C - Alaska Division of Geological & Geophysical Surveys

108 Pages·2006·3.29 MB·English

ROCK-UNIT REPORTS OF 228 WELLS DRILLED
ON THE NORTH SLOPE, ALASKA
Kenneth J. Bird
U. S. Geological Survey
Menl.0 Park, California
Open-File Report
82-278
This report i s preliminary and has not
been reviewed for conformity with U.S.
Geological Survey editorial standards
and stratigraphic nomenclature. Any
use of trade names i s for descriptive
purposes only and does not imply
endorsement by the USGS.
Menlo Park, California
January 1982
TABXLE OF CONTENTS
Page
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
fntroduction . . . . . . . . . . . . . . . . .I . . . . . . 1
Format of rock.-u.n.it .re.p.or.t . . . . . . . . . . . . . . . . . . . . . . . 2
Stratigraphy . . . . . . . . . . . . . . . . . . . . . . . . . . .2
Rock-unit re.p.or.ts . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
References 104
ILLUSTRATIONS
. . . . . . . . . . .
Figuxe 1 . Explanation of format of rock-unit report . . . . . . . . 3
Figure 2 . Cretaceous-Tertiary stratig.ra.ph.ic. t.er.mi.no.lo.gy. . . . . . . . . 8
Figure 3. Pebble shale nomenclature . . . . . . . . . . . . 10
Figure 4 . Explanation of API well number system. . . . . . . . . . . . . 12
Figure 5 . Well location map for 5 quadrangles . . . . . . . . . . . . . 13
Figure 6 . Well location map for 7 quadrangles . . . . . . . . . . . . . 14
Figure 7 Well location map for 4 quadrangles 15
TABLES
. . . . . . . . . . . . .
Table 1 . North Slope stratigraphic nomenc.la.tu.re. . . . . . . . . . . . .
Table 2 . Listing of wells by API nu.m.be.r . . . . . . . . . . . . . . . .
Table 3 Listing of wells by name
ex-UNIT REPORTS OF 228 WELLS DRILLED :
ON THE NORTH SLOPE, ALASKA L
t
BY
4
, i
Kenneth J. Bird
U.S. Geological Survey
Menlo Park, California
INTRODUCTION
This pper presents in a series of rock-unit reports my identification of
rock Wits and depths of penetration (using wireline and lithologic logs) for
228 wells fram the North Slope, Alaska. Initially, X conceived of the com-
pilation as an exercise to develop a consistent set of interpretations for
wells in the National Petroleum Reserve in Alaska (NPRA). Subsequently, the
study expanded to include most exploratory wells, and selected production
ell^, of the North Slope, utilizing the current files of the U.S. Geological
Survey, Men10 Park, California.
In this paper, the term "rock-unit reportu refers to general well infor-
mation, rock units, and depths which have been computer encoded and printed
for each well. In addition to the rock-unit reports, this paper incorporates:
an explanation of the report format (fig. 1) ; a compilation of North Slope
stratigraphic names (table 1, figs. 2 and 3); various listings of wells
(tables 2 and 31 and maps for locating particular wells (figs. 4 through 7).
Encoding and printing are by Petroleum Information Corporation (PI) of Denver,
Colorado under a contract between PI and the U.S. Geological Survey.
Similar compilations for North Slope wells have previously been under-
taken, and these include: Collins and Fbbinson (1967) for wells drilled in
the exploration of Naval Petroleum %serve No. 4 (Pet-4 program); Tailleur and
others (1978) for industry wells drilled outside of the Petroleum Reserve;
Alaska Geological Society (1971, 1972, 1977, 1981) for wells shown in four
correlation sections; and Bird and Andrew8 ( 1979) and Molenaar ( 1981) for
studies of Cretaceous rocks in NPRA. I have included all wells frm these
previous compilations in addition to many new wells. However, the strati-
graphic names and depths used in this report are not almys in agreement with
these earlier compilations.
Numerous people have contributed to this compilation. I gratefully
acknowledge the invaluable discussions and support of L. B. Magoon (U.S.
Geological Sunrey), discussions of stratigraphy wer the last 20 years with
North Slope investigators too numerous to mention, and the efforts of Do
Headley, Po Ro LeGrand, M. Ao Martikt W. L. Matera, N o A. palik, L. A.
Wilcox, and G. R. .Wnger (PI). mis manuscript has benefited from the review ,
and criticism of w.' P. ~rosge'a nd C. Molenaart however, the author accepts
Mo
. full responsibility *for its content.
FOflMAT OF mK-UNIT REPORT w *
The rock-unit report consists of a heading of general. knell information I
above a tabulation of rock units and depths. Format detal,ls are offered in
9igure 1. Heading information is obtained from well hiatory~documents.
i.
i
hti*de and longitude for bottom-hole locations, which are not provided
in the well history for slant-drilled holes, were measured from mapa made by
the Alaska Oil and Gas Conservation Commission of the Harrison Bay, Prudhoe
&y, and Mikkelsen Bay areas (scale: 1 in. = 5,280 ft). Accuracy of the
bottom-hole locations thus obtained is estimated to be within five seconds of
latitude or longitude.
In each report only the penetrated rock units are listed. The rock-unit
names are abbreviated, and the abbreviations are explained i n table 1. Not
shown in table 1, but present in the PI computer file, are abbreviations for
thrust faults (T/FAULT) and normal faults (N/FAuLT). Both types of faults are
known to intersect North Slope wells, but only thrust faults that repeat rock-
unit boundaries are included in these xeports.
Rock-unit identification is according to published definitions, or as
explained in the stratigraphy section of this report. Evidence used t o
identify rock unita is included in the reports (fig. 1)s the most common type
reported is "LOG" evidence. Distinct log deflections were used to pick a
precise horizon, but identification of most units depended on the lithology as
well as the log character. With the exception of surface depths, all depths
are rounded off to the nearest five feet to compensate for inconsistencies
produced by cable stretch between log runs.
In slant-drilled holes four depth columns are presented instead of the
usual two columns for vertical-drilled holes (fig. 1). There are two columns
of "measured" and "true vertical" depths for each of the rock-unit tops and
lmttorns- Measured well depths have been converted to true vertical well
depths by using the conversion tables provided with the well history-
STRATIGRAPHY
Stxatigraphic nanencla ture in the rock-unit reports employs both formal
and informal terms. In the selection of rock units for inclusion in the
reports, my object -8 to show regional relations rather than l o a l details.
Hence, groups and formations axe reported more often than members.
Informal names are used for new, unnamed rock units or in instances where
present terminology does not accurately express the stratigraphic relations.
These names are marked with an asterisk in table 1, and by their use I hope to
draw attention to an increased level of stratigraphic information and the
consequent need:fot;additional study. To d.e fine new rock unita or to redefine ,
old ones is beyond 't>e scope of this paper
Table 1 presents a list of a l l formal and informal North Slope strati-
.
, graphic names, abbreviations, and ages currently in the PI computer Pile.
. .
.
.A
CI
--
TYC: 11u CGCX 1st stc: 4 swr.
L~T:1 16 10 ?1 ~oh'r:l a0 F IS LW?. AC1 NUMBEI: ~0-029-?!1Tb-O0-00
L-L-~:*- TO- #I. 6 s LD*~: I ~ CDC 12 rtn. TOT~LP CISURL~ DCFTV. irzlr
*r LLtv*: U WnCr u*lT AT i.@.:CslICorl tauc rcuTtcAL DCrTh: 9939
-----------.*--------...II~CCCcC-C.--.~--~--~~~-.~~-~*-~"~~--~.--*.~~*
--.- -----
PO" Uklt tVP1 -.--m- m W--m.- -. fvrt *31S5111
11---1.- .I--
TOP = top of rock unit in strsight hole
M ~ O P= Qtuured depth in runt bole
m/TOP true vertical depth in nlmt hola
I
H/m rarured depth in &&t hole
TV~~TI= Htr ue vtrticrl depth in @laat hola
Figure 1. Explanation of format of the rock-unit report. The
report shown here is that of a slant-drilled well which
characterkst$gally has two depth columns more than a report
for a vertical well bore. A11 elevations and depths are
expressed in feet.
I
Table 1. Listing of North Slope stratigraphic names, agee, and
rock-unit abbreviationa currently in the PI computer file.
Order of listing i a from younpest to oldest: however, super-
porition of units I6 not implied. Asterisk (*f indicates
informal name. Number6 correspond to comments i? this report.
Tuluvak Tongue
Bchrder Bluff
I I
Bcntinel Hill
Bvrov Trril
RogerB Creek
Nllik Tonsut
Tuktu
I
KO-
miltatone
pebble ahale
X d k Sandstone
--
Table 1. continued
-
EARLY mm
EARLY JURASSIC
URLY CRLUCEOUS
mud1ton.
16
Karen Creek
I I
nr* Crcrk ~ilt#tone' (.fir. Creek ~iltrtone)
frllhu Budatone (.Wp Surdltonc)
.-
I*
PmKLAn
In-
Jw Creek
lukm
Uabumr
1
--
Table 1. continued
m.3u~rn nss.
w watcnt
ypp.r lirabm* Wlt
Napdl tCltetmc
.Do1mitc tat
limertmc mit
Kun.
Twik
K o q a
maorrk
wchmuth Ihamtont
Utukok
-
WICIES. DFVOllUIO
M6SISSIPPI.W 1tldlyUl.l
Kayak SW.
Kekiktuk C-ate
-
KISS. DEYCllfAU ht.L Bud.ton.
UTE D N O W Kulmyut cone-t.
"
Runt Pork Ehale
The most recant cmprehermive 8-ry of North Slope ptxatigraphic names
b '
.is that of Aopf (1970). Names used herein and propored singe his aumImry are 1
referenced# informal names are explained in the foll1wing paragraphs
- (paragraph number corresponding to the number in table 1).
,* # I
(1) Quaternary depsits on the North Slope have been assigned to the
?
Gubik ~oz&ation or surficial deposits. In most wells, rock8 of this age are
unconsoli'dated, leaa than a few hundred feet thick, and neither sampled nor
logged. To reflect this general lack of information, the informal term
"surficial &poaita/Gubik Formationn is used i n the rock-unit reports, and the
thickness is usually estimated (EST). For information on these rocks east of
NPRA see Dettenaan and others (19751, and for NPRA see Williams and others
( 1977)
(2) The Sagavanirktok Formation, defined by Gryc and others (19511, has
been aubdivided by Detterman and others (1975) into members. The formation
and members are characterized by incomplete and widely scattered surface ex-
posures. These poor exposures and the lithologic similarity to overlying and
underlying strata make the accurate mepping of this formation most difficult.
with the availability of well data, the problem of the limits of the formation
arose. To clarify the limits, Detterman and others (1975, p. 37) include
within the Sagavanirktok Formation "all of the beds above the top of the Upper
Cretaceous Prince Cr.ee k. F.on aation and below the Quaternary (Gubik.Formation1
surficial deposits " Because of the remaining uncertainty of the
lithologic distinctions and the importance of age to the definition, this
formational name was not used in the rock-unit reports. Instead, a set of
informel terms was used, a s explained below.
(3) Tertiary-Cretaceous stratigraphic relations showing both formal and
informal nomenclature are surmnarized i n figure 2. These informal names are
used i n the rock-unit reports, and, as explained below, they are based on
gross lithologic features without regard to age.
"Saga~nirktok-Colville undifferentiatedn includes a l l strata assigned t o
the Colville Group and to the Sagavanirktok Formation. F r a west to east this
informal rock unit progressively overlies the Wnushuk Group, the Torok Forma-
tion, and the pebble shale. The age is Late Cretaceous and Early Tertiary.
This rock unit consists of two parts: an upper pnrt composed mostly of sand-
stone and shale and a lower part canposed mostly of shale.
"Sagavanirktok-Colville sandstone," representing the upper part of the
,
nSagavanirktok-Colvil le undifferentiated " consists of interbedded sandstone,
shale, coal, and conglomerate. The upper boundary is placed a t the base of
the surficial deposits, and the lower boundary is placed a t the base of the
lovest consistent sandstone overlying a thick (1000+ f t ) shale section. In
the weet (NPRA) this rock unit is moatly of Iate Cretaceous age and includes
tws
the Prince Creek and Schrader Bluff Formations. East of NPRA rock unit
is of Late Cretwoue and Tertiary age, and includes the Sagavanirktok
Formation, the "Co~villeG roup sandstone" of Pessel and others ( 1978a 1 , and
the recently proposeLd West Sak Sandstone of Jamison and others (1980).
"Colville ~roups hale," representing the lower, predominantly shale
portion of the "Sagavanirktok-Colville undifferentiated, is a term used by
"
WEST 120 miles EAST
-
. , Ii
(CoMlk River) (Prudhoe Bay area) (Carmtng River)
G
.
.
Tertiary
. . . . .
.* *
Cretaceous
Figure 2. Generalized Tertiary and Cretaceous stratigraphic
relations and nomenclature for the coastal plain province,
eastern half of the North Slope as discussed i n this report.
Amount of time represented by pebble shale gamma-ray zone is
poorly controlled and largely conjectural. Early Cretaceous,
sub-pebble shale rock units are not shown here. Informal
names are enclosed in quotation marks.