Role of geoinformation in decision making in the complicated conditions of well drilling

The possibility of estimation and forecasting of trouble intervals (intervals with AHPR, absorption zones) is considered in drilling process on the basis of data obtained as a result of geological and technological explorations. Methods are proposed to estimate the density of drilling fluid, gravity degree of drilling fluid absorption in the complicated conditions. An expression was obtained to calculate the density of drilling fluid. Linguistic rules were also formulated based on fuzzy cluster analysis. Gravity degree of absorption depending on petrophysical characteristics was estimated. Two approaches - statistical and fuzzy were proposed for predictive estimate of gravity degree of absorption depending on the character of input data.

Statistical estimation is performed on value of the absorption coefficient.

In case of lack of information or its insufficiency, the method based on fuzzy cluster analysis is proposed. Five classes were obtained, each of which is characterized by relative gravity of absorption, the corresponding characteristics of layers and the intensity of absorption on the basis of which linguistic rules were compiled for qualitative estimation of absorption degree depending on petrophysical characteristics according to principle ‘if…, so…”.