Adjustable Cone Meter Adapts Automatically to Wet-Gas Conditions

Abstract

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 207505, “Using an Adjustable Cone Meter To Measure Wet Gas,” by Sakethraman Mahalingam, SPE, Saudi Aramco; Gavin Munro, SPE, GM Flow Measurement; and Muhammad Arsalan, SPE, Saudi Aramco, et al. The paper has not been peer reviewed. _ A traditional fixed-size Venturi meter has a turndown of approximately 8:1 under dry-gas conditions that may drop to as low as 3:1 under wet-gas flow. When the well conditions change, a replacement of the original Venturi meter with one of a different size is needed. In the complete paper, the authors present the design, development, and testing of an adjustable cone meter that has the ability to adapt itself to flow conditions automatically and provide a turndown of as much as a 54:1 under dry-gas conditions and as much as 20:1 under wet-gas conditions. Adjustable Cone Meter Design The adjustable cone meter is a variation on a traditional differential pressure cone meter. A moveable sleeve is placed within the meter, and its position is moved using a rack-and-pinion arrangement. When the flow rate is high (Fig. 1a), the sleeve is downstream of the cone and the meter operates like a normal cone meter. This means that the differential pressure at the cone (P1–P2) is sufficiently high and within the measurable range of the meter. When the flow rate drops below a preset value, however, the differential pressure (P1–P2) drops below the measurable range of the meter. While a conventional cone meter would be unable to measure such flow rates, the adjustable cone meter is able to achieve accurate measurements because the meter detects that the differential pressure is below the measurable range and moves the sleeve automatically so that it covers the cone (Fig. 1b). This reduces the internal diameter of the flowline around the cone and causes the differential pressure to move into the measurable range. The meter then uses the differential pressure to again produce accurate flow measurements. In addition, the meter has a second differential pressure sensor downstream of the cone. This is used to measure the liquid fraction of the wet gas. Meter Design Exhaustive finite-element analysis (FEA) was conducted to determine the operating stresses within the meter body and its pressure-containing components during operation. The sliding sleeve can maintain full line pressure and features double-pressure seals at either end, safely containing fluids inside the flowline. The primary risk is the deformation and failure of the sliding sleeve because it is a thin metal structure. However, FEA established the minimum working pressure of at least 1,200 psi for the sleeve, gearbox, and meter body, using industry-standard safety factors. Cone meter calculations are provided in the complete paper.