Jawaharlal Nehru Technological University Hyderabad
Jawaharlal Nehru Technological University Hyderabad B.Tech IV RESERVOIR STIMULATION Previous Question Paper (September - 2020 - R15)
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What is superposition principle? Write the uses of superposition principle in pressure buildup analysis.
Answer
The superposition principle states that for a linear partial differential equation, the total pressure drop at any point in a reservoir resulting from the simultaneous action of multiple wells or multiple rate changes is equal to the algebraic sum of the pressure drops caused by each individual well or rate change acting independently. Mathematically, for a well with varying flow rates, the pressure change at time t is expressed as the sum of the effects of each rate change occurring at specific times.
In pressure buildup analysis, the superposition principle is essential for the following applications:
- Accounting for Production History: It allows the conversion of a variable-rate production history into a single equivalent time, often represented as the Horner time or equivalent time, to accurately model the pressure response during the shut-in period.
- Multi-well Interference: It enables the calculation of the pressure drawdown or buildup at a specific well by accounting for the cumulative influence of neighboring producing or shut-in wells within the same reservoir.
- Boundary Effects: It is used to simulate the effects of reservoir boundaries (such as faults or sealing barriers) by using the method of images, where the boundary is represented by an imaginary well that superimposes its pressure effect on the actual well.
- Correcting for Afterflow: It helps in modeling and correcting for wellbore storage effects that occur immediately after shut-in, allowing for a more accurate determination of reservoir parameters like permeability and skin factor.
Briefly explain the properties of rock.
Answer
Rock properties are fundamental in determining the storage and flow capacity of a reservoir. Key properties include:
- Porosity: The ratio of void space to the total bulk volume of the rock, indicating the storage capacity for hydrocarbons. It is classified as primary (formed during deposition) or secondary (formed post-deposition through processes like fracturing or dissolution).
- Permeability: A measure of the rock's ability to transmit fluids through its interconnected pore network. It is governed by Darcy's Law and is influenced by pore throat size and connectivity.
- Compressibility: The change in pore volume per unit change in pressure, which is critical for calculating reservoir energy and fluid expansion.
- Wettability: The preference of a rock surface to be in contact with one fluid (oil or water) over another, which significantly impacts relative permeability and residual oil saturation.
- Mechanical Properties: Parameters such as Young's modulus and Poisson's ratio, which define how the rock responds to stress and are essential for designing stimulation treatments like hydraulic fracturing.
Write the short notes on micro hydraulic fracturing.
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How to develop a fracture propagation model and draw a diagram of different components in a fracture propagation model.
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Write the types of fracturing fluid. What are the chemicals required to design a fracturing fluid?
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Explain the characterization of proppant transport properties.
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Which type of data needed prior to the preparation of the stimulation treatment design.
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Write a short note on foam fracturing techniques.
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Discuss the seismic method after fractures or post fracture seismic measurement.
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What are the parameters affecting the acid fracturing treatment?
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