GEOL. CROAT. 49/2 339 I ZAGREB 1996 

Ahsfract - Note 

Improvement of Time Section Quality Through 
Approaching Perfect Static Corrections 

"" W0 ---.' , 

" 

Ali MEMA and Durim GOXHAJ 
PROCEEDINGS 

The Plashniku region extends into the Berati tecto­
nic bell of the External Albanides. Due 10 the discovery 
of two oil fields in the vici ni ty (Kucova and Marinza), 
the area is cons idered to be attractive for petroleum 
explora tion. In order to improve the quality or seismic 
data, great efforls were made by careful processing with 
the present software. In the regions of morc compli­
cated geological structure, like P lashnik, additiona l pro­
ced ures were applied to improve the static corrections. 
As a result, th e top of the Mol ish ti carbonates lhal 
appeared to be notched, came out in the time sec tion as 
a serratcd one. In this way corrections were made, and 
the seismic data were improved considering deeper lev­
els than the Molishti. 

The mcthod is essentially based on the fact tha t 
upon processing with the Gath programme (plott ing of 
the C.D.P. traces), thc traces that fo rm a Comm on 
Depth Point for a reflected wave group should be united 
according to a horizontal line. However, after having 
applied the Gath programme, we observed that the 
traces of the top of Mo[ishti carbonates for each C.D.P. 
are not in a horizontal line. Th is anomaly is caused by 
two connected fac tors - fi rstly by the inadequate preci ­
sion of the static corrections applied, and second ly by 
inadequate realisation of dynamic corrections (N.M.O.). 
That's why authors suggest the second step be avoided. 
To make corrections in this way is simple. Based on the 
average phase of correlation of the main hori zon (top of 

Albseis, Fi er, Albania. 

the Mo[ishti carbonates), for each C.D.P. a horizontal 
line is drawn on the time sect ion across the bunch of 
traces which form this C.D.P. Each C. D.P. wi ll thus 
have a correspond ing line with lime To of an average 
correlation in the time section. This line is then used as 
a reference line to read-off the time-shifts J"or each 
trace. The data are registered in a tab le containi ng: 
C. D.P. numbers, stacked traces (l-48) and the cor­
rection applied to each trace. These values arc then used 
10 correct the time of each trace before the stacking pro­
cedure is realised. 

After testing the procedure on a seismic section, an 
increase in the reliability oj" correlat ion of the Molishti 
limestone was noticed, whilc the wave form under thi s 
horizon remained the same. In other words, an increase 
or reliability was achieved without affecting the quality 
of data in deeper levels. The conclusion can be drawn 
that in thi s particular case, the absencc of deeper reflec­
tions is not related to the uncertainties of the stal ic cor­
rections but rather to a very complex geological struc­
ture (Plashnik overthrust), which was confirmed by the 
Jaler drilled well PI - I. 

Use of thi s method is advocated, especial ly in 
regions with shallow horizons that are not very strong. 
The method requ ires no additional field work/expenses, 
becau se all the operations are done in the processing 
centre. 



] 40 Geologia Cro:ll ica 49n