Standard Methods of GEOPHYSICAL FORMATION EVALUATION

Hallenburg, James K.

doi:10.1201/9780367812614

Cited by 4 publications

(3 citation statements)

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“…Resistivity may be low (<100 Ω•m) along fault zones that were fractured enough to have once hosted fluids, generally water or brine, from which conductive minerals were deposited. Higher subsurface temperatures decrease fluid viscosity and cause greater mobility of ions in the fluids, therefore reducing rock resistivity (Hallenburg, 1998). The rocks and sediments in this study area contain varying percentages of clay and sulfide minerals, both of which have a negative correlation with measured bulk resistivity.…”

Section: ■ Geophysical Methodsmentioning

confidence: 92%

Supplemental Material: Deep resistivity geophysics of the San Juan–Silverton caldera complex, San Juan County, Colorado

Rodriguez,

al.

2024

Preprint

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Section: ■ Geophysical Methodsmentioning

confidence: 92%

Supplemental Material: Deep resistivity geophysics of the San Juan–Silverton caldera complex, San Juan County, Colorado

Rodriguez,

al.

2024

Preprint

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“…Electromagnetic geophysical methods detect variations in the electrical properties of rocks, in particular electrical resistivity or its inverse, electrical conductivity. In the upper crust, the electrical resistivity of geologic units largely depends on their fluid content, porosity, fracture density, temperature, and state of alteration, as well as the presence of conductive minerals, such as clay, graphitic carbon, and metallic minerals (e.g., Keller and Frischknecht, 1966;Hearst and Nelson, 1985;Keller, 1987;Palacky, 1987;Nelson and Anderson, 1992;Hallenburg, 1998;Hearst et al, 2000). Fresh-water-saturated, unconsolidated, terrestrial, alluvial sediments are commonly conductive to moderately conductive (2-70 ohm-m).…”

Section: Magnetotelluric Data and Methodsmentioning

confidence: 99%

A shallow rift basin segmented in space and time: The southern San Luis Basin, Rio Grande rift, northern New Mexico, U.S.A.

Drenth

Grauch

Turner

et al. 2019

Rocky Mountain Geology

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Interpretation of gravity, magnetotelluric, and aeromagnetic data in conjunction with geologic constraints reveals details of basin geometry, thickness, and spatiotemporal evolution of the southern San Luis Basin, one of the major basins of the northern Rio Grande rift. Spatial variations of low-density basin-fill thickness are estimated primarily using a 3D gravity inversion method that improves on previous modeling efforts by separating the effects of the low-density basin fill from the effects of pre-rift rocks. The basin is found to be significantly narrower—and more complex in the subsurface—than indicated or implied by previous modeling efforts. The basin is also estimated to be significantly shallower than previously estimated. Five distinct subbasins are recognized within the broader southern San Luis Basin. The oldest and shallowest subbasin is the Las Mesitas graben along the northwestern basin margin, formed during the Oligocene transition from Southern Rocky Mountain volcanic field magmatism to rifting. In this subbasin, sediments are estimated to reach a maximum thickness of ~400 m within a north–south elongated structural depression. Other subbasins that likely initially developed during the Miocene are the dominant tectonic features in the southern San Luis Basin. This includes the Tres Orejas subbasin, which formed in the southwestern portion of the basin by the Embudo fault zone and a hypothesized fault zone along its western margin. This subbasin reaches a maximum thickness of ~2 km, as indicated by magnetotelluric and gravity modeling. The Sunshine Valley, Questa, and Taos subbasins occupy the eastern part of the southern San Luis Basin. The southern Sangre de Cristo fault zone is the dominant tectonic feature that controlled their development after ~20 Ma. The east-down Gorge fault zone controlled the western margins of significant parts of these eastern subbasins, although much of the Taos subbasin may be superimposed on the Tres Orejas subbasin. Maximum low-density basin-fill thicknesses are estimated to be 1.2 km for the Sunshine Valley subbasin, 800 m for the Questa subbasin, and 1.8 km for the Taos subbasin. Subbasin-forming tectonic activity along the Gorge fault zone and within the Tres Orejas subbasin ceased by the end of the development of the largely Pliocene Taos Plateau volcanic field. After that, rift-related subsidence became more narrowly centered on the eastern margin of the basin, controlled mainly by the linked Embudo and southern Sangre de Cristo fault zones.

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“…The invasion occurs through the continuous phase, known as mud filtrate (liquid), while discontinuous material (added clays and/ or polymers) cannot penetrate the pores and create a mud cake in the borehole wall. 4 Mud filtrate invasion changes the physicochemical properties of the formation, and it is necessary to know the physical properties of the mud filtrate to extract its effect from geophysical logs. When the mud filtrate behavior is known, it is possible to predict the response of logging tools near the borehole wall (flushed zone).…”

Section: Introductionmentioning

confidence: 99%

Impacts of a New Drilling Fluid Invasion on Electrical Resistivity and Acoustic Velocity Measurements

Baggieri,

Carrasquilla,

Ceia

et al. 2024

Energy Fuels

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When mud filtrate invades a geological formation, it alters its physicochemical characteristics. This invasive process divides the formation into four zones: mud cake, flushed zone, and transitional; immediately after that, there is a virgin area. Each of these zones contains a mixture of fluids: drilling fluids and original formation fluids. Thus, all well-logging measurements are influenced by mud filtrate invasion. The goal of this research was to analyze the effects of a new drilling fluid system invasion, crudeglycerin-based aqueous mud (CGBAM), when estimating a rock− fluid system's physical properties through electrical and sonic properties (V p and V s ). To accomplish this objective, resistivity and transit time laboratory measurements were performed on Berea sandstone samples under dry conditions and brine-and mud filtrate-saturated conditions. According to the results, the invasion of this aforementioned mud filtrate did not affect the characterization of sandstones through sonic properties. Although the crude-glycerin-based aqueous mud has rheological behavior like that of an oil-based mud, it presented unusual behavior from an electrical resistivity and sonic point of view. CGBAM showed sonic properties like the water-based mud and resistive behavior between oil-and water-based muds; therefore, it improves the drilling process and geophysical interpretation regarding the clear distinction between the oil and water zones of the reservoir.

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Standard Methods of GEOPHYSICAL FORMATION EVALUATION

Cited by 4 publications

References 0 publications

Supplemental Material: Deep resistivity geophysics of the San Juan–Silverton caldera complex, San Juan County, Colorado

Supplemental Material: Deep resistivity geophysics of the San Juan–Silverton caldera complex, San Juan County, Colorado

A shallow rift basin segmented in space and time: The southern San Luis Basin, Rio Grande rift, northern New Mexico, U.S.A.

Impacts of a New Drilling Fluid Invasion on Electrical Resistivity and Acoustic Velocity Measurements

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