Rapid and Practical Characterization of Near-Wellbore Layer Structure and Properties in High-Angle and Horizontal Wells

Abstract

Complex geometry effects observed on log responses in high-angle and horizontal (HaHz) wells can create challenges in achieving accurate formation evaluation. The situation is made even more difficult in thinly bedded reservoirs where measurements may respond to multiple layers within their volume of investigation. Recent publications have outlined techniques in which a layered earth model is used to define the geometry of layering relative to a wellbore. A model-compare-update workflow is then used to solve for layer properties. Although these techniques are efficient in horizontal wells, they require good geological understanding to manually create the formation model and can be time consuming if there are many thin layers. This paper presents a semiautomatic method to construct a layered earth model in the immediate proximity of the borehole and to solve for the formation properties and geometry of the layers locally. The approach is particularly useful for shallow-reading measurements and complements the more extensive layered earth models commonly used for modeling the response of deeper reading measurements.