Segregated Flow is the Governing Mechanism of Disproportionate Permeability Reduction in Water and Gas Shutoff

Abstract

Segregated Flow is the Governing Mechanism of Disproportionate Permeability Reduction in Water and Gas Shutoff A. Stavland; A. Stavland RF - Rogaland Research Search for other works by this author on: This Site Google Scholar S. Nilsson S. Nilsson RF - Rogaland Research Search for other works by this author on: This Site Google Scholar Paper presented at the SPE Annual Technical Conference and Exhibition, New Orleans, Louisiana, September 2001. Paper Number: SPE-71510-MS https://doi.org/10.2118/71510-MS Published: September 30 2001 Connected Content Related to: Governing Mechanism of Disproportionate Permeability Reduction Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Get Permissions Search Site Citation Stavland, A., and S. Nilsson. "Segregated Flow is the Governing Mechanism of Disproportionate Permeability Reduction in Water and Gas Shutoff." Paper presented at the SPE Annual Technical Conference and Exhibition, New Orleans, Louisiana, September 2001. doi: https://doi.org/10.2118/71510-MS Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll ProceedingsSociety of Petroleum Engineers (SPE)SPE Annual Technical Conference and Exhibition Search Advanced Search AbstractThis paper describes the mechanism for disproportionate permeability reduction (DPR). Recent papers have discussed possible DPR mechanisms. Most of the papers conclude that there is not yet a single factor that determines DPR. The intention of this paper is to clarify that there is a single model, which explains the observed DPR effects. This model relies on segregated flow of oil and water at pore level and on continuity in the oil phase at placement of the DPR fluid. With this model DPR is demonstrated for both gel and single polymer systems at different wettabilities. Oil continuity is normally easier to obtain for single polymers than for crosslinked gels. Gel systems may, however, be more robust. The paper describes a method for placement of water-soluble gel while maintaining open pathways for oil. Additionally, it is shown that using the phase permeability reduction ratio is not a good measure for defining optimum DPR. Therefore a new selectivity parameter is introduced which demonstrates to be more effective.IntroductionIt is commonly accepted that DPR reduces water permeability more than oil (or gas) permeability and therefore, may be a method for water shutoff. A number of publications have discussed DPR. It seems to be a general understanding that DPR is most effective when used against water production caused by coning or in situations where the watered out layers are separated from the oil producing layers. In situations with 2-phase flow a DPR treatment (even an idealized) will cause an increased pressure drawdown because of water saturation buildup in the treated zone.1 The producing WOR is in such situations the same as before the treatment.However, the same general understanding of the governing mechanism for DPR has not yet been reached. The literature has suggested different mechanisms. The most frequent proposed methods are:Polymer adsorption at the pore surface and the possibility to alter the wettability to more water-wet situation as well as some lubrication effectsSelective shrinking (or dehydration) and swelling of polymer and crosslinked gelSegregated flow of oil and waterBalance between the opposing capillary forces and elastic confining forcesFinally, there are suggestions that there could be combinations of these mechanisms. One reason for the lack of consensus about DPR mechanisms may be that DPR is observed for both single polymers and crosslinked gel. It has been argued that DPR depends on the reservoir characteristics (e.g. lithology, pore size distribution and wettability).This paper intends to demonstrate that it is possible to easily explain that the governing mechanism for all types of DPR fluid is caused by segregated flow. In this context segregated pathways, can either result from preferred flow of one phase in a certain set of channels or result from preferred flow of one phase in defined parts of the channel. Keywords: water saturation, gel, corey exponent, pore, restriction, permeability, placement, dpr effect, mechanism, smallest pore Subjects: Reservoir Fluid Dynamics, Improved and Enhanced Recovery, Flow in porous media This content is only available via PDF. 2001. Society of Petroleum Engineers You can access this article if you purchase or spend a download.