2-D Seismic Interpretation of Qadirpur Area East Sindh Pakistan

Abstract

Aim of this dissertation is to interpret 2D-Seismic Reflection time sections of the Qadirpur Area (Sindh Province) Pakistan. This seismic sections are Post-stacked time migrated sections and were provided by the Department of Earth And Environmental Sciences, Bahria University Islamabad and the lines bear the title 985-QPR-01 about 16 kms in length and oriented in SW-NE direction, 985-QPR-04 about 18 kms in length and oriented in SW-NE direction and 985-QPR-08 about 19 kms in length and oriented in NW-SE direction. OGDCL acquired data in October 1998 and processed it in January 1999. The velocity information is in the form of RMS, DIX interval and DIX average at different times is given, and is provided at selected S.Ps. RMS velocity varies from 1500 m/s to 5000 m/s. For interpretation of the Seismic sections, three horizons R1,R2 and R3 were marked on line 985-QPR-01 which were then shifted to Lines 985-QPR-04 and 985-QPR-08 with the help of seismic tie lines, these horizons were marked on the basis of prominent reflections from subsurface horizons due to changes in lithology and diffractions. Using the RMS velocity given in the velocity panels on seismic section for selected shot points, I calculated the times on constant velocity interval of 100m/sec. Then using these calculated times and velocity values prepared the Iso-velocity graphs and average Velocity graphs. In Mean line Method of velocity estimation, velocity vs. time graphs are prepared. From these graphs a mean average velocity is determined. From Seismic Section, arrival times (two ways) of each marked reflector are determined. Using these arrival times, Time Sections have been prepared for the three selected lines. Also using these arrival times, I calculated the average velocity for these times on mean line graphs and then the depth of each reflector has been calculated using s=(v*t)/2 and is represented in Depth Sections of the three selected lines. Depth Sections provide a reliable picture of reflectors and structures present in the subsurface of the area. Well correlation is also done, which satisfy the calculated depths, so horizons have been marked. Interpretation of the Project Area shows that, extensional regime and calm environment prevails in the area Reflectors are almost flat lying. whereas Horst and Graben structures have been found.