Petrophysical analysis of Lockhart Limestone with porosity and thickness correlation of exposed Lockhart Limestone at Nathia Gali with subsurface Lockhart Limestone of Chanda deep-01 well in Upper Indus basin
Keywords:
Nathia Gali; Chanda deep-01; Porosity; Petrophysics and correlationAbstract
The research mainly involves the petrophysical analysis of Chanda deep-01 and to mark the best reservoir zone while second part of the research work was to correlate the Lockhart Limestone of Chanda deep-01 with exposed Lockhart Limestone at Nathia Gali in Hazara region on the basis of porosity and thickness. To interpret petrophysical properties, different logs were used which include gamma ray log, neutron log, density log, long latero log, spontaneous potential and sonic log. Exposed Lockhart Limestone unit was studied in the field and petrographically analyzed. The thickness acquired from field was 242m while porosity estimated by thin section study was about 11%. The petrophysical properties calculated at Chanda deep-01 well estimated the thickness to be 170m and porosity to be 9.5% along with volume of shale 5.5% and water saturation 29.3%. In the same zone, hydrocarbon saturation turned out to be 70.6%. These values confirmed Lockhart limestone to be the best reservoir in Chanda deep-01 well. The exposed unit in Hazara was then correlated and the porosity difference with subsurface unit in Chanda deep-01 was estimated to be 1.86%. The changes in porosity at different locations of same formation were interpreted to be due to overburden pressure, facies changes, diagenesis and pressure dissolution.
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