Temperature Data Processing

 

ODP logging contractor: LDEO-BRG

Hole: 808C

Leg: 131

Location: Nankai Trough (NW Pacific Ocean)

Latitude: 32° 21.17' N

Longitude: 134° 56.66' E

Logging date: April, 1990

Bottom felt: 4685.5 mbrf (used for depth shift to sea floor)

Total penetration: 1327 mbsf

Total core recovered: 572.4 m (55 %)

 

Water Depth: 4674.6 mbsl

Temperature Tool Used: LDEO-TLT

Depth versus time recording available: NO

 

Logging Runs

 

Logging string: DIT/BHC/NGT

Wireline heave compensator was not used because the sea was calm.

 

Tool Information

 

The LDEO-TLT tool is a self-contained, high precision, low-temperature logging tool that is attached to the bottom of the Schlumberger tool strings. The tool provides two temperature measurements (in degree Celsius, recorded by a fast-response and a slow-response thermistor.  The fast-response thermistor, though low in accuracy, is able to detect sudden, small temperature excursions caused by fluid flow between the formation and the borehole. The highly accurate, slow-response thermistor can be used to estimate heat flow. Pressure and the two temperature measurements are recorded as a function of time: conversion to depth can be based on the pressure reading (Legs 123-157) or, preferably, on simultaneous recording (by Schlumberger) of depth and time (Legs 159-181).

 

Data Processing

 

The data was recorded through drill pipe from 0 to 770 mbsf. A pressure-depth relationship was originally used to calculate depth, but no documentation is available about the actual calculation. As no original data was available at the time of this review, no re-processing could be performed. The calculated depths were smoothed with a 50-samples running average. Temperatures were smoothed with a 5-samples window.

 

Information about the temperature logging operations can be found in the Site Chapter (Operations, Downhole Measurements, and Heat Flow sections), ODP IR volume 131.

 

Cristina Broglia
Phone: 845-365-8343
Fax: 845-365-3182
E-mail: Cristina Broglia