A Presalt Operator Experience with Different Resistive Imaging Tools in NCM Environment

Abstract

Abstract Considering the challenges faced in the Brazillian presalt, the importance of acquiring good quality borehole imaging (BHI) data in exploratory and production wells in this amazing province is crucial. The BHI is used to provide detailed information needed for geological, geomechanical and petrophysical analysis. The objective of this study was to compare the images of four different wireline borehole imaging tools acquired in a non-conductive mud (NCM) system with the main purpose of investigating the use of the conductive technology imaging tool to operate in this type of environment. The use of borehole image technology allows the visualization of geological, geomechanical and petrophysical features such as facies, lithological boundaries, fractures, small-scale faults, drilling induced fractures and breakouts, invasion, fluid contacts and secondary porosity. This study proposes an integrated analysis between the data acquired with a high-resolution resistivity formation imager wireline tool originally designed for conductive mud systems, in a non-conductive mud system, with two other resistivity imagers designed for non-conductive mud systems and with an acoustic imaging tool that works in both environments. The four data image files logged in the well were processed and interpreted by the operator including quality control. The operator used an integrated approach during planning, acquisition, processing and interpretation. Since they are an important part to understand the results, the measurement principles of each technology are briefly described in the Borehole Imaging (BHI) & Previous Studies section. The acquisition of an image using a tool developed for the conductive environment in a non-conductive mud system was successful. But when these results were compared with the images from two other imaging tools designed for this type of drilling fluid, it was clear that the latter had better performances presenting good quality images in most part of the logged interval. The results show that imaging tool designed for the conductive environment presented a borehole image with good quality in a non-conductive environment with a good repeatability when compared to images from tools designed specifically for this latter environment.