Start with a section -- it's 1 mile by 1 mile. A section contains 640 acres. For discussions of land, you might hear the section broken into quarters, e.g., a deed might say, "the NW quarter of Section 10, " or some such thing. So, the NW quarter of the section would contain 160 acres.
Let's go further -- if you own less, then that quarter of a section might be broken down even more. Your deed might say something like, "the SW quarter of the NW quarter of Section 10." This would refer to the 40 acres in the SW quarter of that NW quarter of Section 10."
If your tract is smaller and/or more irregular, then it might describe the perimeter as beginning from some defined point, and something like "going north xxx ft, then due east yyy feet, proceeding to some point, and returning to the defined point." Something like that.
Now, onto Townships and Ranges.... Township numbers run North and South, while Range numbers run East and West. So, say you have land in T15N, R14W. This defines an area 6 miles x 6 miles and is composed of 36 sections. You'll need a map to find out exactly where your land is, if you don't know. The sections in the 6X6 mile square are laid out a bit strange (at least to me), with Section 1 in the NE corner, and section 2-6 running due west. Section 7 is due South of Section 6 and then 8 - 12 run back due east, so Section 12 is directly South of Section 1. Repeat this layout for sections 13-24 and 25 - 36, and you fill up the 6x6 mile area.
My advice is to visit or call the tax assessor's office in the parish in which you own land (if you don't live there, it ought to be on the web), and ask them (politely, since they are very busy) for a map of your property. If you have the info on the last tax bill, they can give you a map. (The office in DeSoto parish was very helpful to me, on this.)
Follow up question. In some cases there are irregular sections that have more or less than 640 acres. For example, in my township there are at least 51 sections. How are drilling units formed in this situation? Would it still be based on sections, even if a particular section had, say, 250 acres?
As exciting as this is, we know that we have a responsibility to do this thing correctly. After all, we want the farm to remain a place where the family can gather for another 80 years and beyond. This site was born out of these desires. Before we started this site, googling "shale' brought up little information. Certainly nothing that was useful as we negotiated a lease. Read More