Siberian Federal University: Heater Pad to Optimize Oil Production in the Arctic
Krasnoyarsk researchers have simulated the operation of a device for an oil well to heat pipes during oil recovery.
SibFU scientists have developed a thermal control device for oil wells designed to reduce asphaltene sediments. Such sediments settle on pipes, reducing their internal diameter and throughput capacity, complicating oil recovery and operation of oil-production equipment. In extreme cases, it leads to complete clogging of rising pipes. Krasnoyarsk researchers have simulated the operation of a device that can be lowered into an oil well and used to heat pipes during oil recovery. The design features of the device will allow oil production in the extreme conditions of the Arctic. Maintaining a high temperature of the inner surface of a pipe will prevent the solidification of asphaltene sediments.
The main components of asphaltene sediments are paraffin-naphtenic or paraffin-naphtenic-aromatic hydrocarbons. They often initiate paraffinization, forming large accumulations that fall out on the surface of pipes. For oil production in the fields of Western Siberia, asphaltene sediments are formed when oil has a density of about 790-860 kg/m3 and contains 1.5–8% paraffin. Wells suffer, the flow rate (the volume of production per unit of time) of which is no more than 50 m3/day.
According to scientists, the most common methods used to prevent the formation of asphaltene sediments are mechanical or chemical cleaning, steam cleaning of pipes, or the use of pipes with a glass, enamel or paint coating. More high-tech methods are considered to be electric heating of a well from the inside using an induction heater or heating cable, as well as the use of special magnetic systems (Energomag, Enerket, Marm-7, etc.). At the same time, the solidification of unwanted sediments in pipes depends on the chemical composition and physical properties of the oil and, as a rule, begins at a depth of 500-900 m.
“The proposed device has a number of design features — for example, the heating elements are mounted on the tubing. Moreover, to reduce the heat flow of a well, an outer pipe with thermal insulation shells was added to the device,” explained Praskovya Pavlova, study’s author, associate professor of the Department of Oil and Gas Field Machinery and Equipment SibFU, senior researcher of the Laboratory of Physical and Chemical Technologies for the Development of Hard-to-Recover Hydrocarbon Reserves.
The researchers also reported the results of numerical simulations using the ANSYS Fluent 2021 software. A section of a steel pipe with a length of 1 m, a diameter of 73 mm and a thickness of 5.5 mm was chosen as a geometric model. Such pipes are used in the domestic oil production and oil refining industry.
For numerical calculation, scientists changed the number of heating elements 5 cm long (firstly, they used one, then two). Also, they used heat density of 2 W/cm2, 5 W/cm2 and 8 W/cm2, liquid consumption from 5 to 1000 m3/day. The distance between the heating elements varied from 10 to 50 cm.
As a result, the scientists saw that by changing the temperature on the inner walls of the tubing of a downhole device, it is possible to significantly reduce the amount of asphaltene sediments. To develop a downhole device, it is recommended to reduce the heat density coming from a heating element. The elements themselves should be located at a distance where the temperature on the inner wall of a pipe between the heating elements is higher than the crystallization temperature of asphaltene sediments.
According to Praskovya Pavlova, in the future, the problem of changing the temperature along the tubing wall with an increase in the number of heating elements depending on the technological processes and parameters of an oil well will be solved.