Discriminating the Mineralogical Composition in Drill Cuttings Based on Absorption Spectra in the Terahertz Range

Abstract

Understanding the geological units of a reservoir is essential to the development and management of the resource. In this paper, drill cuttings from several depths from an oilfield were studied using terahertz time domain spectroscopy (THz-TDS). Cluster analysis (CA) and principal component analysis (PCA) were employed to classify and analyze the cuttings. The cuttings were clearly classified based on CA and PCA methods, and the results were in agreement with the lithology. Moreover, calcite and dolomite have stronger absorption of a THz pulse than any other minerals, based on an analysis of the PC1 scores. Quantitative analyses of minor minerals were also realized by building a series of linear and non-linear models between contents and PC2 scores. The results prove THz technology to be a promising means for determining reservoir lithology as well as other properties, which will be a significant supplementary method in oil fields.

Determining the Humidity-Dependent Ortho-to-Para Ratio of Water Vapor at Room Temperature Using Terahertz Spectroscopy

“…The hybrid beams composed of the THz pulse and the probe laser beam were focused onto a 2.8 mm thick <110> ZnTe for electro-optic detection. 20 The set-up was placed in an enclosure and filled with laboratory air with a relative humidity of $55% at 25.2 AE 0.5 C. Various quantities of nitrogen were purged into the box to reach different humidity levels (55.0% to 0% AE 1.0%). The measurements were performed in replicates of four under ambient atmospheric pressure.…”

Fabrication and Characterization of an 8 × 8 Terahertz Photoconductive Antenna Array for Spatially Resolved Time Domain Spectroscopy and Imaging Applications

“…Terahertz (THz) frequency band (0.1 to 10 THz) has received a lot of attention in recent years due to increasing number of technological applications in the fields of telecommunications, imaging and sensing [1]- [7]. Due to its non-ionizing nature and higher penetration depth when compared to optical infrared (IR) waves, the THz imaging is promising in such applications as security screening [8]- [10], biomedical imaging [11]- [16] and industrial process control [17], [18]. Moreover, the THz waves feature higher spatial resolution…”

Simultaneous Determination of Organic Distribution and Content in Oil Shale by Terahertz Imaging

“…Fourier-transform infrared spectroscopy, Raman spectroscopy, mass spectrometry, and nuclear magnetic resonance were used to characterize the properties of oil shale. − Owing to the location between far-infrared and millimeter-wave spectrum bands, terahertz (THz) spectroscopy has recently emerged as an efficient tool in various aspects because of its unique advantages. − The response of a THz wave is strongly related with the materials’ dielectric properties . To date, THz technology has been utilized to evaluate the dielectric properties of various minerals and rocks, including kaolinite, montmorillonite, halloysite, sandstone, limestone, marble, etc., showing different quantitative relations between the mineral’s content and THz parameters. − In the study of oil shale, relations were built between THz absorption and the oil content in semicoke, which could be a significant indicator of pyrolysis process optimization. − The anisotropic optical responses of oil shales were measured by THz spectroscopy, revealing a refractive index ( n ) anisotropy associated with the bedding planes. Increasing organic content has promoted the anisotropic degree of oil shale, and a linear correlation can be built between the n anisotropy and the oil yield, providing an alternative parameter for oil yield characterization .…”