Personally, I would not sign it. Here is an example why.
The general formula for one section is: net acres/spacing acres (actual) x royalty x % perforations in your section.
For example: 10 acres net, 640 spacing, 20% royalty, well 50% in your section. 10/640 x .20 x .50= 0.0015625 decimal interest. For every horizontal well in that section, each one would have a certain split based upon the % of perforations in your section, so the decimal interest might vary slightly. They cannot drill within either 330 (or 660’) feet of the east or west edge. But that spacing only holds one section. You get paid on every well that lands in your section. If the well is totally within the section, the last term is 1.0. If the well is partially in another section, then the third term is according to the % perforations in your section.
if they space at 1280 (2 sections), then the equation is: net acres/spacing acres (actual) x royalty. 10/1280 x .20= 0.0015625. Same decimal, but you don’t include the last term since the well is 100% within the 1280. Again, I am assuming a north-south well and no drilling in the easements. You get paid on every well that lands in either/or both sections.
If the spacing becomes 2560 (4 sections), then the equation is: net acres/spacing acres (actual) x royalty. 10/2560 x .20=0.00078125. That means that you would have a smaller decimal with every increase in spacing. On the one hand, if they drill lots of wells, they do not have to abide by the 330’ spacing on the lease line and can add another well in. You would get paid on any well in the four section unit. That is the upside. The downside is that they can hold that entire 2560 acres with only one well and you would only get a small fraction of it. Personally, I would rather see them drill the original two section well in the east 1280 and another one on the west 1280 first to confirm the geology before I signed the unit agreement. Read the agreement and see how many wells they are proposing. You have to hope that they would actually drill them. But suggested wells are just that. They do not have to drill them.