Aqua-Cleen®’s superior metal surface wettability has been proven by using a wettability test for surfactant screening(1). The Water Wetting Capability Test (WWCT) or Reverse Emulsion Test (RET) designated by API was used by Bishop et al. to compare the wettability of Aqua-Cleen® and similar ethoxylated alcohols. In this experiment, a water-based conductive fluid containing a surfactant was added to a non-conductive oil-based liquid. As the surfactant-containing liquid was added, the conductivity was measured. Once the electrical reading reached a predetermined value (175 Hogans-Hn) and it was stable, the emulsion was considered reversed from oil-based to water-based indicating the amount of surfactant-containing liquid needed to remove the oil from the surface (cleaning). The information displayed in figures 1,2 and 3 was obtained from Bishop et al’s publication and it shows that for three different spacer fluid compositions, much less Aqua-Cleen® than comparable ethoxylated alcohols was needed to reach the same apparent wettability(2).
(1) Bishop et al, US2020/0002595A1
(2) Wettability Test Apparatus C1001, Fann Instrument Company.
WETTABILITY TESTS FOR SURFACTANT SCREENING
The Wettability Test can be conducted in two ways. API designates a test method called the Water-Wetting Capability Test (WWCT), known also as a Reverse Emulsion Test (RET), in which the conductivity of the fluid is measured as the spacer is added. Since the mud will be non-conductive, a stable measurement of conductivity as a spacer is added will indicate the spacer is able to water-wet the surface. A second, non-API method of determining wettability is to observe the weight percent of mud removal that occurs after a mud-soaked rotor (with a meshed screen grid attached) has been in contact with the spacer while rotating on a viscometer (apparatus on right).