Real-Time Visualization and Geometry Reconstruction of Large Oil and Gas Boreholes Based on Caliper Database - Visual Computing: Scientific Visualization and Imaging Systems - page 232

Fig. 13.3 The framework of the 3D Caliper tool (GeoPoço 3D)

13.3.1 Data Acquisition

A borehole failure can be detected by different measurement instruments, like the
following caliper logs: Borehole Geometry Tool; Resistivity logs; Ultrasonic logs.
The caliper tool is inserted into drilling spot to perform a series of measurements
used to evaluate the borehole's feasibility [ 1 ]. It measures the borehole diameter
variation by depth, i.e., its shape and can also give other important information, as
well hole irregularities or damages. The caliper log can have two, four, or more
extendable arms arranged around the tool. Figure 13.4 shows a simple schema of
the tools and obtained data. Among all these measures P1AZ represents the
alignment of the first arm with the magnetic north in degrees, DEVI represents the
tool's inclination and combined with HAZI gives information about the direction.
All this informations are strictly necessary to reconstruct the borehole geometry,
and these variations on every section will allow the borehole to make curves,
creating the sensation of a real borehole and not just a simple geometric form like a
cylinder.
For each position along the borehole, information such as sensors' position and
orientation, rock's resistivity and acoustic data are obtained. These data allow the
user to find flaws in the soil, leaving to the geologist the decision whether the well