The Lab Study of Electromagnetic Field Flowing Imaging Logging
Authors: Jing Yongqi , Wang Zhonghao , Wu Xiling , Zhao Liang 
Published: December 2007

Based on the considerable discrepancy of dielectric constant and electric conductivity between water and hydrocarbons (oil and gas). A series of cross-sectional flow images can be generated from the recently developing multi-phase flowing imaging measurement. According to the flow features of downhole and the low frequency electromagnetic field pattern resulting from the multi-probe configuration, founded are the multi-phase flow finite element (FE) simulation software package and the image reconstruction algorithm. The experimental oct-probe is fabricated in lab. The images are satisfactory which are measured by HP8751A Network Analyzer and reconstructed on IBM-486 microcomputer far oil/water two-phase flow. Unlike the conventional product logging methods, it can be used to identify the flow pattern, provide the local distribution of segregated fluids across the downhole et al.

Introduction

With the development of oil field stepping into secondary or/and tertiary recovery, the variation of productive status and the new technique application are claiming for new production profile logging. These claims concentrate on the accurate identifying of flowing pattern, the calculating of holdup and the computing of phase velocity et al. How to face the phenomena? It is becoming an important research work and a developing direction that using the image measurement technique developed rapidly to provide a visual monitor method and to supply the key parameters for preparing development program.

But, How and where to develop for the production image logging? In 1996, Steve Maddox, a service manager of Halliburton Energy Services, reported a downhole video that can visualize the flowing and movement of various fluids, gases, and particles in real-time for some typical wells such as a clear water one in Ref. 1. Ref 2 presents another new production logging tool that discriminates between water and hydrocarbons by means of four identical binary probes symmetrically positioned across the wellbore and provides an image of the distribution of segregated fluids. Based on the considerable discrepancy of dielectric constant and electric conductivity between water and hydrocarbons, this paper describes a electromagnetic field flowing imaging logging method recently developed by the authors at Jianglian Petroleum Institution. By measuring the responding signal of two arbitrary electrodes in array positioned across the wellbore, using the responding field function obtained from the finite-element simulation, and choosing an effective image reconstruction algorithm, the cross-sectional electric parameter's distribution can be obtained, then the flowing imaging measurement realized. The principle of the measurement

Electric parameter's difference between oil and water. The electric parameters of fluids which act as the measured medium in productive well are dependent on the characteristic equation of Maxwell equation group. These consist of dielectric constant, electric conductivity, and magnetic conductivity. After regarding the mixed fluids as isotropic medium. The dielectric constant and magnetic conductivity both are real numbers in ideal medium (electric conductivity is none). For decay medium, these are complex numbers. Take the dielectric constant for instance, following is its representation

(1)

where the real and the imaginary part are related to displacement current and conductivity current respectively.

Because the magnetic conductivity difference among the mixed fluids in wellbore is very small, the electric conductivity and the dielectric constant is chosen to be the measured parameters for these difference between the segregated fluids (the relative constant of oil is 2, water about 80 and the electric conductivity of oil is zero, water changes with the salinity).

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