SHALE ENERGY: Developing the Barnett—Lateral lengths increasing in Barnett shale

Gene Powell, Powell Barnett Shale Newsletter

A Powell Barnett Shale Newsletter database of the 8,158 horizontal wells with production was evaluated using the lateral length of each well. A lateral length in this analysis was the distance measured from the surface location to the bottomhole location as measured in a straight line on the surface with data from the RRC drilling permit. The one obvious factor that the data showed was that the lengths are becoming longer.

The newsletter staff examined the location of the wells with the longest permitted laterals. Not surprisingly 9 of 10 of the longest laterals (to May, 2009) ranged from 7,071 ft to 8,965 ft and were drilled at DFW International Airport in far northeast Tarrant County and far northwest Dallas County by Chesapeake Energy Corporation. Since we began ‘tracking’ lateral lengths and Peak Month Daily Average (PMDA) in 2003, our analysis is that there is too much interaction of variables to show a trend in lateral length vs. PMDA of Barnett Shale horizontal wells in the Fort Worth Basin. There is a trend to longer laterals, more frac stages and smaller sand size (predominate sand size moving to 100 mesh) and numerous wells into double-digit frac stages.

The biggest well to May 1, 2010, based on a peak month daily average (PMDA) is the Chesapeake Energy Corporation’s Day Kimball Hill #A1H (API No. 42-439-33058 in SE Tarrant County in Mansfield/Arlington which had a PMDA of 12,464 Mcfgpd, producing 402.1 MMcf in October 2009. This is the first well to average over 10 MMcf gas per day in its peak month. The well has produced 1.5 Bcf in its first 10 months to May 1, 2010. This well had a lateral length of 7,470 ft with 16 separate frac stages. The sands were balanced among three sizes: 30/70; 100 mesh; 20/40 with amounts about 120,000 lb each for each stage. Slick water for each stage averaged about 11,000 bbl.

Technology continues to advance in the Barnett Shale with longer laterals providing the need for fewer wells from fewer drilling pad sites. Some individual drilling pad sites are projected to be able to support as many as 35 horizontal well surface locations. This is a big advantage in the urban environment of Fort Worth, Arlington, Dallas and the hundreds of smaller communities of the 24 counties with Barnett Shale production in the Fort Worth Basin.

Fig. 1. Lateral lengths in the Barnett shale play have increased from about 3,000 ft in 2003 to as long as 8,965 ft in 2009.

NO AIR QUALITY BENZENE CONCERNS

One would believe from all the articles in print and on the internet that there were many high benzene test results in areas of Barnett Shale production in north Texas. That is not the case. Texas Commission on Environmental Quality (TCEQ) has performed thousands of tests around Barnett Shale wells and equipment for air quality have only shown two tests out of bounds. Those two equipment problems were both in Wise County, northwest of the DFW area and were quickly fixed. The one-hour air quality short-term level in Texas, as set by the TCEQ, is 180 parts per billion. Some benzene exposure levels to compare to the short-term level (one hour) of 180 parts per billion are when you put fuel in your vehicle, you are likely exposed to short-term levels of benzene up to 11,000 parts per billion; if your house has an attached garage and you park your cars inside it, benzene levels in the garage may be about 60 parts per billion, and levels in your house can be around 10 parts per billion. If you have at least one smoker in your house, levels can increase as much as 3 parts per billion.

The long term annual level (the average of a minimum of at least each sixth day for a year) is 1.4 parts per billion. Both the EPA and TCEQ have stated that if a person was exposed 24 hours a day for 70 years to a benzene level of 1.4 parts per billion, the would be a 1 in 100,000 chance of getting cancer from that exposure level. According to Dr. Bryan W. Shaw, Ph.D., Chairman of the TCEQ, the federal Environmental Protection Agency (EPA) would take action only if the long term level averaged 14 parts per billion, much less stringent than the TCEQ level of 1.4 parts per billion.

There are now four AutoGC (automatic gas chromatographs) in north Texas which monitor about 45 chemicals in the air each hour including benzene. No tests have yet to exceed either the short-term or long-term levels set by the TCEQ. These units cost $250,000 each with about $100,000 in operational costs each.

More air quality tests were run around Barnett Shale wells and compressors in July 2010 by the independent environmental firm Titan Engineering on behalf of the gas operator supported Barnett Shale Energy Education Council (BSEEC). None of those tests for benzene and other chemicals exceeded federal or state standards for safe air quality. The City of Fort Worth’s Air Quality Study Committee selected Massachusetts-based Eastern Research Group from among three finalists to perform an air quality study of Barnett Shale natural gas production facilities for the city in August 2010, during the hot summer months, at the insistence of the anti-drilling environmental groups. These small factions continue to scare the public with their speculations, then demand that local communities and organizations to spend their  money to trying to prove the theoretical dangers. So far, any tests that show that Barnett Shale production does not harm the air quality are invalid, regardless of who runs the tests, according to the anti-drilling folks. They will never be satisfied until we produce shale natural gas according to their standards, which is in most cases very expensive and totally unnecessary.