Development of a High Temperature Low Toxicity W/O Organophilic Clay

An organophilic clay was developed using octadecyl benzyl dimethyl ammonium chloride, a polymer ENVAMOD-95 and a purified sodium montmorillonite, and analyzed with X-ray and simultaneous thermal analyzer DSC-TGA. A water in oil mud was prepared with the organophilic clay, and was tested for its properties against a mud sample taken from a well. The analyses showed that octadecyl benzyl dimethyl ammonium chloride and ENVAMOD-95 can both enter into the space between the layers of montmorillonite to form organophilic clay. ENVAMOD-95 actually enhanced the thermal stability of the organophilic clay. In laboratory experiment, the viscosity and gel strength of the mud first increased and then decreased with temperature. The prepared water in oil mud retained its properties after hot-rolling 16 hours at 210℃, showing that organophilic clay made from ENVAMOD-95 had better thermal stability than other two polymer samples tested. Water in oil mud prepared with this organophilic clay at rig-site retained good properties after hot-rolling at 150℃, showing its potential for field use in HTHP wells.