Structure and Pattern Recognition
-
Upload
rosa-k-chang-h -
Category
Documents
-
view
225 -
download
0
Transcript of Structure and Pattern Recognition
-
7/27/2019 Structure and Pattern Recognition
1/20
9- 1
Structure and Pattern Recognition
Structure and Pattern RecognitionObjec t ive o f t h i s Chap te r :
Recognition the basic dip patterns of:
Red - downdip thickening Blue - downdip thinning Green - constant section
These patterns will be used to define:
Structural dip from the green patterns.
Copyright 1999
Schlumberger Oilfield Services
4100 Spring Valley Road, Suite 600, Dallas, Texas 75251
Reproduction in whole or in part by any process , including lecture, is prohibited.
Printed in U.S.A.
Version 9.2
-
7/27/2019 Structure and Pattern Recognition
2/20
9- 2
Structure and Pattern Recognition
Structural AnalysisStructural analysis consists of defining the structural dip and the evaluation of unconformities andfaults.
Dipmeter ProcessingDipmeter processing of the data recorded with the electrical images is an excellent quick look fordetermining structural dip as well as for locating some faults and unconformities. Dipmeterprocessing is very useful in resolving low structural dip.
Structural DipDip computation of either the borehole images or dipmeter processing is a measurement of structuraldip and not regional dip. Regional dip, as determined from multiple well logs is an area, can bedifferent from structural dip resolved from a single well. Dips computed from either boreholeimages or from dipmeter can be influenced by compaction or structural changes. The figure oppositeillustrates the influence of compaction and structural uplift.
Structural dip is a n average of many dip co mputations ; therefore, a dipme ter plot will yield thestructural dip more accurately than a point by point manual computation in low structural dipsituations. A long correlation length, eight feet, will usually yield an accurate dip. In higherstructural dips, image analysis can provide higher confidence data. The two types of processing docompliment each other. Structural dip and mega-patterns from dipmeter processing will be presentedfirst.
Regional Dip vs. Structural Dip
R e g i o n a l D i p
Rule : Structural dip may be projected horizontally as far asthe green pattern extends vertically.
S t r u c t u r a l D i
p
-
7/27/2019 Structure and Pattern Recognition
3/20
9- 3
Structure and Pattern Recognition
Structural Dip v s. Regional Dip ExampleAn example opposite illustrates the importance of structural dip determination. Well No. 1penetrated a carbonate at 3814 ft. There was a strong oil show. Regional dip was 1SSW. Well No.2 was located 2210 ft to the NNE and did penetrate the carbonate in a much better structural positionas 3754 ft. This was the expected depth from regional dip projection. Well No. 2 produced oil atthe rate 55 BOPD but with 120 BWPD. A dipmeter was run in Well No. 2. The structural dip wasdetermined to be 2 NNE. This indicated a closure to the SSW, which is regionally downdip. WellNo. 3 was located 736 ft WSW of Well No. 2 and along the WNW-ESE structural strike. Final welllocation was 100 ft to the ESE of Well No. 2. (A well located only 736 ft from a marginal well wasnot deemed to be politically sound). Well No. 3 produced oil at the rate of 200 BOPD with no waterproduction. Structural dip determination is very important in locating potential closur es.
Example of Regional vs. Structural Dip
Subsea at Pay Zone Production Structural Dip
No. 22NNE
No. 1Assumed
1SSW
No. 3
Flat Dip
2/3
1/3
N
2210 f t
Re giona l Dip = 1 SSW
Structu ral D ip
Well No. 3 3 7 54200 BOPD0 BW P D
Well No. 2 37 7 65 5 B O P D + 1 2 0 B W P D2 N NE
Regiona l DipWell No. 1
38 1 4Oi l Show?
-
7/27/2019 Structure and Pattern Recognition
4/20
9- 4
Structure and Pattern Recognition
Dip PatternsThere are four basi c groups of dip pat terns defined b y Al Gilreath:
Downdip thinning Blue
Constant downdip Green Downdip thicken ing Red
Random Bedding Yellow
All patterns must have a constant azimuth, but the dips either increase upward, decrease upward, orremain constant.
0
NWSEN
Blue Pattern:Constant Azimuth
Increasing Upward MagnitudeDowndip Thinning
N
E
W
S
0 30 60 90
Downdip to NE
or zonta ert ca
45
Dipmeter
Dip AngleFrom Horizontal
Borehole
0
SENWS
Red Pattern:Con stant Azimuth
Decreasing U pward Magnit udeDowndip Th icken ing
NE
WS
DipmeterBorehole
FMS
0
NWSEN
Green Pattern:Con stant Azimuth
Constant Magn itude
Constant Downdip Section
N
E
W
S
DipmeterBorehole
FMS - BORMAP
ConstantSectio n
DowndipThickening
Blue:Downdip Thinning
Green:Constant Thickness
Red:Downdip Thickening
-
7/27/2019 Structure and Pattern Recognition
5/20
9- 5
Structure and Pattern Recognition
Pattern Recognition Exercise 1Objec t ive : Determination of dips and mega -patterns from arrow plots.
Ques t ions : Complete the blanks opposite.
Pattern Recognit ion Exercise 1
7 2 0 0
7 0 0 0
6 8 0 0
6 6 0 0
6 4 0 0
0 90Tad pol e ( de g )
Magnitude Azimuth
Construct Arrow Plot of
45 10017 34575 335
Mark the patterns (red, blue, green)
-
7/27/2019 Structure and Pattern Recognition
6/20
9- 6
Structure and Pattern Recognition
Borehole Drif tUnless controlled, the magnitude and direction of borehole drift is a useful indication of structuralevents. The borehole deviation is presented much as the dipmeter arrow plot. The body of thetadpole indicates the magnitude of the borehole deviation and is measured with reference to gravity.The arrow points in the direction of borehole drift and is measured with reference to magnetic northbut presented as true north.
Borehole drift in a consolidated formation will vary with the structural dip and with the boreholefluid. The bit will drift updip in mud drilled boreholes and downdip in air drilled boreholes. Themagnitude of drift reflects the structural dip in the lower dip ranges but does not respond when thestructural dip exceeds approximately 60.
Borehole Deviation Borehole Drifts - Consolidated
Updip in mud drilled boreholes Downdip in air drilled boreholes
Borehole Drifts - Unconsolidated and Flat Dip
Tend to spiral Doglegs may occur at
Faults Unconformities
Structural dip changes
Borehole Drift
0 10
Drift is to the NE at
5 from ver tical
Calipers Pseudo-Images 0 Dips 90 Drift0 20
-
7/27/2019 Structure and Pattern Recognition
7/20
9- 7
Structure and Pattern Recognition
Pattern Recognition Exercise 2Objec t ive : Pattern recognition.
Ques t ions : Mark the dip patterns.
AzimuthFan
Plot
BoreholeDrift
-
7/27/2019 Structure and Pattern Recognition
8/20
9- 8
Structure and Pattern Recognition
Pattern Recognition Exercise 3Objec t ive : Pattern recognition.
Ques t ions : Mark the patterns.
-
7/27/2019 Structure and Pattern Recognition
9/20
9- 9
Structure and Pattern Recognition
Pattern Recognition Exercise 4Objec t ive : Pattern recognition.
Ques t ions : Mark the patterns.
Ref: True~ 445 samples ~
: All
900 Tadpole (deg)
10300
10400
10500
10600
~ Scale 1 : 388 ~
CAUTION:If a fracture/dip belongs toseveral sets it will be codedaccording to the latestShow selection.
Well Overview: 10300.0 - 10600.0 ft - FracView 1. 3A
-
7/27/2019 Structure and Pattern Recognition
10/20
9-10
Structure and Pattern Recognition
Pattern Recognition Exercise 4Objec t ive : Pattern recognition with structural dip.
Ques t ions : Mark the patterns.
Ref: True~ 445 samples ~
: All
900 Tadpole (deg )
10300
10400
10500
10600
~ Scale 1 : 388 ~
CAUTION:If a fracture/dipbelongs toseveral sets itwill be codedaccording tothe latestShow selection.
Well Overview: 10300.0 - 10600.0 ft - FracView 1.3A
Ref: Relative~ 124 samples ~
: All
900 Tadpole (deg )
10300
10400
10500
10600
~ Scale 1 : 388 ~
CAUTION:If a fracture/dipbelongs toseveral sets itwill be codedaccording tothe latestShow selection.
Well Overview: 10300.0 - 10600.0 ft - FracView 1.3A
If structural dip greater than 4 then always use the structural dip subtract (relative) when markingdip patterns.
-
7/27/2019 Structure and Pattern Recognition
11/20
9-11
Structure and Pattern Recognition
Structural Dip Exercise 1Objec t ive : Determination of structural dip from arrow plots.
Ques t ions : What is the structural dip?
An offset located 1000 structurally up dip should gain ____________ feet.
1000
Structural gain = ___________ ft.
-
7/27/2019 Structure and Pattern Recognition
12/20
9-12
Structure and Pattern Recognition
Structural Dip Exercise 2Objec t ive : Determination of structural dip from arrow plots.
Ques t ions : What is the structural dip?
8400
8300
8250
8200
0 9 0Tadpo le (deg )
G R (A PI) 1 5 0
Ref : T rue~ 3 4 5 S a m p le s ~
: A l l
~ S c a l e 1 : 3 2 1 ~
CAUTION:If a frac ture/ dip belongsto several s ets i t wil l becoded acco rd ing t o thelatest 'Show' selection.
W el l O v e r v ie w : 5 0 0 0 .0 f t - 9 0 0 0 . 0 ft - F r a c Vi e w 1 .3 A
8350
0
-
7/27/2019 Structure and Pattern Recognition
13/20
9-13
Structure and Pattern Recognition
0 60 120 180 240 300Orientation: North
TD:67/260
TD:10/95TD:15/90TD:13/90
TD:3/350
TD:51/71
TD:65/250
TD:27/259
TD:26/256
TD:62/87
TD:12/301
TD:10/329TD:6/325
TD:15/256
TD:11/313
TD:11/302
TD:10/253
TD:60/75
8262
8260
8258
8256
8254
8252
8250
82482514
2515
2516
2517
2518
Display 1 ; scale 1/20
-
7/27/2019 Structure and Pattern Recognition
14/20
9-14
Structure and Pattern Recognition
Structural Dip Exercise 3Objec t ive : Determination of structural dip from arrow plots.
Ques t ions : What is the structural dip?
0 90Tadpole
(deg)
Ref: True~ 194 samples ~
: All6750
6800
6850
6900
~ Scale 1:221 ~
Caution: If a fracture/dip belongs to severalsets it will be codedaccording to the latestShow selection.
Well Overview: 6477.0 - 7006.5 ft - FracView 1.3A
-
7/27/2019 Structure and Pattern Recognition
15/20
9-15
Structure and Pattern Recognition
: E x a m p l e s e
t
: A l l o t
h e r s
A z i m u t
h H i s t o g r a m
R e f : T r u e ,
N . H
e m i s p h e r e
~ 1 5 0 s a m p l e s ~
S t e r e o n e t : 6
7 5 0 . 0 - 6
9 0 0 . 0 f t - F r a c V
i e w
1 . 3 A
S t e r e o n e t : 6
7 5 0 . 0 - 6
9 0 0 . 0 f t - F r a c V
i e w
1 . 3 A
: E x a m p l e s e
t
: A l l o t
h e r s
W u l
f f S t e r e o n e t
( U p p e r
H e m
i s p h e r e )
P o l e s
t o p l a n e s
R e f : T r u e ,
N . H e
m i s p h e r e
~ 1 5 0 s a m p
l e s ~
E x a m p l e s e
t :
2 . 1 / 3 1 4
M e a n o r
i e n t . : d i p
/ a z i m u t
h
: E x a m p l e s e
t
: A l l o t
h e r s
R e f : T r u e
~ 1 7 2 s a m p l e s ~
F L I P V e r s
i o n
4 . 4 A
( C ) S c
h l u m
b e r g e r
1 9 9 0
C A U T I O N :
I f a
f r a c
t u r e
/ d i p
b e l o n g s
t o s e v e r a
l
s e t s i t w
i l l b e c o
d e d
a c c o r d
i n g
t o t h e
l a t e s t
S h o w
s e l e c t
i o n .
~ S c a l e
1 : 2 2 1 ~
W e l
l O v e r v
i e w : 6
4 7 7 . 0 - 7
0 0 6 . 5
f t - F r a c V
i e w
1 . 3 A
6 7 5 0
6 8 0 0
6 8 5 0
6 9 0 0
0
9 0
T a d p o
l e ( d e g
)
-
7/27/2019 Structure and Pattern Recognition
16/20
9-16
Structure and Pattern Recognition
Structural Dip Exercise 4Question: What is the structural dip?
RAB Images / Dips Electrical Images / Dips
-
7/27/2019 Structure and Pattern Recognition
17/20
9-17
Structure and Pattern Recognition
Structural Dip Exercise 5Quest ion: What is the structural dip?
1 1 2 2 4
1 1 2 2 5
1 1 2 2 6
1 1 2 2 7
1 1 2 2 8
1 1 2 2 9
1 1 2 3 0
1 1 2 3 1
I m a g e
1 1 2 1 9 -
1 1 7 3 5 F t -
F r a c
V i e w
1 . 3
L I P V e r s i o n
4 . 4 A - (
C ) S c h
l u m
b e r g e r
1 9 9 0
1 1 0 8 0
1 1 2 5 0
W
N S
E
S t e r e o n e t :
1 1 0 0 0 . 0 -
1 1 6 9 0 . 0 f t
. - F r a c V
i e w
1 . 9 A
W e l
l O v e r v
i 3 e w :
0 0 9 0
. 0 -
1 1 6 3 0 . 0 f t -
F r a c V
i e w
1 . 3 A
0
9 0
T a d p o l e
( d e g
)
R e f :
T r u e
~ 6 0 s a m p
l e s ~
: A l l
W u
l f f S t e r e o n e t
( U p p e r
H e m
i s p
h e r e )
P o
l e s
t o p l a n e s
R e f :
T r u e ,
N . h
e m i s p
h e r e
~ 5 3 s a m p
l e s ~
: G r e e n
S e t
G r e e n
S e t :
7 1
. 8 / 6 3
M e a n o r i e n
t : d i p / a z i m u t h
-
7/27/2019 Structure and Pattern Recognition
18/20
9-18
Structure and Pattern Recognition
Structural Dip Exercise 5 (continued)Quest ion: If the following information is used
1. Vert ical wel lbore; and
2. Measured thickness of pay sand is 202 ft.
then
1. What is the true sand thickness?
2. If 50 ft is a minimum thickness, is this a commercial well?
Measured
Thickness
202 ft.
-
7/27/2019 Structure and Pattern Recognition
19/20
9-19
Structure and Pattern Recognition
Structure and Pattern Recognition Exercise - AnswersPattern Recognition
Exercise 1
7200
7000
6800
6600
6400
0 9 0Tad pole (deg )
Magnitude Azimuth
17 4525 14029 2854 105
Construct Arrow Plot of
45 10017 34575 335
Mark the patterns (red, blue, green)
-
7/27/2019 Structure and Pattern Recognition
20/20
9 20
Structure and Pattern Recognition
Exercise 2
a. Structure Interpretat ion:
Blue from top to 320 ft
Green from 320 ft to 530 ft
Red from 530 ft to TD
b. Stratigraphic Interpretation
Many red/blue/green patterns
Exercise 3
1 . R ed Pa tte rn .
Exercise 4
1. Major red from 10400 f t to 10540 ft .
Structura l Dip
Exercise 1
1. 10.1 at 48.84; gain = tan 10.1*1000= 178
Exercise 2
1. 6.5 at 276 above 8248 ft
6.2 at 39 below 8248 ft
Exercise 3
1 . 2.1 at 314
Exercise 4
1. FMI: 56.97 magnitude at 115.55 azimuth, RAB: 59:25 magnitude at 110.26 azimuth.
Exercise 5
1 . 70.8 at 63
Yes, thickness is 66.43 ft
70.8 202
True Thickness
Cos 70.8 = True thickness/ 202= 66.43
T r u e T h i c k n e s s
If 80, then = 35.1
: Fractures: Faults: Structure below: Structure above: All others
Azimuth Histogram
Ref: True, N. Hemisphere~ 65 s amp le s ~
: Structure below fault: S t r u
S t e r eone t : 8168.1 - 8469 .0 ft - F r acV iew 1 .3A
8200
8300
8400
0
N
S
EW
N
S
EW
Wulff Stereonet(Upper Hemisphere)
Poles to planesRef: True, N. Hemisphere
~ 72 s amp le s ~
: Structure below fault: Structure above fault: Faults: Fractures
Structure below fault:6 . 2 /89
Structure above fault:6 . 5 /276
S te r eone t : 8168.1 - 8469 .0 ft - F r acV iew 1 .3A
Mean orient.:dip/azimuth
Wel l Ove rv i ew: 8168 .1 - 8469 .0 f t - F r acV iew 1 .3A
Ref: True~ 167 s amp le s ~
~ Scale 1:389 ~
CAUTION:If a fracture/dipbelongs toseveral sets itwill be codedaccording to thelatest 'Show'selection.