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

Abstract

Systems and processes for dry hot rock drilling operations using sCO2 expanded across one or more downhole J-T valves or chokes to cool MWD components. Methods of modeling same.

1 . 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. 
   
     
     
         2 . The method of modeling of  claim 1  wherein the estimating comprises modeling control of the pressure in first and second portions of the annulus and in a closed-loop carbon dioxide recycle system by operating one or more chokes. 
     
     
         3 . The method of modeling of  claim 1  wherein the estimating comprises modeling removal of a major portion of drill cuttings and solids fines from well returns by routing the well returns to one or more cyclones, one or more filters, and combinations of these. 
     
     
         4 . The method of modeling of  claim 1  wherein the estimating comprises modeling of cooling of the one or more MWD components by Joule-Thomson effect cooling by routing the supercritical carbon dioxide through a pressure letdown valve, a choke, or a Joule-Thomson valve. 
     
     
         5 . The method of modeling of  claim 1  wherein the estimating comprises the one or more MWD components being selected from one or more temperature measurement devices, one or more pressure measurement devices, one or more density measurement devices, one or more mass flow measurement devices, one or more volume flow measurement devices, one or more radiation measurement devices, one or more gyroscopes, one or more magnetometers, one or more accelerometers, and combinations of two or more of these. 
     
     
         6 . The method of modeling of  claim 1  wherein the estimating comprises the one or more MWD components being selected from one or more gyroscopes, one or more magnetometers, one or more accelerometers, and combinations of two or more of these.