Page 11 - A Primer of Oilwell Service and Workover Completion
P. 11
LOGGING AND TESTING A WELL
Petroleum Extension-The University of Texas at Austin
LOGGING AND TESTING A WELL
ogging and testing wells DRILL STEM TEST
L occur during drilling, com-
pletion, service, and work over. The drilling crew runs a drill
Logging and testing specialists stem test (or DST) to test a for-
use many types of instruments mation it has just drilled into. PRODUCTION
VALVE
and techniques to reveal infor- The DST gives accurate data
mation about the condition and about a formation’s pressure and
location of the reservoir, forma- the composition of the fluids in
tion fluids, wellbore, circulation it. A DST tool is run in on the
fluids, and equipment in the end of the drill stem (fig. .). PRESSURE
hole. This chapter is an overview It has one or two packers that RECORDER
of some of the main types of isolate the zone to be tested. A
logs and tests. perforated pipe between the two
A log is a permanent record packers, or between one packer DRILL
STEM
of information about the forma- and the bottom of the hole, TEST
tions a well has drilled through. allows formation fluids to flow TOOL
There are many ways to log, in. A pressure recorder inside
or survey, a well. Some involve the tool above the packer and
obser vations of the drilling another below the perforated PACKER
conditions and rock, and oth- pipe chart the pressure. When
ers involve lowering a tool into the pressure testing is finished,
the well that sends signals to an valves in the DST tool close to
observer on the surface. trap a fluid sample, the packer
is released, and the tool is
retrieved.
PRESSURE
Analyzing the DST reveals RECORDER
reservoir pressure, average per-
meability, the presence and loca-
tion of permeability changes,
formation damage, production Figure .. A drill stem test tool
potential, and pressure depletion records pressure and samples the
rate. formation fluid.
