Complex Permittivity Logging Tool Excited by Transient Signal for MWD/LWD

Abstract

This paper proposes a new logging while drilling (LWD) method to evaluate rock moisture content and reservoir hydrocarbon saturation. Transient signal with broadband spectrum covering the sensitive range of fluids contained formation was used as excitation signal in the near-bit MWD system. Continuous measurement in the whole spectrum with both fluid type and saturation changes caused differences in frequency distribution of response signals and achieved integrated evaluation of formation hydrocarbon and water saturation. Linear system analysis was optimized by adding oil/water saturation parameters, and analytic calculating results were presented to verify the performance of the proposed transient MWD system. Compared with conventional wireline and LWD tools, the method presented in this paper provided higher resolution and signal intensity.

Investigation of a Conductivity Logging Tool Based on Single Coil Impedance Measurement Using FDTD Method

“…Many works have been done by laboratories and research institutes in recent years regarding the resistivity and permittivity of formations [2][3][4]. Logging while drilling (LWD) sensors are widely used in real-time borehole measurements of petrophysical parameters for hydrocarbon exploration [5]. In LWD systems, conductivity (resistivity) of formation is one of the basic indicators of the concentration of hydrocarbon saturation [6,7].…”