Multiphase Flow Measurements Sensitivity Assessment and Management - A Cost Effective Methodology for Surveillance Engineers and Field Operators

Since the mid-1990s, Multiphase Flow Meters (MPFM) has evolved from a revolutionary new technology into a consolidated solution widely adopted by all the major operators worldwide. This evolution has taken place mainly due to the need for high quality measurements at low operational cost and the capability of enabling remote monitoring with ease. More than 80 MPFMs have been installed in Saudi Aramco's offshore Safaniyah field offshore Saudi Aramco. The utilization of MPFM technology goes back to 2003 thus enabling Saudi Aramco to gather the reliable production data from the field and significant knowledge of operating such equipment1. MPFMs like other devices in the field are prone to failure and therefore are subjected to regular checkups and routine maintenance. Not only the physical equipment but also the data provided by MPFM must be quality checked and calibrated periodically as part of building sound Intelligent Field Infrastructure (IFI). Therefore, to ensure a continuous flow of valid production data from the field to the desktop, several measures of data QA/QC are implemented and will be presented in this paper. One of these measures was the establishment of a service contract with one of the major MPFM suppliers to service and maintain the integrity of the MPFM software and hardware. The objective of this case study was, therefore, to analyze the main issues related to both data quality and physical checks faced by Saudi Aramco and the service company during the last nine years of MPFM operations in the Safaniyah field. Also to share experiences and lessons learned over such an extended period of time of working with MPFM, especially in an offshore environment dealing with various operating conditions, flow regimes and an artificial lift. In this paper, the effect of field PVT variation over time on MPFM will also be discussed.

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In-Line Measurement of H2S Content in Flow with a Multiphase Flow Meter - Case Study in a Giant Field under Sour Gas Re-Injection

Lindsell¹,

Wang²,

Clarke³

et al. 2015

Day 1 Mon, November 09, 2015

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A new approach in advanced multiphase metering methodology designed for use in sour fields, quantifying H2S content in flow and properly accounting for it in the different phase rate measurements is presented. Flow metering in sour fields is challenging due to the need for containment of produced fluids and the effect of fluid properties in the interpretation of the measurements. The addition of H2S measurement provides additional information for production and reservoir monitoring and also yields improvements in flow metering, accounting for variations in fluid properties used for multi-phase calculation. Multiphase Flow Meters (MPFM) utilizing multi-energy gamma-ray fraction measurements are based on the ability of oil, gas, and water to absorb gamma rays of two different wavelengths. Adding an extra measurement at a third level of energy and leveraging the large contrast between the attenuation of sulfur and that of hydrocarbon and water components makes it possible to determine the mass fraction of H2S as an additional output. This technique was applied in Tengiz field, Kazakhstan, characterized by a high H2S content. In order to maintain reservoir pressure, improve recovery and utilize produced associated gas, a sour gas miscible flood pilot was started in 2007. The monitoring of compositional variation in producers is critical in the understanding of solvent (sour gas) distribution and thus in managing production-injection patterns to optimize plant throughput. Early field trials of the method were made comparing metered H2S content with surface PVT samples, confirming the accuracy of the methodology. The technology was then implemented systematically but strategically across the field. The in-line H2S measurement with automatic updates for variation in fluid properties was applied in two distinct areas: within the sour gas injection pilot area, where solvent levels vary, and outside the area where hydrocarbon composition is known to be homogeneous and constant. Long and short term tests with multi-rate well tests were conducted. Full datasets were collected from the MPFM to evaluate measurement stability and representativity under different flowing conditions and compared to results obtained without accounting for compositional changes. The results show a stable, accurate and continuous measurement of H2S content in produced fluid and an enhanced measurements of water, oil and gas rates comparable with PVT results. The in-line H2S measurement based on multi-energy gamma ray measurements is the only continuous H2S measurement technology available in multiphase flow conditions. It can be retrofitted to existing MPFMs, allowing to get additional parameter and enhanced stability of flow rate measurements where properties of produced fluid vary continuously. This paper will begin with a presentation of the theory, formulation and validation of the in-line H2S measurement and then go on to present a case history of the application in the Tengiz field, Kazakhstan for Tengizchevroil (TCO).

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Multiphase Flow Measurements Sensitivity Assessment and Management - A Cost Effective Methodology for Surveillance Engineers and Field Operators

Cited by 3 publications

References 15 publications

Predicting Oil Flow Rate due to Multiphase Flow Meter by Using an Artificial Neural Network

Predicting Oil Flow Rate due to Multiphase Flow Meter by Using an Artificial Neural Network

Evaluation and Quality Checks to Ensure Reliability and Sustainability of Safaniyah Multiphase Flow Meters (MPFMs)

In-Line Measurement of H2S Content in Flow with a Multiphase Flow Meter - Case Study in a Giant Field under Sour Gas Re-Injection

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