Patent ID: 8088716

Claim:
A drilling mud comprising: reusable compressible objects for use with a drilling fluid in a wellbore, the reusable compressible objects including a shell that encloses an interior region, wherein each of at least a portion of the compressible objects has; (a) an initial aspect ratio between 3 and 4 in an initial state when an initial state pressure external to the compressible object is substantially equal to an initial state internal pressure in the interior region, and the initial state internal pressure is (i) greater than 200 pounds per square inch, and (ii) selected for the shell to compress and expand at a predetermined pressure range, (b) a spherical or near spherical shape in an expanded state when the external pressure is substantially atmospheric pressure, and (c) a compressed state aspect ratio that is higher than the initial aspect ratio when the external pressure is greater than the internal pressure and wherein the shell has an engineered architecture designed to compensate for localized strains on the compressible object and wherein the shell is configured to experience less strain when the external pressure within the wellbore is about equal to the internal pressure within the compressible object than when the external pressure is greater than the internal pressure or less than the internal pressure, during expansion and compression of the compressible object; and wherein the density of the drilling mud changes due to the expansion and compression of the reusable compressible objects between the states.