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 Moxa Arch Frontier Development Success Through Increased Fracture Conductivity — Part 2
S.K. Schubarth, SPE, Falcon Petroleum Consultants, Inc.,
R.A. Chabaud, SPE, Bannon Energy Incorporated;
G.S. Penny, SPE, STIM-LAB, Inc.
This paper is a case study in Wyoming encompassing over 550 wells. The study suggests that fracturing with sand proppants could achieve a dimensionless fracture conductivity (CfD) of 10 in the Moxa formation when formation permeability is less than 0.06 md. Resin-coated sands were adequate for formation permeabilities up to 0.035 md. With formation permeability exceeding 0.035 md, ceramic proppants are required. A strong correlation between condensate yield and production response was noted, yielding multiphase flow evaluation and verification.
Production responses increased 60% for wells stimulated with Intermediate Strength Proppants (ISP’s). Wells stimulated with ISP’s averaged 340 mscfd incremental production compared to wells stimulated with sand. More prolific wells in the interior of the field showed even greater incremental returns. The economic analyses are summarized in an interesting way in this paper: it is argued that the potential loss as a consequence of unnecessarily using a superior proppant is limited to the incremental cost of that proppant ($84,000 for the example cited). But the potential profit has no fixed upper limit; and it is shown to easily exceed $84,000 gain on a good well. The study indicated that, when formation permeability is not precisely determined from well logs, it is preferable to use high conductivity proppants in the entire field. Providing adequate conductivity for the “sweet spots” in the reservoir more than justifies the cost of running premium proppant in the entire field.
Conclusions: Even in "tight" gas wells, ISP was justified. This interesting method to consider riskanalyses may be particularly desirable in a braided-stream deposit, where reservoir quality and areal extent is hard to predict from logs. Please note for this analysis that the authors "combined" results of using pre-cured resin coated sand and low density ceramic proppant into one group to increase the sample population for their ISP category. Multiphase flow effects were found to be significant; and must be considered in frac design. The bibliography references papers showing CfD should exceed 10 to facilitate cleanup of frac fluids.
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