Kevin’s Blog / SAGD short stories:
A technical writer’s take on
SAGD Well Pads Training
“SAGD short stories” is a blog series concerning SAGD operations.
I remember when all I knew about the ‘oil and gas’ industry was my Dad’s car needed oil changes now and then and a gas fill-up when the gauge was near empty. Of course, the oil and gas I’m talking about are motor oil and gasoline. The Oil and Gas Industry, however, encompasses every operation from crude oil and natural gas production from underground (or undersea) reservoirs to refined, saleable products ranging from heavier greases and oils to lighter hydrocarbon liquids and gasses.
In today’s short post we will be taking a bit of time to go over the SAGD Extraction Process and in particular Well Pads and Bitumen Extraction.
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Being Canadian, I have always known about the Alberta Oil Sands, but I really never looked at how it was being developed. If you think drilling for ‘oil’ means putting a pipe in the ground so liquid oil flows out, you’re in for a surprise. The ‘oil’ in the Oil Sands is called bitumen, and it is as dense as cold peanut butter. Maybe even thicker!
Getting the Bitumen Flowing
Now, you might be asking, ‘how do you get peanut butter to flow up a 100-meter long pipe?’ Well, an easy way would be to melt the peanut butter to lower its density, add some peanut oil to thin it out even more, and then pump it up the pipe. Pretty simple, right?
Well, that’s pretty much what the Steam Assisted Gravity Drainage (SAGD) method does with bitumen. While the details are complex, the operating principles are easier to understand.
SAGD Questions Answered
The most important part of the extraction process happens at the Well Pads. These sites can be miles and miles away from a production facility and are the location where the formation is actually tapped for extraction.
A SAGD Well Pad is made up of multiple pairs of wells, one for high-pressure (HP) steam injection (Injector), and one for the production of oil (Producer). The biggest innovation leading to the development of the SAGD process was the perfection of directional drilling. This process allowed a well bore to be drilled vertically down to the reservoir depth before transitioning to a horizontal plane. This accuracy is critical as the Well-Pairs are drilled with the horizontal section of the Injector a few meters above the horizontal section of the Producer.
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The HP (high-pressure) steam that is injected via the upper well condenses to hot water as it gives up its heat to the bitumen formation, creating a ‘steam chamber.’ The heated bitumen mixes with the hot water and drains by gravity to the lower well, leaving the ground in place. This unintrusive process makes it easier for production companies to minimize the environmental impact of this oil sands extraction method.
SAGD Well Pairs
High-Pressure Steam Injection Wells and Oil Production Wells are operated as a pair to achieve the desired downhole conditions to maximize production.
It is also critical to understand how the downhole steam chamber maintains heat and flow, over the lifespan of the well pad. Since the bitumen is naturally too dense to flow, only by adding considerable heat so it can be produced into a consistency that can make it to the surface. Most of the steam condenses and mixes with the bitumen to create a superheated, less-dense, mobile emulsion of bitumen, water (condensed steam), gas, and reservoir solids (mainly sand).
The SAGD Method
The SAGD method requires high-pressure steam in considerable volumes, and the course explains how the high-pressure (HP) steam supply pipeline system delivers the HP steam to the well pads.
SAGD recovery often requires some artificial lift to maintain effective recovery flow rates. The dominant industry choices are using an Electric Submersible Pump (ESP) installed in the well bore or Lift Gas Injection into downhole production tubing, and each is explained in greater detail throughout the course.
From Separation to Production
All production is directed through a Group Separator for bulk separation of gas from the liquids. A Test Separator is used to verify wells individually for efficiency and provides detailed information concerning the well being tested. All production fluids from a Well Pad are sent to the Central Processing Facility through a pipeline, while Produced Gas is forwarded to the CPF through its pipeline.
To find out more about how bitumen is processed to sales oil in a SAGD facility,
you can view thevarious chapters of Contendo’s SAGD Oil Sands Online – Well Pads and Bitumen Processing Courses.
Kevin Fox is a senior technical writer at Contendo.
He is a power engineer who has written process education programs for industrial clients since 2009.
To Learn More
At Contendo, we have been providing in-depth online operator training to the Oil Sands and SAGD industry for the better part of a decade. If you want to learn more about this complex but highly efficient extraction method, stay tuned for more posts like this or contact us to hear more about our SAGD Oil Sands Online Training Course.
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