Identifying Reservoir Sweet Spots in Field
Development Using
Hydrocarbon Mapping: An
Example
from the Pietu Siupariai
Oil
Field
in Lithuania
Rick Schrynemeeckers
Amplified Geochemical Imaging
The 3 Km by 6 Km Pietu Siupariai field
had until the end of
1999 produced a total of 0.2 MMBO from 3 wells. The Cambrian
Daimena Formation reservoir was 70 meters thick in the
field
and had a porosity of 5 % to 15 % and a permeability 0.1
to 400 milliDarcy. The structure had a relief of only 30 meters
above the 1,970 meter sub sea oil/water contact. Productivity
of the old wells in the
field
varied considerably from no production
in the G-14 well to 160 BOPD in the PS-1 well. The G-
12 well tested 750 BOPD on a DST but was not completed
due to mechanical problems.
Although the G-18 and G-7 wells both produced 120 BOPD, the latter well only penetrated the uppermost 15 meters of the reservoir.
The survey was performed with the objective to identify reservoir
sweet spots within the closing contour. Towards that end
99 field
modules were placed in a 250 meter by 500 meter
grid within a 20 Km2 area over the
field
. The passive surface
modules were exposed for 17 days. For calibration purposes
30 calibration or model modules were installed at a producing
well, a dry well and a well with shows.
Probability maps displaying similarity to the modeled geochemical
fingerprints were statistically generated by correlating
the field
module fingerprints and the well model fingerprints.
Since the survey microseepage mechanism was driven
by a combination of reservoir pressure, porosity, and net pay
thickness, the project results demonstrated a definite correlation
between the geochemical probability maps and test/
production
data
.
The data
also showed that production varied considerably between
wells within the closing contour, namely in the range
from 0 to 160 BOPD in past wells, potentially indicating nonhomogeneous
reservoir characteristics. Total production was
approximately 403 BOPD.
After the geochemical survey three wells were drilled on positive
geochemical anomalies. Production from these three
wells totaled 6,130 BOPD resulting in a production increase of
approximately 15 times. The survey demonstrated that it was
possible to use surface geochemical hydrocarbon mapping to
determine reservoir sweet spots and predict subsurface reservoir
quality variations within a producing oil field
.
AAPG Search and Discovery Article #90185 © AAPG Geoscience Technology Workshop, Revisiting Reservoir Quality Issues in Unconventional and Conventional Resources, Austin, Texas, November 12-13, 2013