Oil pipeline being added to gas pipeline

[morongobill]

I do not work in this field just looking for information.

Questar has the Southern Trails gas pipeline in the southwest and are thinking of adding oil capability in about a 100 mile section running through the California desert. This is in the very beginnings of the regulatory approval process, in fact, no decision has been made to build it. But if it is built, there will be 2 routes considered to bypass Joshua Tree National Park.

It is my understanding that this will be a one way pipeline, bringing crude from the interior to refineries at Wilmington, and that it will be a 16 inch pipeline. I assume it will be built alongside the existing gas pipeline in their right of way.

My assumption is that there will have to be pumping stations a certain distance apart and that these will require electricity to operate.
Does that mean that large electrical infrastructure will have to be built in areas where this none existing currently? If so, what type?
What about sections that are on a long downhill grade? Perhaps gravity flow might suffice?

In a 6 mile section that I am interested in seeing stay as-is, the grade would be downhill for virtually the whole way, my guess is less than 5% average and the gas line is currently buried. Do you believe that the oil pipeline, if built, would be buried as well? There is no infrastructure there in place, i.e. pump stations for the gas line, nor are there any power lines running through the area. Would the addition of an oil component mean that said infrastructure would have to be built in place?

I have seen diagrams online that show the 16" line placed inside an insulated 20" outer pipe,is that common? I have also noticed that the heavy equipment lays the pipe from the side, how wide should the roadway be?

Let me lay my cards on the table. There is a very environmentally sensitive section that one proposed leg might have to be built in. There is existing graded dirt road with laydown areas in place for staging equipment and supplies. The direction of oil flow would be downhill, hence my questions about pumping stations and electrical equipment needs such as power lines and transformer stations.

My sense is that if this project will require added infrastructure to where there is now only a buried gas line and a dirt road, or if the pipeline is built above ground, it will be overwhelmingly opposed by the people of the area as well as environmental groups. If not, it still may be. So I am hoping that some here might know the answer to my questions or if I am at the wrong forum, can direct me to other ones.

 

[BigInch]

Probably pump stations at 50 -70 mile intervals should be considered, but that depends on operating pressure, diameter and flowrates. Pressure in oil pipelines builds quickly with a decrease in elevation and drops fast with increasing elevation, so if there is a large elevation difference between high and low points along the section, maximum pressures of oil pipelines may face limitations much lower than have been allowed in the gas pipeline. In either case, pump stations may need to be placed closer together, or near the elevation increase, possibly using lower maximum discharge pressure limits.

The pipeline will be buried.

Rather than bring in HV electrical line power, crude burning diesel, or gas purchased from the nearby gas pipeline can be used to fire internal combustion engine driven pumps and electrical generators might be considered to supply electrical power for operating the station. Gas driven generators might also power the station and even provide power for electrical motor driven pumps. Depending on size of the engines & generators, it may fall under the air pollution reporting limits, or maybe not. I'd guess it would.

Normally insulation on buried pipelines will not be required. The surrounding soil is a good insulator in most all cases. If the oil is very heavy and requires heating, or the pipeline is not buried, or not buried in the mud under water, that can be another story.

The temporary width of the pipeline right of way during construction would probably be around 75 feet wide. The permanent right of way could be less, say 20 to 30 feet.

The Pipelines, Piping and Fluid Mechanics Forum is normally where these questions are discussed, but I got you covered. Stay here if you like. Most pipeliners cruise this forum too.

Independent events are seldomly independent.

 

[LittleInch]

I would eco and confirm all BigInch says. For this distance they may not need to be any more than one pump station at the beginning, but is very dependent on the profile of the pipe looking at elevation of the ground all the way along the pipeline. It is very unlikely that the design would include any facilities within an environmentally sensitive region and often reduced working area or special re instatement activities are used to replace the ground in the same way as it was before.

If you could scan a copy of the section you refer to that would help us explain it a it could be a casing used sometimes under road or railroad crossings or be something else.

Pipeline will be buried with a cover over the top of the pipe of at least 3 feet.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[morongobill]

Thanks for the informative responses guys. I hiked through the area in question yesterday and found(which I am going to verify)out that , for sure, the Questar Southern Trails pipeline goes through the area, as well as SOCALGAS and there are signs that also say petroleum pipeline, do not excavate. I pretty much have a good idea of the route so things are a lot clearer now. Thanks again.

 

[BigInch]

Take water with you. It looks hot out there.

Independent events are seldomly independent.