Manual of Petroleum Measurement Standards Chapter 6.1

Lease Automatic Custody Transfer (LACT) Systems

SECOND EDITION, MAY 1991 ADDENDUM 1, AUGUST 2020

Special Notes

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Copyright © 1991 American Petroleum Institute

Foreword

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Contents

Page

1. Introduction 1

2. Scope 1

3. Field of Application 1

4. Referenced Publications 1

5. Requirements for All LACT Systems 2

6. Displacement and Turbine Meter LACT Systems 4

Annex A (informative) Determining Normal Operating Conditions 8

Figure

1 Typical Displacement or Turbine Meter LACT Unit Schematic Design 6

Tables

1. Additional Tolerances 8

2. Sample Data Set 10

3. Sample Data Set 12

4. Sample Data Range: Flow Rate (bbl/h) 12

5. Frequency and Cumulative Frequency: Flow Rate (bbl/h) 13

6. Sample Data Range: Pressure (psig) 14

7. Frequency and Cumulative Frequency: Pressure (psig) 15

8. Sample Data Range: Temperature (°F) 16

9. Frequency and Cumulative Frequency: Temperature (°F) 17

10. Sample Data Range: Density (°API) 18

11. Frequency and Cumulative Frequency: Density (°API) 18

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Lease Automatic Custody Transfer (LACT) Systems

Introduction

This publication has been prepared as a guide for the design, installation, calibration, and operation of a lease automatic custody transfer (LACT) system.

A LACT system is an arrangement of equipment designed for the unattended custody transfer of liquid hydrocarbons from producing leases to the transporting carrier. The system must determine net volume and quality, provide for fail-safe and tamperproof operation, and meet requirements of accuracy and dependability as agreed to by mutually concerned parties, such as the producer, the transporter, the royalty owner, and federal, state, and municipal regulatory bodies.

1. Compliance

   
   

   Compliance with the provisions of this standard may result in an approach to accuracy or may establish safeguards that are not necessary under all conditions. When not required, those portions of this standard not considered applicable may be disregarded with the mutual agreement of all parties concerned.

   
   

   The compulsory verb form “shall," while not necessarily binding for all conditions, has been used when a deviation from the standard is likely to adversely affect the satisfactory operation of a system that is designed for optimum operation under typical producing conditions.

   
   

2. Future Developments

Although this standard presents the concurrence of the industry on system requirements for lease automatic custody transfer, it is not intended in any way to restrict future developments. Equipment now exists in the design or field-proving stages that may further improve the art of lease automatic custody transfer. The industry encourages such developments, and when concerned parties mutually agree to use such systems or components, every effort should be made to expedite their use and standardization.

Scope

This publication describes the metering function of a LACT unit and is intended to complement API Specification 11N, Specification for Lease Automatic Custody Transfer (LACT) Equipment. LACT equipment includes a meter (either displacement or turbine), a proving system (either fixed or portable), devices for determining temperature and pressure and for sampling the liquid, and a means of determining nonmerchantable oil. Many of the aspects of the metering function of a LACT unit are considered at length in other parts of this manual and are referenced in 6.1.4.

Field of Application

The field of application of this publication is the unattended and automatic measurement by meter of hydrocarbon liquids produced in the field and transferred to a pipeline in either a scheduled or a nonscheduled operation.

NOTE The information contained in Chapter 6.7 should also be considered when measuring viscous fluids by meter.

Referenced Publications

Many of the aspects of the metering function are discussed at length in other parts of this manual. Please refer to the following chapters for more information.