Page 352 - Standard Handbook Petroleum Natural Gas Engineering VOLUME2

Enhanced Oil Recovery Methods 319

New Wells

When drilling new wells for residual oil determination, special attention
should be given to using a bland drilling mud that contains no additives likely
to alter interfacial tension or wetting properties. If full-diameter cores are
obtained (which is desirable if economics permit), the sponge coring technique
should be used with precautions being taken to ensure that flushing is minimal
during coring. It is also recommended that the vertical distribution of residual
oil be determined with a suite of open-hole logs that can include resistivity and
dielectric constant. In cases where good data on capture cross-section are
available, residual oil saturation can be obtained with a pulsed-neutron-capture
log. If a log-inject-log scheme is used (for example, with PNC), this should not
involve chemical flushing. The tracer test should be run after completion
of logging measurements. All of these measurements can be backed up by
laboratory displacement tests which should be carried out on preserved cores.
ENHANCED OIL RECOVERY METHODS

Definition
A general schematic of the enhanced oil recovery (EOR) process is depicted
in Figure 5-174. The more common techniques that are currently being investi-
gated include:

TYPICAL EOR PROCESS
INJECTOR PRODUCER
WELL WELL

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-1

PRODUCING
FORMATION

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z - - -
L c
Fiaure 5-174. General schematic of enhanced oil recovery.