Seawater drilling fluid technology in Shengli Oilfield-its forming and development

A total of 348 wells and an overall footage of 737,866 m have been drilled by the Offshore Company of Shengli over the 23 years. Its history of using sea water drilling fluid technology in offshore drilling can be divided into several stages. The first stage was from 1978-1985, the early days of using seawater drilling fluid. Many downhole troubles were encountered during this stage because of improper use of mud additives. Form 1985 to 1988, fresh water drilling fluid was used, and MHP non-fluorescence sloughing control agent was developed for exploratory well drilling. It was good for mud logging and hole stability, and it improved cementing quality and protected formation. Since the year of 1990, low solids and non-dispersing seawater drilling fluid, with PAC-141 as the main additive has been used. By using this seawater system, drilling operations were smoothly carried out, and regular borehole, good cementing quality were achieved. At the same time, the skin factors and blocking ratio were low, and the value of LC50 was over 10,000 mg/L, which met the requirements of pollution control. The direction on RD of novel seawater drilling fluid technology was proposed.