Drilling and completing shale gas wells has kept rig crews busy in basins throughout the US and has increased the demand for proppants of all sorts. Companies are drilling longer laterals and running multiple hydraulic fracturing stages, requiring ever larger volumes of proppants to keep the fractures open and producing. Protecting porosity and enhancing permeability of producing shale formations is critical. Billions of pounds of sand and ceramics are used every year in the US, and demand is growing outside the US as well.

“It’s a very volatile marketplace right now,” said Jason Renkes, President of Louisiana-based Patriot Proppants, adding “Using proppants accelerates the production of hydrocarbons, which is in everyone’s best interest.”

Resin-coated sand grains appear golden in this 40x photomicrograph. (Image courtesy of PropTester Inc.).

Renkes recognized the growing demand for high-quality proppant materials as a market opportunity, driving his business model. In late 2008, Renkes conceived a plan to build a new proppant manufacturing facility that could serve the needs of operators in nearby regional shale plays-Haynesville, Fayetteville, Barnett, and Eagle Ford. Renkes said many service companies shared the consensus that the escalating proppant shortage would continue for years and justify the capital expense to put a new plant in the middle of the play. He scouted 27 locations in East Texas and Louisiana before settling on a site in northern Louisiana in the heart of the Haynesville shale play. Chief among the criteria were railroad access and daily rail switching service as well as required road infrastructure needed to deliver proppant directly to the well site.

Construction

In early 2009, Renkes and his team were involved in due diligence assessments and reviewing engineering plans for a new plant. In October 2009, Patriot Proppants broke ground for a two-line, resin-coated proppant facility in Webster Parish, La.

Patriot is building on 27 acres in the South Webster Industrial District, near Highway 371 (also called Hwy 7) and Interstate 20. The site provides road access for truck transport into the Haynesville and Cotton Valley operations and access to the Kansas City Southern (KCS) rail line. In building the infrastructure, Patriot laid two spurs off the KCS line that will serve its inbound raw material and outbound finished goods operations.

Patriot Proppants will use the KCS rail line to bring in northern white Ottawa sand under long-term supply contracts. The majority of Patriot’s product mix is a 40/70 grade sand coated with a premium resin system, but the company plans to coat 20/40 mesh size as well.

RC proppants

Adding a resin coating to sand produces a tough outer shell and spreads the stress across the grain, Renkes said, improving strength and conductivity. The crush strength of RC-proppants is comparable to high-strength ceramics. The resin coatings can be completely or partially cured in the manufacturing process or can be designed to bond within the fracture. Whereas the alumina silicate in some ceramics can dissociate and clog pore space in the proppant pack, an advantage of RC proppants is the lack of any diagenesis effects. The resin coating also encapsulates fines if the grains crush, keeping them from migrating in the proppant pack.Manufactured proppants can perform better than plain sand in formations with high gas flow rates, as they maintain conductivity better in low-stress regimes.

Demand, transportation

Fracture operations in a typical Haynesville shale well use 2.5 to 5 million lb of proppant, injected in eight to 25 stages, typically about 15 stages. Because of the variation in the Haynesville, the proppant selection varies among operators and contractors. Service companies use 100-mesh size material, some uncoated sand, pre-cured RC-sand, and even some ceramics.

Wells in the Barnett shale are generally shallower than Haynesville wells, with lower closure stress and lower temperatures. Operators typically pump 5 to 6 million lb of sand over 15 to 18 stages when stimulating a Barnett well. Renkes said this is typically 100-mesh sand, 40/70 uncoated, and then the crew tails-in with a 20/40 curable resin-coated sand. Curable RC-sand keeps proppant in fractures and prevents flowback and proppant embedment.

In the Fayetteville shale, operators are drilling long laterals. Closure stresses are typically lower than those in Barnett wells, so fracture jobs generally require plain sand and some tail-in with manufactured proppants.

Ensuring the materials are available on site when they are needed is an imposing challenge.

A typical rail car holds approximately 100 tons (200,000 lb) of sand. Therefore, a 1 million-lb frac job requires five railroad cars of sand, and a 5 million-lb frac job requires 25 railroad cars of sand. Few wells are drilled adjacent to rail lines, of course, so all that sand needs to be trucked to the well sites.

A typical truck holds 50,000 lb of sand, so it would require at least four trucks to carry the load of a single rail car, 20 truckloads to carry 1 million lb of sand, or 100 truckloads to carry 5 million lb of sand to a well site.

“When you fracture stimulate on a 24/7 schedule, the service requirements to replenish proppant are critical to ensure fracturing operations run smoothly,” Renkes said.

Future

According to Renkes, construction of the new RC plant is on schedule and close to budget, and the work will be substantially complete by August 2010. The site will include a 100-ft (30.5-m)-tall production tower, quality-control laboratory, administrative building, and extensive finished goods silo storage. When operating 24 hr/d, 7 days/week, the plant will employ as many as 40 full-time people, working in shifts.

Patriot Proppants is building its business on high-quality sand and patented resin technology.