oil-gas poetntial, offshore south italy

8/11/2019 Oil-Gas Poetntial, Offshore South Italy

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OIL AND GAS POTENTIAL - OFFSHORE SOUTHERN ITALY

Jack Holton, Wavetech Geophysical, Inc., Denver

Oil and Gas Journal, Vol. 97, No. 48, 49, 51 (1999)

Opportunities for exploration and production by international companies in Italy will expand dramatically in the

next few years, the result of recent changes in Italian law, rapidly increasing demand and the interest generated by

several very large oil discoveries in southern Italy during the last decade.

Membership in the European Union has necessitated changes in Italian law, opening a number of formerly

restricted industries to outside investment and participation. Several recent articles in industry publications (OGJ,

Sept. 6, 1999) have highlighted regulatory changes that have opened Italy's gas and power generation industries to

participation by foreign companies. In addition, Italy's dependence on imported oil and natural gas is expected to

increase significantly over the next ten years. Forecasts indicate that the proportion of Italian gas demand satisfied

by imports will rise from 66% in 1997 to 90% by 2010. Over the same period, imports will also account for over

90% of the crude oil consumed in Italy. These changes are expected to result in substantial new opportunities for

foreign companies in all aspects of Italy's energy sector.

The increasing need for hydrocarbons has resulted in a more attractive climate for exploration in Italy, especially in

areas which remain relatively unexplored. In light of the very large reserves discovered in the lightly exploredsouthern Apennines over the past decade (> 1.0 BBOE recoverable), attention is now concentrated on southern

Italy. This article summarizes the petroleum geology of Italy and Sicily and examines the potential of the virgin

deep water areas offshore of the southern coast on the basis of new regional seismic.

HISTORY

The level of hydrocarbon exploration in Italy and Sicily has remained quite modest since the first hydrocarbon

exploration well was drilled in 1895. This was especially true through the first five decades of exploration. At the

end 1951 the total number of wells that had been drilled in the country stood at only 359. The early part of the

1950's saw a substantial increase in the exploration for hydrocarbons, as the Italian economy recovered from thedestruction of World War Two. The total number of exploration and development wells drilled for hydrocarbons

increased from 13 during 1951, to 101 in 1957 (Figure 1).


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A variety of reasons can be cited for the historically low levels of activity in Italy. Most important is undoubtedly

the relative complexity of its geology. Due to its location at the margin of several different plate and tectonic

regimes, Italy's geology ranks among the most complex and interesting in Europe. However, for the same reasons

its structure, stratigraphy and petroleum potential remain some of the least understood, especially that of the

Mesozoic carbonate section of the southern Apennines.

During the 1970's a very limited drilling program resulted in the discovery of a few modest Mesozoic fields in the

southern Apennines. Further exploration was curtailed by the poor quality of seismic data in the area, the result of

the rough topography and complex, thrusted subsurface geology. However, improved seismic techniques, including

3D, resulted in the discovery of a major new oil province in the Val D'Agri area of the southern Apennines in 1989.

At least four large fields have been discovered in the area so far. Total recoverable reserves for three of the fields

(Monte Alpi, Monte Enoch and Cerro Falcone) are estimated at 600 MMBOE. Those for the fourth, Tempa Rossa,

are estimated at 420 MMBOE.

The discovery of the large Val D'Agri oil fields, in combination with large gas fields discovered previously in

southern Italy (Luna field, 1.3 TCF) suggested that the virgin deep water areas to the south could also hold the

potential for large discoveries. It was not until the recent development of deep water drilling technologies that

exploration in those waters was feasible. In addition, prior to late 1998 seismic coverage in the area south of Italy

was limited to a few scattered lines acquired by various organizations for academic purposes. These data were

generally of insufficient quality and extent to be useful in evaluation of the hydrocarbon potential of the area.

Therefore, in order to provide a regional grid of modern seismic data for evaluation of the deep water areas, during

late 1998 Wavetech Geophysical and Fugro-Geoteam acquired 3,350 km of high fold, long offset seismic data

(Figure 2). That data set provides the basis for the ideas presented here.

CURRENT OIL AND GAS DEMAND

Italy is the third largest user of hydrocarbons in Europe, behind only Germany and the UK. Government statistics

for 1997 ("Attivita di Ricerca e Coltivazione di Idrocarburi in Italia Nell'Anno 1997", Ministero Del'Industria, Del

Commercio e Del'Industria) show that Italian use of natural gas outstripped domestic production by a ratio of

almost 3:1. Natural gas consumption for 1997 was 2.045 TCF (57.9 Bm3), while domestic production totaled only

688 BCF (19.5 Bm3). From 1996 to 1997 gas demand increased by over 3%, while domestic gas production fell by

4%. The disparity between domestic supply and demand was even greater for crude oil. Italy's 1997 oil production(44 MMBO) satisfied less than ten percent of demand.

Oil currently accounts for 56% of the energy balance in Italy, with natural gas at 27% and the remainder coal and

other fuels. This balance is expected to reverse over the next decade as the majority of Italy's oil-fired power

generation facilities are converted to natural gas. By 2010 natural gas consumption is expected to reach 3.18 TCF

per year (90 Bm3).

GENERAL STRUCTURE AND GEOLOGY

The general structure of southern Italy and Sicily are similar, except in orientation. Tectonic structure is dominated

by the north-northeast oriented Apennine thrust system in southern Italy, and the roughly east-west trending

Maghrebian wrench/thrust system on Sicily. Each includes four general structural zones. The oldest and highest ofthese is formed by Hercynian metamorphic and magmatic rocks exposed in extensive nappes of the Calabrian zone

of northeastern Sicily and southwestern Calabria (Figure 2 and Figure 3). These rocks overlie an allochthonous

sequence of intensely deformed Mesozoic oceanic sediments and obducted ophiolites of the Liguirian nappes. The

central portion of each area is dominated by an extensive, allochthonous section of Miocene flysch, deposited in

front of and subsequently deformed by the eastward and southward advancing Apennine and Maghrebian thrust

fronts. Immediately east and south of the respective thrust fronts lies a Pliocene-Pleistocene foredeep section of

widely variable thickness. Beneath the allochthonous Miocene section lies a thick section of Triassic through Early

Miocene platform carbonates. These carbonates are allochthonous in the southern Apennines, but are

autochthonous on the Hyblean Plateau in southern Sicily and the Apulian platform of southeastern Italy.


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Hydrocarbon production has been established in all of the zones except the Calabrian and Ligurian nappes.

Mesozoic carbonates are oil productive from thrust stacks of the Val D'Agri play of the south Apennines and

autochthonous platforms in southern Sicily. Allochthonous Miocene flysch sandstones produce gas and occasional

oil in eastern Italy and central Sicily. Sandstones of the Plio-Pleistocene foredeep section are the major gas

reservoirs of the Po Basin, Adriatic and along the Apennine thrust front in east-central Italy.

EmiliaNappe

Tunisia

Tyrrhenian Sea

Sardinia

Corsica

Malta

RomagnaNappe

Outer BoundaryZones C, D, F, G

ApulianPlatform

Hercynian metamorphicand magmatic rocks

Ligurian Nappes(include ophiolites)

Mesozoic basinal faciesincluding Lagonegro rocks

Mesozoic-Paleogeneshelf carbonates

Tertiary volcanicsand intrusives

Miocene flysch

Gas FieldOil Field

Figure 2: Geology of Italy and Siclly

2000m

BarbaraComplex

Villafortuna

Benevento

Val D'AgriFields

S SalvoTorrente Tona

Candela

Torrente Vulgano

Luna

Nilde

Vega

Gela

Gagliano

Plio-PleistoceneForedeep

2000m

2000m

2000

m

Vallecupa

Po Basin

Malta Escarpment

CaltanissetaBasin

Etna

Pisticci

ApennineThrust Front

Maghr

ebianT

hrustF

ront


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Mt Etna

CaltanissetaBasin

Pantelleria

CalabrianNappe

Ligurian

Nappe

HybleanPlatform

GelaN

appe

Gela

Perla

Tyrrhenian Sea

Vega

Alexia

Malta

E

scarp

ment

Gagliano

Malta

Nilde

Figure 3: Geology of Sicily

Hercynian metamorphicand magmatic rocks

Ligurian Nappes(include ophiolites)

Mesozoic basinal faciesincluding Lagonegro rocks

Mesozoic-Paleogeneshelf carbonates

Tertiary volcanicsand intrusives

Miocene flysch

Gas FieldOil Field

Ragusa

STRUCTURAL EVOLUTION

MESOZOIC

The structural evolution of Italy and Sicily is the product of post-Hercynian interactions between theEuropean and African-Arabian continents caused by differential spreading rates in the central and southern

Atlantic. During the Triassic Italy and Sicily lay just south of the Hercynian fold belt on the broadnorthwest shelf of the Tethys, an area of broad carbonate platforms separated by narrow, deep-marine

troughs. The Upper Triassic section includes both extensive shelf carbonate reservoirs and important source

rock intervals, including organic rich black shales, marls and limestones. Several of the large fields of

southwestern Sicily produce heavy oil derived from Upper Triassic source rocks and reservoired in Upper

Triassic shelf carbonates.

By Middle Jurassic time active spreading along the southern edge of Europe had connected the narrow

Alboran, South Penninic-Ligurian, and Dinarid-Hellenic troughs with the Tethys, leaving the shelf as a

broad promontory (Italo-Dinarid) extending north from Africa. Internally, the promontory consisted of

three broad carbonate platforms. The Apenninic platform occupied the western third of the promontory,

with the Apulian and Karst platforms to the east. The narrow troughs dividing the platforms continued to

subside during Jurassic time. Deep marine shale, marl and limestone were deposited in the deep marineLagonegro trough between the Apenninic and Apulian platforms, as well as the smaller Molise trough,

which lay within the Apulian platform.

During the Late Jurassic and Early Cretaceous, the western and central Mediterranean area underwent a

major shift in tectonic regime. Late Jurassic spreading in the Central Atlantic initiated a counterclockwise

rotation of Africa with respect to Europe, along with major movements along the Azores-Maghrebian-

South Anatolian wrench system. In the central Mediterranean area the net result was a north-northeast

convergence of Africa/Arabia with Europe. By Aptian-Albian time the western portion of the Tethys had

disappeared and the northeastern Italo-Dinarid promontory was in active collision with Europe along the


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Alps on the north and Hellenides on the east (Figure 19). Despite the active thrusting along the northeastern

margin of the promontory carbonate deposition continued over its western and central parts, persisting into

Lower Miocene time in a few areas.

Outcrops of Mesozoic carbonates are extensive in southern Italy and Sicily. Allochthonous Apenninic

platform carbonates are exposed along the western side of the peninsula, with allochthonous rocks of the

Lagonegro and Molise troughs in the central portion. Autochthonous carbonates of the Apulian platform

are exposed in southeastern Italy, from the Gargano Peninsula through the Apulian platform. On Sicily,

carbonate rocks of the Apenninic platform are exposed in several areas along the northwestern coast and on

the Hyblean Peninsula to the south.

Ap

enninic

Platfo

rm

Hellenides

BayofBiscay

BlackSea

Karst

Apu lian Platfo rm

IberianMassif

Tethys Sea

MoliseTro

ugh

Lag

oneg

roTroug

h

Platform

Europe

Italo-DinaridPromontory

Azores-SAnatolian

Fracture Zone

Alp s

Af ricaSicily

Italy

Italo-Dinarid

PromontoryCarbonateplatform

Deep marine

troughCratonic,Continental

Foredeep

troughUplift

Generalized

plate motion

CS

Figure 19: Paleocene Paleogeography

EOCENE - OLIGOCENE

Tectonics in the central Mediterranean region were dominated by the Eocene-Oligocene main phase of Alpine

orogeny, as the collision of the Italo-Dinarid promontory with Europe continued (Figure 20). Following the

Late Oligocene incorporation of the Karst platform, active consumption of the promontory by underthrusting

along the Dinarides and Hellenides nappe systems slowed. Concurrently, Apennine thrusting was initiatedalong the western side of the promontory as it collided with the Corsica/Sardinia block. This fragment of the

Hercynian Spanish-French continental margin was rifted away from the continent and rotated southeastward

(counterclockwise) during the Oligocene. It collided with the west side of the Apenninic platform in the Late

Oligocene, thrusting deep oceanic sediments and ophiolites of the Ligurian Nappe eastward onto the platform.


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Cratonic orcontinental sed.

Carbonateplatform

Deep marinetrough

Foredeeptrough

Uplift Generalizedplate motion

Ca

labria

Figure 20: Upper Oligocene Paleogeography

IonianSe

aBasin

Hellenides

BayofBiscay Karst

IberianMassif

Europe

Af rica

Sicily

ItalyApen

ninic

Cyrenica

Platform

Apu lian Platfo rm

PelagianShelf

Alps

(Lagonegro

Tro

ugh)

CS

LOWER-MIDDLE MIOCENE

Following the collision of the Corsica/Sardinia block and Apenninic platform convergence was replaced by

a period of active back-arc spreading in the southern Tyrrhenian Sea. The Corsica/Sardinia block retreated

largely intact, but left one fragment permanently accreted to the western edge of Apenninic platform. TheHercynian metamorphic and magmatic rocks of this fragment form the Calabrian Nappe of southernmost

Italy and northeastern Sicily (Figure 3).

Thrusting continued in the Apennines throughout the Miocene, producing successive nappes of Ligurian,

Apenninic and Lagonegro rocks. Ahead of the advancing thrust sheets, a thick wedge of Miocene

(Numidian) flysch sediments were deposited in the foredeep created in the eastern part of the Lagonegro

basin.

UPPER MIOCENE

During Late Miocene time the continuing rotation of Africa-Arabia progressively narrowed the connection

of the Mediterranean area with the Tethys (Figure 21). With the eventual collision of the Arabian plate withsouthern Europe, and Spain with Africa at Gibraltar, all connections between the Mediterranean and the

open marine waters were severed. This restriction of marine circulation, coupled with the tectonichighlands that surrounded the Mediterranean, resulted in the deposition of the Messinian evaporite

sequence. Thick sections of Messinian evaporites were deposited in the Algero-Provencal, Tyrrhenian and

Ionian-Levantine basins, along with lesser amounts in various local depocenters. These local depocenters

often included "piggyback" basins on the back of the advancing thrust front. Such was the case in southern

Sicily, where thick Messinian evaporites have been mined commercially for decades in the Caltanisseta

basin. Evaporite deposition ended with a major Early Pliocene transgression and the return of deep waters

and normal salinities to the region.


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Cratonic orcontinental sed.

Carbonateplatform

Deep marinetrough

Foredeeptrough

Uplift Generalizedplate motion

D

inarides

Pyrenees CS

Sicily

Italy

IonianSeaBasin

BayofBiscay

IberianMassif

Europe

Af ricaCyrenicaPlatform

PelagianShelf

Alps

Hellenides

Figure 21: Upper Miocene Paleogeography

PLIOCENE AND LATER

Early Pliocene rocks are dominated by deep water facies, including diatomaceous shales and marls. At the

conclusion of Early Pliocene time the Lagonegro and Miocene flysch sections were thrust eastward over

the western edge of the Early Pliocene foredeep and the western part of the Apulian platform. Significantthicknesses of Upper Pliocene and Quaternary rocks are largely confined to the resulting foredeep, with

only a thin cover in other offshore areas.

Large scale vertical movements along the margins of the Malta-Hyblean and Apulian platforms probably

began during Late Miocene time, with the initial foundering of the central portion of the survey area

between the two platforms. Even greater subsidence along the platform bounding normal fault systems was

reserved for Late Quaternary time, where the faults underlie the present bathymetric escarpments.


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OIL AND GAS FIELDS

The oil and gas fields of Italy and Sicily produce a variety of oil and gas types, from a wide range of traps. The

major oil and gas fields of Italy can be divided into four general structural/stratigraphic settings. These zones,

which extend from west to east in the Apennine system and from north to south in the Maghrebian, consist of

the internal zone of the Apennine thrust system, the external zone of the Apennine and Maghrebian thrust

systems, the Plio-Pleistocene foredeep and the Mesozoic carbonate foreland.

INTERNAL ZONE - APENNINE THRUST SYSTEM

The western (internal) portion of the Apennine system is composed of stacked, imbricate thrust sheets

containing rocks ranging in age from Late Triassic to Upper Miocene. Oil and gas fields have been

discovered in allochthonous Mesozoic carbonates throughout the length of the system. The northernmost

fields of the internal zone are Gaggiano and Villafortuna, located just south of the intersection of theApennine system with the Alps. Gaggiano and Villafortuna produce light oil (34-42oAPI) from thrusted

Middle Triassic dolomites, at depths of 4,650-6,200 m. Villafortuna, discovered in 1984, is currently Italy's

most productive oil field (60,000 BOPD).

During the last decade attention has also been focused on the internal zone of the southern Apennines. The

discovery of several fields containing light to medium gravity oil during the 1970's sparked initial interestin the area. These fields, including Castelpagano (31oAPI, 1971) and Benevento (46oAPI, 1973), are

productive from stacked sections of allochthonous Mesozoic carbonates (Figure 5). However, further

progress was hampered by the poor quality of seismic data in the region, the result of rough topography and

the structural complexity of the subsurface. Improved seismic techniques, including 3D, led to the first

discovery in the prolific Val D'Agri area in 1988. To date at least four major fields have been discovered in

the area, Tempa Rossa (1988), Monte Apli (1988), Monte Enoch (1994) and Cerro Falcone (1992). These

fields are characterized by high flow rates (3,000 - 12,000 BOPD) and large oil columns (600-1,000 m).

The total recoverable reserves for the four fields are estimated at 1.02 BBOE. The Val D'Agri fields arediscussed in more detail later in this article.

Allochthonous Miocene (flysch) sandstones are also productive within the internal Apennine system. They

form reservoirs for light oil, gas and condensate fields in the Emilian and Romagna nappes, along thesouthern edge of the Tertiary Po basin of northern Italy.

Cretaceous-PaleogeneCarbonates

U Triassic-JurassicCarbonates

Figure 5: Internal Zone, Apennines (Val D'Agri Oil Play)

West East

Miocene flysch


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EXTERNAL ZONE - APENNINE AND MAGHREBIAN THRUST SYSTEMS

Fields of the external zone are dominantly gas productive, but also include several oil and condensate

fields. The main reservoirs are allochthonous Miocene flysch and Lower-Middle Pliocene foredeep

turbidite sandstones.

The largest field of the external zone is Luna (Figure 7), a gas field that along the west side of the Gulf of

Taranto in southernmost Italy. The field contains large reserves of dry gas in sandstones, which lie at or

immediately above the top of the allochthonous Miocene flysch section. The structure is the product of both

Upper Miocene and Lower Pliocene movements. A thin section of Messinian evaporites is present on the

flanks, but is absent over the crest of the Luna structure, the result of Early Pliocene uplift and erosional

truncation of the Messinian. Lower Pliocene shales, possibly olistostromal, provide the seal.

Gas Oil

Miocene flysch

U Plioc ene-Pleistocene

MessinianEvaporites

L Pliocene

Figure 7: Luna Gas Field, Apennine External Zone

West East

The gas from Luna is dry (99% methane) and biogenic in origin. The field was discovered in 1971 and

currently includes 35 wells. Initial recoverable gas reserves were estimated at 1.3 TCF. During the four

year period from 1994 to 1997 gas production from offshore Zone D (which consists only of Luna and

several small nearby fields) was 348 BCF, and remained stable during 1998 at 70 BCF.

Gas fields with allochthonous Miocene reservoirs of the external zone of the Apennine thrust system are

common throughout the length of the Italian peninsula. The gas from most of these fields is dry and

biogenic, although the presence of heavier hydrocarbons in a few areas probably indicates limited mixing

with thermogenic gases.

The Apennine system of peninsular Italy is replaced by the regional Maghrebian wrench-thrust system on

Sicily. The Maghrebian system extends southwest from Sicily through Tunisia and westward across

northern Africa to the Atlantic. The external zone of the Maghrebian thrust belt contains several significant,

structurally trapped fields in north-central Sicily, as well as offshore to the west of the island. The largest

onshore field is Gagliano, which contains gas, condensate and light oil in allochthonous Miocene flysch

sandstones at depths of 2,800-3,000 m (Figure 8). Offshore, Nilde field produces 39oAPI oil from highly

productive Middle Miocene organic limestones, at rates of up to 10,000 BOPD.

PLIOCENE-PLEISTOCENE FOREDEEP

Pliocene and younger sandstones of the foredeep contain the majority of Italy's proved gas reserves. Most

of these reserves are currently located in the north-central Adriatic and Po basin of northern Italy. During

1998, production from four of the larger offshore fields (Barbara, Angela, Porto Garibaldi and Agostino)

totaled more than 270 BCF. The dry, biogenic gases lie in both stratigraphic and structural traps. Reservoirs

range from turbidite sandstones to gravel. Several of the larger fields of the north-central Adriatic and

central Italy are described below.


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The large Barbara, N Barbara and NE Barbara gas field complex was discovered in 1971 in the north-

central part of the Adriatic. A total of 112 productive wells have been drilled to date. Gas production is

from an Upper Pliocene sandstone at an average depth of 1,400 m. The trap is a simple low relief (less than

100 m) structure draped over a broad uplift in the underlying Mesozoic foreland.

Onshore in central and southern Italy, South Salvo, Torrente Vulgano and Pisticci fields produce gas from

Lower and Middle Pliocene foredeep sandstones. South Salvo is stratigraphically trapped by the updip

pinchout of multiple Pliocene sandstones, which are overlain by approximately 800 m of allochthonous

Miocene flysch. The field includes 74 productive wells, with an average depth of 1,200 m. In addition to

Pliocene gas, Pisticci field also contains heavy oil in autochthonous foreland carbonates along the western

side of the field (Figure 6).

GasOil

Miocene flysch

Miocene-Cretaceouscarbonates

Figure 6: Pisticci Field, Apennine External Zone

West East

Pliocene-Pleistocene

At least two fields, Torrente Tona and Candela, produce both light oil (40oAPI) and gas from Middle and

Upper Pliocene foredeep reservoirs along the east coast of central Italy. At Torrente Tona, sandstones and

limestones are stratigraphically trapped by updip olistostromes derived from the eastern south Apennines.

MESOZOIC CARBONATE FORELAND

Several large oil fields have been discovered in the relatively undisturbed platform carbonates of the

Mesozoic foreland of southern Italy and Sicily, both on and offshore. Onshore, the fields are overlain by

various thicknesses of allochthonous Miocene flysch and in some cases a thin section of Plio-Pleistocene

sediments. Offshore the allochthonous Miocene section is generally absent and the Mesozoic foreland

sequence is overlain by sediments of the Plio-Pleistocene foredeep.

Sicily's largest oil field, Gela, is located along the southwestern coast of the island, on a broad anticline inthe autochthonous foreland section (Figure 9). Productive Upper Triassic shelf carbonates are overlain and

sealed by organic-rich black shales of the Triassic Streppenosa formation and Cretaceous-Eocene basinal

limestones. The southern feather-edge of the allochthonous, olistostromal Gela Nappe and a thin interval ofPlio-Pleistocene sediments cap the section.

Gela was discovered in 1956 and includes 104 productive wells. Depth to the reservoir averages

approximately 3,300 m. Gela oil is the heaviest (10oAPI) produced from the foreland fields of southern

Sicily. All of the oils of the area are characterized by relatively low gravity oils (15-21oAPI) and a

significant sulfur content. Ragusa field, second to Gela in size, produces 19oAPI oil with a sulfur content

of 2%. Studies indicate that the relatively heavy oils of southern Sicily are immature, the result of a low

thermal gradient and the early expulsion of hydrocarbons from organic rich Upper Triassic shales. Only

Gela oils are believed to be additionally biodegraded.


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Perla field is located offshore, just south of Gela. The reservoir lies at the top of an interval of Lower

Jurassic shelf limestones (Siracusa formation) at depths of slightly less than 3,000 m. The reservoir is

overlain and sealed by marls and evaporite, and underlain by rich source rocks of the Streppenosa shale.

Further to the south Vega field produces similar oils (15-21oAPI) from the same stratigraphic level.

THE VAL D'AGRI OIL PLAY

The Val D'Agri fields, Tempa Rossa, Monte Alpi, Monte Enoc, Cerro Falcone and Costa Molina (Figure 4) rank as

some of the largest in Europe. The total proved recoverable reserves for the four fields are estimated at 1.02 BBOE

(AGIP, 1998). Production from Monte Alpi, Monte Enoc, Cerro Falcone and Tempa Rossa fields is expected to

reach 165,000 BOPD by 2002. Oil will be transported via a new pipeline (to be completed in 2001) to a refinery

and marine oil terminal at Taranto.

Tempa D'Emma 11998

Tempa Rossa 11989

Gorgoglione 11997

Tempa Rossa 21991

Perticara 11997

Cerro Falcone 1, 1A, 1B1992, 1992, 1999

Cerro Falcone 2, 2A, 2B1996, 1996, 1997

Volturino 11998

Caldarosa 1,1A,1Ast1986,1989,1997

ME Ovest 11998

ME NW 1, 1A1992, 1996

Monte Enoc 11994

Alli 11998

MA Ovest 11994

MA Nord 31992

MA 21991

Monte Alpi 11988

CM W 11993

Costa Molina 11981

CM 21983

CM 31988

MA Est 11996

MA 31993MA 4

1992

MA 51996

Monte AlpiField

Monte EnocField

Tempa Rossa Field(420 MMBOE)

Cerro FalconeField

Figure 4: Val D'Agri Area Wells

Tempa Del Vento

Perticara

Cerro Falcone

Monte Alpi

Gorglione

Tempa D'EmmaCaldarossa

Total600 MMBOE

Val D'Agri wells are productive from multiple zones in a variety of carbonate facies, with oil columns of 600-1,000

m. Although the specific type and character of the zones varies, in general the reservoir properties of the productive

limestones and dolomites are excellent. The reservoirs include dolomites and leached, sometimes karstic, vuggy

limestones. The section is also characterized by large, open fracture systems. Flow rates in the recent South

Apennines oil discoveries range from 3,000-12,000 BOPD, plus associated gas. The produced oils display a wide

range of gravities, from 17-46oAPI, but most commonly cluster from 32-37o.

Tempa Rossa Field

Tempa Rossa was discovered in 1988 by a group of companies headed by Petrex. To date six wells have

been drilled in the field, including the Tempa Rossa 1, 1A and 2; Tempa D'Emma 1; Gorgolione 1; and

Perticara 1. All of the wells are oil productive from Miocene through Cretaceous limestones and dolomites.

The oil column in the field is estimated at 1000 m gross and 700 m net. Proved recoverable reserves are

estimated at 420 MMBOE, with associated gas forming about 7% of the total (AGIP, 1998). Production is

expected to reach 45,000 BOPD by 2002.


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Tests rates range up to 8,038 BOPD and long term test results from at least two wells have been published.

The #2 well produced a total of 116,000 BO (17o API) during a 135 day test, at an average rate of 1,220

BOPD. The test produced no water and produced no decrease in reservoir pressure. A 1992 sidetrack of the

#1 well tested oil rates of over 7,600 BOPD (17-22oAPI) and had produced over 500,000 BO through

December 1996 during "test" production. As of the end of 1996 the well was producing at a rate of 3,700

BOPD.

Monte Alpi Field

Monte Alpi was discovered in 1988 by a group headed by Fina Italiana. The field currently consists of 9

wells (all productive), including the Monte Alpi 1, 2, 3, 4, 5; Monte Alpi Est, Nord and Ovest wells; and

the Volturino 1. Oil (30-37oAPI), with associated gas, is produced from Upper Cretaceous limestone and

dolomite reservoirs. The oil column is 1,060 m gross and 702 m net. Oil flows (constrained by gas flaring

restrictions) range up to 6,793 BOPD. The production of 45,000 BOPD is projected for the field by 2000.

Monte Enoc Field

Monte Enoc was discovered in 1994 and currently consists of 8 wells, all of which are oil productive (30-

37oAPI), including the Monte Enoc 1, 2, 3 and 9; Monte Enoc NW 1 and 1A; Monte Enoc Ovest 1; and

Alli 1A). Oil flows (constrained by gas flaring restrictions) range up to 7,717 BOPD.

Cerro Falcone Field

Cerro Falcone consists of 6 wells, all oil productive, drilled between 1992 and 1997. Oil (32-36oAPI) has

been tested at rates of up to 6,600 BOPD, along with significant volumes of associated gas (up to 4.4

MMCF/D). The field produces from Miocene to Cretaceous carbonate reservoirs, with an oil column of 760

m.

A total of 42 production wells are currently planned for Monte Alpi, Monte Enoch and Cerro Falcone

fields. Eighteen of these have been completed, with four wells currently on production. Production is

expected to peak at 120,000 BOPD in 2002. Total recoverable reserves for the three fields are estimated at

600 MMBOE, of which approximately 12% is associated gas (AGIP, 1998).

SOURCE ROCKS AND HYDROCARBON TYPES

The oil and gas fields of southern Italy and Sicily contain a wide variety of hydrocarbon types, all of which are

believed to have been generated within three general source rock intervals.

Mesozoic oil-prone carbonates

Miocene oil and wet gas prone clastics of the syntectonic flysch sequence

Pliocene-Quaternary foredeep clastics

The large volumes of heavy oil discovered in carbonate reservoirs of the Mesozoic foreland can be traced to the

development of organic-rich carbonates in the narrow troughs between the Mesozoic carbonate platforms. Theseinclude black shales and marls of the Upper Triassic-Lower Jurassic Streppenosa Shale and Noto Formation of

Sicily, and the Upper Triassic Meride Limestone of northern Italy. The oils generated from these intervals are

relatively heavy (11-22oAPI), contain significant amounts of sulfur and are thought to be thermally immature.

Moderate to light oils (25-40o, no significant sulfur) have been found in Miocene and Pliocene reservoirs in

scattered fields of the Italian peninsula, and in the allochthonous Mesozoic carbonates of northern Italy

(Villafortuna field) and the Val D'Agri trend of the southern Apennines. The characteristics of these oils indicate

that they originated in source rocks within the Miocene flysch section, although specific intervals have yet to be

identified.


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Analysis of the gases found in Miocene, Pliocene and Quaternary reservoirs, including the fields of the Po Basin

and Adriatic, indicates that over 80% are biogenic in origin, derived from terrestrial organic matter in the abundant

clays of the foredeep section.

OFFSHORE POTENTIAL

The new seismic data indicate that all three of Italy's major productive sequences are present and prospective in the

deep water areas offshore. No direct well ties were available for this interpretation, but the overall sequences can beidentified on the basis of their character and relationship to the timing well established structural movements. The

seismic figures included here have been selected to illustrate several of the general sedimentary and tectonic

provinces within the area of the survey. In deference to the original survey subscribers, the location of the specific

portions of the seismic data shown in the figures is described only generally.

The area extending from the southern coast of Italy to roughly the 2,000 m bathymetric contour is characterized by

thick Miocene and Pliocene sections and large scale thrusting which extends into the Mesozoic carbonate section.

Two different periods of compression are evident. The earliest, probably Late Messinian to Early Pliocene in age,

involved Mesozoic through Messinian rocks in moderately high angle thrusts (Figure 10). The relief produced by

these movements resulted in large thickness variations in the post Lower Pliocene section and a prominent

unconformity over the crest of some of the structures (Figure 11). The steep slopes also resulted in the development

of large Pliocene slump related depositional structures like those shown in Figure 12. A second period ofcompression began in Late Pliocene time and is expressed in vertical offsets in the current sea floor (Figure 13). It

included both reactivation of earlier faults and the introduction of large scale, low-angle thrusting.

The sections shown in Figures 10, 11 and 12 include a number of potential prospective structures at various

stratigraphic levels. Thrusted Mesozoic carbonates and Miocene flysch reservoirs may be prospective for light oil

and gas on the large structures shown in Figures 10, 11 and 13. The Pliocene depositional features of Figure 12 may

hold large reserves of dry gas and the thrusted anticline to the right may be prospective at all three levels.

Large structures dominated by normal faulting (Figure 14) or by a combination of normal and high-angle reverse

faulting (Figure 15) are also present in the area. Such an association of normal and reverse faulting strongly

suggests that the latter is wrench related. These structures may also hold potential in all three of the major

productive sections.

Figure 16 shows an especially intriguing feature from the eastern part of the area. A pronounced unconformity tops

the large horst block in the left center of the section. Subsequent uplift of the block produced several hundred

milliseconds of relief at the unconformity surface.

1.0 sec

Miocene

Pliocene

Mesozoic

N S

Figure 10: Late Messinian age high-angle reverse faulting, offshore Italy

42 km


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1.0 sec

Miocene

Pliocene

Mesozoic

25 kmSW NE

Figure 11: Mid-Pliocene unconformity over structural crest, offshore Italy

1.0

sec

35 kmN S

Figure 12: Upper Pliocene Depositional Structures, Offshore Italy

Pliocene

Miocene

MesozoicCarbonates


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Miocene

Pliocene

1.0 sec

30 kmN S

Figure 13: Late Pliocene Thrusting, Offshore Italy

1.0

sec

52 kmSW NE

MioceneMesozoic ?

Pliocene

Figure 14: Pliocene normal-fault dominated uplift, offshore Italy


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Miocene

Pliocene

1.0 sec

30 km

Figure 15: Possible wrench faulting, offshore Italy

SW NE

1.0 sec

Unconformity

25 kmW E

Figure 16: Large horst block topped by unconformity, offshore Italy

A second distinct province within the survey area is shown in Figure 17. The stratigraphic section consists of thinPlio-Pleistocene interval, thick section of Miocene without internal reflectors, and a relatively undisturbed

Mesozoic foreland section. Within the central part of the survey area the province is confined to a relatively narrow,

north-south band just east of the faults of the Malta Escarpment. In the southern part of the area however, it appears

to extend much farther to the east.

The section is notable both for the lack of reflections from within the thick Miocene section and for the presence of

the undisturbed foreland section in an area east of the Malta Escarpment. It most probably represents an area of

early foundering of the eastern margin of the Malta-Hyblean platform. The Miocene section may be allochthonous,

although it is not clear. The lack of internal reflectors suggests that it may be internally olistostromal, similar to

allochthonous Miocene section of the adjacent Caltanisseta basin of southern Sicily.


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Messinian

MioceneFlysch

Pliocene

MesozoicCarbonates

1.0 sec

42 kmW E

Figure 17: Miocene flysch over autochthonous foreland carbonates,adjacent to Malta escarpment, offshore Italy-Sicily

In the offshore areas to the south and east of the Maghrebian and Apennine thrust fronts, the Malta-Hyblean and

Apulian platforms are overlain by relatively thin sections of Plio-Pleistocene sediments. Anticlines controlled by

modest normal faulting form structural traps for the large oil fields of southern Sicily. Figure 18 shows a strike line

over a large undrilled structure on the Malta-Hyblean platform. The feather edge of allochthonous Miocene-Lower

Pliocene rocks can be seen at the left end of the section. If structurally closed the feature would be highly

prospective for oil.

Miocene

Plio-Pleist.

MesozoicCarbonates

NW SE

70 km

Figure 18: Malta-Hyblean Platform

1.0 sec

CONCLUSIONS

Ready markets, abundant infrastructure and recent legal changes should make Italy an attractive area for future

exploration, especially in the southern Apennines. The new seismic data, upon which this assessment is based,

indicate that all three of the major onshore producing sections are also present offshore, along with substantial

numbers of large structures.

oil-gas poetntial, offshore south italy

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