U. S. DEPARTMENT OF THE INTERIOR

U. S. GEOLOGICAL SURVEY

Bulk Densities and Porosities of Cenozoic and Cretaceous Basin-Filling
Strata

and Cretaceous and Older Basement Rocks, Los Angeles Basin, California,

Determined from Measurements of Core Samples

by

L. A. Beyer1 and T. H. McCulloh2

1998

Open-File Report 98-788

This report is preliminary and has not been reviewed for conformity with
U. S. Geological Survey editorial standards or with the North American
Stratigraphic Code. Any use of trade, firm or product names is for
descriptive purposes only and does not imply endorsement by the U. S.
Government.

1U. S. Geological Survey, MS 977, 345 Middlefield Road, Menlo Park, CA
94025-3591

27136 Aberdeen Avenue, Dallas, TX 75230-5407

ABSTRACT

This report describes and provides a digital data file of selected bulk
properties of subsurface rocks sampled in and around Los Angeles basin,
California. Selected properties include measured dry bulk density (range
0.78 to 3.01 g/cm3), measured or estimated grain (matrix) density,
calculated water saturated bulk density (range 1.47 to 3.01 g/cm3),
calculated total porosity (range 0 to 69 porosity percent), geologic
age, and lithology. Most of the rocks are conventional core samples
taken from wells drilled by the petroleum industry. A small percentage
of the core samples are from shallow borings. Rocks studied range in age
from pre-Cambrian (?) to Recent and include sedimentary (98.8%), and
volcanic, metamorphic and intrusive (1.2%) samples. Core samples studied
were taken from measured drillhole depths that range from 35 to 20,234
ft (11 to 6,167 m). Version 1.0 of the data base (dated June 1998)
contains information for 7378 samples from 234 wells, including two
redrilled wells. This report/data base can be accessed on U. S.
Geological Survey servers at
http://geopubs.wr.usgs.gov/open-file/of98-788. Periodic additions to the
on-line data base will be provided as new data is gathered.

TABLE OF CONTENTS

Introduction 4

Previous work 5

Well descriptions and locations 6

Summary of data base 6

Bulk density and porosity equations 19

Methods 19

Sample selection, preparation and weighing 19

Grain volume measurements 20

Bulk volume measurements 20

Reliability of measurements 21

Grain density 21

Dry bulk density 21

Total porosity 22

Saturated bulk density 22

Discussion 23

Industrial data 23

Stratigraphic designations and age assignments 24

Lithologic descriptors 24

Estimates of overburden removed 25

Acknowledgements 25

References 27

Appendix 1: Explanation of core sample data base 29-32

Appendix 2: Core sample data base 32-33

TABLE 1: Well descriptions 7

FIGURES 1 to 11: Well locations 8-18

**INTRODUCTION**

Motivated by the specific need to prepare a meaningful density model of
the Los Angeles basin, California, for quantitative gravimetric
calculations of the basin and some of its parts, we have collected
density data of several kinds. The basic foundation of our modeling
effort is a collection of laboratory measurements of 7,378 subsurface
rock samples, most of which are selected representative samples of
conventional core from wells drilled for petroleum. A description of
this collection, together with explanatory notes and comments, is the
subject of this report.

The bulk density, grain density and porosity of rocks significantly
influence gravitational, magnetic, thermal and electrical fields as well
as acoustical and mechanical properties, and thus are important
parameters to the interpretation of a variety of geophysical data.
Certain mass properties are also crucial to the practical evaluation of
rocks that act as reservoirs for petroleum or water resources or as
conduits for fluid movements. Lastly, selected mass properties, combined
with geologic and lithologic descriptors, provide information about the
burial history, particularly of sedimentary rock sequences.

Bulk density, grain density and porosity of sedimentary and some
volcanic rocks are the result of many factors: (1) Constituent
composition (provenance); (2) depositional environment that exerts
control on original grain size, texture, sorting and, in some instances,
organic content; (3) post-depositional influences, such as temperature,
pressure, and pore-fluid histories (including fluid chemistry and
circulation rate) that, together with sediment composition and texture,
control diagenesis; (4) deformational history; and (5) associated rocks
that influence the chemical nature and flow rate of available pore
fluids. Bulk density, grain density and porosity of intrusive,
metamorphic and wholly or partly crystalline volcanic rocks are
controlled primarily by mineral composition, texture and burial history
that influence chemical alteration and deformational history. A wide
range of these factors are present in this data set. Thus summary plots
and tables are misleading and are omitted in this introductory
presentation.

**PREVIOUS WORK**

An empirical basis for understanding the processes by which clay-rich
sedimentary rocks (\"shales\") increase in density with increasing
burial depths began with the pioneering work of Athy (1930) and Hedberg
(1936), followed closely by related contributions from Haskell (1941)
and Faust (1950), and augmented later by notable results of many others
(for example, Dickinson, 1953; Hamilton and Menard, 1956; Dallmus, 1958;
and Storer, 1959). Most of this early work depended in varying degrees
on laboratory measurements of samples of rock cut from conventional
cores from wells. These efforts took place in parallel with a vastly
larger body of work focused on pore volumes of petroleum reservoir
rocks, especially sandstones and carbonates.

During this period, basic questions about how well laboratory
measurements of core samples match underground rock densities
undisturbed by drilling continued as topics for debate (especially among
geophysicists) until 1965 when an underground density profile based on
gravity measurements in a vertical shaft was shown to validate a density
profile based on accurate laboratory measurements of core samples
(McCulloh, 1965). Multiple subsequent intercomparisons have demonstrated
that conventional cores of even very soft, high porosity mudrocks or
friable sandstones, low density diatomites, or fractured cherty rocks,
yield valid laboratory measurements if core recovery is good, sampling
is representative, laboratory measurement methods are not biased, and
borehole gravity measurements are corrected for significant anomalous
vertical gravity gradients (McCulloh, 1967a; McCulloh and others, 1967;
McCulloh and others, 1968; Beyer, 1971; Beyer, 1987; Beyer and Clutsom,
1989).

In the interim, a very large number of different suggested porosity
versus depth relationships were added to those mentioned above
(Hermanrud, 1993, Figure 1 and accompanying text). This body of data and
relationships between its parts suggest that porosity (or density)
versus depth functions are subject to large method-dependent errors or
that fundamentally diverse geological factors are at play, or both.

**WELL DESCRIPTIONS**

Descriptive information for wells from which cores were studied is given
in Table 1. Locations of these wells are shown Figures 1 through 11
which are ordered first by increasing longitude and then by increasing
latitude. Most location figures are groupings of four 7 1/2-minute U. S.
Geological Survey quadrangles.

**SUMMARY OF DATA BASE**

Rock properties in the data base include measured dry bulk density,
estimated or measured grain (matrix) density, calculated total porosity
and calculated water saturated (\"natural\") bulk density. Geologic
descriptors include lithology, age, presence or absence of oil staining,
and drillhole position of sample relative to observed shallowest
occurrence in a well of the zeolite mineral laumontite (where present).
Estimated thickness of overburden removed by erosion from a drillhole
site is included (where reliably available) as an indicator of prior
maximum burial depth in instances where complications of subsurface
erosional unconformities are not present. (There are sample sets from
drillholes at locations where overburden removed is significant but is
not estimated.)

Geographic descriptors include elevation, latitude and longitude of
drillhole wellhead. Depth of sample is expressed as (1) measured well
depth below ground surface, derrick floor or kelly bushing
(undifferentiated) and (2) vertical subsea level depth. Corrected
vertical subsea depth is given for samples from wells significantly
deviated from the vertical (but geographic position is not adjusted
except for drillholes in the Long Beach Unit of the Wilmington oil
field). Drillholes are identified by the state, county/area and well
numbering system of the American Petroleum Institute (API).

**Table 1: Well Descriptions**

Table 1 is in a separate spreadsheet in Microsoft Excel 2000 format,
available from the website for the this report (OFR 98-788):

<http://geopubs.wr.usgs.gov/open-file/of98-788>

The URL for Table 1 itself is:

<http://geopubs.wr.usgs.gov/open-file/of98-788/OFR98-788Table1.xls>

![](media/image1.jpeg){width="5.876388888888889in"
height="7.476388888888889in"}

![](media/image2.jpeg){width="5.759722222222222in"
height="7.336805555555555in"}

![](media/image3.jpeg){width="5.720138888888889in"
height="7.266666666666667in"}

![](media/image4.jpeg){width="5.9944444444444445in"
height="7.710416666666666in"}

![](media/image5.jpeg){width="6.0in" height="7.656944444444444in"}

![](media/image6.jpeg){width="5.9944444444444445in"
height="8.89861111111111in"}

![](media/image7.jpeg){width="5.9430555555555555in"
height="5.376388888888889in"}

![](media/image8.jpeg){width="5.8in" height="7.836805555555555in"}

![](media/image9.jpeg){width="5.833333333333333in"
height="7.396527777777778in"}

![](media/image10.jpeg){width="5.823611111111111in"
height="7.379861111111111in"}

![](media/image11.jpeg){width="5.826388888888889in"
height="7.420138888888889in"}

**BULK DENSITY AND POROSITY EQUATIONS**

Dry bulk density, grain (matrix) density, total porosity, and water
saturated bulk density reported here are defined by the following
equations:

![](media/image12.emf){width="5.875in" height="1.9861111111111112in"}

Density and total porosity are reported in g/cm3 and percent,
respectively. Saturated bulk density is calculated by assuming a
pore-fluid density (ρf) of 1.00 g/cm3 because most Los Angeles basin
formation waters have salinities considerably less than that of
seawater.

**METHODS**

**Sample Selection, Preparation, and Weighing**

Most core materials studied by the Geological Survey were gathered from
spot-sampled collections of pieces of conventional core and therefore
contain possible biases due to uncertainties about core recovery rates
and representativeness of prior spot sampling of recovered cores.
Sampling procedures generally sought to characterize the range of
lithologies and the maximum, mean, and minimum bulk densities present in
the spot sampled collections. Core chips that visually showed evidence
of alteration by drilling fluids generally were not sampled. Cores
analyzed by petroleum companies usually were sampled at regular
intervals, commonly (though not always) at 1-foot spacing.

Core chips prepared by the Geological Survey were cut, usually with a
dry saw or, in the case of extremely hard samples, with a saw lubricated
with free flowing water, to (1) remove surfaces previously exposed to
drilling fluids or long exposed to the atmosphere, (2) remove rough
surfaces capable of trapping bubbles during immersion in mercury, and
(3) size samples to fit the helium and mercury pycnometers. Samples cut
for weight and volume measurements were dried in a pre-heated oven for
24 hours at about 105 ∞C to drive off H2O- (adsorbed water) (e. g.,
Breger and Chandler, 1969). Amounts of unbound H2O- that remained
probably are negligible to less than 1 weight percent.

Samples were cooled in a desiccator after drying, weighed to the nearest
0.001 g and stored in the desiccator until bulk volume or grain volume
measurements were made with a mercury or helium pycnometer. Sample
weights ranged from about 15 to 90 g.

**Grain Volume Measurements**

Where grain density was measured, grain volume in most cases was
determined by the gas displacement-Boyle\'s law method with a Beckman
Model B5 Air Comparison Pycnometer operated with helium (e.g., McIntyre
and others, 1965). Helium injection pressure into sample pores was 4
psi. Repeated zero or reference readings to within 0.02 cm3 without a
sample in the pycnometer, before and after sample measurements, was the
criterion for acceptance of a sample volume measurement. Sample volume
measurements were also made until values repeated to within 0.02 cm3.
The Beckman pycnometer was calibrated with volume standards provided by
the manufacturer.

**Bulk Volume Measurements**

Bulk volumes of core samples were measured by the mercury displacement
method using a mercury pycnometer slightly modified from that described
and illustrated by McCulloh (1965). This vacuum-equipped mercury
immersion bulk-volume pycnometer is designed to minimize bubble
entrapment against the sample surface and to minimize and permit
evaluation of the amount of mercury lost to pore spaces and natural or
artificial cracks during immersion. All measured volumes of samples were
corrected for mercury lost to pore spaces or artificial cracks.

The accuracy and precision of bulk volume measurements depends on the
reading resolution and the precision of the mercury pycnometer, the
accuracy of the pycnometer calibration and the sample volume. A skilled
operator can read the burette tube to 0.02 cm3 and repeat volume
measurements of non-porous test samples to 0.05 cm3 or better. Measured
bulk volumes of our samples range from about 5 to 40 cm3 but generally
are between 10 and 30 cm3.

Pycnometers were calibrated by adding to the burette tube known weights
of mercury at known temperatures. Incremental mercury volumes,
calculated from weight and temperature data, were compared to burette
volume readings. The calibration was checked by determining the bulk
density of large, transparent quartz crystals; these measured bulk
densities were within 0.002 g/cm3 of accepted values after correction
for temperature.

**RELIABILITY OF MEASUREMENTS**

**Grain Density**

Grain densities for the majority of the data base were estimated. The
estimates were made from knowledge of the mineralogy of the various
sample lithologies (Davis, 1954). [Errors in estimated grain density are
believed to be about 0.03 g/cm]{.underline}3. In the case of measured
grain densities, the error equation assumes negligible errors in weight
measurements and a precision of 0.02 cm3 in the helium pycnometer grain
volume measurement.

![](media/image13.emf){width="6.083333333333333in"
height="0.2638888888888889in"}

Using eq. 1, [the error in measured grain density is 0.004
g/cm]{.underline}3 for an estimated average value of 15 cm3 for grain
volume measurements and a sample of grain density 2.65 g/cm3. For all
reasonable values of grain volume and grain density, the error in
measured grain density will be less than 0.011 g/cm3.

**Dry Bulk Density**

The error equation for dry bulk density also assumes negligible errors
in weight measurements and a precision in the mercury pycnometer bulk
volume measurement of 0.05 cm3.

![](media/image14.emf){width="6.041666666666667in"
height="0.20833333333333334in"}

Using eq. 2, [errors in calculated dry bulk density of rocks in the data
base range from 0.002 to 0.014 g/cm]{.underline}3 for measured bulk
volumes between 10 and 30 cm3 and dry bulk density values between 1.0
and 2.8 g/cm3.

**Total Porosity**

Assuming [additive]{.underline} errors due to uncertainties in grain
density and dry bulk density (the worst case), the error equation for
calculated total porosity is given by

![](media/image15.emf){width="6.069444444444445in"
height="0.4722222222222222in"}

Using eq. (3), [errors in calculated total porosity of rocks in the data
base range from 0.5 to 1.7 porosity percent]{.underline} if an average
grain density of 2.65 g/cm3 and an estimated grain density error of 0.03
g/cm3 are assumed, and errors in dry bulk density range from 0.002 to
0.014 g/cm3 and dry bulk density values range from 1.0 and 2.8 g/cm3.

**Saturated Bulk Density**

Assuming [additive]{.underline} errors due to uncertainties in
calculated dry bulk density and total porosity (the worst case), the
error equation for saturated bulk density is given by

![](media/image16.emf){width="6.083333333333333in"
height="0.20833333333333334in"}

Using eq. (4), [errors in calculated saturated bulk density of rocks in
the data base range from 0.007 to 0.031 g/cm]{.underline}3 for the
ranges of errors given above for calculated dry bulk density and total
porosity.

# Discussion

For the vast majority of samples in the data base, errors in calculated
dry bulk density, total porosity and saturated bulk density lie in the
middle parts of the ranges given in preceding sections. There are other
reasons why the bulk densities and porosities reported here may not
accurately represent equivalent *in situ* values of the strata from
which the cores were taken (McCulloh, 1967b; Beyer 1971). These include
large scale irregular porosity (such as fractures) not represented in
small pieces of core, possible pore and bulk volume expansion due to
removal of confining stresses and, for calculated saturated bulk
density, presence *in situ* of pore fluids whose densities differ from
1.00 g/cm3. The effects of these factors will be discussed in a later
paper that compares and integrates the various types of density data
assembled for Los Angeles basin.

**INDUSTRIAL DATA**

Approximately 56 percent of the data base is from petroleum industry
files released to the Geological Survey and is indicated by a lithology
code of \"50\". Most industrial data were provided as porosities, in
which case grain density was estimated and dry and saturated bulk
densities were back-calculated. The remainder of the industry data were
given as bulk density, in which case porosity was calculated after
estimating grain density. The reliability of these industry data
generally can not be directly evaluated. An indirect measure of their
reliability is provided in some cases by interpersed data from
Geological Survey measurements of core chips from the same set of well
samples.

**STRATIGRAPHIC DESIGNATIONS AND AGE ASSIGNMENTS**

Biostratigraphy is the fundamental basis for the stratigraphic
subdivisions, correlations and age assignments of most of the
sedimentary rock samples. Marine, mostly benthic foraminiferal, faunas
are widely used throughout the basin to subdivide most of the clastic
sequence (Wissler, 1943, 1958; Natland, 1952; Blake, 1991). In local
areas, especially in a few outcrop sections, molluscan faunas have also
been used. For a few non-marine units of more-or-less local occurrence,
distinctive volcanogenic or red-bed lithologies, weathering horizons, or
aquifer characteristics are the basis for identification and
correlation. Although fossils are the main fundamental basis for
subdivision, identification and correlation, local correlations and
assignments depend heavily on interpretation of well log characteristics
and distinctive lithologies or lithologic sequences or unconformities.
All of these approaches have been used in assigning formation names or
faunal zone designations to the samples reported here. In a few cases
that involve pre-sedimentary \"basement\" rocks, distinctive
petrographic and geochronologic characteristics also influenced
formation assignments.

**LITHOLOGIC DESCRIPTORS**

Most of the samples in our compilation have been given lithologic
descriptors on the basis of hand lens examination (almost entirely by
the second author). Some of these (many in the case of samples of
\"basement\" rock units, volcanogenic samples and zeolitized sedimentary
rocks) have been augmented through thin section petrography. Lithologic
descriptors of a few of the more organic-rich, petroleum source rocks
have been augmented also by organic geochemical assay data. The
reliability or accuracy of the descriptors is greatest for coarser
grained rocks (conglomerates, sandstones or crystalline \"basement\"
rocks), and probably is least for fine-grained strata and highly altered
volcanogenic lithologies. Small numbers of cherts and dolomitic rocks
(and possibly some diatomaceous mudstones) may have been misidentified
in particular.

**ESTIMATES OF OVERBURDEN REMOVED**

Estimates of overburden removed are based on objective criteria and are
conservative. Geologic cross sections have been drawn through wells
where evidence is clear that erosion of surface strata followed maximum
burial. Reconstruction of the eroded overburden was estimated by
projecting measurable thicknesses to the eroded site, making allowance
in many cases for the fact that depositional sequences thin toward basin
margins or onto high tracts. Where data are insufficient to permit such
interpretive reconstructions, no estimate of removed overburden is
given. Likewise, where a subsurface unconformity indicates a now-buried
erosional episode, no estimate has been made of the amount of eroded
paleo-overburden.

**ACKNOWLEDGEMENTS**

Most of these data were gathered over 40 years of intermittent work by
one author (McCulloh). The remainder of the data was released to the
Geological Survey by various petroleum companies or gathered by other
investigators and the senior author. A very large number of
organizations and individuals contributed material or information
contained in the data base described by this report. Individuals who
were particularly influential include J. E. Schoellhamer, L. J. Simon
(deceased), W. R. White, R. C. Clawson, B. K. Johnson, T. L. Donovan, E.
L. Christenson, H. E. Stark, and G. C. Brown. Companies that were
especially helpful at various stages of the work include Standard Oil
Co. of California (Chevron USA Inc.), Richfield Oil Co. (ARCO), Texaco,
Union Oil Co. of California (Unocal), Shell Oil Co., and The Ohio Oil
Co. (Marathon Oil Co.). Special thanks are due to the California Well
Sample Repository of the California State University at Bakersfield and
to J. C. Beyer who, with uncommon accuracy, encoded the data from a
variety of records. Assembly of this report and data base was supported
by the Southern California Areal Mapping Project of the National
Cooperative Geologic Mapping Team and figures were prepared by C. L.
Powell.

**REFERENCES**

Athy, L. F., 1930, Density, porosity, and compaction of sedimentary
rocks: American Association of Petroleum Geologists Bulletin, v. 14, p.
1-14.

Beyer, L. A., 1971, The vertical gradient of gravity in vertical and
near-vertical boreholes: U. S. Geological Survey Open-File Report 71-42,
229 p.

Beyer, L. A., 1987, Porosity of unconsolidated sand, diatomite and
fractured shale reservoirs, South Belridge and West Cat Canyon oil
fields, Califonia, *in* Meyer, R. J., ed., Exploration for heavy crude
oil and natural bitumen: American Association of Petroleum Geologists
Studies in Geology No. 25, p.395-413.

Beyer, L. A. and Clutsom, F. G., 1989, Basic data and preliminary
density and porosity profiles from three borehole gravity surveys made
in the Kuparuk River and Prudhoe Bay oil fields, Alaska: U. S.
Geological Survey Open-File Report 89-369, 26 p.

Blake, G. H., 1991, Review of the Neogene biostratigraphy and
stratigraphy of the Los Angeles basin and implications for basin
evolution, *in* Biddle, K. T., ed., Active Margin Basins: American
Association of Petroleum Geologists Memoir 52, p. 135-184.

Breger, I. A., and Chandler, J. C., 1969, Determination of fixed water
in rocks by infrared absorption: Analytical Chemistry, v. 41, no. 3, p.
506-510.

Dallmus, K. F., 1958, Mechanics of basin evolution and its relation to
the habitat of oil in the basin, *in* Weeks, L. G., ed., Habitat of
oil\--a symposium: American Association of Petroleum Geologists, Tulsa,
Oklahoma, p. 883-931.

Dickinson, George, 1953, Geological aspects of abnormal reservoir
pressures in Gulf Coast Louisiana: American Association of Petroleum
Geologists Bulletin, v. 37, p. 410-432.

Eckis, Rollin, 1934, South coastal basin investigation\--Geology and
ground water storage capacity of valley fill: California Department of
Public Works, Division of Water Resources Bulletin No. 45, 279 p.

Faust, L. Y., 1950, Seismic velocity as a function of depth and geologic
time: Geophysics, v. 16, p. 192-206.

Hamilton, E. L., and Menard, H. W., 1956, Density and porosity of
sea-floor surface sediments off San Diego, California: American
Association of Petroleum Geologists Bulletin, v. 40, p. 754-761.

Haskell, N. A., 1941, The relation between depth, lithology, and seismic
wave velocity in Tertiary sandstones and shales: Geophysics, v. 6, p.
318-326.

Hedberg, H. D., 1936, Gravitational compaction of clays and shales:
American Journal Science, 5th serial, vo. 31, n. 184, p. 241-287.

Hermanrud, Christian, 1993, Basin modelling techniques\--an overview,
*in* Dore′, A. G., ed., Basin modelling: advances and applications:
Norwegian Petroleum Society (NPF), Special Publication No. 3, p. 1-34.

McCulloh, T. H., 1965, A confirmation by gravity measurements of an
underground density profile based on core densities: Geophysics, v. 30,
p. 1108-1132.

McCulloh, T. H., 1967a, Borehole gravimetry: New developments and
applications: Seventh World Petroleum Congress, Mexico City, 1967,
Proceedings, v. IIb, p. 735-744.

McCulloh, T. H., 1967b, Mass properties of sedimentary rocks and
gravimetric effects of petroleum and natural gas reservoirs: U. S.
Geological Survey Professiona Paper 528-A, 50 p.

McCulloh, T. H., Schoellhamer, J. E., Pampeyan, E. H., and Parks, H. B,
1967, The U. S. Geological Survey-LaCoste and Romberg precise borehole
gravimeter system\--test results, *in* Geological survey research 1967:
U. S. Geological Survey Professional Paper 575-D, p. D101-D112.

McCulloh, T. H., Kandle, J. R., and Schoellhamer, J. E., , 1968,
Application of gravity measurements in wells to problems of reservoir
evaluation: Society of Professional Well Log Analysts 9th Annual Logging
Symposium Transactions, p. O1-O28.

McIntyre, D. B., Welday, E. E., and Baird, A. K., 1965, Geologic
application of the air pycnometer: A study of the precision of
measurements: Geological Society of America Bulletin, v. 76, p.
1055-1060.

Natland, M. L., 1952, Pleistocene and Pliocene stratigraphy of southern
California: unpublished Ph. D. dissertation, University of California at
Los Angeles, 350 p.

Schoellhamer, J. E., and Woodford, A. O., 1951, The floor of the Los
Angeles basin, Los Angeles, Orange, and San Bernardino Counties,
California: U. S. Geological Survey Oil and Gas

Investigation Map OM 117.

Storer, A., 1959, Costipamento dei sedimente argillosi nel bacino
Padano, *in* I giacimenti gassiferi dell\'Europa Occidentale: Acad.
Nacionale dei Lincei, Roma, v. 2, p. 219-536.

Wissler, S. G.,1943, Stratigraphic formations (relations) of the
producing zones of the Los Angeles basin oil fields: California Division
of Mines Bulletin 118, p. 209-234.

Wissler, S. G., 1958, Correlation chart of producing zones of Los
Angeles basin oil fields, *in* Higgins, J. W., ed., A guide to the
geology and oil fields of the Los Angeles and Ventura regions: Pacific
Section, American Association of Petroleum Geologists, p. 59-61.

**APPENDIX 1: EXPLANATION OF CORE SAMPLE DATA BASE**

The data base (Appendix 2) is constructed as a table or spread sheet in
which each row provides data for one core sample. The following codes
describe column entries from left to right.

**MAP:** One to three digit well code used in Table 1 and Figures
1through 11.

**SC:** Two-digit American Petroleum Institute (API) state code: 04 =
California.

**CC:** API county/area code.

037 = Los Angeles County

059 = Orange County,

065 = Riverside County

071 = San Bernardino County

237 = State waters area offshore Los Angeles County

259 = State waters area offshore Orange County

312 = Federal waters Santa Catalina Area (east of longitude 119˚ W).

**WN:** Five-digit API well number.

**RD:** Redrill code: 1 = first redrill, 2 = second redrill, etc.

**LAT:** Latitude (decimal degrees).

**LON:** Longitude (decimal degrees).

**ELEV:** Depth reference elevation at wellhead such as Kelly bushing,
derrick floor or, if not available, ground level elevation (feet).

**UVSD:** Upper vertical subsea depth of sample interval or vertical
subsea depth of sample if specific depth given (feet). Minus numbers are
feet above sea level.

**UMD:** Upper measured or drilled depth of sample interval or specific
drill depth of sample (feet).

**LVSD:** Lower vertical subsea depth of sample interval (feet). Minus
numbers are feet above sea level. Blank if specific sample depth given.

**LMD**: Lower measured or drilled depth of sample interval (feet).
Blank if specific sample depth given.

**LITH:** Two-digit numerical code identifying lithology of core sample.

01 carbonaceous shale

02 bituminous shale

03 shale

04 claystone

05 phosphatic claystone

06 foraminiferal claystone

07 bituminous claystone

08 mudstone

09 silty mudstone

10 sandy mudstone

11 siltstone

12 silty sandstone

13 fine-grained sandstone

14 medium-grained sandstone

15 coarse-grained sandstone

16 pebbly sandstone

17 sandy conglomerate

18 conglomerate

19 sandstone and siltstone

20 sandstone and shale

21 diatomite, diatomaceous mudstone or shale (opal-A phase predominant)

22 chert or quartz phase predominant

23 tuff

24 volcanic breccia

25 volcanic rock (massive)

26 andesite

27 basalt

28 dacite

29 diabase

30 slate

31 schist

32 metavolcanic rock

33 metamorphic rock

34 metagabbro

35 foliated granitoid rock

36 granitoid rock

37 granodiorite

38 schist breccia

39 sheared granitoid rock

40 fractured shale

41 clay

42 silt

43 sand

44 gravel

50 sandstone, oil saturated (petroleum industry description; sample not
examined by USGS).

**PF:** blank \-- sample not oil stained

1 \-- sample oil stained

2 \-- not determined

**DBD**: Dry bulk density (g/cm3)

**DS**: Data source:

blank \-- Dry bulk density determined by USGS by weighing dry sample and
measuring its bulk volume with a mercury pycnometer.

1 \-- Bulk density value and lithologic description published by
Schoellhamer and

Woodford, 1951. Method of density determination unknown.

2 \-- Bulk density or porosity value obtained from unpublished petroleum
company reports. Various methods of measurement not documented.

**GND:** Grain density (g/cm3)

**CD:** blank \-- assumed grain density value based on lithology.

1 \-- grain density measured by air or He pycnometer.

2 \-- grain density measured by liquid displacement method.

**POR**: Porosity (percent)

**SC**: blank \-- porosity calculated from dry bulk density by assuming
a value for grain density.

1 \-- porosity calculated from dry bulk density by using a measured
value of grain density.

2 \-- porosity measured directly or determined by unknown method (may be
effective porosity).

**SBD**: Saturated bulk density (g/cm3) calculated by assuming pore
space is occupied with water of density 1.00 g/cm3.

**LAU**: blank \-- sample shallower than first observed occurrence of
laumontite.

1 \-- sample deeper than first occurrence of laumontite observed in thin
section.

**OBR**: Estimated or measured thickness of overburden removed from site
of well by erosion since maximum burial of section (feet).

0 means overburden removed by erosion is insignificant.

minus 1 means overburden removed is significant but not quantifiable
from available information.

minus 99 means that one or more erosional unconformities above sample
depth

prevents estimation of overburden history.

**AGE**: Estimated or verified biostratigraphy or lithostratigraphy of
core sample:

01 Pico and younger

02 Repettian

03 Delmontian A and B

04 Delmontian A

05 Delmontian B

06 Mohnian C and D

07 Mohnian C

08 Mohnian D

09 Mohnian E

10 Mohnian volcanic rocks

11 Topanga Group

12 Sespe and Vaqueros Formations

13 Silverado and Santiago Formations

14 Upper Cretaceous

15 Mesozoic and pre-Mesozoic crystalline rocks

16 Middle Miocene volcanic intrusive

17 Middle Miocene volcanic rocks

18 Oligocene volcanic intrusives

19 Age uncertain

**APPENDIX 2. CORE SAMPLE DATA BASE** (see Appendix 1 for explanation)

Appendix 2 is in a separate spreadsheet in Microsoft Excel 2000 format,
available from the website for the this report (OFR 98-788):

<http://geopubs.wr.usgs.gov/open-file/of98-788>

The URL for Table 1 itself is:

<http://geopubs.wr.usgs.gov/open-file/of98-788/OFR98-788Appendix2.xls>

[Notes pertaining to Release 1.0:]{.underline} GND does not appear for
some measured samples but can be computed using DBD, POR and GND =
DBD/(1 - POR) where POR is expressed as a decimal fraction instead of
percent. Directional surveys have not been located for wells 69, 92a and
139 so that depth entries (UVSD, UMD, LVSD and/or LMD) are incomplete
(47 samples). API well number (WN) is unknown for wells 49 and 51. Later
releases will add additional sample measurements and may fill in data
missing in Release 1.0.