Electric heating oil production technology and dev

2022-09-21
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Hollow sucker rod electric heating oil production technology and device

heavy oil can be divided into three categories according to its viscosity under reservoir conditions: the viscosity is 50 ~ 10000mpa S is called ordinary heavy oil; The viscosity is 10000 ~ 50000mpa S is called extra heavy oil; Viscosity> 50000mpa S is called super heavy oil. Under reservoir conditions, ordinary heavy oil can flow, extra heavy oil is difficult to flow, and super heavy oil can't flow basically. However, heavy oil is very sensitive to temperature. When the crude oil temperature drops to a certain value, its viscosity rises sharply. The thicker the oil, the stronger the reaction. This temperature value is usually called the inflection point temperature of heavy oil. Practice has proved that there must be two basic conditions for exploiting heavy oil: first, heavy oil can flow in the reservoir; Second, it can lift the crude oil flowing into the bottom of the well to the ground through certain technical conditions. With these two conditions, heavy oil can be exploited on a large scale. At present, there are many methods to solve the problem of heavy oil flow in the oil layer, and various treatment methods are mainly carried out on the basis of reducing the viscosity of the machine oil and improving the driving ability of the oil layer after the use of the thick oil testing machine in the oil layer. For example, water injection (cold water or hot water), steam injection, CO2 injection, and burning the oil layer. The appropriate exploitation method can be selected according to the physical properties of oil layer and heavy oil

to solve the second condition, namely, wellbore lifting technology, the key is to increase the temperature of wellbore oil flow, reduce viscosity, and improve the flow capacity of crude oil in the wellbore. At present, there are mainly three basic methods used: the first is hot oil or hot water tracing method, that is, the heat carrier is injected from the annulus, mixed with the oil from the oil layer, and lifted to the ground by the pump (there are also unmixed and separate circulation methods), so as to improve the oil flow temperature and achieve the purpose of viscosity reduction; The second is the wellbore chemical dosing viscosity reduction method, that is, the annulus continuously injects the chemical agent into the bottom of the well to form an emulsion (oil in water type) with the bottom oil, so as to reduce the viscosity of the crude oil; The third is the downhole electric heating technology, which is to lower the hollow rod into the heating cable, so that the hollow sucker rod and the heating cable form a skin effect heating body, and use the power frequency skin effect heating principle to make the crude oil get new materials in the wellbore, which is the precursor of the development of the material industry to viscosity reduction and lifting. The hollow sucker rod electrothermal oil extraction device developed by our company is successfully developed on the basis of the above heating technologies. This set of device is a new innovation of wellbore lifting technology in heavy oil production at home and abroad, and is the key technology for developing special and ultra heavy oil

II. Device composition and working principle

(I) device composition

hollow sucker rod power frequency electrothermal oil extraction device is mainly composed of hollow sucker rod, heating cable, electric control cabinet and special transformer

1. Hollow sucker rod

in addition to transmitting the power of the pumping unit to the oil well pump and pumping well fluid, the hollow sucker rod can also make the special cable pass through the pump barrel and go down to the pump for heating, reduce viscosity and drag, make the crude oil fully enter the pump, and improve pump efficiency. The specifications and performance of hollow sucker rods currently used are shown in the table below. Single stage rods are generally available for on-site use. If the well depth exceeds 1000m, two-stage mixed rod columns can be considered. According to the maximum load calculation and field application, the above hollow rod is adopted, and the allowable pump depth is 1500m and the heating depth is 1800m

2. Special cable

it is a special cable specially made according to the needs of hollow rod pump heating, the temperature of the shaft and the depth of going down the well. At present, there are four kinds of special cables applied on site, and their main characteristic parameters are shown in the table below.

the main insulation performance and service parameters of special cables are:

insulation resistance: immerse in water for 1 hour, 1 km is greater than 750m Ω

insulation strength: withstand AC voltage of 10kV after soaking in water at room temperature for 1 hour? 5min;

service voltage: 1000V

DC resistance: ≤ 0.6250 Ω/km (20 ℃)

the long-term operating temperature is 110 ℃ ~ - 40 ℃ and 205 ℃ ~ - 60 ℃

3. The electric control cabinet

the hollow sucker rod over pump power frequency electrothermal oil production technology is matched with kd-iii-2 electronic control cabinet, which uses integrated circuit chips to realize the functions of electrical control protection and electrical parameter display. Its structure is composed of main circuit and control circuit, and the oil pump electromechanical shall be closed. The cabinet is divided into front and rear double door structures, with the main circuit at the back and the control circuit at the front. See figures 3 and 4. The main circuit power comes from a special transformer and is connected to the input end of the automatic air circuit breaker. The live wire output end is led out and sent to the oil well heating cable through the contactor. The output end of the zero line is sent to the hollow rod through the current sensor

the principle of the control circuit is to amplify the voltage, current and 2015 temperature signals into 0 ~ 200mV signals, and then send them to the special integrated circuit for digital display. At the same time, compare them with the corresponding set values, and send the corresponding out of limit signal and light up. Control the connection or disconnection of solid-state collector to realize the purpose of automatic control and protection

the main technical parameters and service conditions are as follows:

main circuit voltage: 0~1000v

rated current of main circuit: 250A, of which the lower limit and lower limit can be set and controlled automatically

temperature display range of heating cable: 0~l 50 ℃, its upper and lower limits can be set and automatically controlled

power supply: the rated voltage of the main circuit is 0~1000v, the control circuit is 220V, and the rated current is 0~200a

the allowable ambient temperature is - 30~50 ℃, and the relative humidity is 90%

4. Special transformer

special transformer is designed and manufactured according to the requirements of hollow sucker rod power frequency over pump electrothermal oil extraction device and the service conditions of conventional oil immersed power transformer. According to the distribution of oil wells and the required power, it is divided into single well points and multi well points (platform wells). At present, the special transformers used on site mainly have the following five specifications

current position technology products oil exploitation hollow sucker rod electric heating oil extraction technology

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