THE USE OF ACOUSTIC LOGS IN THE EVALUATION OF SANDSTONE RESERVOIRS

Geophysics ◽  
1960 ◽  
Vol 25 (1) ◽  
pp. 250-274 ◽  
Author(s):  
G. R. Pickett
Keyword(s):  
Acoustic Velocity ◽  
Pressure Differential ◽  
Well Bore ◽  
Laboratory Measurements ◽  
Theoretical Relation ◽  
Hexagonal Packing ◽  
Empirical Relations ◽  
Borehole Logs ◽  
Acoustic Velocities ◽  
Self Potential

It is shown that acoustic velocities in sandstones are primarily dependent on porosity, shaliness, and pressure differential between overburden and fluid pressures. Although there are undoubtedly other variables which have some effect on acoustic velocities in sandstones, usable porosity predictions can be made from acoustic borehole logs if measured velocities are corrected for effects of pressure differential and shaliness. A theoretical relation between acoustic velocity and pressure differential in a hexagonal packing of spheres has been empirically extended by correlation of laboratory measurements on cores with actual well‐bore measurements. A system of empirical relations among acoustic velocity, porosity, and self potential of sandstones is developed. Further, it appears that the resistivity of water in permeable rocks can be estimated from the velocity and resistivity of adjoining shales. When this is possible, the SP log can then be used to estimate the shaliness of a sandstone in order to correct velocities for porosity estimates.

Laboratory Measurements of Acoustic Velocities in Dry and Fluid-Saturated Sandstones

2019 ◽  
Author(s):  
Caroline Jones ◽  
Martin Trusler ◽  
Geoffery Maitland ◽  
Claudio Delle Piane ◽  
Ronny Pini
Keyword(s):  
Laboratory Measurements ◽  
Acoustic Velocities

Evaluating timber quality in larger-diameter standing trees: rethinking the use of acoustic velocity

Holzforschung ◽  
2019 ◽  
Vol 73 (9) ◽  
pp. 797-806 ◽  
Author(s):  
Luka Krajnc ◽  
Niall Farrelly ◽  
Annette M. Harte
Keyword(s):  
Mechanical Properties ◽  
Bending Strength ◽  
Small Diameter ◽  
Longitudinal Direction ◽  
High Ratio ◽  
Acoustic Velocity ◽  
Timber Quality ◽  
Standing Trees ◽  
The Mean ◽  
Acoustic Velocities

AbstractThe use of acoustic velocity for different purposes is becoming widespread in the forestry industry. However, there are conflicting reports on how well this technology reflects the mechanical properties of trees. In this study, the prediction of timber quality using acoustic technology was evaluated on mature standing trees of three softwood species. The velocity in 490 standing trees was measured in several directions (longitudinal, radial and tangential). A sub-sample of trees was felled and the acoustic velocity was measured in 120 logs which were then sawn into structural-sized timber. A total of 1383 boards were tested for bending, as were small clear specimens extracted from the structural-sized boards. The mean tree values of the timber grade-determining properties (elastic modulus, bending strength and density) of both specimen sizes were related to the acoustic velocities and tree slenderness. The correlations between the mean tree mechanical properties and acoustic velocities were relatively low, most likely due to a high ratio of diameter to measurement distance. The transverse directions showed similar correlations with mechanical properties in larger-diameter trees to the longitudinal direction, as did tree slenderness. The results suggest that while the acoustic velocity in the longitudinal direction can reflect the mean tree mechanical properties in small-diameter trees, alternatives are needed to achieve the same in larger-diameter trees.

APPLICATION OF CONTINUOUS VELOCITY LOGS TO DETERMINATION OF FLUID SATURATION OF RESERVOIR ROCKS

Geophysics ◽  
1956 ◽  
Vol 21 (3) ◽  
pp. 739-754 ◽  
Author(s):  
Warren G. Hicks ◽  
James E. Berry
Keyword(s):  
Field Data ◽  
Acoustic Velocity ◽  
Gas Oil ◽  
Laboratory Measurements ◽  
Reservoir Rocks ◽  
Fluid Saturation ◽  
Saturated Sands ◽  
Similar Character ◽  
Water Saturated

Recent studies of continuous acoustic velocity logs indicate that these logs may provide important assistance in differentiating gas, oil, and water saturations in reservoir rocks. In general, velocities are appreciably lower in sands carrying oil or gas than in water‐saturated sands of otherwise similar character. Specific examples from field logs illustrate this application. Laboratory measurements have been made of acoustic velocity of synthetic and natural rocks. Published studies, both empirical and theoretical, of other workers concerned with the transmission of sound in porous media have been considered. All of these at least qualitatively confirm the conclusions drawn from field data.

Effect of cementation on ultrasonic velocities in sandstones

Geophysics ◽  
2007 ◽  
Vol 72 (2) ◽  
pp. E53-E58 ◽  
Author(s):  
Ashraf M. Al-Tahini ◽  
Carl H. Sondergeld ◽  
Chandra S. Rai
Keyword(s):  
Saudi Arabia ◽  
Microstructural Analysis ◽  
Acoustic Velocity ◽  
Minor Role ◽  
Point Counting ◽  
Ultrasonic Velocities ◽  
Thin Sections ◽  
Acoustic Velocities ◽  
A Minor

We determine the acoustic velocities for samples cored from the Jauf and Unayzah sandstone formations of Saudi Arabia. We use microstructural analysis including thin sections and point counting to quantify cementation. Velocities in these formations are strongly controlled by the combination of porosity and cementation. Consequently, rocks of similar porosity but with different cementation materials display different velocities. The objective of this study is to understand the effect of cementation on the acoustic velocity. Cements in these two formations have variable compositions and properties. Pure quartz overgrowth plays a major role in increasing velocities while clay and clay coatings play a minor role. We found that clay coatings inhibit the quartz overgrowth cement leading to a decrease in velocities. Understanding the influence of various cementation types on velocity, and thus elastic properties in sandstone cores, enables an understanding of the variation of sonic velocities and moduli across these formations. The uniqueness of this study is that we emphasize the quantification of the role of cement and not just mineral volume.

1984 SEG Workshops Report of the special workshops presented December 6–7, 1984, following SEG’s 54th Annual International Meeting and Exposition in Atlanta

Geophysics ◽  
1985 ◽  
Vol 50 (7) ◽  
pp. 1183-1219
Keyword(s):  
Sedimentary Rocks ◽  
Acoustic Velocity ◽  
Seismic Exploration ◽  
Laboratory Measurements ◽  
International Meeting ◽  
Individual Basis ◽  
Transient Electromagnetic ◽  
Electromagnetic Soundings ◽  
Seismic Measurements

The workshop was organized into three topical units. The first unit included a presentation of laboratory measurements on a variety of frozen sedimentary rocks and permafrost, and an overview of problems and geophysical phenomena associated with permafrost. The second unit presented results of transient electromagnetic soundings in onshore and offshore permafrost environments. Comparisons were made with other geophysical results including acoustic velocity logs. Unit three of the workshop treated a variety of seismic measurements in diverse permafrost environments and served to focus the workshop on problems pertinent to seismic exploration for petroleum. This overview of the workshop was prepared by the organizers with review by the participants. Its purpose is to relate the principal topics and questions discussed in the workshop. Limitations on space require that greater detail on any topic be solicited on an individual basis from the appropriate participants.

scholarly journals Characteristics of a fracture network surrounding a hydrothermally altered shear zone from geophysical borehole logs

Solid Earth ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 829-854
Author(s):  
Eva Caspari ◽  
Andrew Greenwood ◽  
Ludovic Baron ◽  
Daniel Egli ◽  
Enea Toschini ◽  
...  
Keyword(s):  
Shear Zone ◽  
Damage Zone ◽  
Fracture Network ◽  
Core Material ◽  
Petrophysical Properties ◽  
Brittle Deformation ◽  
Borehole Radar ◽  
Borehole Logs ◽  
Self Potential

Abstract. Hydrothermally active and altered fault/shear zones in crystalline rocks are of practical importance because of their potential similarities with petrothermal reservoirs and exploitable natural hydrothermal systems. The petrophysical and hydraulic characterization of such structures is therefore of significant interest. Here, we report the results of corresponding investigations on a prominent shear zone of this type located in the crystalline Aar massif of the central Swiss Alps. A shallow borehole was drilled, which acutely intersects the core of the shear zone and is entirely situated in its surrounding damage zone. The focus of this study is a detailed characterization of this damage zone based on geophysical borehole measurements. For this purpose, a comprehensive suite of borehole logs, comprising passive and active nuclear, full-waveform sonic, resistivity, self-potential, optical televiewer, and borehole radar data, was collected. The migrated images of the borehole radar reflection data together with the optical televiewer data reveal a complicated network of intersecting fractures in the damage zone. Consequently, the associated petrophysical properties, notably the sonic velocities and porosities, are distinctly different from intact granitic formations. Cluster analyses of the borehole logs in combination with the structural interpretations of the optical televiewer data illustrate that the variations in the petrophysical properties are predominantly governed by the intense brittle deformation. The imaged fracture network and the high-porosity zones associated with brittle deformation represent the main flow pathways. This interpretation is consistent with the available geophysical measurements as well as the analyses of the retrieved core material. Furthermore, the interpretation of the self-potential and fluid resistivity log data suggests a compartmentalized hydraulic behavior, as evidenced by inflows of water into the borehole from different sources, which is likely to be governed by the steeply dipping structures.

Differences in acoustic velocity by resonance and transit-time methods in an anisotropic laminated wood medium

Holzforschung ◽  
2005 ◽  
Vol 59 (4) ◽  
pp. 428-434 ◽  
Author(s):  
Shakti Singh Chauhan ◽  
Kenneth M. Entwistle ◽  
John C.F. Walker
Keyword(s):  
Resonance Frequency ◽  
Transit Time ◽  
Weighted Average ◽  
Acoustic Velocity ◽  
Laminated Panels ◽  
Acoustic Velocities ◽  
The Law ◽  
The Difference

Abstract The influence of inhomogeneity on acoustic velocity measured by a resonance-based WoodSpec acoustic tool and a transit-time-based Fakopp-2D tool was investigated. Four laminated panels with different degrees of inhomogeneity were prepared and acoustic velocities were measured using both tools. Velocities measured by the Fakopp-2D tool were always higher than those measured by the WoodSpec tool in all panels. The difference in the two velocities was found to vary depending on the magnitude of inhomogeneity. It was demonstrated that the velocity measured by the resonance frequency obeys the law of mixtures and is controlled by the volume-weighted average stiffness of the material. In contrast, the velocity measured by the Fakopp-2D tool was the velocity of the pulse that first reached the detector travelling at the dilatational speed.

scholarly journals Characteristics of a fracture network surrounding a hydrothermally altered shear zone from geophysical borehole logs

2019 ◽  
Author(s):  
Eva Caspari ◽  
Andrew Greenwood ◽  
Ludovic Baron ◽  
Daniel Egli ◽  
Enea Toschini ◽  
...  
Keyword(s):  
Shear Zone ◽  
Damage Zone ◽  
Fracture Network ◽  
Core Material ◽  
Petrophysical Properties ◽  
Brittle Deformation ◽  
Borehole Radar ◽  
Borehole Logs ◽  
Self Potential

Abstract. Hydrothermally active and altered fault/shear zones in crystalline rocks are of practical importance because of their potential similarities with petrothermal reservoirs and exploitable natural hydrothermal systems. The petrophysical and hydraulic characterization of such structures is therefore of significant interest. Here, we report the results of corresponding investigations on a prominent shear zone of this type located in the crystalline Aar massif of the central Swiss Alps. A shallow borehole was drilled, which acutely intersects the core of the shear zone and is entirely situated in its surrounding damage zone. The focus of this study is a detailed characterization of this damage zone based on geophysical borehole measurements. For this purpose, a comprehensive suite of borehole logs, comprising passive and active nuclear, full-waveform sonic, resistivity, self-potential, optical televiewer, and borehole radar data, was collected. The migrated images of the borehole radar reflection data together with the optical televiewer data reveal a complicated network of intersecting fractures in the damage zone. Consequently, the associated petrophysical properties, notably the sonic velocities and porosities, are distinctly different from intact granitic formations. Cluster analyses of the borehole logs in combination with the structural interpretations of the optical televiewer data illustrate that the variations in the petrophysical properties are predominantly governed by the intense brittle deformation. The imaged fracture network and the high-porosity zones associated with brittle deformation represent the main flow pathways. This interpretation is consistent with the available geophysical measurements as well as the analyses of the retrieved core material. Furthermore, the interpretation of the self-potential and fluid resistivity log data suggests a compartmentalized hydraulic behavior, as evidenced by inflows of water into the borehole from different sources, which is likely to be governed by the steeply dipping structures.

Self Potential Tomographic Technique to Detect Soil Water Movements in the Vadose Zone: Laboratory Measurements.

2008 ◽  
Vol 1 (1) ◽  
pp. 137-153
Author(s):  
D. MARCHESE ◽  
G. DI BELLO ◽  
M. GRECO ◽  
V. LAPENNA ◽  
E. RIZZO ◽  
...  
Keyword(s):  
Soil Water ◽  
Vadose Zone ◽  
Laboratory Measurements ◽  
Tomographic Technique ◽  
Self Potential

scholarly journals SAND RIPPLE GEOMETRY AND SAND TRANSPORT MECHANISM DUE TO IRREGULAR OSCILLATORY FLOWS

1988 ◽  
Vol 1 (21) ◽  
pp. 129 ◽  
Author(s):  
Shinji Sato ◽  
Kiyoshi Horikawa
Keyword(s):  
Transport Mechanism ◽  
Field Data ◽  
Sand Transport ◽  
Laboratory Measurements ◽  
Oscillatory Flows ◽  
Sand Ripples ◽  
Irregular Wave ◽  
Sand Ripple ◽  
Empirical Relations ◽  
Flow Transport

This paper describes characteristics of sand ripples and sand transport mechanism in regular and irregular oscillatory flows on the basis of detailed laboratory measurements. A set of empirical relations were proposed to evaluate the sand ripple geometry as well as the onset of the sheet flow transport. The applicability of the proposed relationships to the irregular wave conditions with prototype scales was confirmed with existing field data.

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