My PhD Thesis, PDF 3MB - Stanford University

More documents

Recommendations

Info

$Drilling-induced tensile wall-fractures - Stanford University$

D e p t h ( f e e t ) 2580 2640 2720 2800 2880 2960 3040 3120 160 120 80 Q-value 40 (a) P wave Q -log (b) Waveform log - 131 - 0.4 1.2 Travel Time (ms) Figure 5.9 (a) A Qp log for McElroy Well #1202, obtained by the frequency shift method. (b) The waveform log for comparison. At each depth, only the first trace recorded in receiver array is shown. 5.5 CONCLUSIONS
The generalized reflection and transmission coefficients method is applied to numerically investigate seismic wave attenuation in the simple open borehole and complicated boreholes with invaded zones. In order to measure the intrinsic attenuation we need to remove the geometrical spreading effect which is complex and highly frequency-dependent. If we use the frequency shift method to estimate intrinsic attenuation for a simple open borehole, we can introduce a frequency-dependent geometrical spreading factor, exp(-gfz), to do the correction (but only for open hole). It is difficult to determine the details of the frequency-dependent geometrical spreading for the complicated boreholes. I introduce an apparent geometrical spreading factor expressed by 1 / z p , which may approximately include the effect of the frequency- dependent term exp(-gfz) if we select a proper power p. Simulation tests show that the power p=1 for a simple borehole, p1 for a flushed zone model. How large the power p deviates from 1 depends on the structure of the invaded zones, such as the velocity contrast and the invaded depth. For the specific borehole models investigated in this chapter, p=0.5 for the invaded zone model and p=1.21 for the flushed zone model. Chapter 6 - 132 -
Page 1 and 2:
SEISMOGRAM SYNTHESIS IN COMPLEX BOR
Page 3 and 4:
I certify that I have read this dis
Page 5 and 6:
developed in this thesis do not hav
Page 7 and 8:
Finally, I would like to thank my w
Page 9 and 10:
2.4.2 Cased borehole 2.4.3 Borehole
Page 11 and 12:
6.4.3 Attenuation estimation from t
Page 13 and 14:
3.4b Seismograms calculated using t
Page 15 and 16:
List of Tables 2.1 Model parameters
Page 17 and 18:
Seismogram synthesis can help us un
Page 19 and 20:
calculate the wave fields (e.g., St
Page 21 and 22:
modeling techniques to crosswell se
Page 23 and 24:
oth synthetic data and field data.
Page 25 and 26:
simultaneously determine both phase
Page 27 and 28:
to measure formation properties fro
Page 29 and 30:
x ( r , z ) are used. Since there
Page 31 and 32:
normalized Hankel functions of n th
Page 33 and 34:
(1 ) ?u r ( r ) (1 ) ? ( r )
Page 35 and 36:
Figure 2.2 Pictorial explanation of
Page 37 and 38:
Figure 2.3 Pictorial explanation of
Page 39 and 40:
(1 ) (1 ) ( 1) (1 ) (1 ) ? ( r )
Page 41 and 42:
imaginary angular frequency I also
Page 43 and 44:
Figure 2.4 (a) Seismogram calculate
Page 45 and 46:
Figure 2.5 (a) Seismograms calculat
Page 47 and 48:
Table 2.3a Model parameters of a si
Page 49 and 50:
profiling. Chen et al. (1994) gave
Page 51 and 52:
Figure 2.7 (a) Configuration of the
Page 53 and 54:
Figure 2.8a An invaded zone model u
Page 55 and 56:
Two special examples for single bor
Page 57 and 58:
measurement technique: seismic atte
Page 59 and 60:
Let us start with the elastodynamic
Page 61 and 62:
Substituting equation (3.2) into eq
Page 63 and 64:
where { E pq with ( j) ( r ; l , n
Page 65 and 66:
different dimensions. Moreover, R
Page 67 and 68:
3.4 GENERALIZED REFLECTION AND TRAN
Page 69 and 70:
3.6 DETERMINATION OF EIGEN FUNCTION
Page 71 and 72:
Eigenvalues ( n ( j ) ) 2 and ( n
Page 73 and 74:
peak frequency 1KHz. Figures 3.4b g
Page 75 and 76:
Figure 3.4b A common source gather
Page 77 and 78:
3.5b). Figure 3.5a shows the synthe
Page 79 and 80:
(a) Synthetic full waveform sonic l
Page 81 and 82: (a) Seismograms. The peak frequency
Page 83 and 84: 3.9 CONCLUSIONS A semi-analytical a
Page 85 and 86: Seismic wave attenuation includes i
Page 87 and 88: Under this model, the high frequenc
Page 89 and 90: the amplitude. In this study, I con
Page 91 and 92: and the variance to be 2 S 0 (
Page 93 and 94: o dl 18 ( f S f R ) / B 2 - 92 -
Page 95 and 96: Spectrum Shape Figure 4.3a A boxcar
Page 97 and 98: decreases from 370 Hz to 280 Hz ove
Page 99 and 100: Here, the index i represents the it
Page 101 and 102: comparison. We can see that the tom
Page 103 and 104: Figure 4.7 Synthetic test on 2-D at
Page 105 and 106: Figure 4.8 The data picked from the
Page 107 and 108: profile curves within the tomograms
Page 109 and 110: Figure 4.10 The attenuation and vel
Page 111 and 112: Chapter 5 Acoustic Attenuation Logg
Page 113 and 114: decreases with the increasing offse
Page 115 and 116: Assume that the intrinsic attenuati
Page 117 and 118: 2 i 0 ( f f ) i 2 R ( f ) df i
Page 119 and 120: Figure 5.3b Micro-seismograms calcu
Page 121 and 122: This simulation shows the central f
Page 123 and 124: Figure 5.5b Micro-seismograms recor
Page 125 and 126: Figure 5.8 Centroid frequency picks
Page 127 and 128: p 1 log [ z i 1 z i log [ ] R ( f
Page 129 and 130: spreading. To understand how the in
Page 131: 5.9b, in fact, shows the velocity s
Page 135 and 136: eflection and transmission (R/T) co
Page 137 and 138: where, signs "+" and "-" refer to o
Page 139 and 140: Therefore, equation (6.5) is a disp
Page 141 and 142: [ ?v n ( ), ?v p , ?v s ] [ v n
Page 143 and 144: tested for three typical radially l
Page 145 and 146: Figure 6.2 A plot of the function d
Page 147 and 148: 6.4.3 Attenuation Estimation from t
Page 149 and 150: References Aki, K, and Richards, P.
Page 151 and 152: Parker, K., Lerner, R. & Waag, R.,
Page 153 and 154: A-2 ELASTODYNAMIC EQUATION IN TERMS
Page 155 and 156: ? (1 ) (1 ) ( 1) (1 ) ( r , k , )
Page 157 and 158: where, ( j ) k 2 ( j) e 32 ( j )
Page 159 and 160: ( j ) ( j ) ( j ) ( j) ( j ) ( j) E
Page 161 and 162: - 160 -
Page 163 and 164: ( j) E 31 ( j) E 32 ( j) E 33 ( j)
Page 165 and 166: or rewrite it as ( j ) D 11 D 21 (
Page 167 and 168: Appendix C Relationships between th
Page 169: a dl 12 ( f f ) / B o S R ray 2 C
show all

My PhD Thesis, PDF 3MB - Stanford University

Create successful ePaper yourself

Delete template?

Save as template?