Electromagnetic Porosity Forecast in Depth

Abstract

Accuracy of the porosity forecasting below boreholes from the results of electromagnetic sounding in their vicinity and resistivity well logging are compared using the data collected in the northern Tien Shan area (Kyrgyzstan). It is shown that the prediction accuracy using only electromagnetic sounding data from the vicinity of the wells is approximately the same as in other geological regions (in average, 8-10%). Prediction by means of the Archie formula leads to worse results not only when using electromagnetic sounding data, but also in the case of using the resistivity logs. The best results are obtained in the case of joint application of both data types. In particular, in forecasting to a depth twice as large as the well depth the relative error is only 2%. This finding is a good basement for Forecasting-While-Drilling scheme aimed at assessing the porosity/fracturing trends at depths bigger than the drilling depths.