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SOME EXPERIENCE IN SOFTENING THE OILFIELD WATERS BY ION EXCHANGE FOR STEAMFLOOD OPERATION James C. T. Chen, Manager R. O. Engineering Department Koomey Inc. Brookshire, Texas 77423 SUMMARY The needs for softening oilfield produced water for steamflood operations are ever increasing. However, high total dissolved solids (TDS) level of produced water and stringent trace hardness requirement of steamflood water render the processes such as single softening and ion exchanges using strong or weak acid resins either technically or economically unfeasible. Furthermore, few field data or guidelines exist forming the basis of process selection. This paper proposes guidelines and/or limitations for the selection of the softening processes when treating oilfield produced waters. These guidelines were developed based on some field experiences with counter-current regeneration of two-stage series sodium zeolite softening. Influence of salt dosage and hardness on series softener performance was discussed. Salt dosage and quality were found to be critical in softening high TDS water and less critical for low TDS water. INTRODUCTION Selection of viable ion exchange processes for use in softening water for oilfield steam generation is governed mainly by the TDS of the water. These viable processes include: 1) single-stage zeolite; 2) two-stage zeolite; 3) single-stage zeolite followed by carboxylic polisher; and 4) lime soda softening followed by carboxylic polisher. Single-stage zeolite softening with downflow regeneration has been reported to be successful when the TDS of water is below 1,000 mg/1; two-stage zeolite has been operated satisfactorily where TDS of the water is below 3,000. For TDS higher than 3,000 mg/1, single-stage zeolite followed by carboxylic polisher and hot lime softening followed by carboxylic polisher has also been successfully employed. Carboxylic polisher using the sodium cycle is the preferred process because the ion exchange proceeds rapidly and the capacity is not so sensitive to flow rate and temperature as is the hydrogen cycle. The estimated hardness leakage from zeolite softening was based on the TDS of the water and salt dosage used for regeneration. Little information is available regarding hardness leakage attributable to the impurity of salt used for regeneration. Salt impurity becomes more critical when coun- tercurrent regeneration of two-stage zeolite softening is utilized. Any hardness ions retained in the bottom of the resin bed will leak out during the initial normal run. The objectives of this paper are to: 1. determine ihe impacts of impurity salt on the softening capacity and hardness leakage from a two-stage zeolite, 2. determine guidelines and/or limitations for selecting the softening processes when treating oilfield produced water for steamflood operation, and 3. suggest certain parameters used for designing the softeners. THEORY An equation for predicting the hardness leakage level has been developed and is presented below: [B~,=7*(T^ 225
Object Description
Purdue Identification Number | ETRIWC198524 |
Title | Some experience in softening the oilfield waters by ion exchange for steamflood operation |
Author | Chen, James C. T. |
Date of Original | 1985 |
Conference Title | Proceedings of the 40th Industrial Waste Conference |
Conference Front Matter (copy and paste) | http://e-archives.lib.purdue.edu/u?/engext,36131 |
Extent of Original | p. 225-238 |
Collection Title | Engineering Technical Reports Collection, Purdue University |
Repository | Purdue University Libraries |
Rights Statement | Digital object copyright Purdue University. All rights reserved. |
Language | eng |
Type (DCMI) | text |
Format | JP2 |
Date Digitized | 2009-07-14 |
Capture Device | Fujitsu fi-5650C |
Capture Details | ScandAll 21 |
Resolution | 300 ppi |
Color Depth | 8 bit |
Description
Title | page 225 |
Collection Title | Engineering Technical Reports Collection, Purdue University |
Repository | Purdue University Libraries |
Rights Statement | Digital copyright Purdue University. All rights reserved. |
Language | eng |
Type (DCMI) | text |
Format | JP2 |
Capture Device | Fujitsu fi-5650C |
Capture Details | ScandAll 21 |
Transcript | SOME EXPERIENCE IN SOFTENING THE OILFIELD WATERS BY ION EXCHANGE FOR STEAMFLOOD OPERATION James C. T. Chen, Manager R. O. Engineering Department Koomey Inc. Brookshire, Texas 77423 SUMMARY The needs for softening oilfield produced water for steamflood operations are ever increasing. However, high total dissolved solids (TDS) level of produced water and stringent trace hardness requirement of steamflood water render the processes such as single softening and ion exchanges using strong or weak acid resins either technically or economically unfeasible. Furthermore, few field data or guidelines exist forming the basis of process selection. This paper proposes guidelines and/or limitations for the selection of the softening processes when treating oilfield produced waters. These guidelines were developed based on some field experiences with counter-current regeneration of two-stage series sodium zeolite softening. Influence of salt dosage and hardness on series softener performance was discussed. Salt dosage and quality were found to be critical in softening high TDS water and less critical for low TDS water. INTRODUCTION Selection of viable ion exchange processes for use in softening water for oilfield steam generation is governed mainly by the TDS of the water. These viable processes include: 1) single-stage zeolite; 2) two-stage zeolite; 3) single-stage zeolite followed by carboxylic polisher; and 4) lime soda softening followed by carboxylic polisher. Single-stage zeolite softening with downflow regeneration has been reported to be successful when the TDS of water is below 1,000 mg/1; two-stage zeolite has been operated satisfactorily where TDS of the water is below 3,000. For TDS higher than 3,000 mg/1, single-stage zeolite followed by carboxylic polisher and hot lime softening followed by carboxylic polisher has also been successfully employed. Carboxylic polisher using the sodium cycle is the preferred process because the ion exchange proceeds rapidly and the capacity is not so sensitive to flow rate and temperature as is the hydrogen cycle. The estimated hardness leakage from zeolite softening was based on the TDS of the water and salt dosage used for regeneration. Little information is available regarding hardness leakage attributable to the impurity of salt used for regeneration. Salt impurity becomes more critical when coun- tercurrent regeneration of two-stage zeolite softening is utilized. Any hardness ions retained in the bottom of the resin bed will leak out during the initial normal run. The objectives of this paper are to: 1. determine ihe impacts of impurity salt on the softening capacity and hardness leakage from a two-stage zeolite, 2. determine guidelines and/or limitations for selecting the softening processes when treating oilfield produced water for steamflood operation, and 3. suggest certain parameters used for designing the softeners. THEORY An equation for predicting the hardness leakage level has been developed and is presented below: [B~,=7*(T^ 225 |
Resolution | 300 ppi |
Color Depth | 8 bit |
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