Title: Evaluation of sweep efficiency in flooding process of reservoir development using substitution index

Authors: Zhaoqi Fan; Linsong Cheng; Zhenhua Rui

Addresses: Department of Petroleum Engineering, China University of Petroleum (Beijing), 18 Fuxue Road, Changping, Beijing 102249, China ' Department of Petroleum Engineering, China University of Petroleum (Beijing), 18 Fuxue Road, Changping, Beijing 102249, China ' Independent Project Analysis, Inc., 44426 Atwater Drive, Ashburn, Virginia 20147, USA

Abstract: On the basis of a mathematically proposed concept, substitution index (SI), a practical method has been successfully applied to accurately evaluate the sweep efficiency during the development of reservoirs (e.g., waterflooding or polymer flooding). More specifically, the region that is swept by the injected water or the degree of sweeping in a specific region can be quantitively determined by means of the concept SI. As such, SI is considered to not only reflect the exchange degree in the pore between the injected water and initial oil from the microscopic view, but also describe the sweep performance of the whole field from the macroscopic view. Furthermore, a low-permeability reservoir (1.8 mD), which grows abundant high permeability channels and the large throats, is introduced as the case study to validate the proposed evaluation method for sweep efficiency in the process of its development. Waterflooding is firstly applied to recover oil in this field, and then profile control technique by injecting polymer-microsphere is implemented. Finally, it is found that the sweep efficiency increases from 0.282 to 0.311 before and after the polymer-microsphere injection. [Received: June 7, 2012; Accepted: May 27, 2013]

Keywords: substitution index; sweep efficiency; polymer microspheres; profile control; migration; flooding process; reservoir development; water flooding; polymer flooding; oil recovery; low-permeability reservoirs.

DOI: 10.1504/IJOGCT.2015.066930

International Journal of Oil, Gas and Coal Technology, 2015 Vol.9 No.1, pp.1 - 13

Received: 07 Jun 2012
Accepted: 27 May 2013
Published online: 18 Mar 2015 *

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