This paper focuses on rock physics study on the Kati formation in Seri Iskandar, Perak in Malaysia, particularly in modelling the P wave velocity and bulk density log by using petrophysical relation-ship through well log data, and estimate the total and effective porosity from the synthetic log. The absence of density log data and incomplete depth coverage of slowness log from this well have challenged the computation of the formation porosity. Thus, Faust's formula and Gardner's equations were used to obtain the synthetic P wave velocity log (SYNVP) and synthetic density log (SYNDEN) respectively. The SYNVP estimated by using Faust's equation shows a good result with normalize root mean square (NRMSE) of 6.24. In the same depth, SYNDEN estimated by Gardner's equation with NRMSE of 5 and have an exceptional tie with measured bulk density from 111 core samples. A total of 28 core samples have been measured for its effective porosity with helium porosimeter and ranged less than 5 in average. Effective porosity log generated from SYNDEN resulted in good match with effective porosity from core with NRMSE 1.44. The study use core data to validate the model, and NRMSE is used to show the error percentage calculated between the modelled log and core data. The lower the NRMSE value indicates less error model and concluded as reliable synthetic log. © 2019 Slovnaft VURUP a.s.