Josip Sečen, DSc
Message to the Readers
In recent days, all the media in Croatia presented bombastic news on huge oil reserves in a great number of fields in the Croatian Adriatic offshore. President/representative of the Norwegian company is not to blame as his company has acquired the right for seismic survey of this area, and by expecting big discoveries of oil fields similar to the ones in North Sea, his statement is aimed to attract future users of their survey results.
It is unbelievable how certain journalists in Croatian papers have immediately announced financial recovery of Croatian economy, based on those seismic surveys that will enable the discovery of numerous oil fields in the Adriatic. Such thinking has no scientific or expert grounds, regardless of few biologists supporting it, as seismics determines structures within the earth crust that could be traps for hydrocarbon accumulation.
Seismic surveys have not started yet and they have to be followed by public tender where the most favorable company for performing exploration in defined concessions / areas should be chosen. After that, further exploration follows and then, in case of discovery, reservoir development with the accompanying construction of production and transportation system. All the above takes over four years.
This whole story misinforms the public which would not be the case if profession had been consulted. The ones competent to give real evaluation whether the oil potential is promising are Scientific Council for Crude Oil and Gas at the Croatian Academy of Sciences and Arts and Croatian Association of Petroleum Engineers and Geologists (HUNIG) and numerous scientists and experts who have participated in successful development of Croatian oil and gas business.
According to forecasts and promise given in our first (and up to now only) published issue of our journal this year, you have in front of you our second issue, where we are publishing four scientific papers and information from the field of exploration, production, processing and transportation of oil, gas and energy products and energy production. If our financial plans shall be realized, we plan to publish our journal every three months and continue our tradition of uninterrupted publishing of our journal over last 64 years.
Our first paper was prepared by Katalin Sári titled "Comparing Core Analyses and Well Logs Using a Hungarian Gas Field as Example". The purpose of this study was to build small-scale genetic models of a reservoir by comparing the small and medium scale information derived from core analyses and well logs from a gas field situated in the eastern part of the Pannonian Basin. For numerical solution, several single (univariate) and multivariable (multi- variate) statistical methods were used to describe single and multidimensional similarities.
The author of the second paper is M.S. Benzagouta with the title "Investigation on the Impact of Rock Physical Properties on Permeability Variation: Case Study for the Reservoir Heterogeneity Development". He explains how various factors are controlling the reservoir petrophysical characteristics. Investigations have shown that control on reservoir characteristics: permeability and heterogeneities can be ascribed to textural and physical properties of the rocks. Discrepancies of petrophysical properties are caused by variation in grain size distribution and their arrangement. Quality estimate of reservoir rock can be determined by pore radius (R35) and surface grain volume (Sgv).
The third paper titled "Immiscible - Recycle Gas Injection to Enhance Recovery in an Iranian Naturally Fractured Reservoir: a Case Study with Emphasis on Uncertain Parameters" was prepared by Navab Roustami and associates. It studies the immiscible recycle gas injection process in one of the Iranian naturally fractured carbonate reservoirs. Natural gas injection into oil reservoir is the process of reservoir depletion which increases recovery and oil production. The procedure consists of continuous injecting (returning) of produced gas into the reservoir to maintain the pressure within reservoir and to improve oil viscosity. There are numerous studies on such procedures and factors on which their success depends. This paper presents the relations between production and injection wells, quantities of gas injection and injection pressures, which have considerable effect on reservoir recovery.
The fourth paper is actually the first part of a paper prepared by Sanjin Grandić and his associates titled "Peri-Adriatic Platforms Proximal Thalus Reservoir Potential". This work represents a sequel to the study on peri-platform clastics and their petroleum-geological significance. In the papers previously published in our journal, on several occasions it has been pointed out that proximal thalus zone, spreading along the entire Dinarides carbonate platform slope is our biggest exploration unit in peri-Adriatic area. Its length is approximately 550 km and the vicinity of Palagruža depocenter, i.e. potential centers and hydrocarbon generation from potential source rocks, undoubtedly confirm the potential of proximal thalus zone.
We hope that the content of this issue shall meet your scientific and expert interests.