The Haynesville Shale is a rock formation containing oil and gas lying approximately 10,500 to 12,000 feet sub-surface in northwest Louisiana and East Texas. It is also called the Bossier shale in some places. Sub-surface, the formations dip southward toward the Gulf Of Mexico; thus, the formation is found deeper the further south oil and gas wells are drilled.
Shale is also called mudstone. It is very "tight," meaning it has little permeability, a measure of the rock's ability to allow a liquid or gas to pass through it. Typically, shales have low porosity; however, the Haynesville shale's porosity has been surprisingly higher than other shales. The higher the porosity a rock formation has, the more oil or gas its pore spaces can contain.
Shales were deposited millions of years ago in a deep ocean environment. Fine silt particles and countless trillions of marine life forms settled to the depths. Over millions of years, this mud gets pushed progressively deeper by the overburden of the layers being deposited on top, deeper and deeper until it finally turns into rock. Rock containing carbon from the dead sea life. Over millions of years, this carbon is subjected to heat and pressure and became oil and natural gas.
Oil and gas have largely been a 20th century discovery, meaning widespread exploitation of the resource. Prior to the discovery that organic shales could produce gas in commercial quantities, reservoir rock was considered to be of three primary types: sandstone, limestone and dolomite. Shale was the crappy rock you drilled through to get to a good rock. (A good rock being one with good porosity and good permeability.) That all changed in the 80s with the development of a completion technique known as hydraulic fracturing.
Another shale, the Barnett shale, near Fort Worth, Texas has proven to be productive and commercial in some areas. Hydraulic frac techniques in the Barnett are largely attributed to George Mitchell of Mitchell Energy, oil and gas producer. Over many years, many failures and many millions spent, Mitchell proved that the crappy shale rock could produce gas in commercial quantities.
In the period 2006-2008, companies began drilling and attempting completions in the Haynesville shale from East Texas to North Louisiana. Several wells produced favorable results. Some companies feel that the Haynesville may prove to be a great producer of natural gas and a leasing frenzy was unleashed on the ark-la-tex. Many companies are actively buying Haynesville shale oil and gas leases. Some choose to sell mineral rights in the Haynesville shale. Time will tell if this shale play turns out to a bomb or a bust.
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