Archival gamma ray logs standardization by nondestructive core measurements of the low-radioactivity rocks

Abstract

The present study analyzes spectral gamma ray data of low-radioactivity rock cores from Rotliegend Basin. The main goal of this research was standardization of archival gamma ray logs measured in counts per minute to American Petroleum Institute units. Selected core intervals, log data, and additional crushed samples covered three different boreholes: J-1, L-7, and K-2 from Zielona Góra Basin, localized in western Poland, where J-1 was a reference borehole. Core measurements were performed on the sandstone and conglomerate formations by Gamma Logger GT spectrometer, which uses two scintillation detectors containing bismuth germanate crystals. In the cores, real concentrations of potassium, uranium, and thorium were acquired what enabled to calculate total content of radioactive elements and total uninfluenced by uranium. Delivered new total GR_GLGT curve from cores allowed accurate standardization of archival GR curves from L-7 and K-2 boreholes. Presented results showed a very good correlation between logs, core data, and laboratory analyses. These data allow precise shale volume reinterpretation.

Thermal Infrared Radiation and Laser Ultrasound for Deformation and Water Saturation Effects Testing in Limestone

“…Figure 9 shows «σ − ε» plots derived from the above-described experiment. The σ(ε) curves reflect the well-known fact that changes in the strength and deformation properties of limestone samples greatly depend on water saturation [25,27]. Clearly, the inclination of the straight line approximating ( ) is significantly greater than that of the straight line approximating ( ), which indicates higher thermoactivity of water-saturated limestone.…”

“…Figure 9 shows « − » plots derived from the above-described experiment. The ( ) curves reflect the well-known fact that changes in the strength and deformation properties of limestone samples greatly depend on water saturation [25,27]. An IR radiation detector based on a «RTN-31» detector [51] with a bandwidth from 3 to 14 µm was located facing the center of the sample at a distance of 0.5 cm from its surface.…”

“…These methods comprise destructive methods involving load testing under different loading conditions [11,12] and semi-destructive mechanical tests with simultaneous measurement of acoustic emission [13,14]. Non-destructive in situ and laboratory methods for inspecting natural materials are addressed in [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32], including thermal control [16][17][18][19][20], multispectral optical remote sensing [21], ground penetrating radar [22,23], ultrasonic inspection [25,26], gamma-ray logging [27], terahertz spectroscopy [28], X-ray tomography [29,30], neutron radiography [31], and others [32].…”

Modeling the Depositional Environment of the Sandstone Reservoir in the Middle Miocene Sidri Member, Badri Field, Gulf of Suez Basin, Egypt: Integration of Gamma-Ray Log Patterns and Petrographic Characteristics of Lithology

“…These radioactive elements are contained sediments in the form of accessory minerals (Ellis and Singer 2007;Díaz-Curiel et al 2019). The GR curve reflects the total radiation of the mentioned elements, which have different energy peaks that are equivalent to 1.46 MeV, 1.76 MeV, and 2.62 MeV for K, U, and Th, respectively (Blum et al 1997;Ellis and Singer 2007;Skupio et al 2019). Based on their different energy peaks of radiation, a spectral GR device can divide the total radiation curve into three curves representing each of the three radioactive elements.…”

“…where U and Th are concentrations of these elements in ppm, K is potassium concentration in weight percent, and a, b, and c are the mass concentration units of the radioactive isotopes and for standard ones, too. The values for a, b, and c are 4, 8, and 16, respectively (Ellis and Singer 2007;Skupio et al 2019). GR log patterns were used to interpret the depositional settings of the Sidri Member facies based on previous approaches (e.g., Selley 1978;Cant 1992;Chow et al 2005 patterns of GR log.…”