Myself and 3 siblings split 15 nma for a total of 3.75 nma each in Weld County. Individually it’s peanuts in perspective, however, we leased to Mallard in Feb 2019 for $2,200/nma, 20% royalties (total $8,250 bonus for just 3.75 nma). Our group makes all our leasing/sell decisions together, representing 15 nma combined.
We just received an offer for purchase from Patriot Reserves, offering $12k for 3.75 nma. Initially, we have declined to sell. I’m curious if anyone else with small holdings have received offers or negotiated recent sales, and am hoping to obtain some advice on continuing to lease vs. selling. Can we even sell leased rights?
Yes you can sell leased rights. The Buyer will simply step into your shoes and collect any future payments due under the lease, including royalties.
You should look into whether there is any activity going on around you. That may be why you are getting offers to buy. The Colorado Commission has a nice website that will have that information.
cogcc.state.co.us
Or you could try posting your specific location, (Section, Township, Range) and someone here may have some information for you.
Location is: Section 29, Township 08N, Range 59W
Thank you for your reply and the website, any research material is welcome. 
8N 59W.pdf (218.3 KB)
I have attached a map showing the area surrounding your minerals. All of the horizontal wells with available production are shown. The size of the green circles is proportionate to the amount of oil produced. The wells to the west of you are all sub-economic wells. The wells to the northeast are somewhat better, but not great.
Noble Energy drilled several new wells under Sections 9 & 16 in late 2018, but there is no production history available on them yet. Perhaps the offer you got is based on someone’s belief that these new wells are significantly better than the older wells were.
There are wells permitted under Section 29 by Bison Oil & Gas, but I don’t see where any activity has begun.