borehole geometry logging

Borehole Geometry Logging provides a continuous record of changes in borehole diameter determined by tensioned mechanical arms. Borehole Geometry Logging is one of the most useful and simple of all logs obtained in borehole geophysics. Borehole Geometry tools are integral to most standard logging tools because measurement of the borehole axis is an extremely useful parameter for environmental correction, quantitative interpretation, and cement volume calculation. Borehole geometry logs provide indirect information on subsurface lithology and rock quality. Borehole diameter varies with the hardness, fracture frequency, and cementation of the various materials penetrated. Borehole geometry surveys can be used to accurately identify washouts or swelling or to help determine the accurate location of fractures or solution openings, particularly in wellbores with core loss. Borehole geometry logs can also identify more porous zones in a boring by locating the intervals in which excessive mud filter cake has built up on the walls of the borehole. One of the major uses of borehole geometry logs is to correct for borehole diameter effects. Borehole geometry logs also can be used to place water well screens, position packers for pressure testing in foundation investigations for dams or other large engineering structures, and help estimate grout volumes in solution or washout zones.

Mechanical calipers are standard logging service equipment available in one-, two-, three-, four-, or six-arm tool designs. The shape or geometry of the borehole cross section can be determined with the individual caliper arm readings. The calipers must be calibrated against a known minimum and maximum diameter before logging.

Single-arm calipers are typically part of most density and micro-resistivity tools; four-arm calipers are available in standard tools.

Applications

• Borehole Diameter
• Borehole shape
• Borehole volume
• Borehole Break-out analysis

Features and benefits:

• Combinable with Resistivity, Nuclear, and Auxiliary Logging for a complete Formation Evaluation Solution
• More accurate borehole volume and annular volume for required cement volume
• Combined with the orientation package, geometry profile can be oriented with respect to magnetic north;
  provides basic break-out analysis
• Drilling optimization by evaluation of borehole geometry
• Compatible with Warrior™ Acquisition System
• Customizable to client Surface Acquisition System
• Works on proprietary PTX Telemetry System