GEOL. CROAT. 49/2 251 - 257 6 Figs. I 9 Tabs. I ZAGREB 1996 

Review paper 

Selection of Exploration Strategy 

Slevo KOLUNDZIC 

Key words: Exploration, Reserves replacement, Highly 
explo red area, Offshore, Onshore, Risk of expJo­
ration, Turnover, Production cost, Public company. 

Abstract 
The ex ploration of oil and gas depends on investmen ts and 

prospective area to be explored. Exploration as a risky business, has 
\0 be fi nanced from company's resources, nOl through loan. Basical ­
ly, exploration provides oil and gas producers , who are financed 
through actual production. 

Our prospective area is well explored and there is a diminished 
probability of discovering large deposits. Production has a decreasing 
trend. 

Thi s is why the strategy of exploration needs to be checked and 
redefined . Especially as this coincides with poiitical and economic 
changes and with changes in owners hip. Owners and/or their repre­
sen tatives arc ready to invest in exploration if the target is clear, the 
cost defined and there is a high probability of finding oil and/or gas. 

1. INTRODUCTION 

The transformation of the social and political sys­
tem, together with the consequences of war, have 
forced the oil industry of Croatia to redefine its busi ­
ness strategy including that of cxploration. This strate­
gy shall remedy negative trend s and it has to be con­
vi/King enough [or the owner's representatives to make 
decisions on investment in exploration. 

Forecast ing production and the state of reserves 
indicates the required volume o[ replacement reserves 
(over a given period). However, restrictive factors 
includc the access ibility of a quality exploration area 
under acceptable conditions and the availability of capi­
tal for cxploration. 

INA Research & Development, Savska 41/10, HR- lOOOO Zagreb, Croatia. 

PROCEEDINGS 

Kljucne rijeci: istrazivanje, obnova zaliha, visoka 
istrazenost, podmorje, ozemlje, istrazivacki ri zi k, 
ukupni prihod, trosak proizvodnje, javno poduzece. 

Saietak 
Progrnmiranje istrazivanja narte i plina prvenslveno ovisi 0 

velicini sredstava za iSITazivanje i raspolozivom i perspc klivnom 
istraznom prosloru. BuduCi je istrazivanje rizican posao, ono se tI 

pravilu finaneira iz vlastitih sredslava. To uvelike odreduje poliliku 
gospodarenja zalihama, odnosno proizvodnju. 

Nas nacionalni prostor je visokoistrazen i mala je vjerojatnoca 
nalaza velikih zaliha. Proizvodnjaje usia u Irend pada. 

To su dovoljni razlozi da se vrednuje i nade i/ili potvrdi stra!egija 
istrazivanja. Tim vise ~to to u nas koincidira s novim vlas nickim 
odnosima, a ovlastenici prosuduju strategiju koja, u odnosu na druga 
ulaganja, sadrzi nellobieajeno vetik rizik, dodu~e i profit, ali sve 
zastire jednako ncuobicajeno udaljen vrcmenski horizont - desetak i 
vise godina. Nasuprot tome , llspjch u!aganja u proizvodnju cipcla 
vidite u jednoj sezoni, u gradevinarstvu u jednoj god in i, a u veCini 
s lozenijih projeka!<l unlliar pet godina. 

2. RESERVES AND PRODUCTION 
AS CRITERIA FOR DEFINING 
EXPLORATION STRATEGY 

As production depend s both on reserves and the 
policy of exploitat ion, it therefore makes sense to con­
sider the influence of both parameters on defining the 
scope of exploration. On the basis of reserves, the mini­
mal objective in both the medium-term and particularly 
long-term periods, is to discover such rcserves and to 
prevent the decrease of existing ones over a certain peri­
od of time. This means that the replacement coefficient 
should be at least equal to 1 or greater than 1. 

Production depends not only on the state of reservcs 
but also on the market. Therefore, if production has an 
increasing trend, exploration would have to provide for 
reserves, while the economic base for fi nancing the 
exploration would grow as well. Although, generally, it 
depends on the continuity of explorat ion successes, per­
centage of field dcplction and production costs. 



252 

North Amd'ica 

South Amcrica 

Europe 

Africa 

Middlc East 

Asia 

Far East 

Total 
sources 

(223) 
(223) 
(75) 

(259) 
(848) 
(443) 
( 149) 

Reserves by 
conventional 

methods 
proven 

reserves 

45 
74 
30 
59 

268 
96 
30 

potential 
reserves 

67 
45 
IS 

1m 
170 
96 
59 

According to thc production criterion a lone (without 
possible market sales), in the present exp!oatation poli­
cy replacement reserves are required [or covering some 
4 million TOE/i or current annual production. 

3. THE SCOPE OF EXPLORA nON AND AREA 
QUALITY AS CRITERIA FOR NEW STRATEGY 

In terms of explorat ion [or oil and gas, the territory 
of Croatia is a highly explored area. Throughout some 
fifty years the oil and gas production expanded until the 
mid-eighties, which was largely a consequence of suc­
cessfu l exploration. From the discovery o[ the Oojlo 
and Kriz oil fields to that of the Podravina gas fields, in 
each decade discoveries have been at ever increasing 
deplhs, and deposils (of oil and gas) have been found 
under progressively more complex condi tions of pres­
sure, temperature and HUld composition. 

Analyzing the results of exploration in Tcxas and 
Wyoming in Ihe USA (IVANHOE, 1996), il has been 
noted thaI on a sample of over 750 wells there is a sta­
tistical regularity of inverted proportionality of layer 
thickness and permeability as well as permeability and 
porosity, and a direct proportionality of depth and pro­
duction cost. To some extent this is also confirmed in 
Croatia in the discoveries of the Molve, Kalinovac and 
Stari Oradac fields. Deeper and deeper exploration 
objectives require more extensive investments, simulta­
neously with the stagnant low price of oil and gas . 
Bcsides, as mentioned earlier, Croatia represents a 
highly explored area, the probability of finding a large 
quantity reserves has to be inversely proportional to the 
explored level. This aspect has been dealt with in the 
literature, periodically and mainly statistically, with the 
intention of establishing the volume o[ remaining 
reserves, their price, etc. 

During 1987, after the prices dropped precipitously 
from 30 to 10 US$/bbl and then seemingly stabi lized at 

I Tons of oil equivalent per year. 

Additional reserves 
after the application 

ofEOR 
proven 

reserves 

74 
81 
15 
30 

251 
192 
23 

potential 
reserves 

37 
23 
15 
67 
59 
59 
37 

Geologia Croalica 49(2 

Table I Estimate of the volume 
or sources and possibilities of 
conversion into rese rves (in 
I O~ bbl). 

USS 18, the President of Elf Aquilaine stated that with 
a price of 20 US$/bbl it would be possib le to convcrt 
82% of resources into provcn rcserves (OOJ, 1987a), 
which al the time amounted to 2200 bill ion bbl and this 
would cover 85% of annual consumption [rom 1987. 
The current est imates of the time were those based on 
the regional distribution of resources and reserves, 
shown in Table 1. 

According to the same source, with the price of 12 
US$/bbl it was possible to discover and bring to pro­
duction only 58% of the potential world reserves i. e. 
resources, while with a price of up lO 30 US$/bbl, as 
much as 95%. 

In OGJ Report (OGJ, 1987b), there were mentioned 
almost 1000 fields discovered in offshore areas of the 
world, but they were not put into production because or 
the high cost. Most of the fields (293) were found in Ihe 
area oj" Far East, 264 in the region of Africa, and even 
263 in the area of Europe. In South America 98 fields 
were discovered, but only 51 % in the offshore. Approx­
imately one third of these fields were found at sca 
depths of up to 30 m - 271 fields, and 554 fields were 
discovered at depths from 30 to 120 m; at depths from 
120-300 m - 118 fields, and over 300 m - 24 fields. 

_ MI<\dIeED,,\ 
_ E £'IroN. F$U, As'". 0<;""""" 

: _ WKe'1'1's~_AI.-..;".W 

.8 . , 

i 
~ 
l 

i 
~ 

" 

-
Fig. 1 History of oil production growth and forecasts of the flirt her 

course. From IVANHOE, 1996 (I·lubber! curve added by Ivanhoe 
is weighted average of global oit discovered 1915-1992). 



Kolulldiic : Sd(;ctioll of Exploration Strategy 253 

Year 1987 1988 1989 1990 1991 1992 1993 1994 1995' 

Total number of 
ri gs in operation 1050 900 860 1000 850 
in the United 
States of Ailler ica 

Year 1982 1983 

Number of deep wells drilled 1205 577 
Average depth (m) 5290 5175 
A vcrage price per well (1,000 US$) 6636 6095 
Number of producers 600 301 

1t mu st be stressed that through exploration , Croatia 
can discover new reserves but at the present price of oi l 
the cost of new reserves has to be acceptable. Accord­
ing to this, the general philosophy of life reserve con­
firms the justifiability of exp loration even in highly 
explored areas. 

IV ANH OE (l99S), by updating the Hubbert curve 
attem pt s to answer a number of complex questions and 
presents statistica lly based arguments for constructing 
the oil life curve (Fig. I). According to these results the 
world reserves will reach thei r maximum at the end of 
th is century. 

World oil exploration, paI1icularly drilling, has been 
conside rably red uccd si nce 1986, until the present. 
Prom Table 2 it can be observed that , with the excep­
tion of 1990 when the number of rigs in operation was 
somewhat increased , until 1993 there were less rigs in 
operation than in 1987. 

The exploration forecast in the offshore area as well 
as the production es timate were given by KVINNS ­
LAND (1993) on the basis or samples in 89 countries. 
A number of we ll s were analysed and not the number 
of ri gs, but only the wells in the world offshore areas. 
According KY1NNS LAND (1993) , in the four ycars 
following the decrease of ac tivity in 1986/7, the number 
of drilled wells worldwide was increas ing (to over 
1200/year during 1988-1 991), with a si multaneo us 
decrease of wells in both the Americas (less than 900). 
In 1993 therc appcal·cd an incrcasing trcnd of drilled 
wells with an expected further increase in the followin g 
years, in all the regions. 

Access ible papers on future world exploration refer 
to a few general conclusions, which can be useful in our 
business strat egy and especially in the strategy of 
exploration. 

1. The forecasting of a increase in exploration and 
development in the context of oi l and gas pri ces 
encourage our own explorational complex; 

2. Regional forecasting of exploration and development 
suggests that no extensive operations in the Mediter­
ranean are foreseen (this renders more difficult the 

750 

1984 

614 
5099 
5817 
288 

Table 2 Number of drilling rigs 
in operation in lhe period 

650 1000 1000 from 1987 to 1993 (after 
KVINNSLAND, 1993 and 
GALOVIC, 1(96). * - data 
for the fi rst 6 months. 

1985 1986 

566 391 
5170 5198 Table 3 Deve lopments in the 

5574 5394 
USA at the beg inn ing of the 
eighties, until the drop of pri -

284 174 ces (from KVINNSLAND, 
1993). 

marketing of our services, that is, of our free equ ip­
ment and manpower; 

3. With respect to our foreign exp loration , besides 
Community of Independent States and in particular 
Russ ia, effort s should be focused on the western 
coast of Africa, especially Angola where we have 
already been involved . 

Thc US data presented in Table 3 ind icate the devel­
opments at the beginning of the eighties, until the drop 
of prices. 

4. SOURCES OF EXPLORATION FINANCING 

It is well known that the possibi lity of ex ploration 
financing depends on current production. The financing 
of oil and gas exploration, due to the risks involved, is 
sourced as a rule , from the proper equity of the compa­
ny or from the pooled assets of a partner. Credit financ­
ing should not be used . The international accounting 
system appl ied in Croatia since 1994 has brought about 
considerable changes in the method of exploration 
f inancing, and now requires that special care be taken 
over expenditure, in order to provide continuity in 
ex ploration (under the current or cven declining oil 
prices). 

Positive di scovery and revival of production shall 
increase the turnover. Tabl e 4 shows that between 
1960-1981 NaJ'taplin surpassed, in oil product ion , the 
limit 01'0.8 mil. t per year in 1960 and in 1970 it sur­
passed 2 mil. t and in 1980 3 mil. t. Natural gas produc­
tion started vith 100 mil. m 3 in 1964, 500 mil. m 3 in 
1971 surpassing I bi!. m3 in 1981. The turnover and 
particularly income, due to the price policy and to con­
stant economic changes do not completely follow the 
increas ing product ion although th e turnover (and thc 
economic power of the company) do follow, to a cer­
tain degree , the curve of a pretty reg ula r production 
Increase. 

In the eighties (Table 5), increased investment into 
exploration resulted from a large share of the offshore 



Year Oi l Gas 
Tons of oi l 

(I) (1000 m') 
equivalent 

(TOE) 

1960 768,028 38,564 806,592 

1961 1,125,034 55,472 1,080,506 

1962 1,156,476 61,419 1,234,313 

1963 1,151,005 77,837 1,228,842 

1964 1,285,362 130,602 1,415,965 

1965 1,415,921 15 1, 106 1,567,027 

1966 1,545, 110 188,826 1,733,936 

1967 1,702,005 232,359 1,934,364 

1968 1,8 18,336 329,728 2,148,064 

1969 1,931 ,641 408,624 2,340,265 

1970 2,055 ,248 477,671 2,532,919 

1971 2, 136,791 547,537 2,684,328 

1972 2,326,456 569,162 2,895,608 

1973 2,422,930 611,723 3,034,653 

1974 2,470,197 573,796 3, 143,993 

1975 2,669,751 751,310 3,421,061 

1976 2,812,779 911,185 3,723,964 

1977 2,828,717 1,009,052 3,837,779 

1978 2,93 1,166 934,294 3,865,460 

1979 2,971,006 805,668 3,776,674 

1980 3,056,388 983,241 4,039,629 

198 1 3,140777 1,168,926 4,309,703 

1982 3,047,194 1,244,541 4,29 1,735 

1983 2,860,466 1,195,127 4,056,595 

1984 2,853 ,327 1,231,493 4,084,820 

1985 3,020,189 1,463,594 4,483,783 

1986 3,006,856 1,699,388 4,706,244 

1987 2,946,648 1,973,458 4,922,126 

1988 2,844,668 2, 122,910 4,967,578 

1989 2,705,166 2,176,657 4,881,923 

1990 2,496,794 1,982,287 4,479,081 

1991 1,902,956 1,838,876 3,741,832 

1992 1,742,852 1,820,397 3,563,249 

Tablc 4 Product ion of oil, gas and conditional oil in Naftaplin from 
1960-92 (KOLUNDZIC, 1995). 

exploration as well as from the exploration and devel­
opment of deep gas wells in Podravina. In such a way, 
the expenditure was increased from 1/2 of the tota l rev­
enue to more than 2/3 . 

The mosl rapid increase of materi al and energy 
costs (as well as of foreign services) can be observed as 
a consequence of addressing more costly forms of 
exploration: greater depths, offshore dri lli ng area and 
an increase in the number of production fields. Explo­
ration and deve lopment expenditure was being 
increased at lower rates. Besides, the material and ener­
gy costs were increased quite surely as a consequence 
of a great number of wells, particularly for oil. During a 
great reduction of oil and gas prices (as in 1986), there 
shall bc det ermined the limit of profitable production 

Geologia CroMiea 49/2 

per well and those wells which by their production do 
not cover the production costs wil l be cxcluded from 
production. 

Table 6 shows a trend of increasing share or costs in 
the total revenue. Around 1980 that share was betwcen 
39-40% whereupon it started to increase. 

Such a progressive increase of costs after 1985 was 
conditioned by the decrease in oil pricc in 1986, but it 
also shows that the costs were not reduced. 

To estimate exploration financing from 1989, in 
view of the production potential (Fig. 2) over a fifteen­
year period, the resource will decrease with no signifi ­
cant price increasc. 

Such an estimated profile affects the cash flow. 
With respect to the basic products, oil and gas, these 
projections arc shown in Figs. 3 and 4. 

IJ', in pri nciple, we expect ever reducing financia l 
resources for oi l and gas exploration, then these should 
be focused on the elements of efficiency regarding both 
our own services and the quality of concessions as well 
as the efficiency of lhe operators' activi ties. 

The exploration of oil and gas of INA -Na ftaplin 
shows a growth of the efficiency coefficient from J 945 
to 1985. as shown in Table 7. The growlh of d ri ll ing 

efficiency has an intrinsic value, due to the fact that the 
efficiency is being increased although the structures are 
cons istently deeper, drillin g cond itions increasing ly 
more difficult, and the explored level indicator is ever 
higher. However, the correlat ion between the number of 
exp loration metres and tons of new production is, or 
course, not linear and it considerably depends upon the 
explored level indicators of the area concerned. 

The productiv ity as a rate of efficiency, suggests a 
dec line. Through the combin ed influence of a price 
drop and furt her growth (i nstead of reductio n) of the 
number of employees, the productivity has tended to 
decline since the beginni ng of the eighties , and in the 
second ha lf of the decade became dramatic. The time 
dispari ty of the infl ection poi nts fo r the base ac tivit ies 
of INA arises out of constant changes of external and 
interna l cond itions of business activities . A series of 
key indicators from 1970-1990 show a break of conti­
nui ty in the middle of the eighties. 

II may be slaled that from 1970 to 1990 the produc­
tion of natural gas increased and the production of oil 
after 1986 has been in gradual decline. The tota l pro­
duct ion of oil and gas, as shown in tons of oil equiva­
lent is in constant growth; howeve r, due to a fas ter 
growth of the number of employees, the prod uct ion in 
TOE per employee since 1970 has decli ned (Table 8). 

In addilion, the natural production of oil equivalent 
increased from 1970-1980 by 37%, from 1980-1985 by 
11 .4% and from 1985-1990 by 3.6%. The reserves of 

oil and associated gas have decreased, and the rcserves 
of natural gas have increased (Table 8). 

The absence of adequate reactions in the eighties, 
(by 1986 at Ihe latest), should be attributed to the estab­

lished econom ic and political system in Croatia. The 
rat ionalization and reduction of the number of employ-



Kolundiic: Selection of Exploration Strategy 

Year MateriHI 
and energy 

1970 100 

1975 332 

1980 1,485 

1985 28,964 

1989 552,409 

Yem' 

1981 

1982 

1983 

1984 

1985 

1986 

1987 

1988 

1989 

Services of 
others 

lOa 
462 

1,369 

17,428 

172,398 

Depreciation 

100 

559 
6,544 

30,088 

176,991 

Share of costs in 
total revenue (%) 

39.6 

46.4 

46.0 

44.8 

58.8 

77.9 

80.6 

82.6 

96.2 

Table 6 Share of COSIS in the lotal revenue (from KOLUNDZIC, 
1995). 

ees as one aspect of cost reduction was not possible, and 
a number of protective mechanisms depended there­
upon (Table 9). 

In the ten-year period between 1984-1994 a sample 
of oil companies from the United States shows a growth 
of crfectiveness, both through reduction of discovery 
costs of 250% (Fig. 5) and through a high reserve 
replacement rate (Fig. 6). 

However, for the overall improvement of efficiency 
in the field of oil and gas exploration and production, 
cost cutting measures combined with organizational 
adaptation (Down-sizing) will not give result s unless 
thi s is undertaken in conjuction with a reasonable 
explorat ion levcl. 

What is a reasonable level? The data supporting 
exploration efficiency and requirements for rcp lace­
ment of reserves suggest thaI an investment or 6 US$ 
per BOE produced is necessary in order to halt the 
decrease in production. 

I~I!! ! !!!!!!! 
ra Gas Condensate 

I_ Natural Gas 

luI" ! ! ! , ! ! Ii! Iii I ~ ! i 
Y • ., 

Fig.2 Estimate of the produc1ion profile (from KOLUNDZIC, 1995). 

Investment 
main tel1Hl1ce 

100 

395 
202 

6,068 

85,227 

[nvest. into 
explor. & 

development 

lao 
524 

4,113 

49,111 

274,123 

255 

Table 5 Review of a relative 
increase of certain financial 
indicators in INA-Naftaplin 
(from KOLUNDZIC, 1995). 

Naftaplin planned to invest 49 million US$ for 
exploration within Croatia and abroad and 40.5 million 
USS for development in 1995. In the relation to the 
total production of oil and gas and the value obtained at 
actual prices the planned investments make 3.8 US$ per 
produced BOE or 1.9 US$/bbl for o il and gas explo ­

ration. In compliance with some data, 2.4 USS/bbl was 
spent on exploration in 1994. 

The relevant world literature reiterates the necessity 
for investment into new reserves from 6 to 8 USS/bbJ. 
The data of the well-known auditing house Arthur 
Andersen showed on a model of several jnternational 
companies that the investments amounted to 5.6 
US$/bbl in the year 1994. 

However, investments should be increased in rela­
tion to the actual ones within the realm of possibility 
and cont inuity shou ld be provided. The quality of 
exp loration and efficiency should be assured, through 
the possibility of select ing an exploration objective. 

12000 

10000 t----t--
r-.... 

8000 

~ 
m 6000 
§ 

4000 

2000 

~ :;: m 
~ ~ 

I'tt--r---
r-....t--t--

t--t--h--

a 

~ 8 m 
~ 0 

N 
Year 

b 

I t--

f3 Total Net Cash Flow 

o Tax 25% 

oCapex 

N • IS ~ 
0 0 0 
0 0 

" 
0 

N N N 

Fig. 3 Forecasts of oi l production and revenue: a) oil production; b) 
cash now. Kuna (Kn) is Croatian money unit (I Kn - 0.2 US$). 
From KOLUNDZIC (1995) and GALOV rC (1996). 



256 

" "" .. "" 
" "" 

~ " "" .= § 
"'" 
""" 
''': I 

~ ~ ~ 

a 
• Total Nel C&sh ::Icw 

'''''' ,_~~~. __ ~~~~~~~_ oTa... 25% 

""" 

"'" 

b 

rig. 4 Forccasts of gas production and revenue: a) gas production; b) 
cash flow . From KOLUNDZIC (1995) and GALOVIC ( 1996). 

s. CONCLUSIONS 

Exploration is a mult idimensional problem. The 

exp lore rs consider it from a professional, geo logical , 
developmental, technological and user's poin t of view. 
The management reach their final decisions on the basis 
or v~due ~lT1d scope of in vestmen t, rate of return and 
evaluation of risk. 

The owner or his representative is not usually an 
oilman. He rarely has any exp loration and/o r minin g 
sentiment and is additiona lly perplexed by the tim e 
component in the o il business. A time horizon rang ing 
from 5 to 20 years, necessity of inves tment cont inui ty , 
the scope of investmelll - all these are the characteris­
tics which obstruct the vision. 

Through providing a greater selec tion of exploration 
objectives (both within Croatia and abroad) th an the 
planned scope of exploration, it is possible to establish, 
by comparative analysis, a priority between object ives . 
Such basic data also enable comparative analyses with 

Geologia Croatica 49/2 

... 
,.,. 

'''' " .. "'" "" "w 
Fig. 5 Trend of reduction of exploration and developmen t costS in 

USA (from Artur Andcrsen & Co. , Sc: Hyd rocarbon Value Chain 
Analysis. - Unpubli shed Report , Sept. 1995 , lNA-Narlaplin 
Archive). 

I --Production 

1 - ~~coveries and reviSions 

y,1t 

ri g. 6 Curves of growt h for production and discovery of reserves 
(from Anur Andersen & Co., Sc: Hydrocarbon Value Chain 
Analy sis.- Unpublished Report, Sept. 1995, INA-Nartaplin 
Archive). 

the prices of discovered reserves being offered for sale. 
III addition to this, by pas t anal ysis, it can be eas il y 
proven that bot h exploration and production were a 
profitable business. Through bc ttcr organization, and a 
choice of exploration objectives, the efficiency of 
exploration will be increased, probably with a new 
strategy of exploration as follows: 

intensify exploration abroad; 

increase the number of concess ions to 5-10; 

Period TOE Drilling meters (m) Efficiency coerf. 

1945· 1954 727,370 232,492 3.1 3 

1955-1964 7,668, 120 989,662 7.751 
1965- 1974 25,856,600 1,68 1,(J43 5.38 

1975·1984 40,913,982 1,922,339 21.28 

1945· 1984 75 , 167,431 4,825,536 15 .58 

1985 4,606,911 239,646 19.22 

1945· 1985 79,774,342 5,065,182 15 .75 Table 7 Efficiency of dri ll ing 
(from KOLUNDZ1C, 1995). 



KolullCiZic: Selection of E"plor~lt ion Stralt.:gy 257 

Change (%) 

1970 1975 1980 1985 1990 70·75 75·80 80·85 85·90 

Explor. drilling, m 48,863.0 71,319.0 60,379.0 89,282.0 82,000 7.9 3.3 8.1 .1.7 

Oil produclion, 10J I 2,057.1 2,669.7 3,056.4 3,059.2 2,696 5.4 2.7 0.0 -2.5 
Gas produc!., 106 rn' 477.7 7S 1.3 983.2 1,441.0 1,966 9.9 0.7 
Local prod. TOE 2,534.8 3,421.0 4,039.6 4,500.2 4,662 
Product./elll p loyce 600 597 519 SIS 
("TOE")/ernployee 

Oil reserves 

A+B+C , I06 1 35 35 35 25 20 

Natural gas reserves 
LPG 10') m' 15 12 7 6 5 
NG 109 

Ill) 12 15 30 22 40 

Table 8 Production of somc basic products in the period from 1970 to 1990 and production per employee (from KOLUNDZJ<:, 1995). 

1970 1980 1985 

INA - TOlal 22.3 163.6 223.2 
INA JP (Public Company) ' 12.0 199.8 280.8 
I. Ups tream 10.3 126.3 176.4 
II. Processing 32.4 418 .8 369.0 
III. Pelrochelll. 21.6 62 .0 81.2 

define methods or evaluating a concession as well as 

the maximum and minim um participation; 

define (or delimit) the exploration as agreed with the 
owner including a proposal or reinvesting the entire 
profit to Ihe year 2000. 

6. REFERENCES 

GALOV IC, S. (1996): The future of fossil fuel 
resourees.- NaIta, 47/10, 275-294. 

IVA NHOE, L.F. (1995): Future world oil supplies: 
Ihere is a rinite limil. - World Oil , October 1995, 77-
88. 

IVANHOE, L.F. (1996): Updated I-Iubberl curves ana­
lyze world oil supply.- World Oil, Nov 1996,94. 

1989 1990 

118 .6 87.4 Table 9 Economic indicators of 
139.8 101.1 productivity (1,000 US$) 

89.6 61.1 total revenue per employee 

162.7 126.4 
(average value). INA lP 
(Public Company) was cnga-

71.2 48.0 gcd in thc core business of 
INA Group. 

KOLUNDZIC , S. (1995): Contribution to a complex 
modelling of system for production and market sup­
ply with natural gas.- Unpublished PhD T hesis, 
University of Zagreb. 

KVINNSLAND, O.J. (1993): Worldwide act ivity will 
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OGJ (I 987a): Oil executives eye prospects [or erucle oil 
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OGJ (1987b): Development stralegies for producers 
will focus on lower costs, hi g h recovery. - OGJ 
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