TX 75083-3836, U.S.A., fax 01-972-952-9435.

Results of recent field trials with a newly developed fracturing-fluid system and liquid surface-modification additive for coating proppant are presented in this paper. The work was performed in the Underpressured Fruitland Coal (UFTC) gas reservoir in the Northern San Juan Basin of Colorado and New Mexico. This new technology has influenced production in the region. Data of the test-well population are compared to the coal gas and water production from the reservoir. This study identifies and applies the new fracturing system technology for improving production. The results of this study provide information that may apply to other coal-gas reservoirs. The study group of wells uses hydraulic fracturing treatments consisting of a new low polymer loading crosslinked fluid system with a proppant surface-modification additive. The fluid system has increased crosslinked-fluid viscosity, requiring a lower gelling-agent concentration. A liquid additive that coats the proppant and increases its surface adhesion is added in the blender tub during the treatment. The surface friction between the coated proppant grains resists high flow rates during cleanup. Modifying the proppant also influences the migration behavior and blocking effects of fines (coal and precipitates) within the propped fracture.

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TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractIn 1997, a surface modification agent was introduced into the global stimulation market. The agent was designed to enhance and sustain fracture conductivity by making the proppant surface tacky. Several conductivity-enhancing mechanisms were suggested. Two important mechanisms resulting from increased surface tackiness are 1) increased proppant pack porosity resulting in increased pack permeability and 2) increased proppant pack stability that prevents encroachment of formation fines into the pack and migration of fines within the proppant pack. In terms of extended conductivity maintenance, the fines control aspect has proved to be the most valuable property developed from the product. This paper presents a brief discussion on the theory of applying a tacky surface on proppants to mitigate conductivity loss from fines migration in the propped fracture. The paper then offers direct comparison case histories, which contain long-term production data that illustrate the benefits from lower operating expenses and increased production over the use of previous completion methods. Case histories are discussed in reservoirs that are known for fines migration, such as coal-bed methane (CBM) and high permeabilityunconsolidated sandstones. The histories also include zones not widely known for fines migration problems, where the authors feel that this condition does exist.