At the Shonai Oil Field, Yamagata, the sand trouble of producing oil wells are so severe that it is almost impossible to produce oil by ordinary perforated liner pipes. After many trials, the expected production is regularly maintained by using the double anchor pipes 41/2" and 21/2" O. D., having perforations of about 1/16" in diameter.
The writers studied the treatment of crude oil emulsions produced in the several oil fields in Japan. In all cases, it is necessary to keep pH value 7.2-7.8 to obtain the successful resluts for breaking those emulsions.