L 11 - Geology. Flashcards
formation evaluation may come from what ?
electric logs radioactivity logs acoustic logs dipmeter borehole imaging
where was logging invented?
France
there are two types of log measurement
spontaneous / passive (SP, GR)
Induced / active (acoustic)
(mechanical — Caliper)
what two scenarios may a wireline log be ran
open hole
cased hole
what are some sampling rates?
1 / 6 in
1 / 0.1 in
100 / meter
SP conditions of measurement
open hole
fill with conductive mud (ensure its density is different than the formation water)
How does SP work?
measures the difference in potential between an electrode from a borehole vs one at surface
what influences SP?
salinity of the mud filtrate
therefore, limited when offshore wells drilled with salt water based drilling mud
what does a high resistivity value possibly indicate?
porous , hydrocarbon bearing formation.
Because hydrocarbons are extremely resistive
What does a low resistivity value indicate?
porous formation saturated with salt water
true or false? conductivity log is opposite to that of resistivity log
True
what is a limitation of resistivity and conductivity logs?
boreholes with OBMs or WBMs
what are the three types of resistivity logs?
normal
laterolog (for low res. salt muds)
induction
what does a GR pick up?
the formations radioactivity from thorium, uranium and potassium. Shale high GR reading.
density log measures what?
formations bulk density (electron density)
can translate this to porosity