Geological offshore prospectivity
Gas
In the Northern part of Croatian part of the Adriatic, 22 gas discoveries were found with estimated reserves of approximately 1.3 trillion cubic feet. Currently, production is established from 19 gas production platforms, one compression platform and almost 51 wells. Annual production amounts approximately 1,2 billion cubic meter of gas.
In Italian part of the Adriatic Sea ,130 gas fields were discovered with reserves estimation of approximately 23 trillion cubic feet. Currently, they are producing from 45 fields with 197 exploitation platforms and almost 600 exploitation wells. Annual production is about 5 billion cubic meters of gas (Ministero dello Sviluppo Economico).
Oil
In the Croatian part of the Adriatic Sea no commercial discovery has been found although two wells, Vlasta-1 and Jadran-13, had significant oil indication but due to commercial and technical reasons exploitation has not been established.
In Italian part of Adriatic Sea, 24 oil discoveries have been found with estimated reserves of 550 MM bbl. Currently, seven oil fields are in the production which are producing from 7 exploitation platform and 39 wells. Annual production amounts approximately 1,8 MM bbl (Ministero dello Sviluppo Economico).
Comparison of exploration and exploitation of hydrocarbons in Croatian and in Italian part of the Adriatic sea
Hydrocarbon prospectivity
Several potential hydrocarbon plays have been identified, based on processed newly acquired 2D seismic data, which could lead to the new discovery of hydrocarbons after further additional seismic acquisition, interpretation and drilling of wells. Examples of selected newly recorded 2D seismic lines are below presented:
Potential gas discoveries
New 2d seismic line located in northern Adriatic which indicates potential gas accumulation
New 2d seismic line located in northern Adriatic which indicates potential gas accumulation and gas discovery ksenija-1 which has not been developed
New 2d seismic line located in northern Adriatic which indicates potential gas accumulation
Potential oil discoveries
Part of new 2d seismic line located in southern Adriatic which indicates numerous potential accumulation very similar to italian carbonate oil accumulation
Part of new 2d seismic line located in southern Adriatic which indicates numerous accumulation on several locations
New 2d seismic line which indicates potential oil accumulation along edge of carbonate platform
Hydrocarbon prospectivity onshore
Considering that hydrocarbons have been proven and are being actively produced in every region of Pannonian basin onshore Croatia and uncommercial quantities of hydrocarbons have been discovered in the Dinarides prove a working deep hydrocarbon system that is under explored in the region.
The proven hydrocarbon system of the Croatian Pannonian basin contains multiple source reservoir and sealing rocks. In general the main source rocks are composed of:
Seals are generally regional, provided by intra-formational pro-delta and delta-top mudstones. In majority of the fields, the argillaceous interval above the reservoir usually forms the sealing horizon. It may also be the source rock for the overlying reservoir. The Neogene series are considered as top seal to all older reservoirs.
There are five main groups of plays discerned in the Pannonian Basin, best classified according to their structural affiliation (majority of fields involve reservoirs at many stratigraphic levels):
Preliminary analysis of the seismic and other available data shows that the Pannonian contains significant remaining potential and is under explored for unconventional resources. A simple comparison of Hungary and Croatia illustrates that whilst both have similar sized onshore area in the Pannonian, Croatia has only 33% of the number of exploratory wells drilled onshore compared to Hungary (derived from IHS database statistics) and less than 52% of the recoverable reserves discovered to date.
The main undiscovered resources potential is expected to be in the following:
In addition to undiscovered resource potential, according to the IHS fields database, there is currently approximately 65 Mmboe recoverable reserves which are undeveloped.