Published March 2010

Decision making in drilling based on modeling results and nature of information evaluation

O.G. Kirisenko

There are several principles and methodological approaches to the acceptance of optimal decision. Almost in all of those methodological approaches the main stage is model construction for forecasting drilling parameters. The models have been built based on results of the study of geological infuence, technological and technical factors. At that, as usual they should be identified for each particular geological condition. After the model is built it is time for decision making, like choosing bit type and operation parameters for providing maximum rate of penetration and minimum cost per footage drilled for given conditions. For the purpose of choosing the best bit type and operation parameters using built models calculations have been made not only with utilized bits during the drilling of the section, but also with other bit types like: CR-1, MAX-GT1, MAX-CGT1, MX-C1, FS -2643, MSGV, МСЗ GHU, MZ GV, SZ GV, MZ GAU, SGB and etc. The modelling has been performed with identified weights on bit, rotation speed and pump rates for different bit types. Based on the results of penetration rate and cost per meter drilled three-dimensional models are built. For the optimal decision making process on the bit performance have been made several analyses with determination of distribution laws and with records of uncertainty classification results. The selection of decision making method depends on data identification results according to the type of uncertainties. In our case the best decisions were evaluated by three methods: generalized criterion method (penetration rate and cost per meter drilled values were summarized); the least concession method and by applying fuzzy multitude theory. In case when all numbers obey to any distribution law, then all concerned methods give the same results at the end. Otherwise, the best results can be achieved by applying fuzzy multitude theory. Accordingly, while decision-making it is necessary to identify to what type of uncertainties considered information are belong and hence to choose corresponding method.