US 5,513,528 A · Logging while drilling method and apparatus for measuring standoff as a function of angular position within a borehole

Abstract

A method and apparatus for measuring formation characteristics as a function of angular distance segments about the borehole is disclosed. The measurement apparatus includes a logging while drilling tool which turns in the borehole while drilling. Such characteristics as bulk density, photoelectric effect (PEF), neutron porosity and ultrasonic standoff are all measured as a function of such angular distance segments where one of such segments is defined to include that portion of a "down" or earth's gravity vector which is in a radial cross sectional plane of the tool. The measurement is accomplished with either a generally cylindrical tool which generally touches a down or bottom portion of the borehole while the tool rotates in an inclined borehole or with a tool centered by stabilizer blades in the borehole.

Claims9

Dependent claims

A method for determining standoff between a logging while drilling tool and an inclined borehole in which said tool is received, including the steps of,

determining a bottom contact point of said tool which contacts said inclined borehole while said tool is rotating in said borehole;
defining a bottom angular distance segment, called SEGMENT.sub.BOTTOM of said borehole which includes said bottom contact point;
using an ultrasonic transducer in said tool for measuring standoff between said tool and said borehole as a function of angular position of said transducer with respect to said borehole;
for a predetermined period of time, recording each measurement value of standoff which occurs in said bottom angular distance segment to produce a bottom angular distance standoff histogram;
and
determining a signal proportional to average standoff of said bottom angular distance segment called BOTTOM STANDOFF.sub.AVG, from said bottom angular distance standoff histogram.

3 more elements

Apparatus for determining standoff comprising

a logging while drilling tool designed for operation in an inclined borehole,
means for determining a bottom contact point of said tool which contacts said inclined borehole while said tool is rotating in said borehole;
means for determining the extent of a bottom angular distance segment, called SEGMENT.sub.BOTTOM of said borehole which includes said bottom contact point;
ultrasonic transducer means disposed in said tool for measuring standoff between said tool and said borehole as a function of angular position of said transducer with respect to said borehole;
means for recording, for a predetermined period of time, each measurement value of standoff which occurs in said bottom angular distance segment to produce a bottom angular distance standoff histogram;
and
computer program means for determining a signal proportional to average standoff of said bottom angular distance segment called BOTTOM STANDOFF.sub.AVG, from said bottom angular distance standoff histogram.

4 more elements

Dependencies are inferred from the claim text.

Logging while drilling method and apparatus for measuring standoff as a function of angular position within a borehole

Life of this patent

Logging while drilling method and apparatus for measuring standoff as a function of angular position within a borehole

Life of this patent

Abstract

Claims9