Supercritical CO2 Drilling Technology

Abstract:

When the temperature and pressure are higher than 31.10℃ and 7.38MPa respectively, CO2 becomes into supercritical state, the density of supercritical CO2 is similar to that of liquid, but the viscosity is higher than that of air and nitrogen gas, so it can drive the down-hole motor working and carry the cuttings out of the wellbore, which comes into being supercritical CO2 drilling technology. Supercritical CO2 drilling technology has the advantages of fast rock breaking speed, good gas and oil protection and high displacement efficiency, especially has the obvious advantages in the unconventional oil and gas reservoirs development. There are broad prospects for the application of combination of supercritical CO2 drilling and coiled tubing drilling technology in the pressure under balance drilling and pressure depletion formation. The paper introduces the supercritical CO2 technology about its physical characteristics, drilling process and the technical advantages as well as the related research progress and development trend.

Key words:supercritical CO2; drilling; density; viscosity; coiled tubing; temperature; pressure; cutting carrying