CN111594118B - A kind of electromagnetic heating method for enhancing the recovery of heavy oil - Google Patents

Abstract

The invention discloses an electromagnetic heating method for improving recovery efficiency of thickened oil, an antenna for emitting electromagnetic radiation is placed in a production pipe column, a temperature sensor is arranged near a well casing, the temperature near the well casing is collected in real time, the emitting power of the antenna is reduced in a gradient manner when the temperature near the well casing is raised to a set critical temperature, the temperature near the well casing is firstly reduced and then raised, after continuous radiation heating is carried out by adopting the current power, if the temperature near the well casing is raised to the critical temperature, the power of the antenna is continuously reduced in a stepped manner until the power is reduced to about 100W, a production well is opened, thickened oil spontaneously flows to the production well due to the formation pressure difference, and the antenna is continuously heated by electromagnetic radiation at low power, so the problems that the thickened oil yield is reduced and the quality of well casing materials is influenced due to overhigh heating temperature are solved by the electromagnetic heating method of the invention, meanwhile, the heating temperature for keeping the fluidity of the thick oil is ensured, and the exploitation efficiency and the engineering safety of the thick oil are improved.

Description

A kind of electromagnetic heating method for enhancing the recovery of heavy oil

technical field

The invention relates to the technical field of crude oil exploitation, and more particularly to an electromagnetic heating method for improving the recovery rate of heavy oil.

Background technique

Internationally, heavy oil is usually called heavy oil, and crude oil with extremely high viscosity is also called tar sand oil, which is collectively referred to as heavy oil in China. China's heavy oil resources are widely distributed, mainly in the Liaohe oil area, Xinjiang oil area, Shengli oil area and Henan oil area, and a small amount in Daqing, Jilin and Dagang oil areas. Due to the high viscosity of heavy oil, the fluidity is poor, so the technical key of heavy oil recovery is to improve the flow ability of heavy oil. At present, the main methods of heavy oil recovery include steam huff and puff, steam flooding and combustion of oil layers. However, due to the different formation conditions of the actual oil reservoir, these methods cannot be successfully applied all the time. The most common failure reasons are the heat loss of the injection well and the reservoir. too high, low reservoir injectability, bitumen precipitation, steam loss, and greenhouse gas emissions. In order to enhance the recovery of heavy oil, efforts are being made to find an alternative to steam flooding, including electromagnetic heating. As a fast, efficient and environmentally friendly heating method, electromagnetic heating has been studied and applied to the exploitation of unconventional oil and gas resources such as heavy oil, oil sands, oil shale, and coalbed methane.

Electromagnetic waves, especially high-frequency electromagnetic waves, have high frequency and short wavelength, and their transmission distance in the formation is limited. Under formation conditions, when an antenna is installed downhole to emit electromagnetic waves for radiative heating of heavy oil formations, in the electromagnetic penetration area (near wellbore area), although the temperature near the wellbore can be rapidly increased, the thermal conductivity of formation rocks is relatively high. Low, the electromagnetic penetration zone has a low efficiency of transferring heat to the far end. Therefore, if electromagnetic wave radiation is used to heat heavy oil formations continuously for a long time, excessive temperature will be generated in the electromagnetic penetration zone around the electromagnetic heating well. In the area where the temperature is too high, although the viscosity of heavy oil initially decreases with the increase of temperature, if it exceeds 500 °C, it will cause the cracking of heavy oil to generate small molecular gas and reduce the production of heavy oil. At the same time, if the temperature in the overheated area continues to rise, it will also damage the temperature-resistant materials of the wellbore, causing potential safety hazards.

Therefore, how to use electromagnetic heating to improve the recovery factor of heavy oil while ensuring the extraction efficiency and safety is an urgent problem for those skilled in the art to solve.

SUMMARY OF THE INVENTION

In view of this, the present invention provides an electromagnetic heating method for enhancing the recovery rate of heavy oil. Based on the characteristics that the electromagnetic heating power is easy to control and adjust, the electromagnetic heating is adjusted, and an antenna that emits electromagnetic radiation is placed in the production pipe string. At the same time, a temperature sensor is installed near the wellbore to collect the temperature near the wellbore in real time. When the temperature near the wellbore rises to the set critical temperature, the transmit power of the antenna is reduced gradiently. At this time, the temperature near the wellbore first decreases and then increases. After the current power is continuously heated by radiation, if the temperature near the wellbore rises to the critical temperature, the antenna power will continue to be gradually reduced, and the power will be reduced in steps until the power is reduced to about 100W, and the production well will be opened. The difference spontaneously flows to the production well. At this time, the antenna continues to conduct electromagnetic radiation heating with low power. The electromagnetic heating method of the present invention avoids the problems that the heating temperature is too high, which reduces the production of heavy oil and affects the quality of the wellbore material, and at the same time ensures the maintenance of the fluidity of the heavy oil. The high heating temperature improves the recovery efficiency and engineering safety of heavy oil.

In order to achieve the above object, the present invention adopts the following technical solutions:

A kind of electromagnetic heating method for enhancing heavy oil recovery, comprising the following specific steps:

Step 1: Lower the antenna to the heavy oil reservoir area through the production string of the vertical well; at the same time install a temperature sensor to monitor the temperature near the wellbore;

Step 2: turn on the antenna to heat the heavy oil reservoir by electromagnetic radiation, set the initial power to be P1, and collect the temperature by the temperature sensor under the continuous electromagnetic radiation to obtain the maximum temperature near the wellbore;

Step 3: Determine whether the power radiated by the antenna is greater than the set minimum power, and if so, go to Step 4; otherwise, go to Step 6;

Step 4: judging whether the collected maximum temperature near the wellbore is equal to the set critical temperature;

Step 5: If the maximum temperature is equal to the set critical temperature, reduce the power of the antenna according to the set power adjustment step, perform the electromagnetic radiation on the heavy oil reservoir, and return to the step 3 ; otherwise continue the electromagnetic radiation, and return to the step 4;

Step 6: Open the production well, and the heavy oil flows to the production well spontaneously due to the formation pressure difference.

Preferably, the electromagnetic wave of the electromagnetic radiation realizes electromagnetic radiation heating through the mechanism of ion conduction and double-polarization electromagnetic heat generation.

Preferably, the antenna, the temperature sensor and the instrument car communicate through cables, the antenna can be controlled to be turned on in the control room of the instrument car, and the temperature display in the instrument car can display the data collected by the temperature sensor. temperature.

Preferably, the value range of the initial power is 800W-1200W; the critical temperature is less than 500°C; the value range of the power adjustment step is 50W-100W.

Preferably, the minimum power is 100W.

It can be seen from the above technical solutions that, compared with the prior art, the present invention provides an electromagnetic heating method for improving the recovery of heavy oil. The power continuous radiation heating mode not only avoids the overheating area near the wellbore, but also increases the temperature of the heavy oil reservoir with high heating efficiency, so that the viscosity of the heavy oil can be quickly reduced in a short time for subsequent use. production extraction. The electromagnetic heating method of the invention solves the problem of temperature resistance of the material near the wellbore, and at the same time, the heating efficiency is higher than that of intermittent electromagnetic heating.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only It is an embodiment of the present invention. For those of ordinary skill in the art, other drawings can also be obtained according to the provided drawings without creative work.

Fig. 1 accompanying drawing is the flow chart of the electromagnetic heating method provided by the present invention;

The accompanying drawing of FIG. 2 is a schematic diagram of the device for enhancing the recovery of heavy oil by electromagnetic heating provided by the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

The embodiment of the present invention discloses an electromagnetic heating method for improving the recovery factor of heavy oil, comprising the following specific steps:

S1: The antenna for emitting electromagnetic waves is lowered to the target heavy oil reservoir area through the production pipe string of the vertical well, and the electromagnetic waves heat the heavy oil through electromagnetic heat generation mechanisms such as ion conduction and dipolar polarization; meanwhile, near the antenna Install a temperature sensor to monitor the temperature near the wellbore; there is an instrument car at the wellhead to monitor the downhole temperature, as well as control the switch and power of electromagnetic waves;

S2: Turn on the equipment in the control room of the instrument car, conduct electromagnetic radiation on the heavy oil reservoir, set the initial power to P1, and find through the temperature display that the temperature near the wellbore continues to rise under continuous electromagnetic radiation, until after n1 days, the near The maximum temperature T _max of the wellbore is about to reach 500℃;

S3: On day n1, the power of the antenna is adjusted stepwise through the control room, so that the power of the antenna is reduced by about 50-100W at a time, and the heavy oil reservoir is radiated with P2 power. high, after n2 days of continuous radiation, the maximum temperature near the wellbore is about to reach 500 °C again; at this time, the power is reduced by about 50-100W again, and the formation is continuously radiated with P3 power, and so on;

S4: In this power-reducing electromagnetic heating mode, the temperature of heavy oil reservoirs continues to rise, and the viscosity of heavy oil decreases, and it has good fluidity. When the power is reduced to about 100W, the production well is opened. The formation pressure difference spontaneously flows to the production well. At this time, the electromagnetic heating well is not closed, and the heavy oil reservoir is continuously heated with the current low power.

Example

The schematic diagram of the electromagnetic heating enhanced oil recovery device is shown in Figure 2. No. 2-5 vertical wells are heating wells, and No. 1 vertical wells are production wells. An electromagnetic transmitter antenna is installed at the bottom of the heating well to radiate the heavy oil reservoir, and a downhole temperature sensor is also installed to monitor the temperature near the wellbore.

The implementation of the heating record table is shown in Table 1 below

Table 1

The specific implementation steps are as follows:

S1: The antenna for emitting electromagnetic waves is lowered to the target heavy oil reservoir area through the production pipe string of the vertical well, and the electromagnetic waves heat the heavy oil through electromagnetic heat generation mechanisms such as ion conduction and dipolar polarization; meanwhile, near the antenna Install a temperature sensor to monitor the temperature near the wellbore; there is an instrument car at the wellhead to observe the downhole temperature, and to control the switch and power of the antenna that emits electromagnetic waves;

S2: Turn on the equipment in the control room of the instrument car to conduct electromagnetic radiation on the heavy oil reservoir, set the initial power to P1 (usually 800-1200W), and P1=800W; through the temperature display, it is found that the temperature near the wellbore is in the electromagnetic range. Continuously rising under the continuous electromagnetic radiation, until n1 days later, the maximum temperature T _max near the wellbore is about to reach 500 °C, and the maximum temperature T _max is set to 450 °C;

S3: On day n1, the power of the electromagnetic wave transmitted by the antenna is adjusted through the control room according to the power adjustment step size. The power adjustment step size is equal to 50W, so the antenna power is reduced by 50W from the initial power P1 to obtain the P2 power, P2=750W. The oil reservoir is subjected to electromagnetic radiation; at this time, it is observed that the temperature near the wellbore first decreases, then increases, and after continuous radiation for n2 days, the maximum temperature near the wellbore reaches 450 °C again; at this time, the antenna power is reduced by 50W again to obtain the P3 power, P3 =700W, continuously radiate the formation with P3 power, and so on;

S4: In this step-down power-reduction electromagnetic heating mode, the temperature of heavy oil reservoirs continues to rise, and the viscosity of heavy oil decreases, and it has good fluidity; when the power is reduced to about 100W, the production well is opened, and the heavy oil Because the formation pressure difference spontaneously flows to the production well; at this time, the electromagnetic heating well is not closed, and the antenna still maintains 100W power to continuously heat the heavy oil reservoir. Since the temperature near the wellbore and the far end of the reservoir has been greatly increased by electromagnetic radiation, Therefore, the fluidity of heavy oil is very good, thereby accelerating the rise of heavy oil production and improving the recovery factor of heavy oil.

The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same and similar parts between the various embodiments can be referred to each other. As for the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant part can be referred to the description of the method.

The above description of the disclosed embodiments enables any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (3)

1. An electromagnetic heating method for improving the recovery ratio of thickened oil is characterized by comprising the following specific steps:

step 1: lowering the antenna to a heavy oil reservoir area through a production pipe column of the vertical well; simultaneously, a temperature sensor is arranged to monitor the temperature of the near wellbore; the vertical well comprises a heating well and a production well, and an electromagnetic transmitting antenna is arranged at the bottom of the heating well;

step 2: starting the antenna to perform electromagnetic radiation heating on the heavy oil reservoir, setting the initial power to be P1, and acquiring the temperature by the temperature sensor under the condition of continuous electromagnetic radiation to obtain the highest temperature of the near wellbore; the initial power value range is 800W-1200W; the value range of the power adjustment step length is 50W-100W;

and step 3: judging whether the power radiated by the antenna is greater than the set minimum power, and if so, entering a step 4; otherwise, entering step 6; the minimum power is 100W;

and 4, step 4: judging whether the acquired highest temperature of the near wellbore is equal to a set critical temperature or not; the critical temperature is less than 500 ℃;

and 5: if the maximum temperature is equal to the set critical temperature, reducing the power of the antenna according to the set power adjusting step length, adjusting the power of the antenna in a stepped manner, performing electromagnetic radiation on the heavy oil reservoir, increasing the temperature close to the well cylinder after reducing, continuously radiating, and returning to the step 3; otherwise, continuing the electromagnetic radiation, and returning to the step 4;

step 6: and opening the production well, and spontaneously flowing the thickened oil to the production well due to the formation pressure difference.

2. The electromagnetic heating method for improving the recovery efficiency of heavy oil according to claim 1, wherein the electromagnetic wave of the electromagnetic radiation realizes the electromagnetic radiation heating through ionic conduction and an electromagnetic heat generation mechanism of even polarization.

3. The electromagnetic heating method for improving the recovery efficiency of heavy oil according to claim 1, wherein the antenna and the temperature sensor are in communication with an instrument car through a cable, the antenna can be controlled to be turned on in a control room of the instrument car, and a temperature display in the instrument car can display the temperature collected by the temperature sensor.

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