Experiment study on properties of a novle circulative foaming agent for foam drilling fluid

Currently, the circulative foam drilling fluid can be obtained by stabilizing foam, but it need wide area to be defoamed. A novel pH sensitive circulative foaming agent is developed, and its application effect in foam drilling fluid is tested indoor. The results show that, two kinds of amphoteric ionic surfactants of SDAA （sodium-N-dod-ecylaminoacetate） and SDAP （sodium-N-dod-propilaminoacetate）have good foaming performance even after many circles of acid to alkaline and back to acid. The four systems have good liquid carrying capacity in the same gas velocity, including SDAP, Betaine + polyglycol, common frother + PVA, and SDAA + PVA. The SDAP system is a pH tunable system, which can be used at high oil contained conditions, and can realize the controllable circulation with the circulating time of higher than 10, maintaining higher foaming ability. This has provided a direction for adjustable circulative foam drilling fluids.