An Integrated Approach for Evaluating Fractured Reservoirs Utilizing Multiple Logging-While-Drilling Sensors in Challenging Horizontal Wells

Abstract Porosity and permeability are fundamental petrophysical attributes required to evaluate downhole storage volume and fluid capacity. Evaluation of log-derived permeability remains one of the most critical petrophysical challenges in the industry that can be overcome by utilizing multiple logging technologies such as nuclear magnetic resonance (NMR), high-resolution borehole imaging, sonic logs, and formation testing. The objective of this study was to evaluate the permeability variations and fractures in a horizontal evaluation well by calibrating the permeability calculation to the mobility obtained from the discrete formation-testing stations combined with other logging-while-drilling (LWD) technologies. The workflow incorporated multiple measurements in real time to evaluate log-derived permeability in multiple wells. The evaluation was based on empirical relationships using NMR, acoustic, and high-resolution imaging tool measurements. Those relationships were calibrated using mobility values calculated from LWD formation testing in high-angle and horizontal (HA/HZ) wells. LWD formation testers were deployed azimuthally to help evaluate permeability anisotropy and provide a better understanding of the sources of permeability heterogeneity. Different logging suites were utilized in horizontal laterals placed in different directions. The multi-well evaluation was key to understanding the rock heterogeneity and connectivity by integrating the different datasets. Mobility calculated from LWD formation-testing results was successfully utilized to calibrate log-derived permeability of multiple zones in conjunction with other log measurements in those laterals. The calibration of the NMR permeability indicator from the comprehensive logging suite included modifying NMR irreducible water cutoff and was then utilized in the laterals with a simplified logging suite and showed a good correlation with formation testing results. LWD high-resolution micro-resistivity images were also used to evaluate fractures and permeability variations. Detailed image analysis helped to understand the mechanism that governs the permeability profile and revealed the fracture network. This study presents an integrated workflow for evaluating HA/HZ wells utilizing multiple measurements. A key parameter is the permeability evaluation combining LWD formation tester data with multiple log-based permeability indicators and micro-resistivity images.