Reliability analysis and risk assessment of casing in complex well status are the important research of applied theory and technology used for evaluating reliability, safety and prospective life of casing in complex well status including many risk factors, furthermore, preventing effectively casing failure, increasing casing reliability, lengthening casing life.

This paper elaborates the situation of development and application of high-density drilling fluids,analyze the technology and performance,discusses the reasons of downhole complications and reservoir protection technology,and points out the existing problems of current high-density drilling fluids and the development trend.

Hybrid algorithm for three dimensional Bin Packing problem under complex condition;