Simultaneous Characterization of Water Content and Distribution in High-Water-Cut Crude Oil

Abstract

High-water-cut crude oil is currently the main form of underground oil in China. The high water content and the distribution of oil and water have an important impact on the rheological property and exploration efficiency. Terahertz (THz) waves are extremely sensitive to hydrogen bonds and intermolecular forces, and consequently, the responses of oil, water and air exhibit obvious differences. In this work, a series of crude oils with high water content were investigated by using THz timedomain spectroscopy (THz-TDS). Linear models were built between amplitudes of THz-TDS and the absorbance and water content from 50.05% to 100.00% with correlation coefficients (R) of 0.99 and >0.93, respectively. In addition, oil and water were determined to be distributed at different positions, based on THz signals in a series of oriented scans. Moreover, the transparent parts for visible light are identified by scanning the local points. The positions with low and high THz intensities refer to water and air regions, respectively. Therefore, THz technology is expected to act as a supplementary method to characterize highwater-cut crude oil, which will promote the efficiency and safe operation of pumping units and oil pipelines.

Industrial Applications of Terahertz Sensing: State of Play

“…In a broad and detailed study, oil contamination by both water and solids (e.g., sand) was investigated [145], showing that it is possible to measure concentrations of both. With particular reference to oil fields with a high presence of water, both water content and its distribution were characterized [146].…”

High Water Content Prediction of Oil–Water Emulsions Based on Terahertz Electromagnetically Induced Transparency-like Metamaterial

“…10−14 THz time-domain spectroscopy has been used to measure the water content ranging from 50.05 to 100% in crude oil and to characterize the distribution of oil, air, and water simultaneously. 1 Subsequently, combined with 3D printing technology, oil–water mixtures with water content from 1.8 to 90.6% were measured and analyzed with the THz parameters. 15 However, THz waves are strongly attenuated by a water layer, which is a practical limitation in detecting water content for high water cut emulsions.…”

“…Determining the water content is significant in evaluating crude oil dehydration, logging, refining, and exportation. , So far, many conventional approaches have been employed to determine the water content of oil–water emulsions in different situations according to specific needs, such as the microwave technique, the ray, the capacitance, the Karl Fischer titration method, and near-infrared spectroscopy. − In recent years, requirements for accurate high water content measurement in oil have been more and more exigent and attracted widespread attention in theoretical and experimental work. An open measurement method was proposed to accurately measure water content using a suitable electromagnetic wave with the right wavelength based on Rayleigh scattering, which was further proved to be applicable to oil-wells whose water content is more than 80% .…”

Crude Oil Asphaltenes Studied by Terahertz Spectroscopy

“…It has been proven that the THz technique can be used to qualitatively identify the source of crude oil among different samples based on absorption and the refractive index spectrum . Other works include detecting the disaggregation of the crude oil particles in the presence of a magnetic field, characterizing wax crystals in waxy crude oil, measuring the water content in crude oil, , measuring the properties of some crude oil products, − natural gas, and coal, and all of these have only been presented over the past few years.…”