JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech IV SURFACE PRODUCTION OPERATIONS Previous Question Paper (March - 2021 - R16)

A flow control valve is a mechanical device used in surface production operations to regulate the rate of fluid flow from a wellhead to the production manifold or separator. It functions by creating a variable restriction in the flow path, which generates a pressure drop across the valve, thereby controlling the downstream flow rate.

The operation involves the following key components and mechanisms:

• Actuator: The valve is typically operated by a pneumatic, hydraulic, or electric actuator that receives a signal from a controller to adjust the valve position.
• Trim: The internal trim, consisting of a plug and seat, determines the flow characteristics. As the actuator moves the stem, the clearance between the plug and seat changes, modifying the flow area.
• Feedback Loop: In automated systems, a flow meter downstream sends a signal to a process controller. The controller compares the actual flow rate to the setpoint and adjusts the valve opening to maintain the desired flow rate.
• Choke Effect: By adjusting the orifice size, the valve manages the backpressure on the reservoir, which is critical for maintaining optimal production rates and preventing sand production or water coning.

Oil treating is the process of separating produced well fluids into oil, water, and gas, and removing impurities to meet pipeline or refinery specifications. The primary objective is to reduce the basic sediment and water (BS&W) content in the crude oil to acceptable levels (typically below 0.5% to 1%).

The process involves several stages:

• Separation: Initial separation of free water and gas occurs in separators or free water knockouts (FWKO).
• Emulsion Breaking: Crude oil often contains stable emulsions of water droplets. Treating involves applying heat, chemical demulsifiers, or electrostatic fields to coalesce these droplets, allowing them to settle out by gravity.
• Heating: Heaters reduce the viscosity of the oil, which increases the settling velocity of water droplets according to Stokes' Law.

Storage serves as the final buffer before the oil is transported via pipeline or truck. Storage tanks must be designed to:

• Provide sufficient residence time for final gravity separation of residual water.
• Maintain stable pressure to minimize evaporation losses of light hydrocarbons.
• Include safety systems such as pressure-vacuum relief valves and flame arrestors.
• Facilitate accurate measurement and sampling for custody transfer.