Abstract: A realtime monitoring and controlling intelligent system for drilling safety and optimization is designed and realized，which integrates the management of drilling engineering information，the realtime monitored drilling parameters and the Intelligent decision support technology.The knowledge model of the system is constituted of the domain knowledge，reasoning knowledge and task knowledge，and knowledge frame on drilling safety and optimization is established by applying Ontologybased scientific method of knowledge abstraction，and the knowledge integration on drilling safety and optimization is realized by the systemic analysis and induction of drilling data，information and knowledge.The system is used to the monitoring，recognition，forecast，diagnosis，prevention and treatment of abnormal drilling problem in each of the planning，drilling and postwell analysis of the well for the objective of drilling safety and optimization.

Key words: drilling safety, drilling optimization, intelligent system, realtime monitoring and controlling, knowledge integration