Manual of Petroleum Measurement Standards Chapter 20.2

Production Allocation Measurement Using Single-phase Devices

FIRST EDITION, NOVEMBER 2016

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Foreword

This edition of API Manual of Petroleum Measurement Standards (MPMS) Chapter 20.2 supersedes the below-listed sections of API MPMS Chapter 20.1, Allocation Measurement, First Edition, 1993:

• Section 1.5 Liquid Quantity Measurement (subsections not superseded by MPMS Chapter 20.2 include 1.5.2.4 Tanks and 1.5.2.5.2 Indirect Mass Measurement);

  
  

• Section 1.7.2.2.3 Flow Meters;

  
  

• Section 1.8 Liquid Proving and Calibration Techniques;

  
  

• Section 1.10 Gas Quantity Measurement;

  
  

• Section 1.11.4 Meter Calibration;

  
  

• Section 1.14 Gas Calibration and Proving Techniques.

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Contents

1. Scope 1

2. Normative References 1

3. Terms, Definitions, Acronyms, and Abbreviations 2

   1. Terms and Definitions 2

   2. Acronyms and Abbreviations 4

4. Overview 4

   1. Production Processes 4

   2. Single-phase Meters Used for Production Allocation Measurement 5

   3. Capability and Uncertainty 7

5. General Metering 8

6. Liquid Metering 10

   1. Common Liquid Meters 10

   2. Factors Affecting Liquid Allocation Meter Performance 10

   3. Liquid Flow Meter Installation Considerations 13

   4. Liquid Flow Meter Assembly Considerations 15

   5. Proving of Hydrocarbon Liquid Allocation Meters 16

7. Gas Metering 18

   1. Common Gas Meters 18

   2. Factors Affecting Gas Allocation Meter Performance 19

   3. Gas Flow Meter Installation Considerations 21

   4. Gas Flow Meter Assembly Considerations 21

   5. Gas Meter Calibration and Verification Techniques 23

Annex A (informative) Measurement Process Flow Diagram 25

Annex B (normative) Proving Procedures for Separator-based Liquid Metering 26

Annex C (normative) Calibration Procedures for Chart Recorders 30

Annex D (informative) Uncertainty of Meter Proving Results 31

Bibliography 33

Figure

A.1 Example MPFD 25

Tables

B.1 Mean Average K-factor Example 26

D.1 Equivalent Repeatability 32

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Introduction

This standard covers the application of production allocation (determination of flow quantities and rates of oil, gas, water, and other constituents) using single-phase measurement devices in combination with a two- or three-phase production separator.

When fluid flow from different wells’ production streams are commingled into a single processing facility or flow line, it is preferred to measure the flow from each production stream separately, either continuously or on a specified interval, before it enters the common processing facility or flow line. Periodic measurement at a specified interval is the common practice since continuous measurement of an individual well production stream is normally not an available option.

On a production facility, it is common to have multiple production separators continuously measuring multiple combined production streams. Normally, these production separators (bulk separators) are dedicated to the same production streams.

The measurement of these well production streams (both combined and individual) is used in the process of allocating the facility production quantities (gas, oil, and water) back to the producing wells.

The traditional method of measuring multiphase flow has been to separate the flow into multiple single-phase streams (two- or three-phase separation). Single-phase flow meters are then applied to measure the flow of these separated streams.

Factors that can impact measurement include, but are not limited to, the following:

• varying fluid properties,

  
  

• varying operating conditions,

  
  

• varying flow rates,

  
  

• well flow dynamics,

  
  

• varying flow line lengths,

  
  

• separator and process design,

  
  

• piping configuration.

Measurement error, due to these characteristics, can result in inaccurate measurement of production streams and can cause inequitable allocation of the commingled streams.

This document provides guidance with respect to the major factors that could contribute to measurement uncertainty for single-phase devices used in production allocation. It is not intended to prescribe a particular meter type or allocation method. Allocation methodologies are addressed in API MPMS Chapter 20.1.

Production Allocation Measurement Using Single-phase Devices

1. Scope

   
   

   This standard is applicable to single-phase measurement techniques upstream of the custody transfer points where custody transfer conditions are not possible. The standard presents single-phase flow measurement used in the allocation process and located downstream of the first stage of separation on a production facility.

   
   

   This standard addresses common allocation single-phase flow measurement devices for liquid hydrocarbons, water, and gas including ancillary flow measurement systems such as fuel, flare, and recirculation.

   
   

   This standard discusses configuration and operation of flow measurement equipment, fluid properties, production processing, associated flow conditions, and their effects on the quality of the flow measurement results. This standard discusses the possible impacts on these devices during inefficient and/or ineffective separation.

   
   

2. Normative References

The following documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

API Manual of Petroleum Measurement Standards (MPMS) Chapter 4 (all sections), Proving Systems

API MPMS Chapter 4.5, Master Meter Provers

API MPMS Chapter 5.2-2005, Measurement of Liquid Hydrocarbons by Displacement Meters

API MPMS Chapter 5.3-2005 (including Addendum 1-2009), Measurement of Liquid Hydrocarbons by Turbine Meters

API MPMS Chapter 5.6-2002, Measurement of Liquid Hydrocarbons by Coriolis Meters API MPMS Chapter 7-2001 (including Addendum 1-2011), Temperature Determination API MPMS Chapter 11 (all parts), Physical Properties Data

API MPMS Chapter 12.2 (all parts), Calculation of Petroleum Quantities Using Dynamic Measurement Methods and Volumetric Correction Factors

API MPMS Chapter 12.2.3-1998, Calculation of Petroleum Quantities Using Dynamic Measurement Methods and Volumetric Corrections Factors, Part 3—Proving Reports

API MPMS Chapter 13.2-1994, Methods of Evaluating Meter Proving Data

API MPMS Chapter 14.2/AGA Report No. 8 1, Compressibility Factors of Natural Gas and Other Related Hydrocarbon Gases

API MPMS Chapter 14.3 (all parts), Concentric Square-edged Orifice Meters API MPMS Chapter 14.9, Measurement of Natural Gas by Coriolis Meter API MPMS Chapter 20.1, Allocation Measurement

1 American Gas Association, 400 N. Capitol St., NW, Suite 450, Washington, DC 20001, www.aga.org.

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