Experimental Study of Electrical Properties of Oil-Based Mud in the Frequency Range From 1 to 100 MHz

Abstract

Formation-resistivity measurements in boreholes require accurate knowledge about the electrical properties of drilling fluid to exclude any measurement misinterpretations. For many drilling applications, oil-based mud is the preferred drilling fluid because of properties that include excellent shale stability, corrosion inhibition, lubricity, reusability, resistance to contamination, and higher rate of penetration. Although the electrical resistivity of oil-based mud is generally high, it depends on many parameters. We studied electrical resistivity and dielectric permittivity of oil-based muds as a function of frequency and temperature with varying oil and salt content and varying oil/water ratio. Measurements were performed by use of a coaxial test fixture and an impedance analyzer. The accuracy of the measurement system has been determined using standard materials such as air, deionized (DI) water, methanol, nbutanol, and n-octanol. The analysis shows that published models dealing with electrical properties of rocks can be compared well with those of oil-based muds. Resistivity and relative permittivity decrease with increasing temperature and frequency. No clear relationship is revealed between resistivity and water content, but relative dielectric permittivity does depend on water content of oil-based muds. Oil and salt content are of secondary importance. The study shows that the relative dielectric permittivity is related exponentially to the oil/water ratio of oil-based muds, which provides a means of estimating dielectric permittivity of oil-based mud if the oil/water ratio is known.

Influence of the Chemical Composition of Completion Fluids on the Propagation of Electromagnetic Waves within Oil Wells

“…The propagation medium in the well consists of an oilbased dielectric fluid composed of water, oil and salts (typically CaCl 2 ) [7]. This fluid is the centre of all electromagnetic propagation, and therefore, its electrical characteristics must be examined in detail.…”

“…This fluid is the centre of all electromagnetic propagation, and therefore, its electrical characteristics must be examined in detail. A study over the range of 1 MHz to 100 MHz was previously conducted [7], revealing significantly variable behaviour based on the chemical composition of the fluid.…”

“…Similarly, there is increasing variation in the relative permittivity according to the temperature, as demonstrated by [7]. Again, it is used a quadratic model similar to the effective conductivity variation in temperature:…”

Conversion Mechanism of Organic Matter While Cleaning Oil‐Based Drilling Cuttings Using Surfactant‐Free Microemulsions

“…The exploitation scale of shale gas, a clean and efficient energy, is constantly expanding, and the industry continues to develop rapidly. [1,2] Oil-based mud is a necessary guarantee for smooth shale drilling; [3][4][5] however, with the increasing scale of shale gas exploitation, the use of oil-based mud has increased, leading to a dramatic increase in the production of secondary pollutants, OBDCs. [6,7] In addition, other conventional natural gas drilling processes also produce large amounts of OBDCs.…”

Electrochemical characterization of individual oil micro-droplets by high-frequency nanocapacitor array imaging

“…An application of high-frequency measurements is the detection of water content in oil. 21,22 Because the measurement is less affected by the presence of ions in solution, simple analytical models can be used to determine the average content of water in oil. However, no information at a single water droplet level is obtained in this case.…”