New Overseas Methodology of Modern Well Design

The prevailing well design methodology in China was imported more than twenty years ago.It has been proven to be a mature method applicable to conventional projects.In past years,this methodology further evolved in its source countries.Through investigation,analysis and comparison,we find that the overseas well design methodology is advanced additionally in following aspects:(1)extensive use of mathematic models in data mining allows more accurate prediction of pressure;(2)the borehole stability can be effectively maintained using median line principle to design mud weight according to geomechanical theory;(3)setting depth of casing strings is correctly selected based on maximum allowable spill under the principle of dynamic spill control,which can ensure the well integrity in different environments;(4)by comparing the loads on casing strings in the operation of well,the most realistic conditions and several other factors are considered in strength design of casing strings.These trends suggest that modern well design is more scientific,more practical,and safer.This will be valuable and referential for well design in China.