Reservoir Management and Geomechanics - Reservoir Engineering - Petroleum Engineering Previous Year Questions

The average reservoir pressure and fracture gradient of petroleum formation at a depth of 4,000 m are 30,000 kN/m² and 16 (kN/m²)/m, respectively. The density of the formation is 2290 kg/m³. If the reservoir pressure declines to 20,000 kN/m² after a few years of production, the fracture gradient of the formation is _____ (kN/m²)/m. (write answer with one decimal place)

For a process which is in a state of statistical control (within ± 3σ), estimated process standard deviation (σ) is 3 mm. The specification limits for the corresponding product are 100 ± 7 mm. The capability ratio C_p is _____ (round off to 3 decimal places)

The production optimization is evaluated on the basis of discounted revenue to be generated by the projects. The net present value (NPV) for calculating the discounted revenue is defined by
\[ NPV = NPV_R - \text{cost} \]
where, \( NPV_R \) = present value of cash flow discounted at a given rate \( i \).
If \( \Delta R_n \) is the annual incremental revenue after optimization for \( n^{th} \) year, and \( m \) is the remaining life of the project at the end of \( n^{th} \) year, then which ONE of the following options for \( NPV_R \) is CORRECT?

A production tubing string of length 1500 m is tightly held by packers to prevent any expansion in either direction. Production of hot gases from the reservoir increases the temperature of the tubing by 20 °C. The Young's modulus of elasticity of the tubing material is 3000 N/m², and the linear coefficient of thermal expansion is \(5 \times 10^{-6}\) per °C.
Assuming no radial expansion, and neglecting the weight of the gas in the tubing and its viscosity, the increase in the stress of the tubing due to temperature rise is __________ N/m² (rounded off to two decimal places).