Application of Well Log Analysis to Assess the Petrophysical Parameters of the Early Eocene Sui Main Limestone (SML) in Kharnhak-1 Well, Middle Indus Basin, Pakistan

The petrophysical analysis of the early Eocene Sui Main Limestone (SML) has been conducted in Kharnhak-1 well for the prospect of the hydrocarbon exploration of the Khairpur-Jacobabad High, Middle Indus Basin, Pakistan. The petrophysical analysis of SML is carried out on the basis of well logs including gamma ray, spontaneous potential, resistivity, neutron, and density logs. These analyses lead to interpreting the vertical distribution of porosity and permeability in order to measure the reservoir potential of the SML. The Archie equation was used to assess the petrophysical characteristics. The SML has good porosity and poor permeability with positive correlation coefficient between the two parameters. The average volume of shale is 18%. The log signature of SML shows dominance of carbonates (limestone). The reservoir quality of the SML in Kharnhak-1 well is such that it is 77% water saturated. The porosity (x) varies inversely with formation resistivity factor (F) and compressional wave velocity (Vp). However, F and Vp are directly related with each other. Thus, the electric and elastic properties of the carbonate rocks can be influenced by postdepositional alterations, which include porosity enhancement and reduction processes respectively.