--> Porosity Estimation from Image Log - Improving Petrophysics Evaluation in Natural Fractured Formation with Low Primary Porosity System

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Porosity Estimation from Image Log - Improving Petrophysics Evaluation in Natural Fractured Formation with Low Primary Porosity System

Abstract

Abstract

One of the most difficult variables to be determined for a correct estimate of thehydrocarbon saturation in a petrophysical evaluation, in addition to the clay content, is the porosity. The estimate of this variable is complicated by the type of measurement, the quality of logging tools that are selected to measure, the lithology or more precisely mineralogy and the interpretation techniques to define this data. In addition to the above mentioned carbonate formations with little or no dolomitization process they are shown as very low primary porosity, however, with great production potential due to natural fractures that are generated by the fragility of the rock and action of regional stress in these formations.

That is why a correct estimate of the fracture porosity is essential to be incorporated into a more robust petrophysical model for the correct estimation of productivity potential with these characteristics. However, to determine the porosity of fracture is not a trivial to get unknown. Play an important role the high resolution micro-resistivity image log and high resolution ultrasonic images for a good characterization of the type of fracture along with a correct evaluation technique porosity of these fractures.

This document includes acquisition techniques and processing to improve data quality and reduce uncertainty in the fracture interpretation and adding this interpretation to a petrophysics model it is possible to determine the hydrocarbon saturation inside this fractures and provide an easy and qick technic to select production intervals for a completion and production decision.