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

Pipeline modeling models the entire pipeline system to account for 
pressure, temperature and flow at major checkpoints. Based on this model 
the management system can perform: 
•  Pressure balancing to make certain that pressure setpoints are correct to 
meet demand forecasts and avoid potential overload conditions. 

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•  Production allocation, which ensures that producers are able to deliver 
their contractual volumes into the network. 
•  Leak detection, which compares actual measured data against dynamic 
data predicted by the model. A discrepancy indicates a leak (or a failing 
measurement). Simple liquid systems only calculate basic mass balance 
(in-out), while an advanced modeling system can give more precise data 
on size and position of the leak within a certain response time. 
•  Pig or scraper tracking is used to track the position of the pig within the 
pipeline, both from pig detection instruments and the pressure drop 
caused by the pig in the pipeline. 
In case of liquid pipelines transporting batches of different products, a batch 
transfer system is needed. Based on information on when each product is 
injected into the pipeline, and gravity measurement at the receiving end, it is 
possible to sequentially transfer different products, such as gasoline and 
diesel in the same pipeline. Depending on product characteristics, there will 
be an interface section between the two products that widens as the product 
moves along the line. This “off spec” product must be discarded at the 
receiving end to avoid product degradation. It is often disposed by mixing 
with larger volumes of low grade fuel products. This system is often used 
with countrywide refined product distribution to terminals. 
Safety systems are used, as for other process plants, to ensure that the 
systems shut down in case of malfunctions and out-of-bounds conditions. Of