Petrophysical evaluation of Well Turkwal deep-01 and Turkwal deep-X2, Upper Indus basin, Pakistan (P-1016) (MFN 8074)

Abstract

The purpose of this research is to evaluate hydrocarbon potential of Turkwal Deep-01 and Turkwal Deep-X2. Geographically, the study area lies in Chakwal district. Tectonically, the study area is a part of Southern Potwar Deformed Zone. On the north, this area is bounded by MBT and its southern boundary is marked by Salt Range Thrust. Its eastern boundary is marked by left lateral Jhelum fault. On its west boundary right lateral Kalabagh fault is present. The data comprised of Log suit of all the three basic logs. The study area lies in eastern Potwar region. Turkwal field lies on Mandra- Chakwal road which is approximately 45 km away from Rawalpindi, Punjab province. Drilling has been done from Nagri Formation of Pliocene age up to Salt Range of Pre-Cambrian age. because Murree Formation, Sakesar Formation and Chorgali Formation are repeated after Salt Range Formation, which indicates the presence of thrust fault. Primary reservoirs in these wells are Carbonates of Eocene and Miocene age. Log trends revealed that Murree Formation can also act as reservoirs in these wells. In Turkwal Deep-01, on the basis of low gamma ray and high resistivity value zone of interest has been marked in Sakesar Limestone from 3179- 3185 meters. In this zone, average volume of shale is 21.6%, while average volume of clean zone is 78.36%. Average porosity calculated is 14%. Average effective porosity is 10.96%. average saturation of water is 15.23% while average saturation of hydrocarbon is 84.77%. Seven prospect zones have been marked in Turkwal Deep-X2. Based on petrophysical analysis, the average volume of shale in these zones 21%, 33.69 %, 21.77 %, 26.30%, 14.84 % and 15.36 % respectively. The average porosity in these marked zones are 19.4 % ,31.96 %, 20.32 %, 22.51 % ,23.01 % and 22.94 % respectively. Effective porosity in these marked zones of Turkwal deep-X2 are 15.29 % ,20.98 %, 15.83 %, 17.12 %, 19.62% and 19.54 % respectively. The average hydrocarbon saturation in these seven marked zones of Turkwal deep-X2 are 24.96%, 34.65%, 37.32%, 24.96%, 45.40% and 46.67% respectively. Two prospect zones have been marked within Murree Formation in Turkwal Deep-X2. The average volume of shale in zone 1 is 19.85% while average volume of shale in zone 2 is 20.07%. The average porosity in zone 1 is 21.29% and in zone 2 `ii average porosity is 17.56%. The average hydrocarbon saturation in zone 1 is 75.74% and in zone 2 it is found to be 71.53%. The porosities in both wells is relatively higher due to compressional tectonic regime. Another reason can be the presence of fault that has been encountered in both wells. Based on petrophysical analysis, it is revealed that in Turkwal Deep-01 Sakesar Limestone has good hydrocarbon potential. In Turkwal Deep-X2, zone 7 (Chorgali Formation) has a fair amount of hydrocarbon. While both the zones marked in Murree Formation have good hydrocarbon potential. The status of this well is suspended because there is clear possibility that hydrocarbon may have been migrated through a fault present.