Ultrasonic Flow Metering Device and Field Trial Success at Sour Gas Field Development

Abstract

Gas production rate measurement is one of the key tasks in any gas field development, particularly when the field is just put on production. It aims to develop a baseline for sustaining production, managing reservoir depletion, extending plateau production, and accounting/reporting purpose. For a sour gas field development, when the conventional devices such as the target flow meters are installed downstream the wellhead, they are exposed to “debris” such as precipitated elemental sulfur, MEG, corrosion inhibitor, formation solids, water, etc. Any debris in the gas flow, particularly in high gas rate wells, can hit the sensor and cause either temporary or permanent damage. As a result, it has led to a less reliable or inaccurate reading. Abnormal reading may eventually lead to a poor production optimization action/decision. This paper is to present the practical data for several different measuring devices used, and more importantly, the recent field trial of the new measurement technology (i.e., ultrasonic flow meter). With a proper installation and calibration, ultrasonic flow meters have proven a reliable reading device compared to that of the conventional ones. It is even more impressed when the liquid phase is removed, and the reading error is less than 1%. For multiple-phase production stream, the error is consistently ~10%, which can be further improved by calibration with routine well tests. Besides of good accuracy, ultrasonic flow meter shows several advantages. It is safe to be used in the sour gas field development since there is no direct exposure with sour gas and thus, no need to open the production system/pipeline during installation, measurement, and maintenance. Maintenance is also simpler that there is no need to perform any isolation and/or conduct a routine purge job on pipeline.