Electronic flow measurement as applied to the natural gas industry has advanced considerably over the last 30 years. Applications to address Upstream, Midstream and Downstream gas measurement technologies have become more complex. Over time it has become necessary to understand the fundaments that make up this ever-changing environment.

This paper will discuss the important fundamental parameters to consider when designing an Electronic Flow Measurement (EFM) system. Please be aware of the many variances to each specific design and understand this is only a fundamental paper to give new gas industry members a first look at the technologies that are required when considering an EFM design.

Basic Definitions

Custody Transfer: Custody transfer gas measurement implies that a buying or selling transaction is taking place based on the flow computer calculated quantities. This normally requires high accuracy digital resolution and speed, but often custody transfer requires that the flow computer meet American Gas Association (AGA) and the American Petroleum Institute (API) standards. Since this paper is geared to the US market AGA 3, 7, 8, 9, 10 and API 21.1 offer recommendations and or standards in assisting in the design.

Upstream: This term is used commonly during the searching for, recovery of crude oil and natural gas – sometimes referred to as the exploration and production sector.

Midstream: After producing the fluid, a way to move the product to market must be implemented. Pipelines are used to transport products and this sector is referred to as the Midstream portion of the industry.

Downstream: After the gas is produced (Upstream) and transported (Midstream) then delivered to the gas distributors (Downstream), the natural gas could have been measured at least 4 times once it hits the end consumer. Downstream refers to the final delivery of the gas to businesses, industrial sites, factories, power plants, homes etc.