Density neutron self-consistent caliper
AssigneeNL Industries, Inc.
InventorsWilliam C. Paske, Paul F. Rodney, Ray A. Roeder
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Abstract
Two downhole measurement-while-drilling tools, at least one of which is borehole sensitive, are used to make standard measurements of borehole conditions while drilling. From these measurements, and with some prior knowledge of the lithology, the caliber of the borehole is determined by iteration. The preferred tools are a neutron porosity and a density tool with lithology having been determined by prior seismic survey techniques.
Claims21
A system for determining the caliber of a borehole during drilling operations in an earth formation, comprising:
- first means adapted to make a first measurement of a first physical characteristic of an interior property of said formation;
- second means adapted to make a second measurement of a second physical characteristic of an interior property of said formation, said second physical characteristic being different from said first physical characteristic;
- means for determining the lithology of said formation;
- and
- means to compare said first and second measurements and to initiate an interation process based at least in part upon the said determined lithology, to determine a self-consistant borehole caliber.
A method for determining the caliber of a borehole during drilling operations in an earth formation, comprising the steps of:
- taking a first measurement of a first interior physical property of a formation through which said borehole is passing;
- taking a second measurement of a second interior physical property of said formation, said second physical property being different from said first physical property;
- determining the lithology of said formation;
- and
- comparing said first and second measurements, and based at least in part upon the said determined lithology, initiating an iteration process to determine a self-consistent borehole caliber.
Dependencies are inferred from the claim text.