Appalachian Stress Study 1. A detailed description of in situ stress variations in Devonian shales of

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JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 94, NO. B6, PAGES 7129-7154, JUNE 10, 1989
Appalachian Stress Study
ß A Detailed Description of In Situ Stress Variations
in Devonian Shales of the Appalachian Plateau
KEITH F. EVANS
Lamont-Doherty Geological Observatory of Columbia University, Palisades, New York
TERRY ENGELDER
Department of Geosciences, Pennsylvania State University, University Park
RICHARD A. PLUMB
Schlumberger-Doll Research, Ridgefield, Connecticut
We describe an experiment to measure variations in the state of stress within a horizontally bedded
Devonian shale/sandstone/limestone sequence in western New York. A total of 75 stress measure-
ments were made in three wells a kilometer or so apart using a wireline-supported hydraulic-fracturing
system. The stressp rofiles indicate that a major drop in horizontal stress level occurs in the generally
massive shales. This drop occurs principally across the lowermost member of a group of sand beds and
correspondst o an offset in Sh and Sr(cid:127) of 3.5 and 9 MPa, respectively. Above the sands, thrust
regime conditions prevail, although the amount by which Sh exceeds S(cid:127) is undetermined since
instantaneouss hut-in pressures( ISIPs) were clipped at the level of S(cid:127) due to fracture rotation. Below
the sands, the regime is strike slip with both horizontal stresses showing lateral uniformity despite
substantial variations in topography. The magnitude of Sh in the sand beds themselves and a lower
limestone remains at least as great as St, despite the decline in shale stress. Hence stress contrasts
between these beds and neighborings halesb ecome pronouncedw ith depth. The contrast in Sh and SH
between the lowermost sand and the immediately underlying shale is at least 6 and 14.5 MPa,
respectively. SH levels in the lower strike-slip regime are about 1.75 times greater than Sh and are less
than the value required to initiate slippage on favourably oriented frictional interfaces. For the upper
thrust regime and the sand and limestone beds, however, the inferred lower bound on Sr (cid:127) is close to
the slippaget hreshold for a Coulomb friction coefficient of 0.6. The orientation of S(cid:127) is ENE with a
standard deviation of 20ø . Fracture traces were usually splayed, occasionally spanning 30ø of well bore.
No systematic correlation between mean orientation and lithology is evident. Significantly different
orientations were obtained for adjacent tests in which almost identical ISIPs were observed,
suggestingt hat the fractures quickly reorient themselves to propagate normal to the least principal
stress direction. Similarly, vertical traces were observed in those tests where ISIPs apparently reflect
S(cid:127),, suggestingt hat rotation to horizontal was rapid.
INTRODUCTION is to be sensibly interpreted and the physical processes
governing the contemporary stress distribution better under-
Spatial variations in the state of stress of crustal rocks in
stood, it is necessary to characterize the stress variations to
even the simplest of geological situations reflect a poorly
such a degree that whatever systematic relationships may
understood interplay through time between evolving mate-
exist between the stress distribution, material property vari-
rial properties and gravitational or tectonic loading condi-
ations, and local structure are clearly established. Through
tions. Numerous other factors may influence the pattern of
this process, it may be possible to identify the characteristic
stress variations developed at a given locality, notably
signature of those constituent mechanisms which, super-
structural setting and the presence of structural discontinu-
posed through time, account for the observed stress distri-
ities. Stress discontinuities have been observed to coincide
bution.
with basement-sediment interfaces [Haimson and Lee,
It is within the field of petroleum reservoir engineering,
1980]f,a ults[ Marthae t al., 1983; S tephanssoann df i(cid:127)ngman,
where knowledge of formation stresses can significantly
1986], detachments [Becker et al., 1987; Evans, 1989], and
improve the yield of hydrocarbons, that the subject of stress
volcanic intrusions [Haimson and Rummel, 1982] as well as
variations and their origin has received greatest attention
material property variations [Warpinski et al., 1983]. Yet
[Warpinski, 1986]. The emphasis, however, has been to
despite the potential for complexity there can be little doubt
devise methods for predicting attributes of the in situ stress
that the pattern of stress variation contains valuable infor-
distribution from inexpensive surface or wireline log data,
mation regarding the nature of contemporary loading and
rather than to measure the formation stresses themselves
those events in the rocks past which have left some imprint
[Frisinger and Cooper, 1985]. Attributes of particular inter-
on an attribute of the stress distribution. If this information
est are the orientation of maximum stress [Lacy, 1987] and
Copyright 1989 by the American Geophysical Union. the contrast in least horizontal stress magnitude between
Paper number 88JB03448. reservoir rocks and adjacent beds [Kry and Gronseth, 1982;
0148-0227/89/88JB-03448505.00 Warpinski et al., 1982]. Despite this commercial importance,
7129
7130 EVANS ET AL.' APPALACHIAN STRESS STUDY, 1
78ø 76ø I - 44ø
8;> ø
N 44ø-- (cid:127) I
(cid:127) /
;
/
: (cid:127)---
(cid:127) CANISTEO ......
ß RE.A.. . (cid:127)?- -
84 ø
I . 0 ß --42 ø
42o --
j(cid:127)..r,,,.,..½
:(cid:127) 'l 7(cid:127) o
{
CONTOURS TO BASE OF DEVONIAN
SECTION OF THE APPALACHIAN
PLATEAU
38 ø --
CONTOUR INTERVALS OF IOOOF(cid:127) A.M.S.L. DRAWN
ON TOP OF ONONDA6A LIMESTONE OR EQUIVALENT
,(cid:127) SUBSURFFAAUCLWET HSI BCRHE TAHKOE NONDA6A
(cid:127) ALIMNESVTDONI CE I(NDROAITWNNY LF OYR .W)E STERN NEW YORK
....... MAR61N OF SILURIAN SALT DEPOSITS
I I I I 0 I00 200KM
84 ø 82 ø I I I
Fig. 1. Location of the South Canisteos ite and nearby Eastern Gas Shale Project wells in western New York. The
structural trend of the basin is defined by the contours drawn on top of the Onondaga limestone whose stratigraphic
position is indicatedi n Figure 3. Dashed! ineationsi n the study area signifyb lind reverse faults underlyinga nticlinal
structuresßT he bold dotted line denotes the margin of the Silurian salt deposits.
there are few studies which feature sampling of the stress BACKGROUND
field in both the spatial extent and detail necessaryt o reveal
The measurements were made in three boreholes, a ki-
clearly systematic relationships between stress and lithol-
lometer or so apart, which span the side of a 230-m-highh ill
ogy. In this and companion papers we report such a study in
to the west of the village of South Canisteo in Steuben
which 75 hydrofracture stress measurements were con-
County, New York (Figures 1 and 2). The easternmost well
ducted in three boreholes a kilometer or so apart which
(Wilkins 1) lies on the floor of a prominent NNW striking
penetrate a horizontally bedded sandstone/shale/limestone
valley proximate to the village. The neighboringw ellhead
sequence. This paper describes the stress measurements
(Appleton 1) lies some 100 m up the hill a distanceo f 1.4 km
themselves and the pattern of stress variations that they
to the WSW, and the westernmost (O'Dell) lies another 100
define. Our interpretation of the observed stressv ariations is
presented by Evans et al. [this issue] (hereinafter referred to m higher, some I km due west of the Appleton.
as paper 2) where we provide more detailed discussiono f Details of the stratigraphy of the study area are presented
tectonic and stratigraphic background to the study area and in paper 2. Here we mention only those features of immedi-
the results of material property analyses. The basinwide ate importance to the discussiono f the measurementst hem-
counterpart to this study is presented by Evans [1989]. selves.A stratigraphicc ross section along the profile A-A' of
Aspects of the measurements which have implications for Figure 2 is shown in Figure 3. The mechanical base of the
the hydrofracture technique in general are dealt with more section of interest is formed by the extensive Salina salt
fully by Evans and Engelder [1989]. depositsw hich serve to decouplem echanicallyt he Devonian
EVANS ET AL.: APPALACHIANS TRESSS TUDY, 1 7131
77035 ' 77o32'30
42 ø
12'
30
1900 WiLKiNS e
O'DE
LETC
1
I i I 42 ø
I0'
....... FAULTS DRAWN ON ORISKANY SURFACE
Fig. 2. Topographoyf t hes tudya reas howintgh el ayouot f thet hreew ellsT. hed asheldin ess howth el ocatioonf
blind reverse faults.
sectionf rom the underlying strata [Evans, 1989]. In western to calibratet he wireline depth standarda gainstc ommercial
New York the Devonian sedimentsa re prodeltaic and con- naturalg ammaa nd densityl ogsw hichw ere usedt o identify
sist predominantlyo f alternatings equenceso f black and stratigraphich orizonso f specifici nterestf or stressm easure-
graym udstone/siltstotnuer bidirep ilest he coloro f whichi s ment. Figure4 showst he ultrasonicr eflectivityi magingo f a
thought to reflect subsidencep ulses associatedw ith the stratigraphicalleyq uivalent3 0-m sectiono f eachw ell which
Acadian orogeny [Ettensohn, 1985]. Below the Sonyea spansth e K-sand( Grimess andstone)T. he sandc an clearly
Group the lithology is dominantlyc alcareous,w ith the be distinguishedfr om the mudstonesb oundinga bove and
cyclicalr ecurrenceo f calcareouss iltstonesg radingu pward belowb y the higherr eflectivity.T he capabilityo f recogniz-
into limestones [CliJJ(cid:127)' Minerals Inc., 1980]. Above the ing majorb ed boundariesfr om a log run on the samew ire
Sonyea,q uartziticc lasticsb egint o appearw ith quartz-rich line as was used to lower the hydrofracturing tool was
bedsb ecomingi ncreasinglyc ommona bovet he black shale cruciali n permittingp recisep ositioningo f the hydrofractur-
base of the Rhinestreet shale. These thin (< 15 m) quartz-rich ing tool with respect to the sand beds.
beds will be referred to as sands, although in detail they are Owingt o easeo f accesst, he Wilkins well was selectedfo r
composedo f intercalatedb edso f fine-graineds andstonaen d detailed study, and a complete suite of Schlumbergerg eo-
siltstone.T hey are widespreadb ut rarely individuallye xten- physicallo gsw as run. Thesed ata and their bearingo n the
sive on scalesg reatert han tenso f kilometers.A n exception interpretationo f the stressd ataa re discussebdy Evansa nd
is the K-sand known locally as the Grimes sandstonew hich Engelder[ 1987] and Plumb et al. [ 1987].
is recognizedin neighboringc ountiesT. he sectionb elowt he
Stress Measurement Instrumentation
sandsi s cut by a family of blind reversef aults which ramp up
from the Salina salt detachment. Only the larger of these Stress measurementsw ere conducted using the wire line
northeastt rendingf aults which showd isplacementos f up to hydraulic-fracturinsgy stemi llustratedin Figure5 . The sys-
15 m extend sufficientlyh igh to cut the Tully limestone.T hey tem consistso f a trailer-mounted hydraulic winch supporting
most likely formed in responset o compressiond uringt he 1 km of standard 7-conductor armored cable, a hydraulic
Alleghaniano rogenya nd are a commonf eatureo f decolle- high-pressurpeu mpc apableo f delivering1 0 L/min of water
ment thrustingo ver salt [Davis and Engelder, 1985]. at a surfacep ressureo f 50 MPa, and a compressorF. luid to
both inflate the downhole straddle packer and fracture the
interval is delivered downhole via a single high-pressure
FIELD PROCEDURES
hose clamped to the wireline every 30 m to prevent entan-
Depth Calibration and Logging glement.A downholev alve operatedb y wire tensiond eter-
Prior to stresst esting,a boreholet eleviewerl og wasr un in minesw hetherf luid is ported to the fracturingi nterval or the
eachw ell usingt he samet railer-basedw ireline as was used packers[ Rumreeel t al., 1983].F luid pressureis monitored
in the stress measurements.T he objective was to identify downholew ith a transducer( 69 MPa maximum pressurea nd
intervals free of natural fractures for stress testing and also I part in 103p recision)a ndr ecordeda t the surfacet ogether
7132 EVANSE TA L.' APPALACHIASNTR ESSST UDY,1
U
(cid:127)o
u LL I..i.I
(cid:127)o(cid:127) z z z zz
o o
Z (cid:127) (cid:127) c0 (cid:127)c0 (cid:127)_j
O(cid:127) b_ 0 'l '-)Y i <[(cid:127)- I(cid:127)
TZ r-(cid:127) z (cid:127)
I- z(cid:127) (cid:127)-
o(cid:127)
z_(cid:127)
Orr
0
EVANSE T AL.: APPALACHIASNT RESSST UDY,1 7133
:(cid:127)',(cid:127)-r.-..-.¾(cid:127):'.:?':i::(cid:127)!-:(cid:127).(cid:127).::::-.(cid:127):(cid:127)
.. .,.
.g ...;.-...: .(cid:127):.(cid:127)½.:.(cid:127)-...:.'...-..... ..'.(cid:127)
i?.2':(cid:127)JC::. '. ':.ß. ,
.. (cid:127) .(cid:127)
..... ; ..,(cid:127) (cid:127).?(cid:127)
(cid:127).'..;..
ß
(cid:127) (cid:127):(cid:127) ',
(cid:127)..(cid:127) ,.-(cid:127). **
;(cid:127).'.::,.(cid:127)(cid:127)
..-- ; (cid:127)::(cid:127):,, ..(cid:127) ..,(cid:127) ... <.
. (cid:127),& ..:,.(cid:127):;.r.,. (cid:127)
(cid:127).(cid:127) (cid:127) ?:.:.5:F .
:..T. .?.:.. ........:' . . ..(cid:127). :.,(cid:127) .......:..>(cid:127)
.......(cid:127).:,j(cid:127):;.:(cid:127).'..,: (cid:127)..:.... ...(cid:127). :½(cid:127).:(cid:127)..,
..¾ - .;(cid:127):.(cid:127).. ...
(cid:127)..:.j,;?'(cid:127): ....-.(cid:127) ...
..:(cid:127):.(cid:127),. .. .... ..:(cid:127).(cid:127):(cid:127).¾(cid:127).::
. ....:(cid:127) (cid:127).(cid:127)?. ':(cid:127)::(cid:127) (cid:127)..
ß(cid:127) ..' .(.'. (cid:127):((cid:127):,,
ß:(cid:127) :....; -i}....(cid:127).:. ::,....-
(cid:127)'g ,: ..?.:(cid:127):(cid:127)' . 5.
ß(cid:127) (cid:127):-'::::..'..:(cid:127) '-(cid:127)?
e(cid:127):.(cid:127):;-(cid:127);'(cid:127):'/:(cid:127):.:. ....... (cid:127).(cid:127) (cid:127)- .....
½(cid:127).. ':,?,;?:(cid:127)((cid:127)½(cid:127)'(cid:127)' .:.:.:.... (cid:127) '(cid:127)¾-¾ -.'..(cid:127)':.-: (cid:127)L
...... . .(cid:127). (cid:127) .. ;j'(cid:127)'.
..... .... (cid:127) ,
(cid:127)' ;(cid:127) ..... .'>(cid:127).-: .-(cid:127):..(cid:127) .
L*'..' ,%? :(cid:127)??:'5:.:(cid:127)'.-:.:-(cid:127)'.(cid:127):'' (cid:127)'?(cid:127):(cid:127):-l '(cid:127)'::::(cid:127)'(cid:127)*::/:(cid:127)? .....':..' ............
(cid:127)..(cid:127)., .(cid:127),.>-:>. .,(cid:127) . .(cid:127) :(cid:127).. (cid:127) .... -::
. . . (cid:127) ....(cid:127). ..:. .... :(cid:127) .... .':' ....(cid:127):::½ (cid:127).
. ,(cid:127) ,..(cid:127) (cid:127) .... (cid:127).(cid:127)
.....) .,..(cid:127),.. (cid:127)- .
.(cid:127), ........ -.-- ,.
(cid:127) .....
. ...
-.... j ..
(cid:127) :'(cid:127)(cid:127)'.. (cid:127);.(cid:127);.(cid:127) .....
-.(cid:127) .... (cid:127).,.:-(cid:127).' :..(cid:127).½.(cid:127). ;.-: --(cid:127)... (cid:127)... (cid:127).-...
....,. ..... ?(cid:127):
-(cid:127) ½;.' .'(cid:127)};::.,
., .(cid:127). (cid:127):;(cid:127),..-
'(cid:127),.(cid:127) (cid:127): :?(cid:127)..(cid:127):(cid:127) :(cid:127)::- 4-
: ..-:½;
.
ß 156(cid:127)r
?(cid:127).':* . (cid:127).;(cid:127).(cid:127)..
..
.. (cid:127)... .(cid:127) (cid:127);(cid:127).(cid:127)..,:.:;-.(cid:127)-(cid:127);,.::(cid:127)½.:>..': -. .} (cid:127):.- '(cid:127).(cid:127),...(cid:127)-,
:(cid:127).:-.(cid:127)..::f'.i(cid:127).. ;(cid:127) '.
1(cid:127) '7'3O.5-
. m.
APPLE?ON WILKINS
(PRE(cid:127)FRAC) (PRE-FRAC) (POST-FRAC.)
Fig. 4. Boreholtee leviewerer flectivitimy agessp anninthge K -sandin tervailn eacho f thet hreew ellsI.n tervals
stress-tesaterdes howtno gethewri tht heo bserveISd IP.T her ightmolsotg w aso btainefdo llowintgh es trestse stinogf
the Wilkins well. The traces of the induced fractures are visible in the lower intervals shown.
7134 EVANS ET AL.' APPALACHIAN STRESSS TUDY, 1
WIRE LINE SHEAVE
HIGH-PRESSURE HOSE SHEAVE
6-METER HIGH
TR ROOF TRAILOR
LIC WINCH WITH I KM CABLE
DIESEL COMPRESSOR
HIGH-PRESSURE (50 MPo
AT I0 lit/mln) PUMP
500M HOSE DRUM LINES RUN TO FIELD LAB
WITH ROTARY COUPLING
DOWNHOLE SIGNAL
HOSE-WIRLEI NEC LAMP SYSTEMR EMOTE
(EVERY3 OM) CONTROLLI NES
REMOTE HYDRAULIC
LINES FOR FLOW CONTROL
DDLE PACKER
Fig. 5. Schematic diagram of the wireline microfrac stress measurement system used in the study.
with flow rate on strip chart and analog tape recorders. The ceased or changed slope, thereby indicating fluid loss into a
system was developed by F. Rummel and coworkers at both presumed induced fracture. Pumping was then abruptly
Ruhr University and MESY Systems, Bochum, Federal stopped and the interval shut in until the pressure had
Republic of Germany, and is identical in operation to that stabilized. The system was then flowed back at the surface.
described by Rumreel et al. [1983]. The straddle packer used Care was taken to monitor the volume of fluid injected and
is a standard high-pressurew ash tool manufacturedb y TAM returned during all pump cycles. Flow back was interrupted
International of Houston, Texas. A 1.45-m straddle interval periodically to monitor interval repressurization as the frac-
length was used in all stress tests. Packer seal length was ture drained pressurized fluid back into the interval. The
1.04 m. Evans [1987] has reported a laboratory study of the effect of this can be seen as occasional positive jags in the
mechanical behavior of this straddle packer under conditions pressure record during flow back periods. These jags also
which simulate those encountered during the stressm easure- served to confirm that a fracture had been induced. As the
ments. rate of pressure increase during these flow back interrup-
tions is directly proportional to the flow rate of fluid entering
Stress Measurement Technique the interval from the draining fracture, the jags provided a
Upon selection of an interval for stress testing, the pack- measure of drainage state. Once the shut-in repressurization
ers were lowered so as to straddle the interval. Precise depth rate had become negligible (i.e., the fracture had adequately
control was attained through reference to color-coded marks drained), the first reopen pump test was conducted. During
emplaced on the wireline every 10 m and originally cali- this cycle, 10 L of fluid was injected, again at full pump rate,
brated using a laser-ranging distance-measuringd evice hav- and the interval subsequently shut in and flowed back,
ing a standard error of 5 cm over a kilometer. A correction observing the same procedure as in the breakdown pump.
was applied to account for cable stretch under the weight of Once fracture drainage had again diminished to low levels,
the tool. The packers were then inflated so as to apply a further pumping cycles were conducted involving the injec-
squeeze pressure of between 5 and 7 MPa against the tion of progressively larger volumes of fluid.
borehole wall. The downhole valve was then actuated to During the suite of reopening pump tests, instantaneous
isolate the packers and effect a hydraulic path from the shut-in-pressures(I SIPs) tended to decline from one cycle to
high-pressure hose to the straddled interval. The interval the next (Figure 6). Successively larger volumes were
was then ready for testing. A typical test procedure is pumped in subsequent cycles until both the injection pres-
illustrated in Figure 6 which shows the time history of sure and the subsequent ISIP stabilized. The largest fluid
downhole pressure and surface flow rate obtained during the volume injected during a single pump in any test was 100 L.
testing of the Tully limestone interval at a depth of 1009.5 m It is well known that fracture reopening pressuresP RO
in the Wilkins well. A permeability test was first conducted tend to decline with successivep ump cycles. Hickman and
by raising the pressure in the interval by 2 MPa and Zoback [1983] have suggested,l argely on empirical grounds,
monitoring the stability of the pressure after shut-in. A stable that PRO measured on the second reopening cycle is the
pressure was taken as confirmation that no permeable natu- more appropriate value for maximum horizontal principal
ral fractures intersected the straddled interval. Pressure was total stressS u estimation using the method of Bredehoeft et
then released at the surface, and the interval pressure was al. [1976]. Although the physical processes underlying the
allowed to fall to hydrostatic in preparation for breakdown. decline in PRO are not understood, inadequate drainage of
The pumps were then turned on full (at 10 L/min) until the the fracture pressure from the preceding pump cycle is
attendant steady increase in downhole pressure either certainly a contributing factor. To eliminate this potential
EVANS ET AL.' APPALACHIANS TRESSS TUDY, I 7135
WILKINS WELL: !009.5M (DS #W!2)
g (cid:127)o
n- 40 o o
LU 30 _
LU 20
0
'r I0
z
o o
_h_
hrs
210 i i (cid:127)
4O
TIME (minutes]
(cid:127) BRK ' '
._. (cid:127) R(cid:127)01R 02R 03 REOC1 i ition
(cid:127) t I ........'.l eos]St'(cid:127)P
(cid:127)0 , J./ ,ithostat
Z I0
o
ca TIME (minutes}
Fig. 6. Pressurea nd flow rate recordso btainedd uringt he testingo f the Tully limestoneT. he bottomf iguresa re
detailso f the top and showt he pressurer ecordw rittend uringa ll pumpinga nd subsequensth ut-inp eriods.
effect from our estimateso f PRO, we reoccupied2 7 of the induced fracture even though it may run out of the interval.
intervals tested some hours to days after performing the This provedt o be commona nd will be discussedla ter. Con-
initial fracture sequencea nd conducted a fully-drained ventional impressionp acker surveysw ould normally reveal
reopeningp ump test. Where an interval was not reoccupied, only the fracture trace in the interval.
we usedt he value of PROo btainedf or the secondr eopening
pump test. RESULTS
The flow rates and volumes administered during a typical
A tabulated descriptiono f each measurementc onducted
test are modest in comparison to those used by other
including depth, lithology, pertinent pressure parameters,
workers. Calculations which assume that the induced frac-
percentageo f total pumpedf luid volumer eturnedd uringt est
ture can be representeda s a penny-shapede quilibriumc rack
and estimated stressm agnitudesi s presented in Table 1 for
in an idealized elastic medium, constrained by reasonable
the Wilkins, Appleton, and O'Dell wells. A descriptiono f
values of fracture toughnessa nd elastic modulus, suggest
the trace of all induced fractures successfully imaged with
that fracture radii of the order of 5-10 m can be anticipated
the borehole televiewer is presentedi n Table 2. The discus-
usingo ur procedures[ Evans and Engelder, 1987]. Drainage
siont hat follows presentsg raphicalr epresentationso f these
of the fracture between pump cycles is important in limiting
data.
fracture dimensions and also in minimizing the disturbance
to fluid pressures( and hencet otal stressesi)n the vicinity of
Instantaneous Shut-in Pressures
the test interval. In those cases where downhole injection
pressurea ppearedt o be limited by our modesti njectionr ate, A total of 22 intervals were stress tested in the Appleton
slow pump tests were performed to demonstratet he inde- well, 43 in the Wilkins, and 10 in the O'Dell. Instantaneous
pendenceo f instantaneouss hut-in pressuret o flow rate. shut-inp ressurew as selecteda s the pressurea t which the
Inducedf ractureg eometrya t the well bore was determined post-shut-inp ressured eclinec urve departedf rom the linear
by conductingp ostfracturet eleviewer surveyso f the tested drop defined immediately following shut-in (tangent
intervals. Fracture definition was enhanced by setting an method). A tabulation and discussiono f the numerouss uites
impressionp ackera gainste achf racturea t sucha pressureth at of ISIPs obtained during the Canisteo tests is presented by
the squeeze( i.e., radial stress)e xertedb y the packerr ubbero n Evans and Engelder [1989] and is not repeated here. In
the borehole wall was equal to the reopen pressure( to ensure summary we note the following:
that no fresh fractures were induced). The squeeze effi- 1. In almost all tests the tangent method yielded a clearly
ciencyo f the packer in questionw as determinedf rom labora- defined ISIP estimate for all reopen pump cycles. The
tory testsa s 88% [Evans,1 987].T he fracturei magingte chnique inflection point could be determined to within 0.15 MPa.
proveds atisfactoryin 70% of casesa nd hast he advantageso f Pressure versus log time plots of several selected pressure
both speeda nd of revealing( in principle)t he full extent of the decline curves (notably those for the Tully limestone test
7136 EVANS ET AL.' APPALACHIAN STRESSS TUDY,
TABLE 1. Description of Each Measurement
Estimated Parameter
Data Point Descriptors Measured Parameter Values Values
Quartz Interval Breakdown Reopen Tensile Fluid, Method 1 Method2
Fraction, Data Depth, Pressure, Pressure,(cid:127)' ISIP, Strength, Vin/Vout Sn, Sn, T,
Formation Lithologyb % Set m MPa MPa MPa MPa (Pumps1 + 2) d MPa MPa MPa
Wilkins Well
S.S 25 W43 186. 11.5 8.05 c 6.05 9.1 -+ 4.0 0.56 13.8 8.1 3.45
(D-sand)
S.S 35 W42 188.5 18.5 7.4 c 6.25 9.1 _+ 4.0 0.45 7.3 9.3 11.1
(D-sand)
PC Sil.M.S. 5 W41 194.5 35.7 9.2 (cid:127) 6.10 9.1 _+ 4.0 0.65 -9.05 r 7.0 26.5
A S.Sil. S. 23 W40 198.5 26.65 7.3 g 6.45 8.8 _+ 3.0 0.77 -0.(:½ 9.9 19.35
(E-sand)
Sil. S. 15 W1 203.5 21.8 9.7 6.4 8.8 -+ 3.0 0.75 4.0 c 7.3 12.1
Sil. S. 13 W5 207 24.8 8.55 6.7 8.8 -+ 3.0 0.75 1.9r 9.35 16.25
M.S. 0 W20 252.7 22.4 10.4 7.75 8.8 -+ 3.0 0.10 6.95(cid:127) 10.15 12.0
Sil. S. 20 W21 257.2 27.4 16.75 8.1 8.8 -+ 3.0 0.70 2.9 r 4.75 10.65
(F-sand)
Sil.M.S. 5 W22 266.0 27.6 13.15 7.75 8.8 -+ 3.0 0.52 1.6c 7.25 14.45
Sil. S. 16 W4 342.0 19.1 13.85 10.5 8.8 -+ 3.0 0.50 17.5 14.0 5.25
M.S. 0 W23 386.0 28.3 13.45 g 11.45 8.8 -+ 3.0 0.72 10.7 16.7 14.85
M.S. 0 W3 420.0 21.5 13.1 g 13.35 8.8 -+ 3.0 0.2 22.8 22.4 8.4
Sil. M.S. 10 W2 486.0 18.75 17.05 14.4 8.8 -+ 3.0 0.58 28.0 20.9 1.7
S.Sil. S. 20 W30 501.4 21.2 18.1 15.15 8.8-+ 3.0 0.4 27.1 21.95 3.1
(G-sand)
M.S. 0 W39 560.5 18.3 15.7 16.05 8.8 -+ 3.0 0.3 32.65 26.45 2.6
M.S. 0 W14 579. 21.15 15.65 e 17.2 8.8 -+ 3.0 0.3 33.0 29.7 5.5
S.SiI.S. 24 W10 582.5 23.7 21.3 18.2 8.8 -+ 8.0 0.71 33.4 27.0 2.4
(HI-sand)
M.S. 2 W24 592.5 17.4 15.2 (cid:127) 16.5 8.8 -+ 3.0 0.62 34.5 27.95 2.2
SiI.S. 13 W25 597.4 24.9 19.5 (cid:127) 18.3 8.8 -+ 3.0 0.25 32.35 28.9 4.4
(H2-sand)
SiI.M.S. 8 W38 621.8 21.1 18.3 (cid:127) 18.35 8.8-+ 3.0 0.36 37.55 31.55 2.8
S.SiI.S. 5 W26 652.2 17.35 15.7 g 17.0 8.8 -+ 3.0 0.42 35.4 28.25 1.65
S.SiI.S. 17 W27 662.5 19.7 18.0 g 20.6 8.8 -+ 3.0 0.42 43.8 36.7 1.7
(J l-sand)
S.SiI.S 13 W28 674.0 27.05 22.4 (cid:127) 20.6 8.8 _+ 3.0 0.31 36.3 32.15 4.65
(J2-sand)
SiI.S. 9 W29 680.0 20.5 17.3 g 19.1 8.8 -+ 3.0 0.38 38.3 32.7 3.2
M.S. 2 W6 692.0 20.3 16.95 18.5 8.8 -+ 3.0 0.65 36.5 31.1 3.35
S.SiI.S. 20 W31 707.5 21.9 22.7 (cid:127) 21.95 8.8 -+ 3.0 0.6 45.1 35.5 -0.8
(K-sand)
S.SiI.S. 15 WI5 712.5 24.05 20.9 21.85 8.8-+ 3.0 0.6 42.6 37.05 3.15
(K-sand)
R SiI.M.S. 6 WI6 724.0 19.55 15.7 g 15.6 8.8 -+ 3.0 0.23 28.2 23.3 3.85
R Sil M.S. 4 WI7 729.0 19.4 15.8 15.4 8.8 + 3.0 0.24 27.75 22.55 3.6
C Sil S. 13 WI8 747.0 18.45 17.0 15.95 6.6 -+ 1.2 0.20 27.95 22.8 1.45
C Sil M.S. I1 W37 778.15 19.4 16.9 16.05 6.6 -+ 1.2 0.25 26.95 22.85 2.5
M Sil M.S. 17 WI9 832.5 20.8 18.35 17.0 6.6 -+ 1.2 0.19 27.8 23.65 2.45
M Sil M.S. 14 W32 840.0 19.1 17.0 16.25 6.6 -+ 1.2 0.30 27.2 22.7 2.1
WR Sil M.S. 8 W33 860.5 25.15 17.9 17.05 7.8 -+ 1.2 0.42 24.5 23.95 7.25
WR Sil S. 20 W9 889.5 27.25 20.45 18.5 7.8 + 1.2 0.30 26.45 25.45 6.8
PY(b) Sil M.S. 13 W34 951.0 21.9 20.65 20.2 7.8 -+ 1.2 0.30 36.25 29.7 1.25
PY(b) M.S 17 W35 960.5 23.1 20.45 20.0 7.8 -+ 1.2 0.45 34.35 29.2 2.65
L L.S 10 W36 977.6 22.4 21.6 20.85 7.8-+ 1.2 0.27 37.4 30.4 0.8
G M.S 15 W7 985.5 21.7 20.9 19.9 7.8 -+ 1.2 0.33 35.2 28.2 0.8
G M.S 15 W8 991.15 18.9 19.65 19.7 7.8 -+ 1.2 0.28 37.3 28.75 -0.75
T L.S 0 W12 1009.5 35.05 33.3 c 30.6 5.2 -+ 3. 0.40 40.65 47.6 1.75
T L.S 0 Wll 1013.5 26.8 25.5 24.45 5.2 -+ 3. 0.39 30.45 36.95 1.3
Mo Sil. S. 9 W13 1037.1 23.45 21.5 (cid:127) 21.8 7.8 -+ 1.2 0.30 38.55 32.7 1.95
Appleton Well
D Sil. M.S. A 1 186.8 25.1 6.4 (cid:127)' 5.38 9.1 -+ 4.0 0.66 -1.9 r 7.65 18.7
D M.S. A2 230.0 21.5 7.5 g 6.5 9.1 -+ 4.0 0.69 4.6 9.5 14.0
H S.Sil. S. A3 248.5 29.5 9.25 x 7.5 9.1 -+ 4.0 0.57 -0.5 c 10.55 20.25
(B-sand)
H Sil. M.S. A4 277.5 18.0 10.5 '(cid:127) 8.0 9.1 -+ 4.0 0.60 12.1 10.5 6.5
H S.Sil. S. A6 294 18.75 14.7 (cid:127)' 9.0 9.1 -+ 4.0 0.26 14.2 9.15 4.05
(D2-sand)
PC Sil. M.S. A7 305 34.8 10.9 (cid:127) 10.5 9.1 + 4.0 0.24 2.5f 17.3 23.9
A S.Sil. S. A8 312 23.75 11.8 (cid:127)' 10.4 8.8 -+ 3.1 0.76 12.9 16.05 11.95
(E-sand)
EVANS ET AL.: APPALACHIAN STRESSS TUDY, ! 7137
TABLE 1. (continued)
Estimated Parameter
Data Point Descriptors Measured Parameter Values Values
Method
Quartz Interval Breakdown Reopen Tensile Fluid, Method 1
Fraction, Data Depth, Pressure, Pressure,' ISIP, Strength, V,n/Vout SH, Su, T,
Formation Lithologyb % Set m MPa MPa MPa MPa (Pumps1 + 2) a MPa MPA MPa
Appleton Well (continued)
A Sil. S. A9 356.5 31.5 10.0 (cid:127)' 10.0 8.8 _+ 3.1 0.57 3.5 / 14.4 19.7
A S.S. A10 366.0 17.85 15.5 e 10.65 8.8 _+ 3.1 0.65 18.75 12.5 2.35
(F-sand)
R M.S. All 374.25 29.2 12.85 (cid:127) 10.6 8.8 _+ 3.1 0.75 7.35 14.9 16.35
R M.S. A12 440.7 27.55 14.9 12.5 8.8 _+ 3.1 0.45 14.0 17.85 12.65
R M.S. A13 527.5 21.7 15.65 (cid:127) 14.65 8.8 _+ 3.1 0.75 25.4 22.6 6.05
R Sil. S. A14 677.5 20.8 16.9 (cid:127) 18.3 8.8 _+ 3.1 0.50 35.6 3O.7 3.9
R Sil. S. A15 701.0 17.8 15.3 18.3 8.8 _+ 3.1 0.49 38.35 32.05 2.5
R S.Sil. S. A16 704.5 19.8 16.8 (cid:127) 19.2 8.8 _+ 3.1 0.53 39.0 33.0 3.0
(H2-sand)
R Sil. M.S. A17 748.5 18.6 16.8 (cid:127) 19.2 8.8 _+ 3.1 0.50 39.75 32.75 1.8
R S.Sil. S. A18 771 25.35 21.3 e 22.05 8.8 _+ 3.1 0.50 41.3 36.55 4.05
(Jl-sand)
R S.Sil. S. A19 778.5 21.4 16.15 c 22.05 8.8 _+ 3.1 0.55 45.15 41.65 5.25
(J2-sand)
R Sil. S. A20 788.0 23.3 19.3 e 20.1 8.8 _+ 3.1 0.32 37.3 32.5 4.0
R Sil. M.S. A21 834.0 17.35 15.3 (cid:127) 15.9 8.8 _+ 3.1 0.55 30.15 23.4 2.05
M Sil.M.S. A22 927.0 18.7 16.7 (cid:127) 16.4 6.6 _+ 0.9 0.25 27.1 22.4 2.0
WR Sil. S. A23 1000.0 27.35 19.6 (cid:127) 19.6 7.8 _+ 1.1 0.20 28.5 28.45 7.75
O'Dell Well
D S.S OD1 246.8 26.7 19.6 7.5 9.1 + 4.0 0.2 2.25 r 0.25 r 7.1
D Sil.M.S. OD3 342.0 21.5 10.9 9.3 9.1 + 4.0 0.75 11.8 13.5 10.6
PC Sil. M.S. OD2 428.3 42.2 12.5 11.4 9.1 + 4.0 0.2 -3.5/ 17.1 29.7
R Sil. M.S. OD10 864.5 31.6 20.6 8.8 + 3.1 27.9
R Sil. S. OD9 896.5 52.5 24.5 8.8 + 3.1 0.45 20.15
(J2-sand)
R Sil. M.S. OD8 909.5 30.4 19.5 8.8 _+ 3.1 0.3 27.1
R Sil.M.S. OD7 922.5 29.2 20.0 8.8 _+ 3.1 0.4 29.65
R Sil. S. OD4 931.0 30.9 24.2 8.8 + 3.1 40.47
(K-sand)
C M.S. OD6 942.0 44.5 18.2 6.6 _+ 1.2 0.2 6.5/
C M.S. OD5 950.2 33.4 16.2 6.6 _+ 1.2 11.55
aD, Dunkirk; H, Hanover; PC, Pipe Creek; A, Angola; R, Rhinestreet; C, Cashaqua; M, Middlesex; WR, West River; PY(b), Pen Yan
(black shale section); L, Lodi limestone; G, Geneseo black shale; T, Tully limestone; Mo, Moscow.
bLogi nterpretationosf lithologyg enerallya ssumeth ath ighr adioactivitya ndb oundw aterc ontenti mplyh ighc lay andl ow quartzc ontent
and fine particle size. The percentage volume of quartz as estimated from the GLOBAL TM(m ark of Sclumberger) computer-processingl og
is indicated. S.S., quartzitic sandstone,d efinition of lithology in terms of log responsei s low y (80 API), neutron 4>- < density 4>;S .Sil. S.,
sandy siltstone; Sil. S., siltstone, moderate y (100-120 API), neutron 4>(cid:127) 15-20%, p (cid:127) 2.7; Sil. M.S., silty mudstone; M.S., mudstone, high
(<140 API), neutron 4>> 20%, p (cid:127) 2.7.
eReopen pressure listed is for first reoccupation after initial fracturing pump.
aAveragef ractiono f fluid returnedd uringf irst and secondr eopeningp umps.
eReopenp ump 2 value: greater than 3% decline in reopening pressure on subsequentp umps >0.4 MPa.
fEstimatedv alueo f S, < Sha ndi s hencen ot allowable.
gReopen pump 2 value: less than 3% decline in reopening pressure on subsequentp umps <0.4 MPa.
shown in Figure 6) failed to reveal any features that might be become stuck through spalled material and a pull of 2 t was
taken as a higher value for the ISIP than that obtained from applied to the wireline in order to free the tool. Although
the tangent method. examination of the tool at the surface revealed no sign of
2. As is commonly observed, ISIPs tended to decline damage, all subsequent tests yielded pressure histories
from one pump cycle to the next, although they usually which were corrupted during pumping phases. This is illus-
stabilized by the end of the second pump test (Figure 6). trated in Figure 7 which shows the pressure and flow rate
ISIPs observed in the reoccupation tests conducted hours histories obtained during the testing of the interval at 896.5 m
to days following the initial test suite were essentially the depth. The erratic pressure variations begin as soon as the
same as the stable values obtained in the initial tests. trace departs from the initial uniform pressurization rate. In
Following the work of Gronseth and Kry [1983] and Hick- Figure 7 this point coincides with the unusually stable
man and Zoback [1983] among others, we choose the least shut-in pressure level persisting after breakdown (which was
(stable) ISIP as the best measure of least principal stress. also a characteristic of the malfunction), but this was not a
All tests conducted below 500 m in the O'Dell well were general rule. Following termination of pumping, the pressure
hampered by what appears to have been an intermittent histories in most cases appeared perfectly normal and
blockage and/or leakage in the downhole apparatus. The yielded ISIPs which declined with successivep ump cycle in
problem manifested itself after the straddle packer had the manner expected [Evans and Engelder, 1989]. Further-
7138 EVANS ET AL.' APPALACHIANS TRESSS TUDY, 1
TABLE 2. Summary of Trace Data
Extent of Trace Out of Direct Downhole
Strike of Trace, øE of N Interval, m Evidence Packer
Depth, Formation Image of Pressure,
DS m Member a East Limb West Limb Qualityt' Upward Downward Bypass?c MPa
Wilkins Well
W43 a 186.0 H (D-sand) 5 9 9 (cid:127)/(lower) 8.8
W42 a 188.5 H (D-sand) 5 9 9 ,/(lower) 9.3
W41 194.5 PC 229 3 0.0 0.0 X 9.15
W40 198.5 A(E-sand) 64? 4 0.7(?) -0.7 X 9.45
Wl a 203.05 A 88 3 0.96 e -0.75 ? (upper) 7.0
W5 207.0 A 194 2 0.0 0.0 X 6.7
W20 252.7 A 5 9 9 X 8.4
W21 257.2 A (F-sand) 1797 4 -0.4 0.2(?) X 8.6
W22 266.0 R 5 9 9 X 8.6
W4 a 342.0 R 198 2 0.62 0.0 (cid:127)/(lower) 8.4
W23 386.0 R 40 272 2 0.55 0.53 X 10.9
W3 a 420.0 R 88 241 2 0.56 1.0 e (cid:127)/(lower) 9.6
W2 486.0 R 268? 4 0.54(?) 0.79(?) X 9.8
W30 501.4 R (G-sand) 29 2 0.44 0.34 X 12.5
W39 a 560.5 R 94 274 1 0.15 0.97 e X 12.4
W14 579.0 R 83 272 1 0.20 0.46 X 13.4
W10 582.5 R (H 1-sand) 5 0.25 -0.20? X 11.5
W24 a 592.5 R 66 275 2 0.41 0.0 (cid:127)/(lower) 13.0
W25 597.4 R (H2-sand) 230 2 -0.30 0.35 X 13.55
W38 621.8 R 5 9 -0.20 X 13.15
W26 652.2 R 26 222 2-3 0.15 0.20? X 14.65
W27 a 662.5 R (Jl-sand) 43 ñ 35 243 2 -0.2 1.21 e ? (lower) 14.55
W28 674.0 R (J2-sand) 5 9 9 X 15.2
W29 680.0 R 55 249 1 0.65 0.51 X 15.05
W6 692.0 R 59 239 2 0.0 0.0 X 14.8
W31 707.5 R (K-sand) 280 2 0.4 0.0 X 14.65
W15 712.5 R (K-sand) 32 249 2 0.0 0.51 X 14.65
W16 a 724.0 R 96 275 1 0.71 1.07 e X 15.4
W17 a 729.0 R 93 251 1 0.72 1.0 e X 15.45
Wi8 a 747.0 C 64? 2517 4 0.85 e 0.0 (cid:127)/(upper) 15.4
W37 a 778.15 C 5 9 9 ((lower) 15.9
W19 a 832.5 M 38 281 1 0.5 1.6 e (cid:127)/(lower) 16.45
W32 a 840.0 M 79 190 1 1.0 e 0.33 X 16.9
W33 a 860.5 WR 81 261 1 0.41 1.41 e X 17.1
W9 a 889.5 WR 60 2 0.78 1.0 e (cid:127)/(lower) 14.7
W34 a 951.0 PY 63 248 2 0.0 0.30 X 18.0
W35 a 960.5 PY 74 254 2 0.15 1.4 e (cid:127)/(upper) 18.6
W36 a 977.6 L 49 266 2 0.64 1.2 e (cid:127)/(lower) 18.5
W7 a 985.5 G 72 250? 3 1.21 e 1.1 e (cid:127)/(lower) 16.15
W8 a 991.15 G 82 249 1 1.2 e 1.2 e ? (upper) 16.2
W12 1009.5 T 62? 4 0.0 1.1(?) X 16.2
Wll a 1013.5 T 57? 4 9 9 (cid:127)/(lower) 16.7
W13 a 1037.14 Mo 75 2 1.1 e -0.7 X 17.2
Appleton Well
A1 186.8 D 5 9 9 X 11.8
A2 230.0 D 5 9 9 X 11.3
A3 248.3 H (B-sand) 85 3 -0.5 0.0 11.7
A4 277.29 H 85? 4 0.07 -0.6? 12.3
A6 293.78 H (D-sand) 77? 4 0.0 0.0 12.6
A7 a 304.78 PC 67 226 ñ 39 2 0.9 e 0.52 (lower) 12.5
A8 311.85 A (E-sand) 5 horiz. horiz. 13.0
A9 a 356.33 A 72 264 2 0.53 1.25 e (lower) 13.0
A10 365.83 A (F-sand) 78 3 0.0 0.0 13.5
All 374.25 R 5 9 9 13.8
A12 440.49 R 92 272 3 0.0 0.4 13.8
A13 a 527.25 R 99 295? 3 1.36 e 0.75 (upper) 14.8
A14 677.15 R 90? 270? 4 0.0 0.4? 16.7
A15 700.17 R 77 256 2 0.35 0.5 16.7
A16 704.17 R (H-sand) 83 291 4 0.0 0.5? 16.9
A17 748.14 R 85 249 2 0.0 0.9 17.8
A18 a 770.64 R (J-sand) 9 328 4 9 9 (upper) 18.2
A19 778.14 R (J-sand) 25 3 0.0 0.0 18.1
A20 a 787.63 R 1787 4 0.0 1.6 e (lower) 18.3
A21 833.58 R 284 2 0.7 0.5 18.1
A22 926.56 M 233/297 1 0.56 0.0 19.15
A23 999.53 WR 244 1 0.75 0.0 19.9