environmental and exploration geophysics ii
DESCRIPTION
Environmental and Exploration Geophysics II. Dipping layer reflection events and the common midpoint gather. tom.h.wilson [email protected]. Department of Geology and Geography West Virginia University Morgantown, WV. Dipping Layer Reflection Event with Offset Apex. - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Environmental and Exploration Geophysics II](https://reader036.vdocument.in/reader036/viewer/2022081420/5681519d550346895dbfcf66/html5/thumbnails/1.jpg)
Tom Wilson, Department of Geology and Geography
Environmental and Exploration Geophysics II
Department of Geology and GeographyWest Virginia University
Morgantown, WV
Dipping layer reflection events Dipping layer reflection events and the common midpoint and the common midpoint
gathergather
![Page 2: Environmental and Exploration Geophysics II](https://reader036.vdocument.in/reader036/viewer/2022081420/5681519d550346895dbfcf66/html5/thumbnails/2.jpg)
Tom Wilson, Department of Geology and Geography
Dipping Layer Reflection Event with Offset Apex
![Page 3: Environmental and Exploration Geophysics II](https://reader036.vdocument.in/reader036/viewer/2022081420/5681519d550346895dbfcf66/html5/thumbnails/3.jpg)
Tom Wilson, Department of Geology and Geography
Vh
Vh
t
tapex2
cos2
0
How do you find depth h, velocity V and dip ?
cos0
t
tapex
0
1cost
tapex
![Page 4: Environmental and Exploration Geophysics II](https://reader036.vdocument.in/reader036/viewer/2022081420/5681519d550346895dbfcf66/html5/thumbnails/4.jpg)
Tom Wilson, Department of Geology and Geography
sin2hxapex
sin2apexx
h
If you could not see the direct arrival then you could solve for V using either expressions for t0 or tapex.
![Page 5: Environmental and Exploration Geophysics II](https://reader036.vdocument.in/reader036/viewer/2022081420/5681519d550346895dbfcf66/html5/thumbnails/5.jpg)
Tom Wilson, Department of Geology and Geography
![Page 6: Environmental and Exploration Geophysics II](https://reader036.vdocument.in/reader036/viewer/2022081420/5681519d550346895dbfcf66/html5/thumbnails/6.jpg)
Tom Wilson, Department of Geology and Geography
![Page 7: Environmental and Exploration Geophysics II](https://reader036.vdocument.in/reader036/viewer/2022081420/5681519d550346895dbfcf66/html5/thumbnails/7.jpg)
Tom Wilson, Department of Geology and Geography
![Page 8: Environmental and Exploration Geophysics II](https://reader036.vdocument.in/reader036/viewer/2022081420/5681519d550346895dbfcf66/html5/thumbnails/8.jpg)
Tom Wilson, Department of Geology and Geography
![Page 9: Environmental and Exploration Geophysics II](https://reader036.vdocument.in/reader036/viewer/2022081420/5681519d550346895dbfcf66/html5/thumbnails/9.jpg)
Tom Wilson, Department of Geology and Geography
This is referred to as a stacking chart. The significance of the name will become apparent later on.
![Page 10: Environmental and Exploration Geophysics II](https://reader036.vdocument.in/reader036/viewer/2022081420/5681519d550346895dbfcf66/html5/thumbnails/10.jpg)
Tom Wilson, Department of Geology and Geography
For next week at this time construct a stacking chart for a symmetrical split spread consisting of 12 geophones arranged 6 on each side of the source.
Bring questions to class on Tuesday
![Page 11: Environmental and Exploration Geophysics II](https://reader036.vdocument.in/reader036/viewer/2022081420/5681519d550346895dbfcf66/html5/thumbnails/11.jpg)
Tom Wilson, Department of Geology and Geography
![Page 12: Environmental and Exploration Geophysics II](https://reader036.vdocument.in/reader036/viewer/2022081420/5681519d550346895dbfcf66/html5/thumbnails/12.jpg)
Tom Wilson, Department of Geology and Geography
![Page 13: Environmental and Exploration Geophysics II](https://reader036.vdocument.in/reader036/viewer/2022081420/5681519d550346895dbfcf66/html5/thumbnails/13.jpg)
Tom Wilson, Department of Geology and Geography
![Page 14: Environmental and Exploration Geophysics II](https://reader036.vdocument.in/reader036/viewer/2022081420/5681519d550346895dbfcf66/html5/thumbnails/14.jpg)
Tom Wilson, Department of Geology and Geography
![Page 15: Environmental and Exploration Geophysics II](https://reader036.vdocument.in/reader036/viewer/2022081420/5681519d550346895dbfcf66/html5/thumbnails/15.jpg)
Tom Wilson, Department of Geology and Geography
![Page 16: Environmental and Exploration Geophysics II](https://reader036.vdocument.in/reader036/viewer/2022081420/5681519d550346895dbfcf66/html5/thumbnails/16.jpg)
Tom Wilson, Department of Geology and Geography
![Page 17: Environmental and Exploration Geophysics II](https://reader036.vdocument.in/reader036/viewer/2022081420/5681519d550346895dbfcf66/html5/thumbnails/17.jpg)
Tom Wilson, Department of Geology and Geography
![Page 18: Environmental and Exploration Geophysics II](https://reader036.vdocument.in/reader036/viewer/2022081420/5681519d550346895dbfcf66/html5/thumbnails/18.jpg)
Tom Wilson, Department of Geology and Geography
![Page 19: Environmental and Exploration Geophysics II](https://reader036.vdocument.in/reader036/viewer/2022081420/5681519d550346895dbfcf66/html5/thumbnails/19.jpg)
Tom Wilson, Department of Geology and Geography
The effect of the moveout correction on the traces in the common midpoint (CMP) gather is to create a composite normal incidence trace that effectively shares a coincident source and receiver at the midpoint shared by all the traces in the gather. We’ll discuss CMP data in more detail in a couple lectures.
![Page 20: Environmental and Exploration Geophysics II](https://reader036.vdocument.in/reader036/viewer/2022081420/5681519d550346895dbfcf66/html5/thumbnails/20.jpg)
Tom Wilson, Department of Geology and Geography
Stages of development: Sediments pile up and dip into the Gulf. Mass wasting of the shelf proceeded under the pull of
gravity
![Page 21: Environmental and Exploration Geophysics II](https://reader036.vdocument.in/reader036/viewer/2022081420/5681519d550346895dbfcf66/html5/thumbnails/21.jpg)
Tom Wilson, Department of Geology and Geography
Faults rise to the surface in the landward direction as the sediments take a sled ride into the Gulf. These faults accommodate extension at a slow (creeping) but steady pace. Time is always available in excess for the geologist.
![Page 22: Environmental and Exploration Geophysics II](https://reader036.vdocument.in/reader036/viewer/2022081420/5681519d550346895dbfcf66/html5/thumbnails/22.jpg)
Tom Wilson, Department of Geology and Geography
http://www.gcmwenergy.com/seismic_line.htm
From Seismic to reservoir image
![Page 23: Environmental and Exploration Geophysics II](https://reader036.vdocument.in/reader036/viewer/2022081420/5681519d550346895dbfcf66/html5/thumbnails/23.jpg)
Tom Wilson, Department of Geology and Geography
Seismic acquistion to subsurface imaging
http://www.gcmwenergy.com/seismic_survey.htm
![Page 24: Environmental and Exploration Geophysics II](https://reader036.vdocument.in/reader036/viewer/2022081420/5681519d550346895dbfcf66/html5/thumbnails/24.jpg)
Tom Wilson, Department of Geology and Geography
Note the roll-over into the glide zone, synthetic and antithetic faults
![Page 25: Environmental and Exploration Geophysics II](https://reader036.vdocument.in/reader036/viewer/2022081420/5681519d550346895dbfcf66/html5/thumbnails/25.jpg)
Tom Wilson, Department of Geology and Geography
![Page 26: Environmental and Exploration Geophysics II](https://reader036.vdocument.in/reader036/viewer/2022081420/5681519d550346895dbfcf66/html5/thumbnails/26.jpg)
Tom Wilson, Department of Geology and Geography
http://www.osradp.lsu.edu/downloads/BGBB/4/dome.gif
![Page 27: Environmental and Exploration Geophysics II](https://reader036.vdocument.in/reader036/viewer/2022081420/5681519d550346895dbfcf66/html5/thumbnails/27.jpg)
Tom Wilson, Department of Geology and Geography
Complex traps and cap rock
![Page 28: Environmental and Exploration Geophysics II](https://reader036.vdocument.in/reader036/viewer/2022081420/5681519d550346895dbfcf66/html5/thumbnails/28.jpg)
Tom Wilson, Department of Geology and Geography
Questions about the Exploration Project
The Main Fault
![Page 29: Environmental and Exploration Geophysics II](https://reader036.vdocument.in/reader036/viewer/2022081420/5681519d550346895dbfcf66/html5/thumbnails/29.jpg)
Tom Wilson, Department of Geology and Geography
At a minimum you should have digitized the main (synthetic fault – light blue) and the antithetic fault that
cuts back into the main fault (antithetic fault- light green)
![Page 30: Environmental and Exploration Geophysics II](https://reader036.vdocument.in/reader036/viewer/2022081420/5681519d550346895dbfcf66/html5/thumbnails/30.jpg)
Tom Wilson, Department of Geology and Geography
On Monday we went through the horizon digitization procedures
![Page 31: Environmental and Exploration Geophysics II](https://reader036.vdocument.in/reader036/viewer/2022081420/5681519d550346895dbfcf66/html5/thumbnails/31.jpg)
Tom Wilson, Department of Geology and Geography
Just as with the fault your picks can be displayed in map view by double clicking the horizon or by dragging over the
Amplitudes or Times from the horizon list in the project tree
Project tree
![Page 32: Environmental and Exploration Geophysics II](https://reader036.vdocument.in/reader036/viewer/2022081420/5681519d550346895dbfcf66/html5/thumbnails/32.jpg)
Tom Wilson, Department of Geology and Geography
For the remainder of the class work in pairs as you complete your horizon interpretation
Note the presence of fault gaps in your horizon picks. This is where you will draw in a fault polygon.
The gap at left is produced by the intersection of the main synthetic fault with the interpreted horizon
![Page 33: Environmental and Exploration Geophysics II](https://reader036.vdocument.in/reader036/viewer/2022081420/5681519d550346895dbfcf66/html5/thumbnails/33.jpg)
Tom Wilson, Department of Geology and Geography
Fault Gap
We’re running a little bit behind but I think we need to take the time to be sure you have the basics down. So we will conclude this
exercise next Monday
![Page 34: Environmental and Exploration Geophysics II](https://reader036.vdocument.in/reader036/viewer/2022081420/5681519d550346895dbfcf66/html5/thumbnails/34.jpg)
Tom Wilson, Department of Geology and Geography
• Construct a stacking chart for a symmetrical split spread consisting of 12 geophones arranged 6 on each side of the source (see handout).
Bring questions to class next Monday. Chart is due next Wednesday.
•Complete your reading of Chapter 4. Dipping layer reflection events are covered on pages 183-186, with additional discussion on pages 186-196. The idea of common depth point sorting is discussed on pages 225 -229. We’ve talked tangentially about resolution (217-219) and velocity analysis (233-238). We will be talking about stacking of CDP gathers (238- 241) and migration (241-244). Discussions of migration will come later but it is helpful to be aware of the issues early on.
• Look over problems 4.1, 4.4 and 4.8.