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

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on

Up

per

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ne

Lo

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zo

ne

See

Det

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d s

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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

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d lo

gs

Sib

ert

s W

ell #

1 –

Up

pe

r zo

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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.