SPE Reservoir Evaluation & Engineering
Volume 15, Number 1, February 2012, pp. 41-50

SPE-143666-PA

Probabilistic Production Forecasting for Unconventional Reservoirs With Stretched Exponential Production Decline Model

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DOI  More information 10.2118/143666-PA http://dx.doi.org/10.2118/143666-PA

Citation

  • Can, B. and Kabir, C.S. 2012. Probabilistic Production Forecasting for Unconventional Reservoirs With Stretched-Exponential Model. SPE Res Eval & Eng  15 (1): 41-50. SPE-143666-PA. http://dx.doi.org/10.2118/143666-PA.

Discipline Categories

  • 6.7 Reserves Evaluation
  • 6.7.2 Recovery Factors
  • 6.7.4 Probabilistic Methods

Keywords

  • EUR, Unconventional reservoirs, Probabilistic forecasting, Estimated ultimate recovery

Summary

Reserves estimation in an unconventional-reservoir setting is a daunting task because of geologic uncertainty and complex flow patterns evolving in a long, stimulated horizontal well, among other variables. To tackle this complex problem, we present a reserves-evaluation workflow that couples the traditional decline-curve analysis (DCA) with a probabilistic forecasting frame. The stretched-exponential production-decline (SEPD) model underpins the production behavior. Our recovery appraisal workflow has two different applications: forecasting probabilistic future performance of (1) wells that have production history and of (2) new wells without production data. For the new-field case, numerical-model runs are made in accord with the statistical design of experiments (DOE) for a range of design variables pertinent to the field of interest. In contrast, for the producing wells, the early-time data often need adjustments owing to restimulation, installation of artificial lift, or other factors to focus on the decline trend. Thereafter, production data of either new or existing wells are grouped in accordance with maximum rates to obtain common SEPD model parameters for similar wells. After determining the distribution of model parameters using the well-grouping approach, the method establishes a probabilistic forecast for the individual wells.

This paper presents a probabilistic performance-forecasting method in unconventional reservoirs for wells with and without production history. Unlike other probabilistic forecasting tools, grouping wells with similar production character allows estimation of self-consistent SEPD-model parameters and alleviates the burden of having to define uncertainties associated with reservoir and well-completion parameters.

© 2012. Society of Petroleum Engineers

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History

  • Original manuscript received: 7 March 2011
  • Meeting paper published: 14 June 2011
  • Revised manuscript received: 15 September 2011
  • Manuscript approved: 1 November 2011
  • Published online: 9 February 2012
  • Version of record: 29 February 2012