CO<sub>2</sub>-Repurification Microemulsion Detergent for Oil-Based Slurry Cleaning
Yang Wu, Wenjian Yue, Hanmin Li, Xiaojiang Li, Hongsheng Lu
Abstract
In order to solve problems such as environmental pollution and pipeline blockage caused by oily wastewater after washing, N, N -dimethylcyclohexylamine (DMCHA) with CO 2 response was selected as the oil phase, and an O/W microemulsion wellbore cleaning fluid with CO 2 switching characteristics was successfully prepared with erucamide propyl betaine (EAB-40), sodium dodecyl benzene sulfonate (SDBS), n -butanol, silicone defoamer, and water. The water content of the microemulsion was 89.99%, and it had good stability at 40 and −5 °C. The emulsion was rapidly demulsified after being injected with CO 2 in the CO 2 -repurification microemulsion detergent, and CO 2 was removed with a N 2 detergent. The emulsion was restored to its original state, which demonstrated the CO 2 /N 2 switching properties of the emulsion. It is proven that the switching microemulsion has a good wetting transformation ability by cleaning the steel sheet and quartz sheet contaminated by oil-based slurry. The switching microemulsion system can clean the simulated wellbore contaminated by oil-based slurry, and the cleaning efficiency is above 99%. CO 2 can be used at room temperature to separate oil and water from oily wastewater after cleaning.