I’ve owned mineral rights in Oklahoma for awhile but am new to calculating the details.
Regarding a division order (or DO) for SEC 19 and 20, my mineral deed shows ownership of mineral interest of 1/2 in SEC 19 E1/2 SE1/4 SE1/4 of T1N, R1W.
This is also split between me and 2 siblings (so I would think there would be a factor of 1/3 in the net mineral acres calculation).

As far as the numbers go, in SEC 19 E1/2 SE1/4 SE1/4 of T1N, R1W, I’m calculating the following:
net_mineral_acres=spacing_unit_size*(1/2)(1/4)(1/4)mineral_interest(1/3)=637.04*(1/2)(1/4)(1/4)(1/2)(1/3)=3.3179 acres

The factors of (1/2)(1/4)(1/4) account for tract subdivision E1/2 SE1/4 SE1/4. The *(1/3) accounts for division between me and my 2 siblings (since each of us would get 1/3).
Just for SEC 19, I’m getting more net mineral acres than is on division order (1.666667). What specifically am I doing wrong?

For SEC 19 royalty interest alone, I’m calculating:
royalty_int_SEC19=net_mineral_acres*(1/spacing_unit_size)(royalty_rate)(SEC19_allocation_factor)=3.3179*(1/637.04)(1/4)(0.4613)=0.0006065
This is higher than royalty interest shown on DO for BOTH SEC 19 & 20. Do my calculations look correct given the tract size, mineral interest, and royalty rates above?

The Oil company isn’t talking (won’t answer phones, emails or opened tickets through their web site since last May).

Usually the deed does not specify the net mineral acres conveyed. Do you have a title run which shows how many acres your predecessor A owned? Is it possible that he only had a partial interest in the 1/2 minerals? Maybe his predecessor B owned 1/2 and gave half of of his 1/2 to A and the other half of 1/2 to X. Then someone used the earlier deed reference. Second is your acreage the section acreage or the unit acreage? That will affect your decimal. If you post the well info, including county and operator someone familiar with OK can give you more help.

E1/2 SE1/4 SE1/4= 20 acres
1/2 interest=10 acres
1/3 interest=3.333 acres owned
Since its a multi section unit and not a 1280 acre unit from what you stated, the allocation values in the pooling for section 19 need to be factored in to determine your net acres for the well. It sounds like its 50% for section 19, so 3.333 acres x 0.50= 1.666 acres.

Sections along the northern tier and western tier of most OK townships are corrected for the curvature of the earth, so they may be spaced at 640 for a horizontal well, but not actually contain exactly 640 acres. Section 19 is not regular.
Go to the Bureau of Land Management site to get the exact acreage. Home - BLM GLO Records

The equation is: actual net acres/actual spacing acres x royalty x percentages of perforations in your section.

Contact the Continental Resources Division Order department (good luck…) and ask for the equation that they used for your decimal, particularly your net acres and the % split for 19 for your well(s). The split can also be found in the final orders for the well in the OCC case you should have received. Usually the split can be found in tiny tiny print on the DO.

E1/2 SE1/4 SE1/4 is 20 acres. You have some net acreage of that according to the title path of those acreage. Your heir may not have had the total 20 acres. If the DO says 1.666667, then they have a title opinion that traces it.

1.66666/637.04 x royalty x % in 19

If you have multiple horizontal wells, then each DO may be slightly different.

Ok great, thanks, that is helpful. I tried to repeat your search. When I filled out the form, I see the Results list you show, but was unsure where to go from there. I selected the ‘Master Title Plat’ link, but I only see a blank
screen in Land Status Record Details tab:

Don’t have a title run that specifies what predecessor owned. My understanding is the net mineral acres used the spacing unit acres, which I believe is indicated on the division order (so is 637.04 as specified on DO instead of a section’s 640 acres). This is Garvin county OK with mineral interest owner Continental. Regards, GMM

The last map was broken the day I tried it. I happen to have had already made a screen shot of it before. The irregular lots add up to 157.04. The rest of the acreage is 160+160+160, so the sum is 637.04.

The percentage perforations in 19 is calculated from the length of the perforations in 19 from the well bore based upon the final survey. The net acres is calculated using the title information which Continental will have.

It appears that link is for Texas. You’ll have to look at your pooling to determine the allocation factor for your section. For simplification, lets say your section is allotted at 50%, your OGL is @3/16ths, and the unit is 640, all those numbers can be changed to fit whatever situation you run across, here is the equation that they will use.

0.50 (allocation factor) x 3.333 (net mineral acres) x 0.1875 (lease royalty) / 640 (unit size) = Unit NRI