Abstract:
Seismic lines PBJ-2, PBJ-4, PBJ-6, PBJ-8, and PBJ-10 obtained from
Directorate General of Petroleum Concessions (DGPC) was shot by OGDCL in 1980
in the area of Balkassar which lies in the central Potwar on the southern flanks of
Soan syncline.Seismic line PBJ-2, PBJ-4, PBJ-6 are dip lines and PBJ-8, PBJ-10 are
strike line. Five prominent reflectors are R1 (Chorgali Formation), R2 (Sakesar
Formation), R3 (Lockhart Formation), R4 (Tobra Formation) and R5 (Khewra
Formation) were marked on the seismic section on the basis of observed seismic
reflection. A fault was marked which continuities along the Precambrian basement.
Two more thrust faults were marked which showed fault propagating folds in the
form of anticlines of Balkassar. A time section was produced from the seismic section
using the vibrating point and two way time (TWT) of the reflectors and faults. The
TWT were posted on the base map to make a time contour map of the formations as it
was continuing throughout the area. The seismic velocities given in the velocity
windows on the seismic section were used to find the average velocities of the
formations. These average velocities were then used to find the depths of the
formations for the seismic section. The well data of Balkassar Oxy 1 was used to
confirm the depth of reflectors.The geo seismic section showed that the area was
structurally deformed due to salt decollement and compressional tectonic movements.
Traps for hydrocarbons were developed in the anticline as they truncated against the
thrust fault. Salt probably moved into these anticlines due to compressional
movements and a pop-up structure was formed. The Balkassar anticline was the
prospective zone and was primary targets for oil exploration, where the depth of the
Chorgali Formation was almost 2400m, favorable for drilling.
