Page 408 - Compression Machinery for Oil and Gas

Chapter 9

Midstream

†
Benjamin White*, Terry Kreuz and Sarah Simons*
* †
Southwest Research Institute, San Antonio, TX, United States, National Fuel Gas, Williamsville,
NY, United States

Midstream Activities

The midstream component of the oil and gas industry covers the transportation
of gas from the upstream processing plant or production site to the downstream
refinery or end user. The transport of gas is most economically, safely, and reli-
ably done through a vast network of pipelines; the network of pipelines in the
United States is shown in Fig. 9.1 with over 210 pipeline systems and
300,000miles of interstate and intrastate pipelines [1]. The pipelines are mostly
buried at least 30in. below the ground surface and are composed of carbon steel
manufactured according to specifications in the American Petroleum Institute
(API) and American Society of Mechanical Engineers (ASME) standards. Pipe-
lines are typically located in right-of-way (ROW) areas, along with other util-
ities, which allow for access for inspection, maintenance, and to restrict certain
activities near the pipeline. For many decades, natural gas was primarily trans-
ported from production sites near the gulf coast up to population centers in the
Northeastern United States. However, in recent years, many pipelines have
reversed their flow directions due to new shale gas production.
There are three types of pipelines in midstream operation as classified by the
US Department of Transportation (DOT): gas gathering or feeder lines, gas
transmission, and gas distribution. Gathering lines are 10–30cm (4–12in.) in
diameter and transport natural gas from processing facilities to transmission
pipelines. Transmission pipelines range from 10cm to over a meter (4–48in.)
and transport natural gas to long distances: intrastate, interstate, and internation-
ally. Transmission lines are composed of main trunk lines, often interstate, that
range from 16 to 48in. in diameter in combination with lateral lines that branch
off the trunk line which range from 6 to 16in. in diameter. Distribution pipelines
distribute natural gas to homes and businesses and are typically smaller than
15cm (6in.). Pipe size selection is based on a compromise between the

Compression Machinery for Oil and Gas. https://doi.org/10.1016/B978-0-12-814683-5.00009-2
© 2019 Elsevier Inc. All rights reserved. 387