SPE Journal
Volume 14, Number 4, December 2009, pp. 721-736

SPE-109799-PA

Analysis of Injection/Falloff Data From Horizontal Wells

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DOI  More information 10.2118/109799-PA http://dx.doi.org/10.2118/109799-PA

Citation

  • Boughrara, A.A. and Reynolds, A.C. 2009. Analysis of Injection/Falloff Data From Horizontal Wells. SPE J.  14 (4): 721-736. SPE-109799-PA. doi: 10.2118/109799-PA.

Discipline Categories

  • 6 Reservoir Description and Dynamics
  • 6.6 Reservoir Monitoring/Formation Evaluation

Keywords

  • nonisothermal waterflooding, nonisothermal Buckley-Leverett theory, perturbation theory solutions, inection/falloff testing, nonlinear regression analysis

Summary

We have constructed new approximate analytical solutions for injection and falloff pressure response that include thermal effects that arise when flooding a reservoir with water that has a temperature considerably lower than that of the reservoir. We have developed an optimization code based on the Levenberg-Marquardt algorithm and coupled it with our new approximate analytical solutions to obtain a procedure for data analysis where our approximate analytical solutions are used as the forward model in the nonlinear regression. We demonstrate that we can generate estimates of absolute permeabilities, the well skin factor, the length of the well and relative premeabilities by matching data to analytical solutions by minimization of a weighted least squares objective function. The relative permeability curves are constructed assuming a power law parametrization. In the horizontal well case, we show that the absolute permeabilities in the three principal directions can be resolved separately, provided the duration of the test is sufficiently long.

Introduction

Heat transfer must occur whenever a temperature difference exists in a medium or between media. When cold water is injected into a hot reservoir, the formation around the water injector will cool down to the temperature of the injected water. This creates a cold water bank around the injector that expands with time into the reservoir. Similar to the saturation front, the temperature front will also propagate in the reservoir. Both the solid and fluid phases contribute to the heat transfer. The heat exchange in the reservoir occurs mainly through three processes: convective heat transfer between injected fluid and solid matrix, heat conduction (vertical and horizontal conduction), and heat transfer by radiation. The last mechanism is not considered to be important in porous media and, therefore, is usually neglected when the gas phase is not involved.

© 2009. Society of Petroleum Engineers

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History

  • Original manuscript received: 1 August 2007
  • Meeting paper published: 11 November 2007
  • Revised manuscript received: 15 June 2008
  • Manuscript approved: 3 July 2008
  • Published online: 8 October 2009
  • Version of record: 22 December 2009