Estimating Energy Loss through Wellhead Chokes

Abstract Chokes are control valves built into the production systems so that wells can be produced at desired rates and in the same time reservoir depletion and sweep can be optimized; and formation and well completion integrity can be protected. The use of surface chokes also allows surface flowlines and facilities to be designed more economically due to reduced pressure ratings. Substantial pressure drops can occur through well surface chokes, especially at early stages of production when the reservoir pressure is still high and lower choke settings are applied. This paper investigates energy loss through wellhead chokes for gas wells with the laws of thermodynamics. Calculation methods and applicable equations are presented. Example calculations show that energy loss can be significant as a result of choking applied to wells. This is especially true when one considers the number of wells and the total daily production that a company has. The energy waste can be potentially avoided by extracting the fluid flow energy to produce electricity. In remote areas, subsea or on offshore platforms, the generated electricity can be used to power equipment present at the wellsites such as sensors, communication devices, heaters or pumps. The electricity can also be fed into existing power grids. The potential benefit includes reduction in field energy consumption and operating costs, energy conservation and environmental protection.