A New-Generation LWD Tool With Colocated Sensors Opens New Opportunities for Formation Evaluation

Abstract

Summary A new logging-while-drilling (LWD) tool that combines traditional measurements of gamma ray, propagation resistivity, gamma-gamma density, and thermal-neutron porosity with measurements unique to the LWD arena, including neutron capture spectroscopy and capture cross section, opens up new opportunities for formation evaluation on LWD. The compact design of the new-generation LWD tool greatly increases the likelihood that measurements will be made before the onset of significant invasion. The colocation of resistivity- and neutron-based sensors also means that key measurements are being made at the same depth at the same time and on a similar volume of the formation. These features ensure that all measurements are essentially seeing the same amount of invasion, thus removing a major complication in conventional LWD interpretation.