| Exploration & Production Geology http://www.epgeology.com/ |
|
| Geophysic Thesis http://www.epgeology.com/geophysics-seismics-f22/geophysic-thesis-t21.html |
Page 1 of 1 |
| Author: | FarukG [ Wed Jun 09, 2010 5:22 pm ] |
| Post subject: | Geophysic Thesis |
Good day Sirs/Madams, I am a Master student in Exploration Geophysics in University of Nigeria. Am currently about to start my thesis. My question: How to using seismic velocity for age of rock and porosity in a oil field. All the datas that is given to me is: check shot, synthetic seismograms, composite log, core sample pictures. Please help, as i much appreciate |
|
| Author: | JacobNestor [ Wed Sep 01, 2010 10:29 pm ] |
| Post subject: | Re: Geophysic Thesis |
Faruk, there is no direct way to get a rocks age data from velocity information. Biostrat will be your only option or correlation with other dated wells. Off course you could use the checkshot and velocity data to tie your well logs to seismic and aid correlation or maybe correlate to seismic horizons which have been dated in other studies. Velocity data says nothing about a successions age, although in general the older the sediment, the more compacted and the higher the sonic velocity will be. Some small kinks in the sonic log or checkshot data may indicate unconformities, which may be linked to eustatic sea-level changes. This is very far fetched though. It;s best ti get biostrat analyses. Hope this helped, good luck! |
|
| Author: | FarukG [ Fri Sep 03, 2010 10:28 pm ] |
| Post subject: | Re: Geophysic Thesis |
This very usefull, I understand many of it, but not all i do... Sorry, can you axplain more? |
|
| Author: | JacobNestor [ Fri Sep 03, 2010 10:42 pm ] |
| Post subject: | Re: Geophysic Thesis |
Faruk, Well I don't know how to explain it better. What do you not understand? I did notice I missed you porosity question. Seismic velocity does relate to porosity, so you could technically derive it from that, but this is complicated. You can use sonic logs (from wells) to derive predict porosity using a relationship that has been found empirically (through measurements). density, velocity and porosity are related rock properties. If you know two of them, you can predict the third one pretty accurately. One way is using Vp n Phi (Porosity) is as follow VP = A - B*Phi - Compaction Factor * C (units - Km/sec) Her, A, B and C are constants and the compaction factor is a shale compaction factor that varies with pressure (eg depth). If you need to know the C. and A = 5.59, B = 6.93. Also, please remember that check shot data is pretty useless if you have composite logs with sonic log already there. They are usually only shot if other logs are too expensive or not necessary. Synthetic seismograms are primarily useful to see a reflector's top or an impedance contrast based on the strata your well runs through. You can later compare this with the seismic that runs through the well location to get a velocity-depth relationship... I hope that answered the rest of your questions. Regards, -J |
|
| Page 1 of 1 | All times are UTC + 1 hour |
| Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group http://www.phpbb.com/ |
|