Study of Dielectric Properties of Dry and Saturated Green River Oil Shale

Abstract

We measured dielectric permittivity of dry and fluid-saturated Green River oil shale samples over a frequency range of 1 MHz to 1.8 GHz. Dry sample measurements were carried out between room temperature and 146 °C, saturated sample measurements were carried out at room temperature. Samples obtained from the Green River formation of Wyoming and from the Anvil Points Mine in Colorado were cored both parallel and perpendicular to layering. The samples, which all had organic richness in the range of 10-45 gal/ton, showed small variations between samples and a relatively small level of anisotropy of the dielectric properties when dry. The real and imaginary part of the relative dielectric permittivity of dry rock was nearly constant over the frequency range observed, with low values for the imaginary part (loss factor). Saturation with de-ionized water and brine greatly increased the values of the real and imaginary parts of the relative permittivity, especially at the lower frequencies. Temperature effects were relatively small, with initial increases in permittivity to about 60 °C, followed by slight decreases in permittivity that diminished as temperature increased. Implications of these observations for the in situ electromagnetic, or radio frequency (RF) heating of oil shale to produce oil and gas are discussed.

Initial results from the thermal and electrical conductivity probe (TECP) on Phoenix

“…Unfortunately, relating the measured dielectric permittivity directly to an absolute unfrozen H 2 O content is not straightforward [ Topp et al , 1980; Jones and Or , 2003; Lebron et al , 2004; Sweeney et al , 2007]; measured permittivity depends on details of the contact between the regolith particles and the TECP needles, in addition to other environmental factors such as temperature and bulk density [ Ulaby et al , 1982; Campbell , 2002]. Indeed, sensors used in terrestrial investigations are not moved during the experimental period, and require unique experimental calibration for each soil to obtain unfrozen water content from probe output [ Yoshikawa and Overduin , 2005].…”

Experimental investigations of the wettability of clays and shales

“…Water has a high dielectric constant (∼80) compared with mineral grains or oils (typically 4–5). At high frequency (1–3 GHz), the value of the dielectric constant reflects mainly the amount of water compared with air, solids and oil (according to a volumetric mixing law) [ Sweeney et al , 2007]. Surface active clay‐rich materials and samples with multiple fluid films exhibit a greater dielectric constant at low frequencies 1–100 MHz.…”

A Fully Coupled Numerical Model for Microwave Heating Enhanced Shale Gas Recovery

“…A MWH technique based on a down-hole radiating antenna is less affected by formation geology and is able to distribute heat over a larger reservoir volume due to the propagation of electromagnetic energy in the medium [27]. MWH has been widely employed for oil shale [16,[29][30][31][32], oil sands [17], heavy oil [15,27,[33][34][35], coal-bed methane (CBM) recovery [28], tight sandstone gas [14,36], but little attention has been paid to shale gas recovery. In all these studies, the two-dimensional model for electromagnetic heating on heavy oil/CBM was solved using a simulator based on the finite element method [28,33,34].…”