NEW METHODICAL APPROACH TO THE CO2-CORROSION ESTIMATION OF HIGH-TEMPERATURE GAS-CONDENSATE WELLS EQUIPMENT

Abstract

The relevance. The prospects for increasing gas condensate – valuable raw material for oil refining and petrochemicals, are largely associated with the further development of the achimov gas condensate deposits in the north of Western Siberia. Large depths, abnormally high reservoir pressure and high temperature of low-productivity formations, along with the presence of carbon dioxide in the gas-condensate formation fluid, put forward, first of all, increased demands on the quality of well completion and hydraulic fracturing operations, the reliability of structures and materials of underground well equipment. These factors are responsible for the high cost of project implementation and operational risks of gas and condensate production, and therefore justification of safe operating conditions for achimov is an urgent scientific and technical task. The main aim of the research is the limiting thermobaric parameters determination of the technological operating modes of the achimov gas condensate wells, taking into account the production of CO2 in products. Objects: reservoir gas-condensate fluid and bottomhole equipment of three achimov gas-condensate wells with carbon steel tailpipes, unstable to CO2 corrosion. Methods: modeling the phase behavior of the produced reservoir fluid in bottomhole conditions by the GasCondNeft software. Results. Phase behavior thermodynamic calculations of the reservoir fluid, taking into account its moisture content, showed that a reservoir pressure decrease at the location of the three considered wells during the development of the achimov deposits for 20 years under project operation modes leads to the formation of a two-phase fluid (gas-unstable condensate) in bottomhole thermobaric conditions. Moreover, the aqueous liquid phase due to the high temperature of the flow at the well bottomhole is not formed during the entire calculation period. Hydrodynamic parameters calculations of the gas-liquid upward flow showed that high flow rates of well products provide conditions for the complete and continuous removal of unstable condensate by the gas flow from the bottom to the surface of all considered wells for the entire 20-year period, thereby preventing the physical and chemical conditions of electrolyte formation on tailpipes surface and carbon dioxide corrosion.

Keywords

• gas condensate fluid
• carbon dioxide
• tailpipe
• well operation parameters
• simulator
• phase diagrams
• water and hydrocarbon dew point lines
• multiphase flow regime
• carbon dioxide corrosion
• anticorrosive well operation