Abstract: Apparatus and methods for determining suitable displacement fluids for use in subterranean cementing operations, and methods of cementing that use such displacement fluids, are provided. Examples of apparatus include apparatus for evaluating fluids. An example of a system is a system for inverting an oleaginous-external/aqueous-internal fluid in a well bore in a subterranean formation.

Abstract: Apparatus and methods for determining suitable displacement fluids for use in subterranean cementing operations, and methods of cementing that use such displacement fluids, are provided. Examples of methods include methods of water-wetting an annulus in a subterranean formation having an oleaginous-external/aqueous-internal fluid disposed on at least a portion of one or more surfaces of the annulus. Another example of a method is a method of using an inverter fluid in a subterranean formation that includes a tubular string disposed therein having an annular region adjacent the outer surface of the tubular string, at least part of the annular region having an oleaginous-external/aqueous-internal fluid on a surface thereof. Another example of a method of the present invention is a method of identifying an inverter fluid to use for inverting an oleaginous-external/aqueous-internal fluid in a subterranean formation.

Abstract: A test method for foamed cement does not transfer the test composition under pressure from one device to another and the equipment is not handled under dangerous pressure, thereby providing a safe test method. Steps include: rotating a paddle at a first speed in a pressurized foamable cement composition in a receptacle in a high pressure, high temperature chamber such that the foamable cement composition becomes a foamed cement; rotating the paddle at a second speed in the pressurized foamed cement for a selected time period; maintaining the foamed cement static after the selected time period and increasing temperature in the chamber during a foamed cement setting period; thereafter reducing temperature in the chamber and reducing pressure in the chamber; removing the foamed cement in a set condition and the paddle from the chamber; removing the set foamed cement from the paddle; and testing the removed foamed cement.

Abstract: A test method for foamed cement does not transfer the test composition under pressure from one device to another and the equipment is not handled under dangerous pressure, thereby providing a safe test method. Steps include: rotating a paddle at a first speed in a pressurized foamable cement composition in a receptacle in a high pressure, high temperature chamber such that the foamable cement composition becomes a foamed cement; rotating the paddle at a second speed in the pressurized foamed cement for a selected time period; maintaining the foamed cement static after the selected time period and increasing temperature in the chamber during a foamed cement setting period; thereafter reducing temperature in the chamber and reducing pressure in the chamber; removing the foamed cement in a set condition and the paddle from the chamber; removing the set foamed cement from the paddle; and testing the removed foamed cement.

Abstract: An inverter fluid that intermixes with a non-aqueous (e.g., oil) external/aqueous internal fluid to cause external/internal inversion is designed. This includes testing a selected inverter fluid with a test fluid having a composition nominally equivalent to the composition of the non-aqueous external/aqueous internal fluid. A quantity of the designed inverter fluid is made and placed in the annulus of a well, such as an oil or gas well, to remove the non-aqueous external/aqueous internal fluid on at least a portion of one or more surfaces of the annulus. This can include pumping the inverter fluid along with a stream of cement. The inverter fluid displaces at least part of the non-aqueous external/aqueous internal fluid in the annular region and inverts the coating of non-aqueous external/aqueous internal fluid sufficient to remove the coating ahead of the cement.