Down-hole logging in brief
-
Upload
anuar-sheikh-ali -
Category
Data & Analytics
-
view
96 -
download
0
Transcript of Down-hole logging in brief
GEOPHYSICAL LOGGING FOR Ground Water
• Introduction • Field Operations • Methods• Log Analysis• Conclusion
INTRODUCTION
• Pioneered by for O&G • Making record of subsurface physical
properties to characterize geology • Also known as down-hole(DH);borehole;
well ;wireline logging(O&G)
WHY LOG?
• To assist in hydro-geological assessment; samples aren’t depth corrected
• To calibrate formation resistivity from GG• To assist in well design • To QC drilling contractor’s work for claims
purpose: diameter, casing/screen installed etc.
FIELD OPERATIONS
• Lowering tool into well using cable attached to auto-winch connected to laptop via hardware and powered by 12V DC
• Refer to Borehole logging – How To @ \\172.16.26.2\Technical Data\Perak\50MLd Groundwater Project in Btg Pdg\Downhole_ Geophysics\NOTES
SCHEMATIC
On Golf Cart@KLGCC
Carried-out Winch @Cluny
In-vehicle winch @Bedford
Under the sun @K. Slim
In the Rain @Cluny East
METHODS
• TCDS/TCGS incl. temp, conductivity ( + gamma)
• ELOG incl. resistivity & natural gamma• CALP – well diameter• SIND – conductivity (calc. resistivity) + gamma• OPTV – Optical televiewer• FLOW – Impeller Flowmeter
1a.TCDS/TCGS
• TCDS/TCGS – Temp, conductivity (+ Gamma)• Thermister measures fluid temperature(deg.
Celsius).• Applied in porous & fractured acquifers• Detects influx/efflux; Logging speed 3m/min• Drilling mud/fluid affect readings
1b.CONDUCTIVITY
• Unit – Siemens• Conductivity = 1/resistivity(Ohmm)• Application in porous acquifers; high-salty• Most well in SEL being relog by SIND tool for
confirmation
TCGS SONDE LAYOUT
• Sample log with temp gradient…..SL290 w/• CALP
TEMPERATURE PROFILE
TEMPERATURE
DEPT
H
SURFACE
CONDUCTIVE GRADIENT
HYDROTHERMAL SYSTEM
UPFLOW
CONDUCTIVE HEAT SOURCE
OUTFLOW ZONE
TEMPERATUREREVERSAL
2.ELOG
• ELOG – Resistivity: short, long,SPR ,SP & natural Gamma
• Applied in porous & fractured acquifers both• Sand/gravel give high readings in resistivity;
low in gamma• Clay & shale give low readings in resistivity;
high in gamma
RESISTIVITY DEPENDS ON
• Porosity &Water content• Water Chemistry • Rock chemistry ; Quartz - high; Clay - low • Degree of rock alteration & mineralization• Temperature
ELOG SONDE LAYOUT
LON
• Sample log with …..SL290
3.CALP
• CALP – measures well diameter• Detects fractures & installed casing.• Applied in fractured acquifers• Logging speed 5m/min; uphole run only• Caliper needs to open completely or incorrect
readings
CALP SONDE LAYOUT
4.SIND
• SIND – Inductive conductivity (EM:Tx/Rx)• Measures conductivity(calc. resistivity)• Applied in porous acquifers (alluvium)• Detects salinity (from cond.); Logging speed
5m/min• Drilling mud/fluid affect readings
SIND SONDE LAYOUT
1. KLT026 (~97m)Raw data as logged on 11/1/2010
Slide 6: SIND Data Slide 7: ELOG Data
Depth: 45m-51mAnomaly observed between 47-50m on resistivity and gamma readings.
FLOW-METER@SPINNER LOG
• Propeller measures flow in well• Identifies depth of water in-flow• Calculate fluid velocity from series of up and
down runs at different cable speeds
Flow-meter
LEDElliptical lens
Protective PVC tape