Petroleum Engineering Mock Interview Questions & Practice

What is the significance of mud viscosity in drilling fluid performance, and what does it primarily affect?

Key points to cover:

• A measure of the fluid's resistance to flow
• Primarily affects the fluid's ability to carry cuttings out (hole cleaning)
• And the pressure losses during circulation

What is the derrick (or mast) on a drilling rig, and what is its basic function?

Key points to cover:

• The tall structural tower above the wellbore
• Supports the hoisting system
• Used to raise and lower drill pipe and equipment

What is the difference between a roller cone (tricone) drill bit and a fixed cutter (PDC) drill bit?

Key points to cover:

• Roller cone: rotating conical elements that crush/gouge rock
• PDC: no moving parts, shears rock with fixed diamond cutters
• As the whole bit rotates

What is the difference between primary porosity and secondary porosity in reservoir rock?

Key points to cover:

• Primary: original pore space formed during rock deposition
• Secondary: develops later through fracturing, dissolution
• Or dolomitization after the rock has already formed

What is gas cap drive, and how does it differ from solution gas drive?

Key points to cover:

• An existing free gas cap above the oil zone expands
• As reservoir pressure declines, pushing oil toward the wellbore
• Differs since the gas cap exists as a separate phase before production

What is the volumetric method of estimating original oil in place, and what basic reservoir parameters does it require?

Key points to cover:

• Calculates OOIP directly from rock and fluid properties
• Requires reservoir volume, porosity, fluid saturation
• And formation volume factor

What is the difference between an open hole completion and a cased hole completion?

Key points to cover:

• Open hole: producing section left without casing/cement
• Exposed directly to the wellbore
• Cased hole: casing/cement run through, then perforated selectively

What is an electric submersible pump (ESP), and what is its basic operating principle?

Key points to cover:

• A downhole, electrically powered centrifugal pump system
• Multiple pump stages driven by an electric motor
• Generally suited for high-volume production

What is a pressure buildup test, and what basic information can it provide about a reservoir?

Key points to cover:

• Shutting in a previously producing well
• And monitoring the resulting pressure increase over time
• Provides permeability, near-wellbore damage (skin), and boundaries

What is hydrostatic pressure, and how does it vary with depth in a fluid?

Key points to cover:

• Pressure exerted by a fluid at rest due to the weight of fluid above
• Increases linearly with depth
• Proportional to fluid density, gravitational acceleration, and depth

What is the Reynolds number, and what does it indicate about a flow?

Key points to cover:

• A dimensionless ratio of inertial forces to viscous forces
• Used to predict whether a flow will be laminar or turbulent
• With a critical value marking the transition

What is cavitation in a centrifugal pump, and what conditions promote it?

Key points to cover:

• Local pressure inside the pump drops below the fluid's vapor pressure
• Vapor bubbles form and then collapse violently
• Promoted by insufficient suction head or excessive pump speed

What is the Second Law of Thermodynamics, and why is it important in evaluating chemical process feasibility?

Key points to cover:

• Entropy of an isolated system never decreases
• Heat doesn't spontaneously flow from cold to hot
• Determines maximum theoretical efficiency and constrains spontaneous processes

What is relative volatility, and what does it indicate about the ease of separating two components by distillation?

Key points to cover:

• The ratio of the vapor-liquid equilibrium ratios (K-values) of two components
• Higher relative volatility indicates easier separation by distillation
• A value close to 1 indicates the components are difficult to separate

How does temperature affect the equilibrium constant of a reaction, and what determines the direction of the effect?

Key points to cover:

• Depends on whether the reaction is exothermic or endothermic
• Exothermic: increasing temperature shifts equilibrium toward reactants
• Endothermic: increasing temperature shifts equilibrium toward products