Scaled Experimental Verification of Single-Well Induction Conductivity Measurement Through Nonmagnetic Casing

Abstract

The electromagnetic induction measurement of dimensions, integrity, or material properties of conductive objects is especially challenging in the case when the electrical conductivity of these objects spans five to seven orders of magnitude. Such an application is the conductivity measurement of the surrounding rocks from within a metal casing of an oil well. The rock conductivity measurement is required in order to determine and revaluate hydrocarbon-bearing layers. We present the first experimental verification of the single-well through-casing induction measurement on a scaled laboratory model of a borehole lined with a stainless steel or copper casing surrounded with a low-conductive medium. The measurements are in the frequency range of 2-16 kHz (10-80 Hz in case of the actual borehole). We explain the theoretical background of the method, describe the scaled model and experimental procedure, and discuss the experimental results. The measurement results are in agreement with the theoretical predictions (relative error less than 15%), and the equivalence of the results for the steel and copper casings (average relative discrepancy less than 10%) corroborates that the rock conductivity measurement can be corrected for variations in the casing properties (dimensions, electrical conductivity, and magnetic permeability).

Radial Electrical Resistivity Measurements of Rocks on Laboratory Core Samples Using an Electromagnetic Sensor: Macro and Micro Eddy Currents

“…The main purpose of this is to calibrate and standardize the device responses, so a careful operation to calculate the constant from the linear curve ( Figure 9) was established for this goal. In this case, the formula to determine the resistivity expression was deduced (21). The results are summarized in Table 1 confirming the good agreement between the two methods: the inductive and the contact one.…”

“…There is a large database of information available to both geologists and geophysicists, especially information on the characteristic parameters of cores: lithology, hydrocarbon show, heterogeneity and factoring porosity, permeability (Klinkenberg, liquid, and reactive permeability), wettability and capillary pressure, and grain and pore size distributions. In order to determine the porosity and mineralogy of rocks, one can use two physical properties: electrical resistivity and magnetic susceptibility [21,22]. In this way, a nondestructive method based on the inductive phenomenon will be described.…”

A novel signal conditioning system for SODAR

“…Moreover, Ikeda and Miyagi [38] implements the DABP technique in the antenna input tuning circuit to enhance the filter response's selectivity. The DABP technique has substantial advantages, such as a stable output response, low sensitivity, and the ability to design high Q filters [39,40]. DABP also permits the adjustment of the central frequency without affecting the Q value of the filter [41].…”