A better focus

Jan. 12, 2009
It’s sad that the oil industry is still approaching the new government with a focus on producing more barrels per day.

It’s sad that the oil industry is still approaching the new government with a focus on producing more barrels per day. That focus will fall on deaf ears.

If instead the oil industry approached the government with how many new jobs it is going to create (by producing more barrels), how many billions of dollars of gross domestic product it is going to generate by increasing domestic production while reducing the level of oil imports (a GDP multiplier effect), and how many more billions of dollars it is going to pay into desperate federal, state, and local tax coffers, our industry would be received at the front of the Obama line, rather than at the end of the line.

Tony Pavone
Menlo Park, Calif.

MEG injection rate

The article “New method yields MEG injection rate” by M. Moshfeghian and R. Taraf (OGJ, Sept. 1, 2008, p. 44), fails to consider two points:

1. In Fig. 2, the MEG rate is difficult to read at low concentrations of MEG in rich solution (x axis). This difficulty makes this graphical method useless for low concentrations of MEG of less than 40%. Injection of MEG for more than 40% needs serious economical evaluation because MEG is more expensive than methanol.

2. These days, software is commercially available; this graphical method is not efficient. Also, users cannot use this graphical method in their programming, optimization, and modeling.

Alireza Bahadori
Curtin University of Technology
Perth, Australia

Authors’ response

1. We agree that with less than 40 wt % MEG in the rich solution, it is difficult to read the required circulation rate in Fig. 2. The question is who needs a reading at less than 40 wt % MEG in rich solution?

For safe operation in most hydrocarbon dewpointing plants (operating at about -10° C. or lower), the lean MEG is around 80 wt % and the rule of thumb is 5-10 % dilution. This means that the rich solution concentration is 70-75 wt %.

The plants normally operate so that the MEG concentration in rich solution stays in the range of 40-80 wt %. Otherwise, the glycols become mushy and difficult to circulate or may even freeze.

2. Our objective in developing these diagrams was not to have them programmed. There are already several computer programs available, as our article mentions. On other hand, the objective was to avoid using computer programs and be able quickly to determine the MEG circulation rate. In addition, graphical presentation aids visual understanding of physical phenomena.

Mahmood Moshfeghian
John M. Campbell & Co.
Norman, Okla.

Roohallah Taraf
Pars Oil & Gas Co.