System and method for measuring sag in a fluid

A system for determining a sag profile of a drilling fluid that has been exposed to elevated temperature and pressure conditions, the system comprising:

• a device comprising:
• a housing that is substantially cylindrical and defines an inner volume, wherein the inner volume is configured to receive the drilling fluid;
• a lower cap that is coupled to a lower end of the housing, wherein the lower cap comprises a base and a wall extending upwardly from the base, wherein the wall is configured to be positioned at least partially within the housing such that an inner volume of the lower cap at least partially overlaps with the inner volume of the housing, and wherein the wall comprises threads on an outer surface thereof that are configured to engage with corresponding threads on an inner surface of the housing;
• an upper cap coupled to an upper end of the housing, wherein the upper cap has an upper cap hole formed therethrough to allow a hydraulic fluid to flow therethrough into the inner volume of the housing;
• a piston positioned within the housing and between the lower and upper caps, wherein the piston is configured to move axially within the housing in response to a pressure differential between the drilling fluid and the hydraulic fluid across the piston, and wherein the piston has a first piston hole and a second piston hole formed therethrough.
• a plug configured to be positioned at least partially within the first piston hole;
• and
• a rupture disk configured to be positioned at least partially within the second piston hole;
• and
• a vessel defining an inner volume, wherein the device is configured to be introduced into the inner volume of the vessel, and wherein a temperature and a pressure of the drilling fluid in the device are configured to be increased while the device is positioned within the vessel.

A method for determining a sag profile of a first fluid that has been exposed to elevated temperature and pressure conditions, the method comprising:

• introducing the first fluid into a housing of a device;
• introducing a piston into the housing, wherein the piston is at least partially above the first fluid;
• coupling an upper cap to an upper end of the housing;
• inserting the device into a vessel;
• heating the first fluid to a predetermined temperature within the vessel;
• and
• pressurizing the first fluid to a predetermined pressure within the vessel.