G EOL. C ROAT . 49/2 1325 -326 1 ZAGREB 1996 1 

Abstract· Note 

The Lower Pannonian (s.str.) in the Sava River Depression -
- A Great Challenge for More Economical Oil Exploration 

Z agorka BOSKO V STEINER 
PROCEEDINGS 

Th e la te ra l ex te n t of the L o we r Panno nian w ithi n 

the Sava basin wil l be d iscussed. Sed iments of this sub­
age have been mapped and sepa rated on outcrops in tile 
rim of depress ion and in cores and logs of dri lled deep 
wells as: the ii hoSlratigraphic unit PrkosjonllQrioll ; the 
bios tra ti g raphic uni ts CeJ lOZOII C Radix croat ica and 

e el/OZOlle Sillzowclla (NubeclIla ria) Jlollorosica , and 

the chronostrat igraph ic unit L ower Pa fl llon ian sub­

stage. 
T here arc signifi cant data showing that these un it s 

may be seri ous ta rge ts for the ex istence of trap ped or 
bypassed oil and/or gas. Sed iment s o f the Lower Pan­
noni an substage were deposited over a re lati vely shon 
period from 11 Ma till 9.5 Ma in a durat ion of 1.5 mil ­
lion years. A scI of pa laeogeographic and biochemica l 
conditi ons resulted in a deposition of a limestone faci es 
(of a lgae and of chemi ca l or igin) and a calcareoll s 
sa nds to ne w ith benthic foram in ife ra , ostracods and 
molluscs. Due to the ir pe trograph ic, pa laeonto log ical 
and s tn.ui graphi c cha rac tc ri stics these sediments have 
bee n s tu di ed by num erous auth ors (GO RJ ANOV IC­
KRAMB ERGER , 189 1; LAS KAREV, 1924; 0 2E­
GOVIC, 1944; JENKO, 1944; MOOS, 1944; BOSKOV 
ST AJNER & TOMA SOVIC, 1967; PLET IK APIC, 
1969; BOS KO V STAJNER & KOC HANS K Y DEV ­
ID E, 1975; PAPP, 1985; YANKO & LARCHENKOV, 
1991 ; S iK IC, 1995 anel ot hers) . The immedi ate base­
ment o f these sedi ments is the Lower Sannatian clayey 
depos it. T he o ve rlaying rock is a ma d stone o f the 
Upper Pannonian. 

Three orogenic phases a ffected this a rea afte r these 
sed iment s and ove rlayin g rocks have been depos ited 
(BOS KOV ST E IN ER , 1986) : the Attican phase ( 10 
Ma ago), the Rhodania n phase (5 Ma ago), and the 
Walachian phase (2.5 Ma ago) . All these fac to rs, 
toge ther wit h an adequatc temperature and presence of 
catalys ts, could have resul ted in the generation of oi l in 
Lower Pann onian sediments. Oi l may ha ve migrated 
int o thin sandstone layers, ri ssures formed during men­
tioned oroge ni c phases and, what is mos t import an t, 
in to the ax ial c res ts o r brach i antic line (BOS KO V 

iVlasarykova 24, Zagreb, Croalia. 

STAJN ER, 1961 ; BRITVIC et 'II. , 1989). Longi tudinal 
and tran sve rse regiona l fa ult s cou ld have effected the 
decay of once ex isting reservoirs, as seen [or examp le 
by the presence of high dens ity and oxid ised o il in out­
crops of the Northern rim of the Sava bas in, in Paklcni ­
ca (BOS KOV STElNER & STEINER, 1995) 

Oil product ion ex ists from dee p we lls dri ll ed al 
more locali ties from these sediments in the Sava bas in 
(BOS KOV ST AJNER & MARINOVIC, 197 1). 111 these 
sediments o il was found: 

a) in the calcareous component in fi ssures of more gen-
erations; 

b) in sand lcnses o f smal l dimensions; 

c) in sand layers of large dimens ions; 

d) in rock mirrors; 

e) in fractures and fissures a long fau lts; 

t) in cres ts of brachi anticli ne axes. 

I have chosen these sed iments to propose the recov­
e ry of the by-passed and captured oil by horizontal o r 
extended-reach wells, s ince it. may be re lati ve ly easy to 
do the preparation for various reasons: basic geological 
maps show ing outc rops o r these sediments a re ava il­
able; outcrops wi th oil in fi ssures, in lenses and in mem­
bers are di sposab le; outc rops cont a ini ng o il are di spos­
abl e in the ea rli er subsurface mining works; the re are 
corcs fro m dee p we ll s dr illed on seve ral localiti es 
through these sediments; 2 D seismic sec ti ons are ava il­
able and may be re interpreted ; we ll logs and dip mea­
surements of deep well s are avai lab le; and struc tu ral 
maps of bedding and th ickness of the Prkos formatio n 
are available . 

A re inte rpre ted map o f o il and gas satu ration fo re­
cast may be elaborated fro l11 ea rl ier maps wit.h addi tion­
al ana lyses and supplementary 2D and/or 3D sc ism ics. 
T he potentia l area has to be defined using : corre lat ion 
of seism ic tim e marke rs; corre lat ion of ciuono­
s tJ"al igraphic un its; a s tudy of the gene ra tive po tent ia l 
(aft er Lopati n, Waples, Barke r and/or othe r me thods); 
and Newcndorp 's method of Monte Carlo simu lat ion of 
the oil or gas reservo ir net recent va lue. 

As to ge t a higher degree of ce rtainty o f the progno­
sis, on each of prospective area a vc rt ica l well may be 
drill ed fo r checki ng the accuracy of ex isting data and 



326 

for the mcasurcment of fis sure orientatioll. 'f he es tab­
lished reserves o f the by-passed and captured oi l we 
may put into production by convent ional and nOll-con­
ventional methods (HORVAT & BOSKOV STEINER, 
1990). l3y the rat ional teamwork of geologists, reservoir 
engi neers and dr ill e rs, horizontal drilling of structures 
containin g rese rvoi rs with the by-passed and/or cap­
tured oil can be programmed and realised (ST EINER & 
BOSKOV STE INER, 1994). 

'fh cse scd in1cnts, based on their recognised cha rac­
ter ist ics, may aid the reconstruction oj" the Sava depres­
sion area as a Datum Level [or the proressional petrol e­
Ll!11 geo logical unde rstanding of the area and for fore­
casting of potent ial places of oil accumulation, and as a 
Datum Level ro r the broader geological scienti fie study 
o f the Sava basin. 

REFERENCES 

BOSKOV STEINER, Z. ( 1986): Speeificnosti potene i­
jab ugJjikovodika i pratecih supstanci u Panonskoj 
depres iji. - Na rt a, 37/7-8, 363-366, Zagreb. 

BOSKOV STErNER, Z. & STEINER, I. ( 1995): Geo­
log ica l Parti cularities of Horizontal We ll s Applica­
tion in Petroleum Engineering. - First Croa ti an Geo­
logica l Congress, Opatija, Proceed ings, L, 113-116, 
Zag reb. 

BOSKOV STAJNER, Z. ( 1961 ): Gcologija brahiantik­
lin~de Mramor I3rclo. Prinos poznavanju neogcnskih 
nas laga 11<1 juznom rll bll Moslavackc gorc.- Gco !. 
vjesnik, 14,97-107, Zagreb. 

BOSKOV ST AJNER, Z. & KOCIl ANSKY DEVIDE, 
V. ( 1975 ): Prilog poznavanju s trati gra fskog st uba 
SW dijckl Punonskc potoline - Brakicni srcdnji sar­
mat ako :iec Zag reba.- Nafta , 26/ I 0, 5 12-5 14, 
Zagreb. 

BOSKOV ST AJNER , Z. & MARINOVIC, Dj. ( 197 1): 
Strat ig raphy of oil and gas fields in the te rritory of 
Yugoslavia.-Narta, 22/6, 524-532, Zagreb. 

BOSKOV STAJNER, Z. & TOMASOVI C, T. ( 1967): 
S[rHtigrafska pripadnost nartnih i plinskih kolek[ora 
u S R I-irva[skoj, Refcrati VI savje[ova nja geologa 
SFRJ, 3, 227-234, Skopje. 

BRITV IC , B. , DRAGt\S , M. & SKANSI , R. ( 1989): 
Piroliticko-vol umet rijski model proracuna genera­
[i vllog potencijala.- Naft a, 40n -8, 375-39 1, Zagreb. 

Geologia Cro:nica 49{2 

GORJANOVIC KRAMBERGER , D. (189 1): Die prae­
pontische Bildungen des Agramer Gebirgcs.- Verh. 
R.A., 40, Wicn. 

HORVAT, K. & BOSKOV STEINER Z. ( 1990): Isku­
stva ist razivanja ugljikovodika od homogcn ih jed­
nostavnih do slozcnih hctcrogcnih lezista. - 12. Kon­
gres geologa Jugoslav ijc, 4, 328-34 1, Ohrid. 

.l EN KO, K. (1944): Strat igrafski i tcktonski snosaj plio­
cena juznog pobocja PozcSkc gore i Kasonja Brda. ­
Vj. rlrv. geol. zavoda, 2-3, 148-159, Zagreb. 

LAS KAREV, V. (1924): Sur les 12quivalents elu sarma­
tien supEricur cn Serbie.- R(;ClIcil d. tray . o ilen s a 
M. 1. Cvijic, 73-86, Beograd. 

MOOS, A. (1 944): Neuc f-ulld c von Limnaeidcn, ins­
besondere von va lencicnesiiden im Panon Kroa[ ­
iens.- Vj. Hrv. geol. zavoda, 2-3, 34 1-390, Zagreb. 

OZEGOVIC, F. (1944): Prilag gcologij i mladeg te rei­
jara na [emelju podataka iz novijih dubokih busoti­
na .- Vj. rTrv. geo!. zavoda, 2-3, 39 I -49 J, Zagreb. 

PAPP, A. (ccl. ) (1985 ): M" Pannoni en. - Chronostratig­
raphy und Neostratotypen, Mioziin der Zcntra len 
Paratethys, VII, Akadcmiai Kiad6, Budapest , 636 p. 

PLETIKAPIC, Z. ( 1969): Stratigntfija, paleogeografi ja 
i nanoplinonosnost Ivanic Grad-rormacije na obodu 
Moslavackog masiva.- Rud. -geo l. -na f. rakliltet, 
Zagreb, 70 p. 

STErNER, I. & BOSKOV STE INER , Z. ( 1994): 
Teh no logija vocloravl1oga buscnja.- I3 arbat, Zagreb, 
170 p. 

SI KI C, K. ( 1995): Prika7. geoloske grade Medvednice, 
S trll ktu rni odnos i i tekt ogencza s ireg podrucja 
Medvednice, T rasa br. 2, pos taja 11. - Gcoloski 
vodic Medvedniec, IGT Zagreb and IN!\-Naftaplin , 
7-40,6 1-66, Zagreb. 

YANKO, V. & LARCTTENKOV, E. ( 1991 ): The Influ­
ence of the Geodynami c and Il ydrologic Regime on 
the Origin and Evolutioll of the Foram inifera in the 
Paralet hys During the End or Middl e Mi ocene and 
Sa rm at ian. - Geodynami c Evolution o f lhe Pal1J101l ­

ian Bas in , SANU. Vol. LXII , 111 -120, l3eograd.