2-D Interpretation of Reflection Time Section of Line No. 904 M\VI-007 in Mianwali Area

Abstract

Oil and Gas Development Corporation (OGDC) carried out seismic reflection survey in East Mianwali and a processed time section was provided. This dissertation pertains to the interpretation of Seismic Time Section in terms of Average velocity variations with time and depth. Three reflectors named (Rl, R2, and R3) have been marked on the seismic time section on the basis of observed reflection events. For the depth calculation two method namely Dix average velocity method and velocity function method have been used. In the Dix average velocity method, the velocity and depth of the r~flector were calculated; Iso-Velocity map and depth section were prepared using Dix Average velocities. In the Iso-Velocity map lateral and vertical velocity variations can b'e observed while in the velocity function method a velocity function was obtained by plotting the given CDP data and depth section was prepared by using this velocity function. The depth section shows that the area is structurally deformed due to tectonic forces and salt uplifting. Therefore reverse faults are present here, and reflectors are not horizontal throughout the line. There is an abrupt change in the velocity at CDP-8SG, which may be due to compaction. On the basis ofDix interval velocity assigning a velocity of < 4000 m/sec to clastic rocks and > 4000 m/sec to non-clastic rocks, the strata can be divided into clastic and non elastic zones.