Upload
pondok-huda
View
233
Download
0
Embed Size (px)
Citation preview
8/10/2019 1979 Devonian shale.pdf
1/36
A WELL LOG METHOD FOR ,
EVALUATI NG THE DEVONI AN SHALES
I N THE APPALACHI AN BASI N
J ohn B. Cur t i s and W Geor ge Fi ngl eton
Sci ence Appl i cat i ons, I nc.
Pr epared f or t he
Uni t ed St at es Depart ment of Ener gy
Morgant own Energy Technol ogy Cent er
East ern GUS Shal es Proj ect
Under Cont r act No. EY- 78- C- 21- 8216 Task 09
J anuar y 8, 1979
8/10/2019 1979 Devonian shale.pdf
2/36
. ?A
- Fi l eNo. 144
.
ABSTRACT
The Devoni an Shal e f ormati ons of t he Appal achi an, I l l i noi s, and M chi gan
Basi ns are bei ng st udi ed by t he Morgantown Energy Technol ogy Center
( U. S. Depart ment of Ener gy) and i ndust r y ( East ern Gas Shal es Pr oj ect )
i n order t o accel erate t he devel opment of t he natural gas pot ent i al
of t he shal es.
Tot al gas resour ce est i mates f or t he Appal achi an Basi n
al one r ange f r om 3 t o 2400 TCFG.
Al t hough r el ati vel y compl ete wel l l og sui t es have been r ecor ded i n
wel l s dri l l ed f or charact er i zati on and st i mul at i on resear ch experi ment s,
t he Devoni an Shal e i s an unconventi onal gas resource and t he reservoi r
i s not r eadi l y eval uated by convent i onal wel l l og anal ysi s. The
econom cs of shal e wel l s and the sensi t i vi t y of t he shal es t o dri l l i ng
muds r equi r e t hat an operat or be abl e t o eval uat e a wel l usi ng a m ni mum
of wel l l ogs, pr ef erabl y r ecor ded i n an empt y bor ehol e.
Log sui t es r ecor ded i n empt y and l i qui d- f i l l ed bor ehol es have been
anal yzed f rom a t ot al of seven wel l s i n t hr ee st ates i n t he Appal achi an
Basi n.
Several t echni ques were at t empt ed t o i dent i f y gas- and kerogen-
ri ch and nat ural l y f ractured i nterval s, i ncl udi ng constr ucti on of
resi sti vi t y and porosi t y overl ays, cal cul at i on of Producti on I ndi ces, ,
anal ysi s of t emperature,
bul k densi t y compensati on and Si bi l ati on,
curves.
The i nformati on ext r acted f r om t he l ogs was compared to
convent i onal core desor pt i on ( off gas) , f r acture and geochem cal
data as wel l as t o comput er- generated synergeti c l ogs. A sui t e of
empt y- borehol e l ogs has been def i ned whi ch wi l l yi el d maxi mum f ormati on
eval uat i on dat a at a m ni mum cost .
' Trademarks of Bi r dwel l
8/10/2019 1979 Devonian shale.pdf
3/36
. .
OpenFi l eNo. 144
CONTENTS
Abstract
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
i
I nt roduct i on
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1
Obj ect i ves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1
Techni ques and Theory
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2
Di scussi on of Resul t s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Sunmary of Observat i ons
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
21
Recommendat i ons
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
21
Ref erences
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
23
Appendi x A
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
A- l
8/10/2019 1979 Devonian shale.pdf
4/36
. .
I NTRODUCTI ON
i
. I
Si nce t he i ni t i at i on of t he East er n Gas Shal es Proj ect ( EGSP) i n
1975, rel at i vel y compl ete r esearch sui t es of geophysi cal wel l l ogs
have been r ecorded i n EGSP- sponsor ed wel l s.
Anal ysi s of t he wel l l ogs i s extremel y di f f i cul t si nce t he
Devoni an Shal e r eservoi r i s an unconventi onal reservoi r and t he
r esponse of t he l oggi ng sondes t o t he kerogen, f r act ure syst ems and
encl osi ng shal e matr i x i s i nadequat el y underst ood. There are no
publ i shed chart s or nomogr ams avai l abl e f or i nt erpr etat i on of t he wel l
l og si gnatures, so l og anal ysi s must be conduct ed by compar i ng anomal ous
and/ or potenti al l y pr oduct i ve zones wi t h known pr oduct i on/ show, of f gas
and f r acture dat a.
The l og anal ysi s seeks t o i dent i f y f r act ures i n
conj unct i on wi t h gas- ri ch shal e zones.
Sporadi c anal yses of some of t he EGSP wel l s has been per f ormed
by Col umbi a Gas System Servi ce Cor porati on ( Sm t h, 1976) , Bi r dwel l
Di vi si on of Sei smogr aph Servi ce Corporat i on ( Myung, 1976) and
Schl umberger ( Hi l t on, 1977).
A nor t her n Ohi o and t wo Li ncol n County,
WV wel l s ar e t he onl y wel l s f or whi ch detai l ed l og anal yses are
avai l abl e, even t hough sever al years have el apsed si nce other wel l s
were dri l l ed and l ogged.
The anal yt i cal approaches t aken by t he t wo l oggi ng ser vi ce compani es
natural l y f avor t hei r respect i ve . propri et ar y l oggi ng tool s and t echni ques.
A pr act i cal l og sui t e must be def i ned f or t he Devoni an Shal es whi ch
opt i m zes t he amount of f ormati on eval uat i on i nf ormati on gai ned i n vi ew
of l oggi ng and r i g t i me costs.
EGSP r esearcher s of t en hear t he st atement
t hat onl y a gamma r ay, bul k densi t y,
resi st i vi t y, t emper at ure and a noi se
l og are requi r ed, but t here has been no pr evi ousl y publ i shed proof t o
ver i f y the st atement .
OBJ ECTI VES
Sci ence Appl i cat i ons,
I nc. ( SAI ) under t ook t hi s study wi t hi n t he
Appal achi an Basi n wi t h f i ve obj ecti ves i n m nd. The Appal achi an Basi n
was chosen si nce t he great est amount of dat a were avai l abl e.
8/10/2019 1979 Devonian shale.pdf
5/36
8/10/2019 1979 Devonian shale.pdf
6/36
.
I .
. . .
OpenFi l eNo, 144
,
. 8
\
.
si m l ar l i t hol ogy, and t he neut r on and densi t y cur ves wi l l r espond i n
oppost t e di r ect&ns due t o t he f act t hat t he neut r on tool ~111 respond
' +?#W@ ng a f al se l ow porosi t y whi l e the bul k densi t y
c&s- hi gh porosi t y.
Temper ature l ogs r espond to gas l eaki ng f r om a f r actur e system i nt o
a borehol e by r ecor di ng a cool i ng eff ect on t he wel l ' s geot hermal
t emper atur e gr adi ent , near t he poi nt of gas ent r y. A more sophi st i cat ed
appr oach i nvol ves t he cal cul at i on, by comput er, of J oul e- Thompson
Coef f i ci ent s and r esul t ant pr edi ct i on of t he degr ee of natur al f r acturi ng,
by cal cul ati on of a f r actur e i ndex (Myung and Cal dwel l , 1977) . A
qual i t ati ve i ndi cati on of f r actur i ng i s der i ved t hr ough t he equati ons
and t echni ques i n t he ci t ed r efer ence.
Both t ypes of t emper at ure dat a
wer e avai l abl e f or st udy.
3. Si bi l at i on ( Dry- Hol e)
Si bi l at i on l oggi ng, as r ef err ed to i n t hi s report , i s a t rademark
of t he Bi r dwel l Di vi si on of Sei smogr aph Servi ce Corpor ati on.
The tool
r esponds t o several f r equency bands of "noi se" and i s abl e to l ocat e,
by sound detect i on, t he escape of gas f r om a f r actur e i nt o a borehol e.
I t i s i mpor t ant t o r eal i ze t hat bot h Si bi l ati on and t emperature l oggi ng
wi l l i ndi cate t he pr esence of f r actures onl y i f gas i s pr esent i n t he
f r act ur e and t he f r act ur e communi cat es wi t h t he borehol e.
4. Resi st i vi t y Cur ve Over l ays ( Dr y and Net- Hol e)
I n a si m l ar f ashi on to t he por osi t y t ool s, t he cur ves r ecor ded
by r esi st i vi t y devi ces wer e over l ai d and anal yzed. The r esi st i vi t y
t ool s empl oyed have di f f er ent dept hs of i nvest i gati on, i . e. a t ool may
r ead onl y t he r esi st i vi t y of t he mudcake, or t he f ormati on i mmedi atel y
adj acent t o t he borehol e, or i t may r ead var yi ng di st ances i nt o t he
f or mati on.
The net r esul t i s t hat some shal l ow- r eadi ng r esi st i vi t y
devi ces ( Laterol og, , Fl i crol aterol og, ) . wi l l respond to vert i cal , mud- f i l l ed
f r actur es, whi l e deeper- r eadi ng i nduct i on t ool s wi l l not r espond and
wi l l read a hi gher val ue of resi sti vi t y. I deal l y, t he cur ve separati on
wi l l be apparent i n a f r actur ed i nt erval , whi l e the cur ves wi l l not
separat e as much and wi l l t r ack each other i n a non- f r actur ed i nt erval . .
Thi s t echni que i s a "qui ck- l ook" method and must be used wi t h car e and
i n conj unct i on wi t h other t echni ques.
3
1
Tr ademar ks of Schl umberger
8/10/2019 1979 Devonian shale.pdf
7/36
5.
Pr oduct i on I ndi ces ( Dr y Hol e)
Product i on I ndi ces ( PI ) as ref er red t o i n t hi s paper are a devel op-
ment of Dr . J ohn I . Myung of Bi r dwel l Di vi si on of SSC. ( Myung, 1976) .
Potenti al pay zones and f r act ur i ng may be i ndi cated by an i ncr ease
i n gamna- r ay i nt ensi t y and resi st i vi t y due t o t he pr esence of kerogen,
other organi c matt er, and gas- f i l l ed f r actures and an accompanyi ng decr ease
i n bul k densi t y due to the l ower bul k densi t y of ker ogen and/ or t he
pr esence of f r actures whi ch woul d appear as i ncreased porosi t y.
Thi s r el ati onshi p, t he Pr oduct i on I ndex, may be expr essed mathe-
mati cal l y as
Pr oduct i on I ndex ( P. I . ) = G_ + R
1
"b
Where: G = API uni t s f r om qamma r ay l og
Aver age API uni t s of Shal e
. I
t
R=
1
Resi st i vi ty fr om i nducti on l og
Average Resi st i vi t y of Shal e
Db
= The bul k densi t y val ue f r om a Densi t y Log
The aver age val ues must be chosen f or each wel l . Pr oduct i on I ndi ces
f or thi s st udy were cal cul ated on t wo f oot i nt erval s. The P. I . may be
pr oport i onal l y r el ated to t he number of gas pr oduct i ve f r actures i n a
shal e formati on ( Myung, 1976) .
Pr oduct i on I ndi ces were cal cul ated f or f i ve of "t he seven wel l s. The
r emai ni ng t wo wel l s had t he I ndi ces pr evi ousl y cal cul ated by Bi r dwel l
on t hei r Cor n- Pr o Log2.
6. Del t a Rho ( Dr y Hol e)
The f i nal t echni que empl oyed i n t hi s st udy was to anal yze t he del t a
r ho or bul k densi t y compensat i on curve to l ocate zones wher e t he
compensat i on i ncreased whi l e t he cal i per showed a uni f orm borehol e. The
i ncr ease i n compensat i on may be due t o t he ef f ect s of f r acturi ng
communi cat i ng wi t h t he borehol e.
I f t he cal i per i ndi cates a washed out
borehol e and t he compensat i on i ncr eases, a f r act ur e syst em may be pr esent .
and the borehol e may be washed out as a r esul t of t he f r act ure.
Because
of t hi s ambi gui t y,
t he del t a r ho t echni que i s a "qui ck- l ook" method and
2
Trademark of Bi r dwel l Di vi si on of Sei smogr aph Servi ce Corpor ati on
4
8/10/2019 1979 Devonian shale.pdf
8/36
.
Open Fi l e No. 144
; :
not a f i rm i ndi cator of f ractur i ng.
/
.
Al l si x of t hese techni ques were appl i ed t o al l of t he st udy wel l s,
i f t he l ogs had been recor ded.
As pr &i ousl y st ated, t he l og anal ysi s of t he Devoni an Shal es must
compare l og data to knownf r actur e, pr oduct i on and of f gas data i n
order t o i dent i f y the l og si gnatur e f or f ract ured, gas- ri ch zones.
Thi s st udy empl oyed data f r om Col umbi a Gas Servi ce Tr ansm ssi on
Corpor ati on ( Ranost aj , et al , 1976), t he cont i nui ng mont hl y and quart erl y
r eport s of data gener at ed by Bat t el l e Col umbus Laboratory and Mound
Faci l i t y, r epor t s compi l ed by DOE/ METC ( Byrer, et al , 1976; Komar, et al ,
1978) and SAI ( Kucuk, et al , 1978) and f r actur e dat a generat ed by C. S.
Dean and B. Kul ander ( Dean, 1979) .
The eval uati on of t he ut i l i t y of each of t he si x pr evi ousl y ment i oned
t echni ques was determ ned by anal ysi s of wel l l ogs f r om t he f ol l owi ng
wel l s:
Col umbi a Gas #20337, Mar t i n County, KY
Col umbi a Gas #20338, W se County, VA
Col umbi a Gas #20401, Li ncol n County, WV
Col umbi a Gas #20402, Li ncol n Count y, WV
Consol i dat ed Gas #11940, J ackson County, WV
Consol i dat ed Gas #12041, J ackson County, WV
I
Reel Energy D/ K Farm # 3, Mason Count y, WV
A di scussi on of each techni que' s uti l i ty f ol l ows.
8/10/2019 1979 Devonian shale.pdf
9/36
OpenFi l eNo. 144
DI SCUSSI ON OF RESULTS
Each of t he si x anal yti cal t echni ques are di scussed separatel y.
The uni f or m t y or non- uni f orm t y of the resul t of each t echni que i s .
compar ed among t he st udy wel l s. Each t echni que i s compar ed to
pr oduct i on, core f r act ur e, of f gassi ng, and carbon cont ent data wher e
i t i s avai l abl e.
Support i ng f i gur es are pr esented f or each t echni que.
These f i gur es are i ntended t o demonst r ate what t he expect ed cur ve
r esponses shoul d be i n a gas- f i l l ed f r acture system and what r esponses
were act ual l y observed i n t he st udy.
Exampl es f r om t he st udy wel l s were chosen f or di scussi on of each
t echni que. The wel l l og anal ysi s r esul t s for al l t he st udy wel l s are
pr esent ed i n Appendi x A.
Porosi t y Cur ve Over l ays
Thi s t echni que i nvol ved t he compari son of acoust i c, neut r on porosi t y,
and bul k densi t y curves.
Thi s anal ysi s was perf or med to determ ne i f
secondary por osi t y ( f r actures) and gas accumul ati on coul d be i dent i f i ed
i n t he shal es. Secondary por osi t y m ght be i ndi cated by a const ant
acoust i c por osi t y r eadi ng t hr ough an i nt erval whi l e t he neut r on and bul k
densi t y curves i ndi cat e hi gher por osi t y val ues through that i nt erval .
Gas accumul at i on may be i ndi cat ed by an anomal ous curve def l ect i on t oward
l ower porosi t i es i n t he neut r on cur ve and a def l ecti on t oward hi gher
porosi t y i n t he bul k densi t y and acoust i c curves. Fi gur e 1 i s an
exampl e of t he "gas ef f ect " on t hese curves i n a sand- si l t i nt erval .
The anal ysi s f or secondary porosi t y was per f ormed on t hr ee of t he
seven wel l s ( DK#3, #20402, and #20401) .
These t hree wel l s were t he onl y
wel l s wi t h a compl ete sui t e of acoust i c,
neut r on, and bul k densi t y curves.
No zones were f ound i n whi ch t he acoust i c curve r emai ned const ant and
t he neut r on/ bul k densi t y cur ves i ndi cated hi gher por osi t i es. For exampl e,
natural f r actures were i dent i f i ed t hr ough core exam nati on of t he D/ K 83
wel l i n t he i nt erval 2859- 2875 f eet . ( Dean, 1979) . Through thi s i nt erval ,
t he t hr ee porosi t y curves show no r esponse t hat woul d i ndi cate secondary .
porosi ty ( f ractures).
Fi gure 2 shows t hi s i nter val and t he r esponse of
t he cur ves.
The absence of curve si gnat ur es i ndi cat i ng the pr esence of
f r actures was t ypi cal t hr oughout t he D/ K#3 wel l and t he other t wo wel l s.
6
8/10/2019 1979 Devonian shale.pdf
10/36
GAMMA RAY
OpenFi l eNo. 144
NEUTRON
DEPTH
-
2160
-
2170
-
2180
-
2190
-
2260
-
2210
-
2220
-
2230
-
2240
;-
2250
-
2260
Fi gur e 1.
Wel l #20337 showi ng a t ypi cal exampl e of curve
def l ecti on ( "gas ef f ect" ) on t he neut r on and
bul k densi t y curves i n a sand- si l t zone.
7
_ _.--.
.~._ ___ __ ._-.--.~---- .---
8/10/2019 1979 Devonian shale.pdf
11/36
. .
OpenFi l eNo. 144
GAMMA RAY
y_l
DEPTH
2840
2850
2 860
2870
2880
2890
2900
NEUTRON
ACOUSTI C
BULK
POROSI TY
At
DENSI TY .
INCREASiNG
ll$REASING
INCREAS l_NG
---
Fi gure 2.
Wel l D/ K#3 showi ng an exampl e of how por osi t y
curve over l ays do not r espond to i ndi cat e a
zone of known f r act ur es.
8
8/10/2019 1979 Devonian shale.pdf
12/36
. .
.
/
Open Fi l e No. 144
: ..
Si x of t he seven st udy wel l s were anal yzed f or the ef f ect of gas
on t he neutr on and bul k densi t y cur ves. Wel l # 12041 di d not have a
neut r on perasi t y survey r un so i t coul d not be i ncl uded i n t he anal ysi s.
Wel l s #2n33f and t 11940 were t he onl y t wo wel l s wher e t he anomal ous
r *. r
def l ecti on ( gas eff ect) of t he por osi t y cur ves was observed i n t he shal es.
I n Wel l 620337 thr ee zones ( 2530- 2610 f eet, 2758- 2904 f eet, and 3094- 3267
f eet) and i n Wel l #11940 t wo zones ( 3426- 28 f eet and 3450 f eet) were
i dent i f i ed as exhi bi t i ng t he anomal ous def l ect i on.
Fi gur e 3 i s an
exampl e of thi s def l ect i on i n Wel l #20337. The i nt erval 3094- 3267 f eet
i n Wel l #20337 was st i mul ated, but t he af t er st i mul ati on data was not
avai l abl e.
110 ot her i nt er val s di spl ayi ng t hi s ef f ect wer e st i mul at ed.
Exam nati on of t he core f r om Wel l #11940 f ound one f r acture i n or near'
each of t he t wo zones showi ng the "gas ef f ect " on t he curves.
No cor e
was t aken i n Wel l 820337.
I f t he anomal ous def l ecti on of t he por osi t y cur ves observed i n
Wel l s #20337 and #11940 i s real l y t he resul t of gas accumul ati on i n
f ractures, i t i s di f f i cul t t o expl ai n why thi s ef f ect was not observed
i n any of t he ot her wel l s.
Thi s probl em cert ai nl y warr ant s f urt her
consi derat i on.
Temperat ure Curves
Temperat ure surveys ar e uti l i zed t o i dent i f y zones where t he
l i berat i on of gas i nt o t he borehol e resul t s i n a cool i ng eff ect
( t emperat ure ki cks) . I t i s general l y bel i eved that t he gas i s rel eased
t hr ough f r actur es t hat ar e i n communi cat i on wi t h the borehol e.
Anal ysi s of t emperat ure curves was perf ormed on al l seven st udy wel l s.
Two of t hese wel l s ( #20337 and #20402) had comput er gener at ed J oul e- Thompson
Coef f i ci ent s t hat were used t o deri ve a t hermal f r acture i ndex. Thi s
i ndex i s used as a r el ati ve i ndi cator of f r acture si ze based on t he degr ee
of cool i ng of t he gas ent eri ng t he borehol e.
I t i s obvi ous t hat i nspecti on of t he t emperature cur ve can gi ve t he
qui ckest i ndi cati on of gas accumul ati on i f i t i s i n communi cati on wi t h t he
bor ehol e.
I n many cases, a "c ool i ng ki ck" on t he t emperature curve was
t he onl y cri t er i a used f or sti mul ati ng an i nt er val . I n Wel l #20337, t he
zone f rom 3526 t o 3574 f eet was i nvest i gat ed. Anal ysi s of al l avai l abl e
l ogs and appl i cati on of t he t echni ques of t hi s st udy over t hi s zone
showed i ndi cat i ons of gas accumul ati on and f r actur i ng as evi denced by a
9
8/10/2019 1979 Devonian shale.pdf
13/36
GpenFUeHo. 144
i .
GAMMA RAY
I
[ API UNI TS1
I NCREASI NG
1
:
-4
: Z,
.
.
3
,
.
DEPTH
Fr 2520
-/1 2530
32
2630
NEUTRON
BULK
POROSITY
DENSITY
J 4CREASI NG .
I NCREASI NG
- -
Fi gure 3. Wel l #20337 showi ng an exampl e of cur ve def l ect i on
.
( possi bl e "gas ef f ect" ) on t he neut r on and bul k
densi t y curves i n a shal e zone.
10
-.._
_-...- .
8/10/2019 1979 Devonian shale.pdf
14/36
Open File I-JO.44
-.
j
.
" cool i ng ki ck" on t he t emperature cur ve.
Based on t he t emper at ure ki ck
and possi bl e Si bi l ati on ki ck,
t he zone was st i mul ated ( Fi gure 4) . Bef ore
st i mul at i on pr oduct i on was zero MCFG/ day and af t er st i mul at i on was 133
bt CFG/ day.
.
T
The' t emperature cur ve i s a good tool f or t he anal ysi s of t he shal es
. r as l ong as t he nat ural f r act ur es ar e i n communi cat i on wi t h t he borehol e.
. a
: +J
=-
I n one st udy wel l , #20338, i nspect i on of t he t emper ature curve showed
,.::j
o obvi ous " cool i ng ki cks" yet t wo zones were s t i mul ated ( 4890- 4910 f eet
i .
.l
7
and 5450- 5480 f eet ) .
Bef ore st i mul ati on resul t s were zer o MCFG/ day f or
bot h zones and af t er st i mul at i on r esul t s were 40 MCFG/ day and 107 MCFG/ day
'
respecti vel y.
The absence of " cool i ng ki cks" t hrough these two zones
. :
may be t he r esul t of t he borehol e not encount eri ng a f r actur e
4
system but t he f r acture system coul d be penetr ated and enl arged through
sti mul at i on.
Fract ur e dat a fr om cor e anal ysi s were not avai l abl e t o
determ ne i f f r actures were encount ered i n t he wel l i n t he t wo st i mul ated
zones.
Si bi l at i on Curves
As di scussed above, t he Si bi l ati on survey i s r un t o "l i st en" f or gas
bei ng l i berated i nt o t he borehol e.
Typi cal l y, the Si bi l at i on survey i s
r un i n conj unct i on wi t h the t emperat ur e sur vey.
I t shoul d be expected
t hat wi t h a "cool i ng ki ck" on t he t emperat ur e curve t here shoul d be a
corr espondi ng "noi se ki ck" on t he Si bi l ati on cur ve, t hus pr ovi di ng an
i
1
2
,
.
d
,
addi t i onal t ool f or l ocati ng gas accumul ati on and f r acture syst ems.
Si x of t he seven study wel l s had Si bi l at i on curves avai l abl e f or
anal ysi s.
A t ypi cal exampl e of t he Si bi l ati on/ t emperature r esponse t o
gas l i berati on i nt o t he borehol e i s shown i n Fi gur e 5. Thi s exampl e
was t aken f r om Wel l #20402 and i ncl udes t he i nt erval f r om 3340 t o 3420 f eet .
The l aboratory anal ysi s of t he core fr om thi s i nterval i ndi cates off gassi ng
of appr oxi matel y 1. 2 cu. f t . gas/ cu. f t . shal e and or gani c car bon cont ent
i r qngi ng f r om appr oxi matel y 3. 5 t o 4. 8 percent . Exam nati on of t he core
i ndi cates open f r actures t hr ough t hi s i nt erval . These f r actures may have
been i nduced dur i ng t he cori ng operati ons. Bef or e st i mul ati on t est data .
was zero MCFG/ day and af t er st i mul at i on dat a was 112 MCFG/ day. I n Wel l
D/ K#3, several zones were i dent i f i ed as pot ent i al l y gas pr oduct i ve based
on "noi se ki cks" i n t he Si bi l ati on cur ve but t he cor respondi ng "cool i ng ki ck"
11
8/10/2019 1979 Devonian shale.pdf
15/36
,F . . __-- ; . . -a .
1_a..
_- _. _.
_
;
^
1
- ,
i
GAMMA RAY
SISILATION
TEMPERATURE
Q
I NCREASI NG
DEPTH
+-Sibilation
Temperaturb-
Normal Tern p.
Gradient 7
' 3490
Fi gur e 4. Wel l #20337 showi ng an exampl e of t emper at ure
curve def l ecti on ( "cool i ng ef f ect" ) wi th
possi bl e Si bi l ati on curve ki ck t hr ough a
zone whi ch t ested 133 MCFG/ day af t er st i mul at i on.
12
8/10/2019 1979 Devonian shale.pdf
16/36
C.
1.. . .
.;
ig?.
GAMMA RAY
[ API UNI TS1
I NCREASI NG
L7
DEPTH
3340
3350
3360
3410
3 420
SIBiLATION
TEMPERATURE
openFI l eNo. 144
I NCREASI NG
I NCREASI NG
*
Temperature
I
Normal Temp.
Gradhnt /
Normal Temp.
Fi gur e 5.
Wel l #20402 showi ng an exampl e of Si bi l at i on
and t emper at ure cur ve r esponse t o gas
ent eri ng t he borehol e.
13
8/10/2019 1979 Devonian shale.pdf
17/36
.
\
-.
OpenFi l eNo. 144
I
.
i .
on t he t emperat ur e curve was not apparent ( Fi gur e 6). Al so, i n Wel l D/ K#3,
I
I
a very
good
"cool i ng ki ck" was apparent t hr ough a zone f r om 2730 t o
: , : .
2820 f eet
but
on t he Si bi l ati on curve there was onl y a margi nal or no.
_ _ . .
:
appar ent r esponse t hr ough t he zone (Fi gure 7) . Thi s pr obl em
was
al so
.
> L
:
f ound i n Wel l #20337 t hrough t he zone 3526 t o 3574 f eet . I t shoul d be not ed
. , ' II I 1 t hat i n Wel l 820337, t he zone 3526 t o 3574 f eet was st i mul ated and af t er
s4
- v'
- 1
st i mul at i on resul t s show a 133 MCFG/ day gas potent i al . Corr espondi ng
?
Si bi l ati on and t emperat ur e ki cks on t he l ogs are cer t ai nl y good evi dence
.
f or gas accumul at i on and f r act ures but zones where ei t her one of t he two
. . i
4
cur ves do not r espond st i l l warr ant f ur t her eval uati on.
Resi st i vi t y Cur ve Over l ays
- _
The pur pose of t hi s t echni que i s t o i dent i f y zones of i ncr eased
por osi t y ( f r actures) as i ndi cated by separati on of a shal l ow i nvest i gati on
resi sti vi ty curve f rom a deep i nvesti gati on r esi sti vi ty curve or curves.
i
Thr ee of t he seven st udy wel l s have t he appr opr i ate l ogs avai l abl e f or
t hi s. anal ysi s ( #20402, D/ K#3, and 20401). Wel l #20402 was t he onl y wel l
where separati on of t he r esi st i vi t y cur ves was apparent . I n t hi s wel l ,
t hese zones are l ocated at 3370 t o 3381 f eet and 3392 to 3400 f eet
( Fi gur e 8) . These zones were al so charact eri zed by Si bi l ati on and
t emperatur e ki cks.
Exam nati on of t he core i ndi cates open f r actur es t hr ough
t he t wo zones.
Of f gassi ng val ues of 1. 2 cu. f t . gas/ cu. f t . shal e and
r el ati vel y hi gh organi c carbon cont ent r ange f r om 3. 5 t o 4. 8 percent were
deter m ned f or t he t wo zones.
Bef or e st i mul ati on testi ng i ndi cated zero
jI
MCFG/ day and af t er st i mul at i on 112 MCFG/ day.
Exam nati on of t he D/ K#3 wel l cor e I ndi cates sever al zones of f r acturi ng,
yet t he r esi st i vi t y curves show no apparent separat i on.
Based on t he l i m t ed number of wel l s avai l abl e f or t he r esi st i vi t y
t ool overl ay anal ysi s,
i t appears t hat thi s t echni que gi ves very l i m t ed
i ndi cati ons f or the l ocati on of f ractures.
Addi t i onal wel l s wi t h the
appr opr i ate r esi st i vi t y l ogs and cores ar e needed f or a more concl usi ve
anal ysi s of t hi s techni que.
Pr oduct i on I ndex
Pr oduct i on I ndi ces were cal cul ated or pr evi ousl y comput er generat ed
f or al l seven study wel l s.
The f ut ur e val ue of usi ng Pr oduct i on I ndi ces
as a r el ati ve i ndi cator of potent i al gas pr oduct i on wi l l r equi r e many more
14
8/10/2019 1979 Devonian shale.pdf
18/36
Open File No. 144
GAMMA RAY
I
[API UNITS1
INCREASING
: I
DEPTH
3220
3230
3240
3250
3260
3270
3280
3290
SIBILATION TEMPERATURE
INCREASING,
INCREASING .
l
t-Temperature
Fi gure 6.
Wel l D/ K#3 showi ng Si bi l at i on cur ve r esponse and
no cor r espondi ng t emper ature curve r esponse to
gas possi bl y ent eri ng the bor ehol e.
15
.
__ __ _. .___ .
8/10/2019 1979 Devonian shale.pdf
19/36
Open File No. 144
GAMMA RAY
[API UNITS]
INCREASING
I