The use of rock physics modeling and petrophysical analysis has become an integral part of quantitative seismic interpretation. In the present study, the above-mentioned techniques are applied to the reservoir interval of Basal Sand of Cretaceous age widely distributed in the Lower Indus Basin of Pakistan. The data used for this purpose consists of complete suits of wireline logs from four well A, B, C and D. The primary goal of this work is to understand the trends of seismic parameters such as P-wave velocity (VP), S-wave velocity (VS), bulk modulus, bulk density as a function of fluid saturation and porosity in this sand interval. Petrophysical analysis based on well logs is used to obtain petrophysical properties such as porosity, the volume of shale, fluid saturation, P-wave velocity (VP), S-wave velocity (VS) and density at reservoir conditions. The results show that seismic parameters are very sensitive to fluid saturation, fluid types and rock-forming sediments. Reservoir porosity and fluid saturation control the elastic response of Basal Sand due to which seismic velocities decrease with an increase in porosity and fluid saturation., Perveiz Khalid, Muhammad Arshad, Muhammad Irfan Ehsan, Aziz Ahmad and Shehzad Khurrum., and Obsahuje bibliografii
A historical and instrumental earthquake catalogue is prepared for the Northwest Himalayan Fold and Thrust Belt and Makran Subduction Zone Pakistan from 1960 to 2019 with homogenized moment magnitude. The local and some international published sources were utilized for the preparation of catalogue. This earthquake catalogue contained numbers of duplicate, repeated, dependent and independent events. Declustering process was opted to remove the dependent events such as foreshock and aftershock from catalogue to separate the mainshock only in term of distance and time space window. The declustering found 2714 clusters of earthquakes with total of 19512 (57.19 %) events out of 34112. Only cluster events which contained the mainshock or independent events were drawn on seismicity map with color identification. Maximum likelihood method was used to compute the value of magnitude of completeness i.e., Mc = 3.8 with estimation of a and b-values. Years vise magnitude of completeness was also computed to check the time period variation. The completeness of magnitude for different intervals of time indicates the impartial approximation of previous recorded seismicity. Temporal and spatial maps were also drawn to investigate the slope “b” and rate of productivity “a” in the study region. It is noted that b-values varied from 0.2 to 2.0 due to stress and intensive tectonic setting whereas a value increases due to increase the seismicity rate with respect to region. Seismotectonic map was drawn to delineate the major faults, seismicity pattern and tectonic activities. This work further can be used for single value hazard assessment for any region and their response spectra to update buildings and bridges codes.