Litostratigraphic Reflection

4. Result and Discussion

According to the Lithofacies, Electrofacies, and Litostratigraphic correlation, there are at least six main facies namely: (A) Calcareous siltstone in the depth of 1565 – 1574 meters, (B) Silty shale in the depth of 1574 – 1588 meters, (C) High burrowing very fine sandstone in the depth of 1595.0 – 1600.35, (D) Fine sandstone with slight mud drapes in the depth of 1600.35 – 1603.55 meters, (E) Organic Shale in the depth of 1603.55 – 1604,95 meters, and (F) Very fine sandstone to intercalated siltstone and shale in the depth of 1604.95 – 1608.35 meters. The Litostratigraphic Correlation can be seen in figure 3. Figure 3: Litostratigraphic Correlation

The volume of shale was calculated to determine the amount of shale

These coefficients were gotten from the formation resistivity factor versus porosity (a and m) graph and also the formation resistivity index versus brine saturation graph. The figure 6 shows that the water saturation values using these three equations are too far from the real water saturation values that obtained from the data cores (red spots). The water saturation values from these methods are relatively high which indicates that all facies are dominated by water. Based on the drill stem test data, the facies C and D in each wells are supposed to be contained by the hydrocarbon. Figure 6: Water saturation at the well X-1 The least square minimization method is a method created by John Doveton in 1994 which is a modification of the Simandoux Equation to obtain a closer saturation water value with the core data. The new formula when compared to the conventional simandoux formula is written as follows:

There are slight distribution of mud drapes. As can be seen at the left picture of figure 9 with 40x magnification that comes from the depth of 1600.90 meters, there are claystone in the range of A and 4-5.

b. Based on the XRD data, the clay minerals in the facies consist of ilit, kaolinite, and chlorite which cover 11% of the rock compostion. The clay minerals when mixed with the water formation would release the cations which increase the conductivity of water formation. As can be seen at the left picture of figure 9, there is a distribution of the kaolinite in the range of H-J and 2.

c. The burrowing texture that spread out across the facies reduce the resistivity values. In addition, these kinds of textures has caused the pyrite minerals to be precipitated. The pyrite mineral is considered a conductive mineral which reduce the resistivity value. As can be seen at the left picture of the figure 9, the pyrite minerals are visible in the form of black spots which is their main characteristic in the PPL thin section.

d. The salinity of water formation in both facies are 13,362 ppm which, according to the USGS classification are belong to the high salinity water. This could be one of the reason the log reading of resistivity is very