Laboratory Analysis Of Core Samples Research Articles

Characterization and estimation of gas-bearing properties of Devonian coals using well log data from five Illizi Basin wells (Algeria)

In Algeria, wells drilled in the Illizi Basin suggest the presence of a significant areal trend of Devonian coal seams with the thickest coal seams penetrated in the Lower Devonian stratigraphic unit F6. This makes them some of the oldest thick coal seams encountered. These coals exist between approximately 1500 and 4000 meters below surface. In particular, numerous coals in these formations drilled in the Oudoume field have recorded gas shows while drilling. A study of basic well log data from five wells penetrating Illizi Basin coals is conducted to characterize their distribution and provisionally evaluate their gas-bearing potential using petrophysical analysis coupled with machine learning. A simple multi-layer perceptron model (one hidden layer with four nodes) is used in a novel way to replicate estimates of gas saturation in the coal samples calculated approximately with the modified Kim equation. It does so by considering three commonly measured well-log variables: gamma ray, sonic travel time, deep resistivity (307 data records from the five wells studied). The log-calculated approximations (modified Kim equation) can be matched to better than plus or minus 1 scf/ton by the multi-layer perceptron model. The results and analysis presented provide preliminary encouragement that suggests the presence of a potentially extensive gas-bearing Devonian coal trend in the Illizi Basin that is worthy of further exploration. Future work is required to integrate data from additional wells and laboratory analysis of core samples to verify the extent of that coal trend and to quantify its gas concentrations. Cited as : Baouche, R., Wood, D.A. Characterization and estimation of gas-bearing properties of Devonian coals using well log data from five Illizi Basin wells (Algeria). Advances in Geo-Energy Research, 2020, 4(4), 356-371, doi: 10.46690/ager.2020.04.03

New empirical model to evaluate groundwater flow into circular tunnel using multiple regression analysis

There are various analytical, empirical and numerical methods to calculate groundwater inflow into tunnels excavated in rocky media. Analytical methods have been widely applied in prediction of groundwater inflow to tunnels due to their simplicity and practical base theory. Investigations show that the real amount of water infiltrating into jointed tunnels is much less than calculated amount using analytical methods and obtained results are very dependent on tunnel‘s geometry and environmental situations. In this study, using multiple regression analysis, a new empirical model for estimation of groundwater seepage into circular tunnels was introduced. Our data was acquired from field surveys and laboratory analysis of core samples. New regression variables were defined after perusing single and two variables relationship between groundwater seepage and other variables. Finally, an appropriate model for estimation of leakage was obtained using the stepwise algorithm. Statistics like R, R2, RP2 and the histogram of residual values in the model represent a good reputation and fitness for this model to estimate the groundwater seepage into tunnels. The new experimental model was used for the test data and results were satisfactory. Therefore, multiple regression analysis is an effective and efficient way to estimate the groundwater seepage into tunnels.

Bazhen Fm matured reservoir evaluation (West Siberia, Russia)

The depletion of the traditional sources of hydrocarbons leads to the situation when the biggest players of the oil and gas production market turn to unconventional reserves. Commercial shale oil and gas production levels in the USA have largely determined world prospects for oil and gas industry development. Russia takes one of the leading place in the world in terms of shale oil resources. The main source rock of the West Siberia, the biggest oil and gas basin in Russia under development, the Bazhen Fm and its stratigraphic and lithologic analogs, is located in the territory of over 1,000,000 square kilometers. Provided it has similar key properties (organic carbon content, porosity, permeability) with the deposits of the Bakken Fm and Green River Fm, USA, it is still extremely poorly described with laboratory methods. We have performed the laboratory analysis of core samples from a well drilled in Bazhen Fm deposits with matured organic matter (Tmax>435 °C). It was demonstrated the applicability of the improved steady-state gas flow method to evaluate the permeability of nanopermeable rocks. The role of natural fracturing in forming voids was determided that allows regarding potential Bazhen Fm reservoirs as systems with dual porosity and dual permeability.

Geotechnical performance of a uranium tailings containment facility at Key Lake, Saskatchewan

The main objective of this paper was to investigate the geotechnical performance of uranium tailings in the Deilmann Tailings Management Facility (DTMF) at Key Lake, Saskatchewan, Canada. Laboratory analyses of core samples indicated that the high water content (100–250%) at the tailings surface gradually decreases with depth and reaches around 60–80% at the DTMF bottom. The corresponding solids content values were found to be 30 ± 5% at the surface and 60 ± 5% at the bottom. The grain size data correlated well with both the water content and the solids content profiles, that is, an increase in fines content or an increase in coarse content was associated with an increase in water content (decrease in solids content) and vice versa. The investigated tailings generally exhibited segregation within a narrow range of +2 to −2%, when scaled with respect to the average solids content over a vertical profile. A fines water ratio of around 50 ± 5% was found to be associated with negligible segregation. The effective stress was found to be up to 600 kPa at the DTMF bottom. At low effective stress (around 5 kPa), void ratio ranged from 3.0 to 5.0, while at high effective stress (around 600 kPa) the range of void ratios was generally between 0.5 and 1.0.

A high‐resolution GIS‐based inventory of the west Siberian peat carbon pool

The West Siberian Lowland (WSL) contains the world's most extensive peatlands and a substantial fraction of the global terrestrial carbon pool. Despite its recognition as a carbon reservoir of great significance, the extent, thickness, and carbon content of WSL peatlands have not been analyzed in detail. This paper compiles a wide array of data into a geographic information system (GIS) to create a high‐resolution, spatially explicit digital inventory of all WSL peatlands and their associated physical properties. Detailed measurements for nearly 10,000 individual peatlands (patches) are based on compilation of previously unpublished Russian field and ancillary map data, satellite imagery, previously published depth measurements, and our own field depth and core measurements taken throughout the region during field campaigns in 1999, 2000, and 2001. At the patch level, carbon storage is estimated as the product of peatland area, depth, and carbon content. Estimates of peatland area are validated from RESURS‐01 satellite images, and the quality of the Russian peatland depth and carbon content data is independently confirmed by laboratory analysis of core samples. Through GIS‐based spatial analysis of the peat areal extent, depth, and carbon content data, we conservatively estimate the total area of WSL peatlands at 592,440 km2, the total peat mass at 147.82 Pg, and the total carbon pool at 70.21 Pg C. Our analysis concludes that WSL peatlands are more extensive and represent a substantially larger carbon pool than previously thought: Previous studies report 9,440–273,440 km2 less peatland area and 15.11–30.19 Pg less carbon than found in this analysis. The complete digital database is freely available for scientific use at http://arcss.colorado.edu/data/arcss131.html.

Geotechnical properties and preliminary assessment of sediment stability on the continental slope of the northwestern Alboran Sea

Laboratory analysis of core samples from the western Alboran Sea slope reveal a large variability in texture and geotechnical properties. Stability analysis suggests that the sediment is stable under static gravitational loading but potentially unstable under seismic loading. Slope failures may occur if horizontal ground accelerations greater than 0.16g are seismically induced. The, Alboran Sea is an active region, on which earthquakes inducing accelerations big enough to exceed the shear strength of the soft soil may occur. Test results contrast with the apparent stability deduced from seismic profiles.

Experimental verification of sea-bed shear modulus profile inversions using surface gravity (water) wave-induced sea-bed motion

SUMMARY A previously developed theory (Yamamoto & Torii 1986) enables sea-bed shear modulus profiles to be extracted by inverting measurements of sea-bed motion and water wave-induced pressures. Based on this theory, a new instrumentation system, known as a bottom shear modulus profiler (BSMP), has been developed and tested. Some modifications to the original theory and extensive experimental data reduction techniques are developed to deal with real ocean situations. Actual experimental results are given, along with quantitative measures of uncertainty and resolution. Comparisons between BSMP inversion results, in situ sediment strength tests, and laboratory analysis of core samples show that this method can predict accurately the magnitude and depth structure of the sediment shear modulus. Theoretical assumptions of small amplitude, elastic sediment behaviour are justified by examining sea-bed displacement time-series, dynamic phase spectra, and sea-bed shear strain profiles.

Quantitative experimental verification of seabed shear modulus profile inversions using surface gravity (water) wave‐induced seabed motions

A previously developed theory enables seabed shear modulus profiles to be calculated through the combination of water wave‐seabed interaction theories and geophysical inversion methods. A new instrumentation system, consisting of three orthogonally mounted accelerometers and a pressure sensor, has been developed to measure water wave‐induced pressures and seabed motions. This new passive remote system provides a fast and convenient method to determine in situ sediment shear modulus with depth profiles, without disturbing the sediment or drilling. Experiments have been conducted in various sediments and water depths off the coast of New Jersey. Extensive experimental data reduction techniques are developed to deal with real ocean data. Actual experimental results are given, along with quantitative measures of uncertainty and resolution. Comparisons between the experimental shear modulus inversions, in situ sediment strength tests, and laboratory analysis of core samples show that this method can accurately...

Successful Stimulation Practices Offshore Holland

Summary Analyses of the Rotliegendes sandstone indicate this formation offshore Holland contains clay minerals of various types, making it somewhat sensitive to water-base stimulation fluids. Both hydrochloric (HCl) and hydrofluoric (HF) acids have been used successfully for acid wash and/or mud damage removal. For hydraulic fracturing, water-base fluids and emulsions are used successfully. Laboratory analyses of core samples assist in determining the most appropriate fluid for treatment. Testing strings have been used, allowing proper zone testing and stimulation through the string if required. Surface equipment requirements for stimulation have been designed around the drilling rig's space and weight limitations. Introduction Offshore Holland has been an active exploration and producing area for several years. The zone of primary interest has been the Rotliegendes sandstone of Lower Permian age. Almost all commercial field development has been in this formation, and it is the subject of this paper.The Rotliegendes sands offshore Holland generally have low permeability, requiring stimulation for commercial production rates. Primarily, these sands are gas bearing; however, liquid hydrocarbons have been discovered in some cases. Depth to the top of the Rotliegendes is approximately 9,840 ft (3000 m). The bottomhole temperature (BHT) and pressure (BHP) are approximately 230F (100C) and 4,750 psi (32.8 MPa), respectively. Considerable laboratory testing of core samples has been carried out to evaluate the effect of various stimulation fluids on the formation. A summary of this information is presented. Because most ofthis stimulation work is conducted from jackup drilling rigs, special consideration has been given to formation testing tools and testing strings. The tool strings are designed to allow proper testing of the zones of interest and, if necessary, stimulation through the string. Examples of tool strings are presented.Also of concern are space availability and weight restrictions on these rigs for stimulation equipment. For hydraulic fracturing, normally 2,000 to 3,500 hhp (2611 kW) is required, with additional supporting equipment.Fig. 1 shows a general view of the North Sea area and Fig. 2 shows the offshore Holland area in more detail. Stimulation Considerations The Rotliegendes formation is primarily a nonmarine sandstone with four identifiable facies. These facies vary from dune deposits, wadi deposits, interdune sabkha, and fluvial deposits. The reservoir quality of the rock may be related to each of these facies.The Rotliegendes zones considered for wellbore cleanup and/or stimulation vary little in mineralogical composition. A generalized X-ray diffraction analysis of Rotliegendes core samples is shown in Table 1. Examples of the Rotliegendes pore-associated minerals are shown in the scanning electron microscope (SEM) views, Figs. 3, 4, and 5. Fig. 3 is a split photo showing the type of Rotliegendes where abundant illite clay is present. Figs. 4 and 5 show a section of Rotliegendes where, at the higher power magnification, very little illite is seen extending into the pore space.Laboratory tests have been conducted to assist in selection of appropriate fluids for wellbore cleanup and/or stimulation of the Rotliegendes. In general, the laboratory tests evaluating wellbore cleanup/mud damage removal indicate that in very low permeability Rotliegendes cores (<0.1 md) removal of matrix damage is difficult with either HCl or HF acid. However, perforation soaks with 7 1/2 to 15% HCl acid have been carried out successfully in these low permeability zones. JPT P. 1211^

貝塚産魚類の体長組成復元における標本採集法の影響について 特にクロダイ体長組成について

In this paper the writers deal with the method and technique for providing a more accurate representation of the body size composition of Jomon shell-midden fish. The specimens analysed here are Acanthopagrus schlegeli (black sea bream) obtained during 1971's excavation of Kamitakatsu shell-midden, Ibaragi Pref. The size frequency distribution of black sea bream premaxillary from the same units, but one derived from laboratory analysis of core samples and another recovered in the trench, were compared (Fig. 2 and Table 1) and, in the former, there occurred a considerable amount of small size specimens of black sea bream which had been missed in the trench. The result shows that the application of core sampling and wet-screening technique furnishes more reliable data on the representation of the body size composition in any prehistoric fishes.