The reason your title company and mortgage company seem unwilling to help may be that the deparment downtown in Fort Worth where deeds are recorded is not especially helpful. Perhaps they are innudated by people looking to buy minerals rights from people to sell to a third party and make a fast buck.
Homeowners associations rarely have information about mineral rights; my last couple of deeds and titles stated if another party retained the mineral rights but not my present one.
I spent an entire afternoon trying to look up the deeds and titles of past owners on my property to see if someone had retained the mineral rights and left it off my title by mistake. However, I had an extremely rude woman who worked there tell me I had no business looking up my title as recorded. (I wanted to compare it to the one I recieved at closing)
By the way, these are public records and I had the names of the last four owners back to when this area was a gravel pit operation, dates the properties were sold, and volumes in which the titles were recorded. Moreover, I had the exact lot location as recorded downtown but I couldn't even see my own title! (This information was obtained from the tax assessors office which was very helpful and told me how to access the records downtown).
Evidently the gas or land company has a way of accessing these records without interrupting county employees. I think Austin has separate records of mineral rights, drilling permits, and production totals but these are not accessible to the public.