Combination of Dual-Energy Gamma Ray/Venturi Multiphase Flowmeter and Phase Splitter for Application in Very High Gas Volume Fraction Environment

摘要

In mature fields, operators are confronted with wells producing high water cut at low pressure with consequently very high gas volume fraction (GVF). Under these conditions, the net oil flow rate is low and therefore, permanent or periodic testing becomes critical to determine profitability and manage the field production. To optimize and monitor the oil production under these conditions, operators are looking to utilize multiphase flowmetering technologies. Accuracies achievable by inline multiphase flowmeters have greatly improved in recent years, but liquid and water-cut measurement accuracies decrease when the GVF is very high. At low pressure to reduce the GVF, it is necessary to separate a large portion of the gas upstream of the multiphase flowmeter, thus enabling optimum measurement of the liquid and water cut under lower-GVF conditions. Market drivers generally dictated by operator requirements have resulted in the formation of an project team with specific Middle East focus to deliver an operational prototype for a production well testing campaign on a fast track basis. The package comprises a partial separation unit and a dual-energy gamma ray/Venturi meter. The selection of a partial separation design was based on a review of the commercially available solutions capable of handling the large operating range required for use in periodic well testing applications in terms of flow rates and pressure rating. The design comprises gas liquid cylindrical cyclone with tangential inlet. The capacity of each device to ensure a dry gas phase with minimum pressure loss over the complete required operating range was critical in the selection process. This paper presents test results validating that a gas liquid cylindrical cyclone located upstream of a dual-energy gamma ray/Venturi meter is an effective partial separation system. With an inlet GVF of 99% and 90% of the inlet gas extracted by the partial separation system, the GVF at the multiphase flowmeter condition is below 90%, and accurate measurement of the 3 phases is achieved.