Oil and gas production handbook An introduction to oil and gas production

Particles and other substances must be free of particulate solids and all 
liquids to prevent erosion, corrosion or other damage to the pipeline and 
satisfy limits on carbon dioxide, nitrogen, mercaptans, etc. 
 
Additives: When the natural gas is intended for domestic use, 
tetrahydrothiophene (THT) is added so that the otherwise odorless natural 
gas can be detected in the event of a gas leak. The sulfurous-smelling 
substance added is equal to a sulfur content of 4-7 mg per scm. 
 

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5.4 Pipelines 
Pipeline installations consist of driving compressors and pumps, valve 
stations, pig receive/launch facilities, where the pig is used for cleaning or 
inspecting the pipeline. A pipeline SCADA system and pipeline management 
system is required to control and operate the pipeline. 
5.4.1 Pipeline terminal 
Pipelines transport gas or 
liquid, and are fed from the 
high pressure compressors or 
pumps. 
 
The pipeline terminal includes 
termination systems for the 
pipeline. A pig launcher and 
receiver is a minimum 
requirement, allowing insertion 
of a pipeline pigging device 
used to clean or inspect the 
pipeline on the inside. Essentially, it is a large chamber that can be 
pressurized and purged to insert and remove the pig or scraper without 
depressurizing the pipeline. 
 
The pig is often driven by pipeline flow, either directly or through a pump or 
turbine arrangement that also drives wheels that roll against the walls and 
mechanisms to rotate brushes and other scraping mechanisms. Intelligent 
pigs also contain instrumentation for remote control and cameras, etc. 
 
5.4.2 Gas Pipelines, compressor and valve stations 
One or more compressor stations are needed to keep the required gas flow 
in the pipeline. Internal friction will cause a pressure drop along the pipeline 
that increases with flow. Thus, the starting pressure must be high enough to 
maintain design capacity flow up to the final terminal. If this is not practically 
possible, additional compressor stations are needed along the total length. 
Typical starting pressure is about 150-250 bar (15-25 MPa).  The final 
pressure can be as low as 50 bar (5 MPa) at the pipeline terminal end.  
 
The compressors are driven in the same way as explained in the 
compressor chapter under production (see Chapter 4.3.3). 
 

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As an example, about 150 MW in compressor power is required to transport 
70 mill scm/day though the 1166 km Langeled pipeline with a starting 
pressure of 250 Ormen Lange Nyhamna. The initial section is 42 in, which 
increases to 44 in at Sleipner, a little more than halfway (627 km from 
Nyhamna, 540 km from Easington, UK), where the intermediate pressure is 
155 bar maximum.  
 
The 1200 km Northstream pipeline from Russia (Portovaya, Vyborg) to 
Germany (by Hannover), has two parallel pipes of almost the same 
dimensions, pressure and compression power each as Langeled.