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mineralization increase, a reduction of the mineralization coefficient, and the change of the water in chloro-calcitic type has been noticed. By analyzing the entire factual abundant material, it is very clear the presence of a hydro chemical deviation in the direction of the water movement, from the top part to the direction of the Southern pericline of anticline structure. Besides hydro chemical data which determine the direction of waters movement, it is also been made the calculation of the piezometric level of the carbonate complex of Visoka oilfield. The hydrodynamic measuring data about the Visoka-Ballsh region, were developed in order to calculate the reduced pressure on a plan surface for comparison, based on the formula: � Fig.2: Cross section in Visoka Oil Field. P = (L + l) ¥ + 2 where: P = the calculated pressure on a surface, L = the absolute depth of the well. L = static level calculated from the sea level; ¥ = specific weight of the water taken from the well. The piezometric level of some wells in Visoka was calculated based on these data (see table). Both the piezometric level and pressure values prove movement of water from the eroded surface, well 651, in South direction, according to the above line of wells. A full compliance between the hydro-chemical and hydro-dynamic indicators has been observed in the Visoka field. Well Reduced Piezometric pressure level 651 208.3 146.1 649 207.4 135.2 G-16 205.9 121.7 Ba-6 206.4 131.2 Ba-13 205.9 123.3 Ba-8 206.1 123.9 Ba-15 206.4 127.06 Ba-1 205.3 115.4 Gr-3 204.5 108.4 Visoka oilfield proves the basic principle of the hydrogeology, that the hydrochemistry is a consequence of the hydrodynamic, and the last one is the result of the geological-structural conditions. In these hydro-dynamic conditions, the Oil-Water contact in Visoka is not horizontal. It is inclined in Southern direction, or in the direction of water movement (636, 1050m, G-180, 1840m), as well as in the West direction (well 627 1325m), and in East (G-238 1680m). The inclined oil-water contact in Visoka is the synthesis of the coordination of the active underground waters to the oil reservoir, as well as their role during the paleo-hydrogeological development in creating the conditions for the reservoir preservation. By analyzing all the geological, hydrodynamic, hydrogeological, physical, chemical, biodegrading, lithological, stratigraphic, and tectonic data, we think that besides the principal factor in the trap formation of Visoka, some other factors have also played an important role, such as: According to hundreds of exploration and exploited wells in Visoka field it is been observed a noticeable heterogeneity of the rock property features between the wells, particularly regarding the permeability. This heterogeneity and the anisotropy have influenced in preventing the oil migration 98 �
from the Southern part to the direction of the top of the structure. Cases of lack of communication from one well to another, and between two double wells, are numerous in Visoka oil field. Such collector barriers are also known in other carbonate oilfields in our country, such as the case of the direct contact of western flank of Mollajt to the Eastern flank of Selenica. At the zone of dry wells G-56, G-57, G-58 and 616, which represents the transition from the Central zone to the Northern one, there is a noticeable lack of communication, low permeability,(Dry wells), which has prevented the oil migration in the Northern direction. The Upper Miocene mollassic deposits lie transgressively over the eroded part of the carbonate, of the Patos-Verbasi anticline structure (Fig.2). It is an undisputable fact that a great quantity of oil and gas reserves has migrated from the eroded carbonate to the sandstone reservoir of these deposits, and has saturated them, up to their outcrop in the surface in South, in Patos. During the geological period Upper Miocene-Quaternary, at the part where these deposits come out to the surface, the oil is oxidized, the light fractions move away, and are turned into bitumen. In the current situation these layers are bitumen-bearing layers. Bitumen has served as a screen (seal) to prevent further migration of the oil. So, it is created a natural coverage, or bitumen screen, which has not allowed the further migration of the oil in the newest geological times. Sandstone deposits are situated in stratigraphic discordance on the eroded surface of the carbonate, or of the argillites, of the Upper Miocene. Being in direct contact on the eroded carbonate, these deposits communicate with the last ones which they are supplied with oil. The presence of the argillaceous lithology, or the compact sandstones, in the southern part of the eroded surface makes impossible the oil migration to this part of the structure from the southern part of the field. The oil of Visoka oil field is very viscous, of specific weight 0.990-1.02 gr/cm 3 . This oil is migrated by the early fluxes of migration, Lower Oligocene and on. During the geological periods thanks to the different structural and geological conditions are moved away the lightest oil fractions. Also, being in contact with the water that moves through the eroded surface of the carbonate, the oil is oxidized. Its swimming force is too small, or zero, when the specific weight is almost the same to the water. In these conditions the movement has been very difficult, or its migration from Visoka reservoir to the direction of the top-most part. The tectonic plan of Patos-Verbas has changed after the erosion of its top part. The northern part of the carbonate eroded surface is under the absolute depth 2000 m today, or lower than the carbonate top in Visoka. This change of the tectonic plan has made possible the fluids movement and reestablishment in this structure. All these factors together have made possible that Visoka oil field is preserved in the current situation of the hydro-dynamic equilibrium of fluids. However, a great quantity of oil reserves has migrated from this structure. The oil field has been created, destroyed, and recreated in the youngest geological periods. Conclusions The Visoka field represents a special case of the trap formation of hydrodynamic type, formed in the southern pericline of an anticline structure. The hydro-dynamic and hydro-chemical measurements of the wells in Visoka and Ballsh prove the existence of a pressure gradient and the underground waters movement from the raised part of Patos-Verbas structure in its plunging direction. The water movement in this direction has made possible the preservation of the oil reservoir in Visoka. � 99 �
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6 th WORKSHOP of the ILP TASK FORCE
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Nr. Prénom NOM Afilation 1 Myqerem
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6th workshop of the ILP Task Force
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11h10-11h30: Vilson Silo, Salvatore
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14h40-15h: Ariana Bejleri, Mensi Pr
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ABAZI Sheribane 71 ADDOUM Belkacem
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ILP TASK FORCE on SEDIMENTARY BASIN
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Topography, sediment and basement O
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REFERENCES Argnani A., Favali P., F
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Fig. 3: Source rocks distribution w
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etc, are found in concentrations hi
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� Fig.�3.�Map�of�the�gr
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Legend Well Fig. 1: A) Hydrographic
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This common or different characteri
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The gross lithologies observed are
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Flame structure:. Flame shaped stru
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Page 67: Fig. 5: Power Velocity and Cumulati
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Page 78 and 79: 41.5° 41° 40.5° 40° 0 50 km 42
Page 80 and 81: Results suggest that: a) The incisi
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Page 84 and 85: features with a NE-SW shortening di
Page 86 and 87: interglacial epochs, on which the r
Page 92 and 93: agreement with the ~E-W extension p
Page 97 and 98: documented six terrace levels in th
Page 99: Koçi R., S Bushati, J.L. Mugnier,
Page 105 and 106: D e p t h (m) D e p t h (m) NW Shku
Page 107 and 108: Abstract ILP TASK FORCE on SEDIMENT
Page 114 and 115: Besides the hydro-dynamic factors,
Page 116 and 117: these basins formed. 2) During the
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Page 124 and 125: Adriatic coastline. The alluvial de
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Page 128 and 129: The first project of "Science for P
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Page 132 and 133: Upper Jurassic of the Ionian Zone c
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Page 136 and 137: ock in extension at the relatively
Page 138 and 139: Fig. 3. In-situ stress measurements
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Page 144 and 145: gneissic) rocks occurred on the nor
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Page 152 and 153: Ionian zones. The thrust belt is ch
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Page 156 and 157: 4. A family of four, including all
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Page 160 and 161: The primary purpose of this study i
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Non Clay Minerals present in Brari
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The deformation can be divided in t
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152
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and Italy in the centre, and the Io
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Figure 1 - Geological context (from
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display rapid lateral variations in
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Figure 1 - Geological context of th
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Figure 2 - Example of porosity meas
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166
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as the Dinarides or Hellenides by a
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Ustaszewski, K., Schmid, S.M., Füg
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172
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In new geological map of Albania (i
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1991), Preapulian and Ionian zones
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Attention has been paid in drawing
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Hilterman, F.J., 1983. Seismic lith
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Figure 4. Heavy mineral strata in t
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References Breesch, L., Swennen, R.
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The Pb isotope ratios of all rocks
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Figure 3: Th/Yb versus Ta/Yb plot.
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192
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References � ermák, V., 1993. Li
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Fig. 2 Integrated Strength of the l
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during the flexure of the foreland.
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(iii) to obtain a continuous record
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