http://www.propublica.org/article/forced-pooling-when-landowners-cant-say-no-to-drilling"Forced pooling compels holdout landowners to join gas-leasing agreements with their neighbors. The specific provisions of the laws vary from state to state, but drillers are generally allowed to extract minerals from a large area or "pool"--in most states a minimum of 640 acres--if leases have been negotiated for a certain percentage of that land. The company can then harvest gas from the entire area. In most cases, drillers aren't allowed to build surface wells on unleased land, so they use horizontal wells or other means to collect the minerals beneath those parcels.
Thirty-eight states have some form of forced pooling law. West Virginia and Pennsylvania each have measures that don't apply to drilling in the Marcellus Shale, and proponents are trying to expand the laws in those states. (Check out our chart of forced pooling laws <2> across the United States.)"