Revisiting Dielectric Logging in Saudi Arabia: Recent Experiences and Applications in Development and Exploration Wells

Abstract

Abstract Dielectric logging was introduced in late 70s to mostly measure water filled porosity in the flushed zone independent of water salinity and Archie exponents m and n. Although the technology generated a lot of interest upon its introduction, it eventually disappeared over the years, mostly due to moderate accuracy of the early devices, oversimplified interpretation models and other hardware related complications. Results from extensive field testing of a new generation of dielectric wireline tools indicate that robust and reliable dielectric logging is now feasible in a wide range of environmental conditions and formations. Benchmarking of dielectric measurements against other logs and core data has shown that water-filled porosity can be measured accurately using dielectric logging tools, provided the matrix mineralogy is well defined. Consequently, the technology has gained rapid acceptance in applications involving flushed zone water saturation in environments with variable or unknown salinity, heavy oil identification, and discrimination of non-reservoir rock with high organic content. Dielectric logging is gradually replacing NMR Log-Inject-Log for residual/remaining oil saturation (ROS) measurement, especially in the situations where connate and injected water salinities can be vastly different. Due to the success in ROS applications, most of the recent testing has been focused towards carbonates drilled with water-based-mud. This technology is also being tested in shaly sands and in wells drilled with oil based mud at present. Additional work is underway to accurately characterize dielectric properties of carbonates so as to be able to perform quantitative textural analysis. In shaly sands, high resolution clay volumes and thin bed analysis are challenges that will be addressed in the future.