Searching for specific text in Adobe Acrobat Reader is getting tons of unwanted results

I have hundreds of pdfs on soil science that I need to search for references to oil. However, when I search for "oil" this also brings up all the references to "soil." There are millions of instances of the word "soil" and I do not want to look at each one of them. Is there an easier way to do this? I am at a loss here. It is taking me a very, very long time

Here is that has not worked:

Searching for "oil" in quotation marks

Searching for " oil" with a space in front of it