Fracturing-Treatment Design and Reservoir Properties Impact Shale-Gas Production

Abstract

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper IPTC 16400, ’Analysis of the Impact of Fracturing-Treatment Design and Reservoir Properties on Production From Shale-Gas Reservoirs,’ by C.E. Cohen, C. Abad, X. Weng, K. England, A. Phatak, O. Kresse, O. Nevvonen, V. Lafitte, and P. Abivin, Schlumberger, prepared for the 2013 International Petroleum Technology Conference, Beijing, 26-28 March. The paper has not been peer reviewed. This paper sheds light on the nonlinear physics involved in the production of shale-gas reservoirs by improving the understanding of the complex relation between gas production, reservoir properties, and several treatment-design parameters. The authors ran 28 simulations to cover the 2D parametric space of proppant size and fracturing-fluid viscosity for a range of parameters (detailed in the complete paper). More than 1,400 simulations were run in this parametric study, and the results provide guidelines for optimized treatment design. Introduction Production from shale-gas reservoirs depends greatly on the efficiency of stimulation. The accumulated experience in our industry with the technique of hydraulic fracturing has led to best practices in treatment design that have contributed to the rapid increase in productivity of shale-gas wells over the last decade. The objective of this paper is to present a parametric study on the relation between the parameters of a treatment design and the production outcome based on numerical simulation. To generate an extensive number of simulations, the workflow is automated with a script that sequentially runs all the simulation cases, archives the results, generates visualization outputs, and creates a simulation report. This method enables more than 100 simulations overnight, depending on the complexity of the cases. The methodology used in this study begins with constructing a base case built from the Marcellus shale data. The outputs for each set of simulations are accumulated production after 6 months, 1 year, and 3 years; total propped length and average propped conductivity are regarded as a function of both proppant size and fluid viscosity. A total of 1,467 cases was simulated for this parametric study (see the complete paper for a full discussion of results of these simulations). Base Case For the base case of this parametric study, permeability is 200 nd and the horizontal stress anisotropy is 1%. The conductivity of unpropped fractures is fixed at 0.001 md-ft. The completion is a horizontal well, and the base case is a single stage of pumping through four perforation clusters that are 100 ft from each other. The treatment is made up of 224,576 gal of fracturing fluid and 183,700 lbm of proppant pumped at 80 bbl/min. The schedule begins with 18% of pad followed by slurry with a proppant concentration of 1 ppa. For simplicity, the fracturing fluid is assumed to have Newtonian rheological behavior.