Evaluation Indexes of Environmental Protection and a Novel System for Offshore Drilling Fluid

摘要

Oil resources are abundant in the offshore area that is an important channel for the human to obtain oil and gas. With oil exploration and development, the marine ecological environment has been influenced increasingly. Through a large number of laboratory tests, the evaluation indexes of the environmental offshore drilling fluid system were established, which are consisted of heavy metal, petroleum, acute biological toxicity, biodegradability, and so on. Four types of agents for environmental offshore drilling fluid and a novel environmental offshore drilling fluid system were developed on the basis of establishing the evaluation indexes. The basic formulation of the novel drilling fluid system is: 400 mL Seawater + 0.3%Na_2CO_3 +0.2%NaOH + 4%Bentonite+0.5%HXB-1 +2%MMF+ 1.5%SDR-30+ 1%HXJ + 1% SDE-1 + 2%NFA-25, and the system has been applied successfully to Bohai Bay in Shengli oil field. The results showed that the environmental offshore drilling fluid system had favorable drilling performances, met the requirements of drilling engineering and marine environmental protection, and realized the source control of the environmental contamination from offshore drilling, the environmental performances of which were superior to sulfonated polymer drilling fluid and oil-based drilling fluid.