Fall 2010

Hexion Provides Proppants Well-Suited for the Eagle Ford Shale

Eagle Ford MapThe Eagle Ford Shale has recently come into prominence in the United States oil and gas industry as one of the most promising plays of the past forty years. Initially discovered in the 1970s, the Eagle Ford Shale contains large amounts of oil and natural gas. Not until recent innovations in horizontal drilling, completion and fracturing technologies has the Eagle Ford been considered economically attractive. This reservoir’s heterogeneity challenges operators to develop and implement innovative fracture treatment designs in an effort to maximize production.

Formation Overview

The Eagle Ford Shale extends from the Mexico border in South Texas north upward to East Texas. It is a large geographical area ranging 50 miles wide to 400 miles long. This cretaceous play containing 70% calcite and 11% clay makes it a brittle, high permeable rock suitable for fracturing. It is located between the Austin Chalk and Buda limestone with thicknesses ranging from 100 to 350 ft (30–107 m).

The Eagle Ford is unique, consisting of hydrocarbon content ranging from three distinct windows. The northern window contains higher volumes of oil at lower pressure. The middle window produces natural gas and condensate, with the southern window containing larger volumes of dry gas. With these windows at varied depths, the average targeted depth is shallowest in the up-dip oil section and increasingly deeper throughout the mid-dip gas/condensate and down-dip dry gas sections. The vertical depths range from 5,000 ft to as deep as 14,000 ft (1524–4267 m) with lateral lengths running between 3,000 to 6,000 ft (914–1829 m). Bottom-hole temperature and closure stress vary depending on depth and location. Typically, gas wells’ initial production (IP) average six million cubic ft (MMcf) per day and decline at a lesser rate than in other shale plays. The additional oil content, often produced along with the gas, makes the Eagle Ford economically attractive – even in times of low natural gas prices.

Fracturing Design

Improving fracture treatment design in the Eagle Ford is a continuous focus. Current techniques to optimize well performance focus on the correlation between the number of frac stages, proppant type and volume per stage, fluid type, and well production. Wells range from having 10 stages to as high as 20 stages, accounting for a significant increase in proppant volume per well. The prevailing treatments are “hybrid” slickwater variations where smaller mesh sand is led in with slickwater and then tail-in with higher concentrations of proppant using a crosslinked fluid. It has been found that more frac stages and higher proppant volumes lead to higher production in the Eagle Ford.     

Horizontal Well Proppant Technology

In the Eagle Ford, two of the most critical fracturing issues encountered are proppant flowback and production decline. The large hydrocarbon content in the Eagle Ford creates an increased drag effect on the proppant, causing proppant flowback. Proppant flowback is very costly, not only causing damage to surface facilities and downhole tubulars, but also deposits along the horizontal wellbore, requiring frequent cleanouts. Proppant flowback also reduces near-wellbore conductivity and connectivity to the reservoir, resulting in steeper production decline rates.

Hexion is committed to developing technologies that enhance hydraulic fracturing treatments and provide improved well production. The success of these treatments requires the proppant to be transported deep into the created fracture and maintain its fracture flow capacity over the lifetime of the well.

PrimePlusPrime Plus™ proppants are an advanced, field proven curable resin coated sand available in 30/50 and 40/70 mesh sizes. Prime Plus resin is applied to high-quality sand to provide a low-cost, results-oriented solution recommended for closure stresses between 6,000 to 10,000 psi. Hexion’s Stress Bond™ (SB) resin system bonds the proppant with a specific combination of closure stress and temperature, eliminating wellbore consolidation and proppant flowback. Prime Plus has been utilized in thousands of wells in every major waterfrac basin in the United States and Canada. Its demonstrated ability to provide improved fracturing treatment results and a superior economic benefit when compared to uncoated ceramics and frac sand make Prime Plus the preferred fracturing proppant for the Eagle Ford.

Hexion’s Infrastructure

Hexion has recently opened a new transload facility in Corpus Christi, Texas, located very near the Eagle Ford activity. With a manufacturing and transload facility in Brady, Texas, and a transload in Rio Grande City, Texas, Hexion is well suited to supply the increasing proppant demands in the Eagle Ford. Our strategically located plant and transloads give us the ability to efficiently service larger fracturing programs with high volumes of quality resin coated proppants. Hexion’s movement forward with infrastructure expansion plans ensures we are able to supply service companies and operators in one of the most valuable resource plays in North America.

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