lower pennsylvanian well log interpretations by richard andrews march 2009
TRANSCRIPT
Lower Pennsylvanian
Well Log
Interpretations
by
Richard Andrews
March 2009
Tension
SP sensor
Induction (resistivity)
Neutron
Gamma-ray
Density
Caliper
Typical modern down-hole wireline equipmentLength in feet
SP & GR Resistivity Conductivity
0 API 150 0 ohms 50
Siberts Well #1
See
Det
aile
d s
ecti
on
Up
per
zo
ne
Lo
wer
zo
ne
See
Det
aile
d s
ecti
on
2800
GR & SP
GR & CAL
Res
isti
vity
PE
; D
ensi
ty &
Neu
tron
Por
osity
1 10 100 1K
30 20 10 00 PE 10
2800
0 150
De
taile
d lo
gs
Sib
ert
s W
ell #
1 –
Up
pe
r zo
ne
GR, SP, & CAL Resistivity
6 Inches 16 1 10 100 1K
Detailed logs Siberts Well #1 – Lower zone
3200
3100
GR & Cal Density & Neutron Φ
6 in 16 30 20 10 00 PE 10
Detailed logs Siberts Well #1 – Lower zone
Questions for the Lower Pennsylvanian log exercise
1. What company drilled this well? Who owned the mineral rights?? What is the wellidentification (other than its API number) and what does it mean?
2. “Joe”, a petroleum engineer from Texas designed the drilling parameters for this well. It isbeing drilled in an area experiencing significant over-pressurization despite its shallow depth.
What is going to happen to “Joe’s” well if he hits pay knowing the type of mud he used?
3. Why wasn’t the well logged to the surface?
4. What is the reference datum for the well logs?
5. What matrix density was used to calibrate the porosity logs?
6. How many GR API units define the shale base-line?
7. What is the lithology throughout the upper and lower detailed sections?Color sandstone = yellow, carbonates = blue
8. Identify zone(s) of mudcake buildup.
9. What is the cross-plot porosity between 3,270’-3,280’?What is the lithology?
10. What is the bulk density (not porosity) and resistivity of the shale between 3,030’-3,050’and between 3,125’-3,164’ and why the difference?
11. What is the cross plot porosity between 3166 – 3180? What causes the large separationbetween the two log traces??
12. In the interval 3,160-3,210, why is the SP response greater at the base despite bothintervals having ~same cross-plot porosity? Why is the resistivity higher in the upper half?
13. What is the Rt at 2,788’; 3,175’; and at 3,204’?
14. Why isn’t there a significant SP deflection at 2,788’? 15. What is the density porosity at 3,113’? Explain.