Temperature (UHT-MSM) Data Processing
ODP logging
contractor: LDEO-BRG
Hole: 1189C
Leg: 193
Location: Manus Basin (Bismarck Sea)
Latitude: 3° 43.242' S
Longitude: 151° 40.524' E
Logging date: December 29, 2000
Bottom felt: 1700 mbrf
Total penetration: 166 mbsf
Total core recovered: no recovery (LWD hole)
Temperature
Tool Used: UHT-MSM
Bottom Hole Assembly Depth: 1710 mbrf
Total Depth Drilled: 1866 mbrf
Total Depth Logged: 1773 mbrf
Depth versus time recording available: YES
Logging Runs
One pass recorded. Data recorded both downhole and uphole. No wireline heave compensation was used for this run.
The Ultra-high Temperature Multisensor Memory tool (UHT-MSM) is a slimhole probe running on the coring line (sand line). The Geophysical Research Corporation developed the tool for the University of Miami and it was deployed for the first time during Leg 169. The UHT-MSM contains internal and ultra-high external temperature measuring devices, a pressure gauge, a multisensor memory unit, and a dewar flask that acts as an insulator to maintain a stable temperature and cool-down rate for the tool. The heat shield is aircraft-grade aluminum bound at both ends by brass heat sinks. The dewar flask can maintain an internal temperature suitable for tool operation for 4 - 5 hr at an external temperature of 400¹C. Operations are possible up to 10 hr if the average temperature does not exceed 232¹C.
The UHT-MSM tool records pressure, borehole temperature (Text), and internal tool temperature (Tint). This tool can only be run in memory mode, where the tool is fastened to the sand line and the data is stored in memory and downloaded upon retrieval. Borehole fluid temperature is recorded with one thermistor located at the bottom of the tool. A pressure transducer is programmed to turn the tool on at a depth specified by the operator, which is typically set to begin 30 min after tool initialization.
Drilling and circulation operations considerably disturb the temperature distribution inside the borehole, thus preventing equilibrated temperature conditions. The amount of time elapsed between the end of drilling fluid circulation and the beginning of logging operations is not long enough to allow the borehole to recover thermally.
To obtain depth records, the internal tool clock was synchronized with rig floor time and the computer in the sub-sea shop. The computer in the sub-sea shop was then used to obtain cable length time-depth records of the sand line as the tool was being lowered in the hole. These depth data were merged with the data recorded in memory by the UHT-MSM tool by matching absolute time in the two data sets. The sub-sea shop measured depth at 4 to 5 sec intervals whereas the tool measured temperature at 1-sec intervals. Therefore, depth values were interpolated from the toolÍs temperature versus depth profile. The depths in the processed files are reported in meters below rig floor (mbrf) and meters below sea floor (mbsf). The pressure data in these files is suspect because the pressure transducer was not working properly throughout the leg.
This hole was re-entered with the UHT-MSM tool approximately 12hours after it was initially drilled with an LWD RAB tool string. The pipe was set 1710 mbrf (10 mbsf) during the temperature run. An obstruction was encountered at 1773 mbrf that prevented the acquisition of temperature logs below this depth.
Information about the temperature logging operations can be found in the Site Chapter (Explanatory Notes, Operations, and Downhole Measurements sections), ODP IR volume.
For further information about the processing, please contact:
Cristina Broglia
Phone: 845-365-8343
Fax: 845-365-3182
E-mail: Cristina Broglia