The Core Barrel Drill String Acceleration tool (DSA) has been designed, manufactured, assembled and tested at LDEO-BRG, for usage on numerous Ocean Drilling Program legs and projects. The primary purpose of the DSA tool is to measure and record the drillbit acceleration and vibration signals while drilling. The DSA tool contains a single axis high sensitivity accelerometer for heave measurements, a three-axial high frequency accelerometer for drillbit vibrations and a high resolution pressure sensor. For ease of deployment, the DSA has been designed as a removable extension of the APC/XCB/RCB core barrels. Using standard threaded connections, the DSA is attached to the top of a selected core barrel prior to core barrel deployment. Except for the connection and disconnection of the DSA, coring activities will not be affected by the presence of the DSA. Upon DSA/core barrel retrieval, the DSA will be disconnected and the data downloaded to the third party data acquisition system in the DHML for immediate analysis.

Applications

1. Downhole heave measurement
2. Drill string vibration
3. Downhole fluid temperture and pressure
4. Reconfigurable to suit

Specifications

Acceleration measurement range (HSA channel)	from -2 g to +2 g
Acceleration measurement range (LSA channel)	t Color
Option 1	from –4 g to +4 g
Option 2	from –25 g to +25 g
Acceleration sampling rate (all channels)	100 Hz
Temperature/pressure sampling rate	1 Hz
Frequency bandwidth (HSA channel)	0 – 2 Hz
Frequency bandwidth (LSA channel)	0 – 50 Hz
Temperature measurement range	from 0°C to +85°C
Temperature resolution	0.5 °C
Pressure measurement range	from 0 to 10,000 psi
Pressure resolution	1 psi
Pressure measurement precision	0.1%FS
Total data recording time:	t C
Drill mode	100 min.
HEAVE mode	8 hr.
Power source batteries	6 "AA" alkaline
Total operation time from 1 set of batteries	about 9 hr.

Deployment

The CB-DSA is housed within our modular digital corebarrel deployment system. It can be swapped with the modular electronics package then deployed with an ODP-style corebarrel. Less than 3 minutes of rig time is consumed rigging up and rigging down this tool.