CORE LABORATORIES
UNION OIL CO. OF CA.
CORE ANALYSIS REPORT
"MCKITTRICK FRONT" 418 WELL
CYMRIC FIELD
KERN COUNTY, CA
CL FILE 92021
PERFORMED BY:
C0RE LABORATORIES
3430 UNICORN ROAD
BAKERSFIELD, CA 93308
(805) 392-8600
FINAL REPORT PRESENTED
JUNE 1, 1992
PROGRAM PARTICIPANTS
DATA REDUCTI0N AND ANALYSIS:
William R. Cooper
Project Geologist
REVIEWED BY:
Jeffry L. Smith
Laboratory Supervisor
INTRODUCTION
Core Laboratories was selected by Union Oil Company Of California to perform a core analysis study upon samples recovered from the Cymric Field, Kern County, California. Conventional plastic sleeve cores and sidewall core samples were submitted. Presented herein are the results of the analysis performed upon the conventional core samples. Results of the sidewall core analysis were bound and presented separately.
This report is divided into four sections. The first section provides a description of services. The second presents the results of routine conventional analysis in tabular form. The third provides a statistical and graphical presentation of the core analysis data. The final section contains an inventory of the core material recovered.
In conjunction with the report, the tabular results of analyses are supplied on an IBM PC compatible floppy diskette with data transfer software, CoreLab© .
We appreciate this opportunity to be of service and hope these data prove beneficial in the development of this reservoir.
TABLE OF CONTENTS
SECTI0N
PLASTIC SLEEVE, SERVICE DESCRIPTION 1
CORE ANALYSIS, TABULAR RESULTS 2
CORE ANALYSIS, STATISTICAL DATA AND 3
GRAPHICAL PRESENTATIONS
CORE INVENTORY LIST 4
PLASTIC SLEEVE
Plastic sleeve coring equipment, in conjunction with water base drilling fluids, was used to extract core samples durinq February, 1992. These cores were handled Core Laboratories field personnel
Core Handling and Marking
Prior to coring, the PVC core barrel liners were marked for orientation
with parallel scribe lines, a red line on the right and a black line on the left,
looking toward the top end of the liner. After each core was cut, the inner core
barrel was laid on the cat walk and the PVC sleeve containing the core was
extruded from the barrel and cut into three foot sections. Each section was
measured and marked for depth at one-foot intervals. Where applicable, depths
were assigned such that any core not recovered was attributed to the bottom of
the cored interval. The core sections were boxed and then placed in a
refrigerated truck maintained at 35¡ F. at the wellsite.
Upon completion of coring the cores were transportod to our Bakersfield facility where it was scanned for spectral gamma activity and placed into chilled storage.
Spectral Gamma Surface Log
Each core was scanned for natural gamma radiation utilizing Corelab's gamma
spectrometer. The cores were passed over the spectrometer's detector at a rate
of one half foot per minute. Total gamma radiation is reported in API units.
Potassium, uranium, and thorium are the elements primarily responsible for
a typical rock gamma spectrum. Corelab's gamma spectrometer reports the
concentrations of uranium and thorium in parts per million and that of potassium
as a percentage.
Core Slabbing
The chilled core segments were slabbed parallel to the core axis utilizing
a one/third - two/thirds cut. Liquid nitrogen was used as the slab blade coolant.
The one/third sections of core were mounted in slab boxes with styrofoam inserts.
The upper surfaces were scraped to remove cuttings and saw marks. The one/third
slabbed sections were then returned to the chiller pending viewing by Unocal's
representatives.
The two/thirds sections of core were returned to their original core boxes and returned to our on-site chiller pending instructions from Unocal.
Sample Preparation
One-inch diameter plug samples were drilled from each selected foot of the
core. Liquid nitrogen vapor was used as the bit coolant.
Each plug was encased in a thin-walled metal jacket and fitted with 120 mesh end-screens. The jackets were set to the plugs under hydrostatic loading conditions at a pressure equal to Equation 1.
P = 400 (1)
Where: P = Confining Pressure
Extraction and Saturation Determinations (Dean Stark Analysis)
Oil and water were extracted by Dean Stark methods using toluene as the
solvent. Samples were removed from the Dean-Stark apparatus after water readings
had stabilized. Following Dean Stark extraction, samples were placed into
soxhlet extractors where complete hydrocarbon extraction was performed with
methylene chloride. The cleaned samples were then dried in a humidity
controlled oven at 60¡C and 45% relative humidity until stable weights were
attained. Prior to analysis, the samples were cooled to laboratory temperature
in sealed zip-lock plastic bags. After grain volume, pore volume and
permeability measurements, the samples were placed into a (convection oven and
dried at 240¡F until stable weights were attained.
Oil and water saturations were calculated by Dean Stark methods by using Equations 2 and 3.
So = [ ( (Wl - W2 - H2OC)/Do)/Vp] x 100 (2)
Sw = [H2OC/Vp] X 100 (3)
Where:
So = Oil Saturation, Percent
Sw = Water Saturation, Percent
W1 = Natural Weight
W2 = Extracted and Humidity Dried Weight
W3 = Extracted and Convection Oven Dried Weight
H2O = Extracted Water, Density Assumed 1.0 gm/cc
H2Oc = Corrected Water = H20 - (W2 - W3)
Do = Density of Oil
Vp = Humid Pore Volume
Grain Density Determination (Dean Stark Analysis)
Grain volume determinations were performed using an extended range helium
porosimeter according to Boyle's Law. Metal jacket and end-screen weight and
volume corrections were applied to the jacketed samples. Grain density was
calculated using Equation 4.
Dma = Mg / Vg (4)
Where:
Dma = Grain Density
Vg = Grain Volume
Mg = Humid Grain Mass
Porosity (Dean Stark Analysis)
The samples were loaded into a hassler core holder at a confining pressure
equal to 250 psig. Direct pore volume measurements were made utilizing Boyle's
Law methods with helium as the gaseous medium. Appropriate screen pore volume
tares were applied to each sample. Porosity was calculated using Equation 5.
0 = [Vp / (Vp + Vg)] x 100 (5)
Where:
0 = Porosity, Percent
Vg = Grain Volume
Vp = Pore Volume
Permeability to Air
Permeability measurements were made following the pore volume determination
by the steady state method with pressure release. Calculations were performed
as defined by Darcy's Equation for compressible fluids, Equation 6.
| Ka= | Pa vg (1000) | Qa L 2 | ||
| ______________________ | x | _______ | (6) | |
| (Pl - P2)[(P1 + P2)/2] | Vb |
Core Photography
After the cores were slabbed one/third - two/thirds, the one/third
sections were cleaned to remove the drilling mud. Composite photographs were
then taken under simulated natural and ultra-violet lighting conditions. The
results of photography were mounted and presented in book form.
Sample Disposition
The plastic sleeve core is stored chilled at a commercial warehouse in
Bakersfield, California pending instructions for additional work or permanent
storage arrangements.