Patent ID: 7677332

Claim:
A system for drilling a wellbore comprising: a wellbore; a variable density drilling mud disposed in the wellbore, wherein the variable density drilling mud comprises compressible particles and drilling fluid; drilling pipe disposed within the wellbore; a bottom hole assembly coupled to the drilling pipe and disposed within the wellbore; and a drilling mud processing unit in fluid communication with the wellbore, wherein the drilling mud processing unit is configured to separate the compressible particles from the variable density drilling mud; wherein the drilling mud processing unit is further configured to insert the compressible particles into the drilling fluid to form the variable density drilling mud; and wherein the drilling mud processing unit comprises: a mud pit; at least one mixer in fluid communication with the mud pit and configured to blend the compressible particles with the drilling fluid to form the variable density drilling mud; at least one monitor in fluid communication with the mud pit, wherein the at least one monitor is configured to determine pressure volume temperature characteristics of the variable density drilling mud at least by monitoring the density of the variable density drilling mud; and a mud pump in fluid communication with the at least one monitor and configured to provide the variable density drilling mud to the wellbore.