Systems, processes, and modeling methods for drilling in hot dry rock using supercritical or dense phase carbon dioxide

A method of modeling use of supercritical carbon dioxide in drilling a well in dry hot rock using a drillstring having a drill bit and one or more measurement-while-drilling (MWD) components, the well having an annulus, the drillstring supported by a derrick having a standpipe, comprising:

• (a) inputting into a spreadsheet program on a processor a transient pressure-enthalpy formulation for carbon dioxide;
• (b) inputting into the spreadsheet program thermodynamic properties of fluid in the drillstring comprising supercritical carbon dioxide and mixtures of noncritical carbon dioxide with other well return fluids;
• (c) inputting into the spreadsheet program surface back pressure;
• (d) computing output plots for temperature, pressure, and specific enthalpy along depth of the well employing the spreadsheet program and the processor;
• (e) computing a state diagram (pressure vs. enthalpy) showing a state path of the fluid in the drillstring and in the annulus employing the spreadsheet program and the processor;
• (f) estimating employing the spreadsheet program and the processor at least one of:
• (i) temperatures at the one or more MWD components, at the drill bit, and of well returns at surface;
• (ii) pressures at the standpipe, the one or more MWD components, and at the drill bit (surface back pressure is given, and a parameter of the problem);
• and/or
• (iii) annular velocity of fluid in the annulus.