|photo credit: nestor galina|
On my recent post “Au reservoir: A Guide to New Oil Discoveries,” Zh asked “Very interesting. Thank you. An appropriate follow up would be to explain how the oil flows from the reservoir, up the borehole and into the pipeline.”
That is a very good idea, thanks.
In some reservoirs, the natural pressure is enough to send the oil (and natural gas) up to the surface. The best example of this is the blow out at Spindletop in Texas (also called a gusher). As more and more oil is removed form the reservoir, natural pressure can decline . When this happens, there are a number of ways to maintain the pressure. One of the ways to raise the pressure (secondary oil recovery) is to inject water into the reservoir . Another way is to inject carbon dioxide. Both methods will bring the pressure back up. The amount of oil flow will depend on the viscosity of the oil (how thick it is) and the porosity of the rock (how many tiny hoes are in the rock) and permeability (ability for liquids to move through the rock).
|photo credit: David C. Foster|
But how does the oil move from the well to the pipeline? There are two devices that help do this. The first is a wellhead. It serves as an interface between the well and the outside world. It can also help to maintain a steady pressure and flow. The other is a Christmas tree – which controls the flow (who has the best Christmas spirit? People in the oilfields – they have a Christmas tree up all year long). It has valves on it that can be opened up or closed to change the amount and pressure flowing through it, so a well can be connected directly to a pipeline. Some of the deep water wells may not have a pipeline running to them. In that case they can use specially constructed ships to take the oil from the well to where it can be offloaded
Since a pipeline’s path is not always downhill, how do they keep it flowing? The pipelines have pumps that keep the product (crude oil, natural, gas, etc) moving along. Crude oil contains a waxy substance so a device known as a PIG (pipeline inspection gauge) (this little pig went to market, this pig went to town, this pig cleaned the Alaskan Pipeline all the way home) is run through every now and again to clean it up.
|A Christmas Tree, on display
in the Wiess Energy Hall
The pipeline network will move the oil from the well to a refining area or a distribution area. There are also pipelines that take finished products out to where they are needed or can be distributed.
I hope that answers your question, zh! If this post – or any other, inspires a question in your mind, pleasepost in the comments or send us an e-mail at firstname.lastname@example.org.