DOWNHOLE THERMOELECTRIC MODULE SYSTEM TO EXPAND THE APPLICATION AND INCREASE THE EFFICIENCY OF THE STEAM GRAVITATION INFLUENCE METHOD

Abstract

The article discusses the existing technologies for thermal insulation of tubing (tubing) when using thermal methods of influencing an oil reservoir with high-viscosity oil, inherent in the fields of Kazakhstan. An urgent problem in the use of steam cycle treatment (CSS), steam gravity treatment (SAGD) and in situ combustion is significant heat loss with increasing well depth, which imposes restrictions on the use of these enhanced oil recovery methods. The large depth of occurrence of productive formations with high viscosity of fluids causes this problem of delivering the coolant to the productive formation with a given steam temperature, since the main indicator of the effectiveness of the use of thermal methods is the temperature of the coolant, in connection with which the solution of the issue of reducing heat losses in the process of delivering the coolant through the tubing string to a productive reservoir is an important technical problem, the solution of which with minimal costs of material resources will increase the interest of mining companies in the application of these methods, namely the SAGD technology. The paper carried out a comparative analysis and recommended a technology that improves the efficiency of the SAGD method for the fields of Kazakhstan. Currently, there are two main technologies for thermal insulation of the tubing string using the SAGD method, in high-viscosity oil fields - vacuum insulated tubing (Vacuum Insulated Tubing-VIT); - heat-insulated tubing. This article proposes a new method based on the conversion of electricity into heat by placing a borehole thermoelectric module in the tubing string. The proposed downhole thermoelectric module system makes it possible to maintain the coolant temperature along the entire length of the wellbore, which makes it possible to apply the SAGD method to depths of 1500 meters or more. The design of the downhole thermoelectric module system is simple, technologically advanced, reliable in operation and easily replicable. The downhole thermoelectric module system, placed in the tubing string, provides the possibility of increasing the depth of wells using the SAGD method and is characterized by a significantly lower cost compared to vacuum insulated tubing (VIT) and heatinsulated tubing systems. Modern heat cables of the SAMREG 40-2CR type, manufactured in South Korea, provide power up to 40 W / m, which is quite enough to maintain the desired temperature of the coolant. The cable is characterized as a self-regulating, heating, heating, shielded cable (braided), operates from a mains voltage of 220-240 V, with a frequency of 50 Hz.