Reservoir Properties Evaluation Of Pab Sandstone, Zamzama Gas Field, Kirthar Foredeep, Pakistan

Abstract

The main objective of the study was reservoir characterization using petrophysical and geomechanical Facies of selected wells from Zamzama gas field . The Zamzama gas field was discovered in 1998 with an estimated 2.4 TCF of wet gas. Zamzama gas field is in the Dadu concession, and it lies approximately 180 km North of Karachi and 10 km west of Dadu city in Sindh province, Pakistan. Marine shales of the Lower Cretaceous Sembar and Goru Formations are presumed to be the source of most of the gas fields in Southern Indus Basin. The main aim of this research is to enhance the knowledge of reservoir characterization on the bases of petrophysical and geomechanical techniques and findings will offer a set of recommendations that will make accurate reservoir parameter estimate possible. Digital data in LAS format of wireline open hole logs was used for the study. The evaluation was performed in Zamzama-2, Zamzama-3 and Zamzama-5. Petrophysical evaluation and Geomechanical properties computation was performed on these wells. The wells were further categorized in pay zones and nonpay zones. Self-Organized method (SOM) was used to perform Facies Analysis, which used Petrophysical and Geomechanical outputs to classify them into three Facies. These facies are ranked from 1 to 3 depending on the quality of the reservoir with 1 being the best and 3 being the worst. Reservoir characterization and classifying it in facies helps getting better flow units and helps during development of the field and workovers. The presence of distinct units with certain Petrophysical and Geomechanical properties help geoscientists establish a strong reservoir characterization. On the basis of Petrophysical Analysis, the Pab sandstone of Zamzama-2 well is the best zone of interest with the Net pay thickness of 111.17 m. Facies-1 is showing maximum thickness in Zamzama-2 and Zamzama-5 which is 137.35 m and 134.22 m whereas in Zamzama-3, Facie-1 is showing maximum thickness of 119.85 m. The combination of Net Pays and Facies Analysis concludes Zamzama-2 being the best as compared to the other wells.