The Barnett Shale, one of the largest gas fields in the country, is slowly but surely being developed to provide an abundant supply of natural gas.

If you own property in the field, in most circumstances you also own the mineral rights. If, however, a previous landowner reserved the minerals rights -- or even a portion of them -- your share is diminished or nonexistent.

If you were offered a lease and accepted it, you would receive part of the drilling proceeds equal to the amount of land you own within the footprint of the well site. There are circumstances, however, when the only money a landowner receives is the initial signing bonus.

Sometimes the contracted terms of the lease lapse before production starts. In other cases, a well is drilled but is capped for future use. Some leases, however, may require the gas company to pay a monthly fee until the well is put into production.

Royalty payments only start when a well produces gas.

If that happens, expect offers from other companies to buy your mineral rights.

To paraphrase a common cliché, beware the buyer. It often seems the offers are rarely in the landowner's interest and are often based on false projections of what might be received. The individual or firm making the offer may claim that the amount is what can be expected over 10 years or more.

What isn't shared are the income projections they are calculating, which may be higher through fluctuations in market price or a change in the number of wells on the property that the potential buyer knows about -- but you don't.

The potential buyer hopes you sell without considering those long-term expectations. Basically, the offers are from investors hoping to buy cheap and make far more over time. All they want you to do is sign the offer and deposit the check that is generally included.

Leaseholders should consider what the long-term income might total, even if calculated at the current rate, over 30 to 50 years, which is the possible lifetime of the Barnett Shale field. If you receive a royalty check of $100 a month, the income over the life of the lease could reach $60,000 or more, should the price of natural gas rise or the producer drills another well that includes your property.

People who aren't current leaseholders should hang onto their mineral rights. With the way North Texas wells are developing, you might eventually be offered one.

It's important to know that if you have a lease and a well that includes your property is drilled within the time allotted in the lease agreement, the well might not go into production for years. Royalty income doesn't start until the well produces, and that includes transporting the gas to the marketplace. It may take months, or years, for the lines to be installed.

If you decide to sell your property, the mineral rights normally remain yours if you have a lease. If you don't have a lease, you must stipulate in the sale terms that you are keeping the mineral rights. If you don't write that into the sales contract, the mineral rights will go to the new property owner.