Experience in applying nuclear magnetic resonance logging while drilling for reservoir saturation assessment in Achimov deposits

Abstract

Background. In the development of low-permeability reservoirs with low-salinity formation water (Achimov formation, Western Siberia), the reliable assessment of formation saturation is a critical challenge. MagTrak™ Nuclear Magnetic Resonance (NMR) logging-while-drilling (LWD) technology provides the capability for continuous formation saturation determination while drilling. However, the influence of active ongoing filtration of oil-based mud (OBM) [4] on NMR-while-drilling data is insufficiently studied. The dynamic nature of the process, the shallow depth of investigation capabilities of LWD tools, and drill string vibrations create unique challenges for interpretation of formation saturation from NMR data.

Aim. Determination of the saturation of Achimov deposits using the NMR method while drilling.

Materials and methods. The materials used included data from nuclear magnetic resonance (NMR) logging while drilling pilot holes.

Results. Data on formation saturation were obtained during the drilling process using nuclear magnetic resonance logging. During the NMR investigations, the influence of oil-based mud was identified.

Conclusion. Positive experience was gained in applying NMR while drilling to assess formation saturation in the conditions of low-permeability Achimov deposits, taking into account the influence of oil-based mud (OBM). This work presents an approach using NMR recordings: both while drilling and after drilling while pulling out the drilling assembly.