Estevan 鈥� One of the novice-level presentations on at the Nov. 27 Canadian School of Hydrocarbon Measurement featured Allen Caron of Caron Measurement and Controls and John Forchuk of Sky Eye Measurement speaking about the 鈥淔undamentals of Sampling.鈥�
Forchuk said after the presentation, 鈥淲hat we鈥檙e trying to do is get some perspective on best practices and the challenges you鈥檒l have in the crude oil industry, sampling of what we鈥檙e producing out of our wells and what we鈥檙e pumping through our pipelines. A lot of times it could be a reservoir validity, or how we鈥檙e reporting what we鈥檙e pulling out of the reservoir for production. But then, now we鈥檝e refined it, it鈥檚 the exchange of products. So I鈥檓 the midstreamer, selling it to other parties. So we have to validate, through sampling, what we鈥檙e buying and selling, and come into agreement. That鈥檚 what the sampling is all about.鈥�
He spoke of three different levels of testing 鈥� atmosphere, low pressure and high pressure. The first is about water cut, the second is about quality, and the third is about sales. 鈥淵ou can start off at the first tier. At the wellhead, you have to determine the oil, water and gas content, to report to the owner, which is the AER or Saskatchewan Econ. It鈥檚 a royalty statement. So I produced it, and I have to show you what I produced. I pay royalties to the government (or freeholder) on that, whoever owns it. I鈥檓 leasing it. So I need to validate your well testing and battery balancing. So it鈥檚 atmospheric, it鈥檚 a more coarse measurement.
鈥淎nd then, as I move into the battery I鈥檓 doing the first level of refining. I separate oil, water and gas, and I send it in different directions. That sampling of just the oil stream, the clean oil stream, is at a low pressure, like maybe 15 PSI. I鈥檓 going to let any free vapour come off of it, because I need to get paid for that. It鈥檚 now been put in a pipe. If it gets heated, and I let it go away in an open container, I lost money,鈥� he explained.
These are considerations when it comes to items like blending and vapour pressures. This also impacts shipping of crude-by-rail, and in particular, the total vapour pressure of the product shipped.
On high pressure, Forchuk said, 鈥淪o we鈥檙e moving out of producing a barrel of oil. In a gas plant, I鈥檓 making a barrel of condensate, which is going to be under pressure, and you wouldn鈥檛 release it to atmosphere. It鈥檚 a higher pressure application. We need a different assembly of components to work at 1,800 PSI versus 15 PSI. And the other part, because it鈥檚 crude quality, and we鈥檙e working with larger pipes, you鈥檙e probably going to want to take a larger volume of that product, so I need a larger vessel.鈥�
This could be up to 15, 16 litres for a sample, he said.
