Advanced Drilling Engineering

UND Petroleum Engineering
Advanced Drilling Engineering Group Project
University of North Dakota

Part 1: Pore Pressure & Fracture Pressure Estimation

Table 1 shows the average bulk densities for a Miocene in the Tucano Region, Northeast Brazil. Assume an average matrix density of 2.60 g/cm³. The normal pore pressure is 0.452 psi/ft. Table 2 shows the interval-transit times for a prospect in the region. Figure 1 shows the assumed Poisson's ratio for the region.

• Determine an expression for the surface porosity (∅₀) and the porosity decline coefficient (K_∅).
• Determine the top of the transition zone.
• Determine the pore pressure curve using the equivalent matrix stress method. The average interval-transit time in the pore fluid is 210 µs/ft. Use a margin of 0.8 lb/gal for the pore pressure gradient. Plot the resulting pore pressure gradient versus Depth (put Depth in the vertical axis, pointing downwards).
• Determine the formation fracture pressure curve using Ben Eaton's model (model presented in the course). Obtain Poisson’s ration from the graph in Figure 1 and overburden equal to 1.0 psi/ft on shales. Use a margin of 1.0 lb/gal for the formation fracture pressure gradient. Plot the resulting on the same graph of item (3).

Table 1: Composite bulk-density

Table 2: Average interval-transit time for the Tucano Region.

Figure 1: Poisson's ratio for the Tucano region (assume overburden of 1psi/ft in shales).

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