Determination of subsurface fracture orientation by analysis of the interval velocity

1992 ◽  
Author(s):  
Chih‐Hsiung Chang ◽  
Gerald H. F. Gardner
Keyword(s):  
Interval Velocity ◽  
Fracture Orientation

THE REFRACTION SEISMOGRAPH IN THE ALBERTA FOOTHILLS

Geophysics ◽  
1956 ◽  
Vol 21 (3) ◽  
pp. 828-838 ◽  
Author(s):  
G. J. Blundun
Keyword(s):  
Operating Conditions ◽  
Radio Communication ◽  
Interval Velocity ◽  
Mississippian Limestone ◽  
Interval Velocities ◽  
Definition Of ◽  
Characteristic Interval ◽  
Consequent Improvement ◽  
Continuous Determination

In the Alberta foothills the most valuable use of the refraction seismograph is for the definition of overthrust faulting in the Mississippian limestone which is overlain by a faulted, overthrust, and overturned Cretaceous section. Normally, two refracted arrivals are recorded with characteristic interval velocities of 14,000 ft/sec and 21,000 ft/sec, the former arising from an unknown Cretaceous marker, and the latter from the Mississippian. In contrast to a shot‐range of 65,000 ft required to record the refracted arrival from the Mississippian at a depth of 10,000 ft as the first event, a range of 20,000 ft permits recording it as the later event, with consequent improvement in the quality and reliability of the data, reduces the amount of surveying required together with smaller dynamite charges, and improves radio communication. A geophone spread of 6,300 ft with single geophones at 300 ft intervals recorded on 22 traces is recommended. Both in‐line and broadside refraction with the Mississippian arrival recorded as the later event have been used successfully with certain advantages to each method. The former permits continuous determination of the interval velocity of the refracted events as well as providing two‐way control; the latter is considerably faster, and often faulting may be observed directly on the seismograms without reduction of the data. Specimen seismograms are included to illustrate the two methods. Field operating conditions pertaining to survey tolerances, shot formation, size of dynamite charges, the weathering shot as a polarity check, filtering, geophone frequency, and costs are discussed.

Seismic determination of fracture orientation

1989 ◽  
Author(s):  
Terry W. Spencer ◽  
Heon Cheol Chi
Keyword(s):  
Fracture Orientation

Determination of critical slip surface of fractured rock slopes based on fracture orientation data

2013 ◽  
Vol 56 (5) ◽  
pp. 1248-1256 ◽  
Author(s):  
Wen Zhang ◽  
JianPing Chen ◽  
Wu Zhang ◽  
Yan Lü ◽  
YuFei Ma ◽  
...  
Keyword(s):  
Slip Surface ◽  
Fractured Rock ◽  
Rock Slopes ◽  
Critical Slip Surface ◽  
Orientation Data ◽  
Fracture Orientation

APPLICATIONS OF THE EXPANDING REFLECTION SPREAD

Geophysics ◽  
1962 ◽  
Vol 27 (6) ◽  
pp. 981-993 ◽  
Author(s):  
A. W. Musgrave
Keyword(s):  
Average Velocity ◽  
Velocity Versus ◽  
Normal Velocity ◽  
Interval Velocity ◽  
Reflection Profile ◽  
Time Average ◽  
Record Section ◽  
Section Form

Techniques have been developed for the usefulness of the expanding reflection profile whose basic elements were described by Dix in 1955. Procedures have been established which make the shooting and interpretation of these expanding reflection spreads simpler and more reliable. Special presentations have been developed for the displaying of these profiles on record sections, and nonlinear paper has been designed for plotting the time‐squared versus distance‐squared graphs. The expanding spread is a valuable seismic tool and has numerous applications. It may be used for the identification of reflections and multiples. From the true reflections, calculations can be made to present the normal velocity survey information, i.e., time, average velocity, and interval velocity versus depth. Among other uses is the determination of the normal moveout curve. Various types of presentations are used to display expanding spreads in record section form. Also, various noise and multiple problems are exhibited.

Determination of Fracture Orientation from Pressure Interference

1960 ◽  
Vol 219 (01) ◽  
pp. 301-304 ◽  
Author(s):  
Lincoln F. Elkins ◽  
Arlie M. Skov
Keyword(s):  
Fracture Orientation

scholarly journals Uncertainties in the Analysis of Avoa for Determination of Fracture Orientation

1998 ◽  
Vol 53 (5) ◽  
pp. 621-627 ◽  
Author(s):  
H. Houllevigue ◽  
S. Harwood ◽  
P. S. Rowbotham ◽  
I. Bush ◽  
P. R. Williamson ◽  
...  
Keyword(s):  
Fracture Orientation

Determination of Fracture Orientation by Multi-Well Interference Testing

2002 ◽  
Author(s):  
Mohamed Cherifi ◽  
Djebbar Tiab ◽  
Freddy H. Escobar
Keyword(s):  
Fracture Orientation

The nonuniqueness of the determination of interval velocities from moveout velocities

Geophysics ◽  
1989 ◽  
Vol 54 (9) ◽  
pp. 1209-1211 ◽  
Author(s):  
Theodor C. Krey
Keyword(s):  
Seismic Profile ◽  
Layered Earth ◽  
Interval Velocity ◽  
Offset Time ◽  
Zero Offset ◽  
Interval Velocities

In earlier papers (Krey, 1976; Hubral and Krey, 1980) I described how to obtain an equation for [Formula: see text], the nth interval velocity in an isovelocity layered earth having interfaces with arbitrary dips and curvatures, provided the velocities [Formula: see text], [Formula: see text], … to [Formula: see text] for the first n − 1 layers and the depths of the first n − 1 interfaces [Formula: see text], K = 1, 2, …, n − 1, are known and have continuous derivatives. Moreover, we assume that the zero‐offset time for the reflection from the base of the nth layer and gradient of the traveltime with respect to the horizontal coordinates are known. Finally, the normal moveout (NMO) velocity [Formula: see text] for the nth interface is observed in one arbitrary azimuth (one only), defined by ϕ, the angle between the x‐axis and the seismic profile.

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