Page 305 - Introduction to Petroleum Engineering

294 MIDSTREAM AND DOWNSTREAM OPERATIONS
gas is the amount of gas that can be withdrawn from the storage facility for use. In
some cases, gas may need to be parked, that is, stored temporarily. Parking may be
used by a customer until a better price can be obtained for the customer’s gas.
Demand for gas is seasonal, which is another reason to store gas temporarily until
demand increases.

15.2 THE DOWNSTREAM SECTOR: REFINERIES

The downstream sector is closest to the consumer and encompasses natural gas
processing, oil refining, and distribution of products. Processing begins at the well
site where the produced wellstream is separated into oil, water, and gas phases.
Further processing at natural gas plants and oil refineries such as the refinery shown
in Figure 15.3 separates the hydrocarbon fluid into marketable products.
Products associated with refining and processing are shown in Table 15.1. An oil
refinery converts a typical barrel of crude oil into gasoline, diesel, jet fuel, liquefied
petroleum gas (LPG), heavy fuel oil, and other products. A natural gas processing
plant purifies natural gas and converts it into products such as LPG, liquefied natural
gas (LNG), and fuel gas for residential, commercial, and industrial use. The opera-
tion of refineries is discussed in this section, and natural gas processing plants are
discussed in the next section.

FIguRE 15.3 South Texas refinery. (Source: © energy.fanchi.com (2002).)