JHN Lufeng 13-1 Oil Field operated by JHN Oil Operating Company (JHN) is located in South China Sea. In the Oil Development Plan (ODP) phase, the maximum water production rate was estimated to be 42,000bpd through 12 production wells, and oil in water (OIW) value of discharging water to sea after treatment was requested to be less than 50 ppm according to Chinese government regulation. In the actual operation phase, the water production was beyond expectation since the reservoir type was strong bottom water drive. As of February 2009 which is the termination of petroleum rights for JHN, the water production rate was exceeding 200,000bpd through 27 production wells. Therefore, JHN had to modify the water treatment system and oil separation system step by step to maximize oil production and to meet required OIW value for discharging water to sea. JHN made every effort to ensure stable and efficient operation with respect to the environment system in line with Chinese environmental and safety regulations. In 2006, Chinese government has announced to all oil operating companies in South China Sea as to the reduction of oil volume in discharging water to sea. So, JHN had modification work for water treatment facilities, and applied acceleration chemical to separate oil and water in water treatment facilities to meet possible further strict control over discharging water.