NATURAL GAS FROM CRADLE TO ENERGY

The entire fractionation process is broken down into steps, starting with the removal of the lighter NLG’s from the stream in the following order:

· De-ethanizer - this step separates the ethane from the NGL stream.

· De-propanizer - the next step separates the propane.

· Debutanizer - this step boils off the butanes, leaving the pentanes and heavier hydrocarbons in the NGL stream.

· Butane Splitter or Deisobutanizer - this step separates the iso and normal butanes.

Sulphur and Carbon Dioxide Removal:- In addition to water, oil, and NGL removal, one of the most important parts of gas processing involves the removal of sulphur and carbon dioxide. Natural gas from some wells contains significant amounts of sulphur and carbon dioxide. This natural gas, because of the rotten smell provided by its sulphur content, is commonly called ‘sour gas’. Sour gas is undesirable because the Sulphur compounds it contains can be extremely harmful, even lethal, to breathe. Sour gas can also be extremely corrosive. In addition, the sulphur that exists in the natural gas stream can be extracted and marketed on its own.

NATURAL GAS TRANSPORTATION

The efficient and effective movement of natural gas from producing regions to consumption regions requires an extensive and elaborate transportation system. In many instances, natural gas produced from a particular well will have to travel a great distance to reach its point of use. The transportation system for natural gas consists of a complex network of pipelines, designed to quickly and efficiently transport the gas from its origin, to its destination.

There are essentially three major types of pipelines along the transportation route: the gathering system, the
interstate pipeline, and the distribution system. Pipelines can be characterized as interstate or intrastate. Interstate pipelines carry natural gas across state boundaries, in some cases clear across the country. Intrastate pipelines, on the other hand, transport natural gas within a particular region. To ensure that the natural gas flowing through any one pipeline remains pressurized, compression of this natural gas is required periodically along the pipe. This is accomplished by compressor stations, usually placed at 40 to 100 mile intervals along the pipeline.

In addition to compressing natural gas to reduce its volume and push it through the pipe, metering stations are placed periodically along interstate natural gas pipelines. These stations allow pipeline companies to monitor and manage the natural gas movement. Essentially, these metering stations measure the flow of gas along the pipeline, and allow pipeline companies to ‘track’ gas as it flows along the pipeline. These metering stations employ specialized meters to measure the natural gas as it flows through the pipeline, without impeding its movement.

Natural gas pipeline companies have customers on both ends of the pipeline - the producers and processors that input gas into the pipeline, and the consumers and local distribution companies that take gas out of the pipeline. In order to manage the gas that enters the pipeline, and to ensure that all customers receive timely delivery of their portion of this gas, sophisticated control systems are required to monitor the gas as it travels through all sections of what could be a very lengthy pipeline network.

To accomplish this task of monitoring and controlling the gas that is traveling through the pipeline, a control station is provided by Supervisory Control and Data Acquisition (SCADA) systems. These systems are essentially sophisticated communications systems that take measurements and collect data along the pipeline (usually in a metering or compressor stations and valves) and transmit them to the centralized control station. Flow rate through the pipeline, operational status, pressure, and temperature readings may all be used to assess the status of the pipeline at any one time.

These systems also work in real-time, meaning that there is little lag time between the measurements taken along the pipeline and their transmission to the control station. As natural gas use increases, so does the need to have transportation infrastructure in place to supply the increased demand. This means that pipeline companies are constantly assessing the flow of natural gas across regions, and building pipelines to allow transportation of natural gas to those areas that are underserved.

Constructing natural gas pipelines requires a great deal of planning and preparation. Installing a pipeline is much like an assembly line process, with sections of the pipeline being completed in stages.

First, the pipeline right of way is cleared; sections of pipes are laid out along the intended path, a process called ‘stringing’ the pipe.

 To be continued on the next edition