not reduced along with time, the process of removing water phase trap by heat shock can be considered to be finished.

Claims

1. The device for removing the water phase trap damage by underground eddy heat shock of the compact reservoir is characterized by comprising a reservoir section oil pipe, an eddy excitation device, a reservoir section sleeve, a wet-dry bulb thermometer, a power supply system and a fixing device, wherein the main structure of the eddy excitation device is a single copper pipe, the upper end and the lower end of the eddy excitation device are provided with an electric control electrode device, the copper pipe is internally provided with an insulating layer, the outer part of the copper pipe is covered with a cylindrical quartz glass cover, the quartz glass cover and the eddy excitation device are connected and installed on the same fixing device in a threaded manner, the fixing device is installed at the end part of the reservoir section oil pipe in a screwing manner, the power supply system comprises a ground power supply and a power supply cable, the power supply cable is wired in the oil pipe and respectively connected with the electric control electrode devices at the two ends of the copper pipe to supply power to the copper pipe, and a loop of the power supply cable passes through the inside of the copper pipe and then returns to the inside of the oil pipe, the eddy current excitation device is equivalent to a single-phase cable in the casing, when alternating current is conducted to the eddy current excitation device, eddy current can appear on the casing of the reservoir section due to the electromagnetic induction principle, and then heat enters the reservoir through a heat conduction mode after the casing of the reservoir section is heated.

2. The tight reservoir downhole eddy current thermal shock water phase trapping damage relieving device of claim 1, wherein the fixing device is a ceramic material, and the wet and dry bulb thermometer is mounted at a wellhead in a fixed distance carrying manner.

3. The device for releasing the water phase trapping damage through downhole eddy current thermal stimulation of the tight reservoir as claimed in claim 1, wherein the heating duration and the heating temperature of the reservoir interval casing can be controlled and adjusted in an intermittent power supply mode, and eddy current disappears immediately after the power supply of the eddy current excitation device is stopped.

4. The method for utilizing the device for releasing the water phase trapping damage of the tight reservoir by the underground eddy current thermal shock of the tight reservoir as claimed in claim 1, is characterized in that after the water phase in the reservoir is heated into steam, the pressure difference between the reservoir and the inside of a shaft can enable the steam to enter a sleeve through a perforation crack and the like and then to be discharged back to the ground, the dry-wet bulb thermometer can measure the relative humidity of gas discharged back to the ground, and when the relative humidity is reduced to a preset standard or is not reduced along with the time, the whole process of releasing the water phase trapping damage by the thermal shock can be considered to be finished.