6 CHEMICALS USED IN WELL DRILLING, WELL PACKING, WELL TREATING, WELL WORKOVER, AND CHEMICALS USED IN PETROLEUM PRODUCTION, SUCH CHEMICALS BEING IN THE NATURE OF THINNERS, CONDITIONERS, WATERLOSS CONTROL AGENTS, CLAY EXTENDERS, SHALE CONTROL AGENTS, SURFACTANTS, DETERGENTS, EMULSIFIERS, DEFOAMERS, LUBRICANTS, FLOCCULANTS, EMULSION BREAKERS, WAX DEPOSITION CONTROL AGENTS, CORROSION INHIBITORS, BACTERICIDES, AND THE LIKE