Abstract: Optimization of bit types used in whole well drilling procedure is a multi-stage deci-sion making. Basing on the systems engineering theory, this paper develops the multi-stage decision tree of optimized combination of whole-well bit series, the state conversion equation of whole-well bit dynamic programming, and index function. Furthermore, the minimization theory is used to seek the optimized tree path, through which the whole-well bit series optimized combination and the optimized working parameter are obtained,This is an essential path to achieve short drilling period, high drilling rate, low cost in drilling deep or superdeep well.

Key words: Bit program, Bit performance, Parmeter optimizaton, Optimizing design