Integrating core and wireline log data to evaluate porosity of Jurassic formations of Injra-1 and Nuryal-2 wells, Western Potwar, Pakistan

摘要

Petrophysical properties of rocks can be better understood by core and well log analysis. Exact porosity estimation in the Potwar sub-basin of Pakistan is one of the main issues because of complex tectonic settings. Core and wireline log data of two wells: Injra-1 and Nuryal-2 drilled in the study area are used for the porosity evaluation in the Jurassic reservoirs. The log interpretation and laboratory analysis show that the Datta Formation of the early Jurassic is mainly sandstone with minor shaly beds. A workflow is developed to correlate the calculated porosity from logs with the measured porosity from core plug samples. The results show that log porosity and core porosity of Datta sandstone are comparable. Porosity in the younger formations is higher than in the older formations, which is an indication of presence of secondary porosity and structurally deformed fractures in sandstone. The Datta sandstone encountered in Nuryal-2 is about 20-30 % less porous than in Injra-1 well.