Wettability and fluid displacement in a well

摘要

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. Determining a suitable inverter fluid comprises: measuring a parameter related to electrical conductivity of an initial mixture including (1) a test fluid having a composition nominally equivalent to the non-aqueous external/aqueous internal fluid and (2) part of a selected inverter fluid; and adding a further part of the selected inverter fluid to the initial mixture until the measured parameter indicates the external/internal phases of the test fluid have inverted.