When you say oil industry are you talking refinery or a fuel oil company such as a lot of towns have for home heating oil and the like. If your talking oil refinery I can't speak as an expert but I worked in the Exxon refinery here in Linden , NJ for a while and all of our pipping was above ground. I actually asked my foreman if any of the pipes were under ground and he said not in this place. Imagine if you had a leak in a pipe under ground, A: you wouldn't see it until way too much time had passed and once you did find it imagine what would be involved in repairing it. That why we have monkey's like you to walk the line checking for leaks. Trust me watching paint dry would be more interesting.
Here's a picture of a very nicely done moderately sized oil refinery and a link to his web page maybe you can get some answers there.
The Walthers 23,500 gallon tankcars would work. The Atlas 23,500 gallon ACF tankcars would probably work. However I am not sure it the prototype existed back then. It probably did, but I am not sure.
"No soup for you!" - Yev Kassem (from Seinfeld)
"I am thinking about putting in an oil industry on my layout. the situation is it's the late 1970's (anywhere from 77-79) and there would be oil pumped out of the ground to the facility, to be moved to a refinery (I'm sure you all know that how that part works, but I thought it might make a difference on what type of car)."
My study of the oil industry in Texas in the 1950s showed comparatively little crude oil moving from wellheads of refineries in railroad tankcars. 1957 figures from the Texas Railroad Commission show "only" 17 thousand tankcar loads of crude petroleum moved that year, compared to almost 50 thousand carloads of gasoline, 450 thousand carloads of other refined petroleum products.
Those products moved by rail to county-level bulk oil dealers:
from which it would go by truck to individual service stations within a 25 to 50 mile radius. Refiners owned or leased cars with their brand names boldly emblazoned.
Large railroads had their own fleets of company service tankcars to take delivery of diesel fuel and lubricating oil...
The military also received railcars loads of fuels. Some fuel depots on bases were the military equivalent of the private bulk oil dealer (bottom picture in set below)
"Gulf sells ammonia produced from petroleum to Spencer Chemical of Kansas City for use in manufacturing fertilizer." Mentioned in news story about proposed Gulf purchase of Spencer, Time Sept.20, 1963 p.92
Refiners also received catalytic agents such as Fluorspar by rail.
The refining process also took carloads of Sulphuric Acid, delivered in special acid tank cars. Stauffer Chemical "regenerated" used Sulphuric Acid and had tankcars specificially assigned to "spent acid'" service.
Leaded gasoline has been generally outlawed since the beginnings of the "environmental era", but there used to be tetraethyl lead antiknock company shipped to refineries-- again in special cars...
Phillips Petroleum produced olefin polymers in the 1950s, and to introduce the Marlex plastic, they worked out a deal to supply the material for the first HULA LOOPS.
I have a list of dozens of tankcars involved in these shipments, maybe I can get back later.
car donated to South Texas Railroad Historical Society and then to Galveston Railroad Museum. 1983 picture by kla.
http://www.trainboard.com/railimages/data/533/humbleoil.jpg
By the way, I model in N scale, don't know what models are available in HO. But you can compare and see what matches the prototype.