STANDARD HANDBOOK OF PETROLEUM & NATURAL GAS ...

MWD and LWD 929
Pressure
Pick-up
Figure 4-239. Sketch of principle of the teledrift tool or teleorienter tool
attached to the drillstring. (Courtesy Teledrift, Inc. [104].)
is inclined, the pendulum catches the grooves at different levels according to
the inclination and stops there. For example, for minimum inclination (Figure
4-240b) it stops the poppet valve past the first restriction. In Figure 4-240d, the
poppet valve stops past the seventh restriction due to the high inclination.
When the circulation is started, the poppet valve travels slowly down, generating
one pressure pulse when passing each restriction. The measurement range
in the standard tool is of 2.5" (also 7" ranges, 1" increments, max. 17").
Table 4-122 gives the inclination angles corresponding to one to seven pulses
with three cones. Fifteen cones are available. The maximum measurable angle
is IO". The range must be selected before lowering the drillstring.