5 ILCS 615/14
Whenever the Department shall find it is in the best interest of the State and of the production of petroleum, it is declared to be lawful for the State, the permittees, lessees, operator or any person owning or controlling royalty or other interest in separate properties of the same producing or prospective petroleum field, to enter into agreements with themselves or among each other, subject to the approval of the Department, for the purpose of cooperative exploration, development and operation of all or a part or parts of such field, or for the purpose of the exploration, development or operation of all or part or parts of such field as a pool or unit, and for the purpose of fixing the time, location and manner of drilling and for the purpose of drilling and for the purpose of regulating the location, sequence and number of exploratory wells required in the case of permits under unit operations and leases, and operating of wells for the exploration of petroleum on State and private lands and for the apportionment and division of the petroleum between the State and the several owners of land embraced within the field so placed in such pool, taking into consideration the relative character and geological showing in respect of said several tracts of land so far as the same is reasonably ascertainable, the apparent probability of producing petroleum from the whole or any part thereof and any and all other apparent factors that may tend to aid in arriving at a fair, just and equitable participation by the State and the several owners in the apportionment and distribution of all the petroleum that shall be recovered and saved therefrom. The purpose of this section is to encourage the development and exploration of petroleum upon State lands by and through the unit plan of development. When it is in the best interests of the State, the Department shall compel the adoption of unit plans of operation in so far as State lands are included in any productive pool or pools if the permittees or lessees of such lands shall fail to agree upon a plan of unit operation acceptable to the Department, the Department is empowered to fix the terms of such unit plan or plans and any permittees or lessees affected who fail to abide by such plan shall suffer forfeiture of their permits or leases upon notice as herein provided.
5 ILCS 615/14