Statistical Evaluation of Laterolog Resistivity Measurements

Galsa Attila

Drahos Dezső

2019-04-04

földtudományok, földrajz

geológia, földtörténet

angol

cikk(ek)

PDF dokumentum

urn:uni-miskolc.hu:midra:31518

31518

Geosciences and engineering

A statistical inversion method was developed to determine the model parameters describing the borehole environment from laterolog measurements. Five types of laterolog tools were applied to estimate the optimal values of the model parameters, their dispersion, the correlation coefficients and the data error. For three-parameter inversion the model parameters were the resistivity of the far zone (Rt), the resistivity of the invaded, flushed zone (Rx0) and the relative diameter of the invasion (D), while for two-parameter inversion Rx0 was fixed and considered to be equal to the apparent resistivity from microlaterolog measurement. Based on the inversion of synthetic data it was established that (1) estimated data error approximates well to the additive error, (2) the higher the additive error, the larger the dispersion of the model parameters, (3) dispersions of the model parameters from two-parameters inversion are lower than from three. Two-parameter inversion was applied to calculate Rt and D in a borehole drilled for hydrocarbon (HC) exploration. Lower estimated dispersion of D and Rt was found in the HC-saturated bed, where the contrast of the resistivity of the far zone and the invaded zone is more pronounced.

statistical evaluation

well log inversion

quality-controlled inversion

laterologs

diameter of invasion