Automatic Evaluation of the Gas Flow Rate from Wells Using a Header-Flowline Gas Gathering System

When operating a gas well, the main issue is controlling the pressure in the well and reaching a certain operating flow rate, the so-called practical productivity of the well at which it is operated optimally. For operational control of the flow rate, one has to control the gas flow velocity through the flowline in real time. This paper proposes using an artificial pressure wave propagating in the gas flow at the speed of sound. Such a wave is generated when adding a hydrate inhibitor to the gas flow after which it propagates to both sides of the generation point. By measuring the time it takes the wave to travel a certain distance upstream and downstream, one can calculate the gas velocity. The automated system uses a two-cycle measurement. First, it finds the current baseline speed of sound in the common header, after which it finds the desired gas velocity at the wellhead where the flowline is connected to the common header. Pressure waves are registered by high-rate pressure sensors. The system uses a wireless data channel. Measurement accuracy is sufficient to find the well status and gas velocity in real time.