Nuclear magnetic resonance pulse sequences for use with borehole logging tools
This patent describes a method for measuring an indication of an attribute of a volume of earth formation with a borehole tool having means for producing static magnetic fields in a volume of a formation, means for producing oscillating magnetic fields in a volume of a formation, and means for measuring an induced magnetic signal. It comprises producing a static magnetic field in the volume of formation; producing oscillating magnetic fields according to a pulse sequence (W{sub i} {minus} 180 {minus} {tau}{sub i} {minus} 90 {minus} (t{sub cp} {minus} 180 {minus} t{sub cp} {minus} echo){sub j}){sub i} where j = 1,2, J, and J is the number of echoes collected in a single Carr-Purcell-Meiboom-Gill (CPMG) sequence, where i = 1, I, and I is the number of waiting times used in the pulse sequence, where W{sub i} are recovery times before a CPMG sequence, and where {tau} are recovery times before a CPMG sequence, and where t{sub cp} is the Carr-Purcell spacing, in order to induce signals in the volume which are measurable by the tool in the borehole; and measuring with the tool the induced signals.
- Assignee:
- Schlumberger-Doll Research, New York, NY (United States)
- Patent Number(s):
- A; US 5023551
- Application Number:
- PPN: US 7-452903
- OSTI ID:
- 6006999
- Country of Publication:
- United States
- Language:
- English
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47 OTHER INSTRUMENTATION
BOREHOLES
CAVITIES
COUNTING TECHNIQUES
DATA PROCESSING
DIAGNOSTIC TECHNIQUES
MAGNETIC FIELDS
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