RESERVOIR EVALUATION OF SANDS OF LOWER GORU FORMATION BY PETROPHYSICAL INTERPRETATION OF BAZ-01, JABO-01, AND JABO-05, SOUTHERN INDUS BASIN, PAKISTAN

Abstract

The study area located in Southern Indus Basin, Badin district, Sindh province, Pakistan and the present study deals with reservoir properties of Sands of Lower Goru Formation which is the lower member of Goru Formation. The name Goru Formation is introduced by Williams (1959) for rocks included by Oldham (1892) in the upper part of his Belemnite beds. Multiple techniques have been used to understand the reservoir character of Lower Goru Formation in Lower Indus Basin. Well log analysis and interpretation are one of the more useful techniques to evaluate the petrophysical parameters of the reservoir. These parameters include estimation of shale volume, total and effective porosities, water and hydrocarbon saturation and identification of pay zones and their approximate thickness. This research mainly focuses on the reservoir properties of sands of Lower Goru Formation with the help of petrophysical interpretation of three wells. These wells are located in Badin district, Sindh, Southern Indus Basin Pakistan with names Baz-01, Jab-01 and Jabo-05. On the basis of petrophysical interpretation and correlation of these wells Lower Goru Formation is divided into different sandy and shaly units. The units which are categorized as sandy units are more important in this research because they are possible reservoir of study area. This study also contains the identification of matrix in the reservoir zones of all three wells. On the basis of well tops of Jabo-05 and GR log the correlation of all three wells is carried out which helped to understand the different sandy and shaly units of study area, after that different cross plot for matrix identification in sandy units are used for further verification of sandy units and their composition. Correlation of wells include both stratigraphic and structural correlation and different models are also prepared which help to understand the stages of deposition and thickness variation of these sandy and shaly units. After the identification of these sandy and shaly units petrophysical interpretation of sand units is carried out because current study only focuses on the Sands of Lower Goru Formation. The petrophysical interpretation of these sandy units is carried out for all three wells and results shows that the first well Baz-01 has very low effective potential for hydrocarbons because of access of shales in the sandy units and high saturation of water. The other two wells Jabo-01 and Jabo-05 have good effective potential for the hydrocarbon accumulation. Jabo-05 shows good reservoir properties among all three wells and contain largest net pay of 16 meters.