To increase the efficiency of field development, more and more wells are drilled with horizontal or high angle section at the end (HAHZ). Despite this, well logging data analysis is based on methodic and models developed using data from vertical and slant wells with relatively low inclination angle. Although it works well for vertical wells, it does not take into account geometric effects associated with high angle of drilling where wells are drilled almost parallel to formation layers. That often leads ambiguities while logging data analysis and formation evaluation in HAHZ wells compared to low angle wells. This fact does not allow using logging data from horizontal wells for geological and hydrodynamic models, which reduces its credibility.
The paper describes uncertainties that exist when using conventional processing and interpretation techniques in horizontal wells and their causes. For demonstration purpose, the paper uses an example from real well XX04, which has been drilled horizontally in complex environment in one of the field of Western Siberia region of Russia.
Azimuthal measurements application together with advanced modeling software packages enable more reliable estimation of well length exposed to reservoir, spatial position of its boundaries and essential reservoir properties, such as porosity and saturation. As a result, the geological model may be refined locally.
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