Summer 2009
What’s Working in the Fayetteville
and Barnett Plays?

Fayetteville Shale
The Fayetteville Shale is a large unconventional gas shale reservoir located on the Arkansas side of the Arkoma Basin. Its thickness ranges from 150 to 300 ft (46 – 91 m) and contains large amounts of silica and fine sediment.

Most of the wells in this play are shallow horizontals with an average of six to eight frac stages. Well depths are very broad and range from approximately 1,500 feet (457 m) to as deep as 7,000 ft (2,134 m). Lateral lengths typically run between 3,000 to 4,000 ft (914 – 1,219 m). Bottom-hole temperatures range from 100 to 150°F (38 – 66°C) with an average fracture closure stress of 3,000 psi (21 MPa) or less. Typical wells Initial Production (IP) at an average of one to three million cubic ft (Mcf) per day and decline at a lesser rate than in other shale plays.

Fracturing Challenges in the Fayetteville
The most pressing fracturing problem in the Fayetteville Shale is proppant flowback. Several of the operators in this play using uncoated frac sand are reporting serious problems with proppant back production.

Proppant flowback poses challenges to operators throughout the oil and gas industry. This can be a very costly problem because sand production not only often damages surface facilities and downhole tubulars, but it also deposits along the horizontal wellbore requiring frequent cleanouts. Besides lost production time from shutting in the wells for repairs, fracture conductivity is reduced and consequentially so is overall well production. Some operating companies have stated that stopping flowback is a main priority on their frac jobs.

The Solution
The proppant types normally used in the Fayetteville are 40/70 uncoated frac sand and resin coated proppants for tailing in. The solution to proppant flowback has been to tail-in with ValuBond 40/70 resin coated proppant. One operator first began using approximately a five to six percent tail-in which is about 25,000 lbs (11,340 kg) of proppant per stage. Recent jobs have included larger resin tail-in volumes which have made a significant reduction in proppant flowback.

Hexion’s ValuBond™ is an advanced, field proven proppant available in a 40/70 mesh size. This curable resin coated sand is performing very well in the Fayetteville and has received good reviews for providing flowback control. Designed for use in the waterfrac basins of North America, ValuBond resin is applied to high quality sand to provide a low-cost, results oriented solution. Recommended for closure stresses between 2,000 and 7,500 psi (14 – 52 Mpa), Hexion’s Stress Bond™ (SB) resin system bonds the proppant in the fracture with closure stress, providing increased fracture flow capacity and proppant flowback control.

ValuBond is the recommended proppant for tailing in since it was designed specifically for the pressure and temperature ranges that are found in the Fayetteville. Operators are stating that ValuBond is very successful at solving their flowback problems. Since ValuBondís superior resin technology eliminates proppant flowback, it allows wells to be flowed back more aggressively. The flexibility of the resin system allows the proppant pack to maintain its integrity even after multiple well shut-ins which place cyclic stress on the pack.

ValuBond has the highest curability in the industry. Since it is such a highly curable resin coated proppant, its grains bond to the formation of any “offshoot” fractures. This feature offers additional fracture flow capacity as the well is produced. Due to its ability to bond, ValuBond will hold open the small microfractures while other proppants may shift and allow the microfractures to close. ValuBond is working very well in the field due to its high bond strength and resistance to crushing.

Unlike precured proppants, ValuBond’s curable nature offers flowback control through its grain-to-grain bonding featuring the Stress Bond technology. ValuBond is ideal where higher fracture flow capacity and flowback control is required.

Barnett Shale
The Barnett Shale located in the Ft. Worth, TX area is similar to the Fayetteville, but it is deeper and thicker. This play became a big success story in 2003 when horizontal drilling became the standard practice. The Barnett Shale really challenged the industry to look at completion strategies from a new perspective. It was impossible to produce gas in commercial quantities until improvements were made in hydraulic fracturing technology and horizontal drilling. The application of these technologies has made this play economically viable.

Most of the wells in this play are horizontals with depths primarily between 7,500 and 8,500 ft (2,286 – 2,591 m) with an average of four to six frac stages. Bottom-hole temperatures reach an average of 150°F (66°C) with average closure stresses of 3,000 to 4,000 psi (21 – 28 MPa). These wells typically IP at an average of two to four Mcf per day. On average, a Barnett horizontal costs approximately 2.8 million dollars.

Proppant Use
As with the Fayetteville Shale, uncoated frac sand is generally being used. Resin coated proppant use is becoming more prevalent with primarily 20/40 mesh used for tail-ins to reduce proppant flowback. Hexionís SB Excel™ 20/40 has been used successfully in several areas in the Barnett. Since some designs require a smaller mesh tail-in, ValuBond 40/70 has also been used; however, in the deeper Barnett areas, Prime Plus™ 40/70 is the primary proppant due to its higher strength and superior flowback control. All of these proppants offer higher near wellbore fracture flow capacity, providing increased well production over raw sand.

Hexionís Infrastructure
Hexion is well suited for supplying proppants to the Fayetteville and Barnett Shales. We have manufacturing plants and transloads located in Oklahoma City, OK and Brady, TX. Our Cleburne, TX facility will soon serve as a new transload with a future manufacturing operation to follow. Hexionís innovative technology and infrastructure is well positioned to help operators and service companies working in these areas Get the Results You ExpectSM.





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