ASTM D3875-15(2023)

Standard Test Method for Alkalinity in Brackish Water, Seawater, and Brines

SIGNIFICANCE AND USE
5.1 Alkalinity as carbonate and bicarbonate of saline water is very important in chemical waterflooding or tertiary recovery processes for recovering petroleum. Alkaline waters offer better wetting to the formation rock and improve oil release. As an additional benefit, ions that provide alkalinity adsorb on rock surfaces occupying adsorption sites and decrease the loss of recovery chemical by adsorption. Determination of alkalinity in waters used in tertiary recovery processes is therefore very important.  
5.2 An alkalinity value is necessary in the calculation of carbonate scaling tendencies of saline waters. It is also necessary to determine the alkalinity if the ionic balance of a water analysis is to be used as a check of the reliability of the analysis.
SCOPE
1.1 This test method covers the determination of alkalinity in brackish water, seawater, and brines.  
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 31-Mar-2023
• ICS: 13.060.50 - Examination of water for chemical substances
• Technical Committee: D19 - Water
• Drafting Committee: D19.05 - Inorganic Constituents in Water

Relations

• Refers: ASTM D1129-13(2020)e2 - Standard Terminology Relating to Water
• Effective Date: 01-May-2020
• Refers: ASTM D2777-12 - Standard Practice for Determination of Precision and Bias of Applicable Test Methods of Committee D19 on Water
• Effective Date: 15-Jun-2012
• Refers: ASTM D3370-10 - Standard Practices for Sampling Water from Closed Conduits
• Effective Date: 01-Dec-2010
• Refers: ASTM D1129-10 - Standard Terminology Relating to Water
• Effective Date: 01-Mar-2010
• Refers: ASTM D3370-08 - Standard Practices for Sampling Water from Closed Conduits
• Effective Date: 01-Oct-2008
• Refers: ASTM D2777-08 - Standard Practice for Determination of Precision and Bias of Applicable Test Methods of Committee D19 on Water
• Effective Date: 15-Jan-2008
• Refers: ASTM D3370-07 - Standard Practices for Sampling Water from Closed Conduits
• Effective Date: 01-Dec-2007
• Refers: ASTM D1129-06a - Standard Terminology Relating to Water
• Effective Date: 01-Sep-2006
• Refers: ASTM D1129-06ae1 - Standard Terminology Relating to Water
• Effective Date: 01-Sep-2006
• Refers: ASTM D2777-06 - Standard Practice for Determination of Precision and Bias of Applicable Test Methods of Committee D19 on Water
• Effective Date: 15-Aug-2006
• Refers: ASTM D1193-06 - Standard Specification for Reagent Water
• Effective Date: 01-Mar-2006
• Refers: ASTM D1129-06 - Standard Terminology Relating to Water
• Effective Date: 15-Feb-2006
• Refers: ASTM D1129-04 - Standard Terminology Relating to Water
• Effective Date: 01-Mar-2004
• Refers: ASTM D1129-04e1 - Standard Terminology Relating to Water
• Effective Date: 01-Mar-2004
• Refers: ASTM D1129-03a - Standard Terminology Relating to Water
• Effective Date: 10-Aug-2003

Overview

ASTM D3875-15(2023) specifies the standard test method for determining alkalinity in brackish water, seawater, and brines. Developed and maintained by ASTM International, this test method is essential in water analysis for industrial, environmental, and petroleum recovery applications. Accurate assessment of alkalinity - mainly as carbonate and bicarbonate ions - is crucial for chemical processes, especially in tertiary oil recovery and scaling tendency evaluation. This standard provides a reliable framework to ensure the consistency and validity of results across laboratories and industries globally.

Key Topics

• Alkalinity Measurement: Outlines how to determine the alkalinity content in saline waters, specifically focusing on carbonate and bicarbonate ions.
• Test Method: Utilizes an electrotitrator or pH meter to track acid addition to the sample until key pH endpoints (pH 8.1 and 4.5) are reached, indicating neutralization of relevant ions.
• Quality Control: Emphasizes strict calibration, blank analysis, duplicate testing, and laboratory control sample analysis to ensure accuracy and reliability.
• Interferences: Notes the potential impact of other anions (e.g., borate, silicate, sulfide, phosphate) and certain organic materials on test outcomes.
• Safety and Compliance: Advises that users establish appropriate safety, health, and environmental protocols and ensure conformity with regulatory requirements.
• International Relevance: Developed under WTO principles, ensuring global applicability.

Applications

ASTM D3875-15(2023) is widely used in multiple sectors requiring precise alkalinity determination:

• Petroleum Industry: In chemical waterflooding and tertiary oil recovery, alkalinity enhances oil release by improving rock wettability and reducing chemical losses through adsorption. Accurate measurement supports more efficient oil recovery operations and resource management.
• Scaling Tendency Evaluation: Alkalinity data are critical in calculating the likelihood of carbonate scale formation in industrial and municipal water systems, aiding in preventive maintenance.
• Water Quality Control: Used in environmental monitoring and analysis of brackish water and seawater samples, ensuring data integrity and analytical validity.
• Industrial Water Treatment: Supports process optimization and troubleshooting in facilities utilizing or producing saline waters.

Related Standards

Several ASTM standards support or complement ASTM D3875-15(2023):

• ASTM D1129: Terminology Relating to Water - Defines key terms for consistency across water testing standards.
• ASTM D1193: Specification for Reagent Water - Specifies purity requirements for water used in analytical methods.
• ASTM D2777: Practice for Determination of Precision and Bias of Applicable Test Methods - Guidance for establishing method accuracy and consistency.
• ASTM D3370: Practices for Sampling Water from Flowing Process Streams - Rules for proper water sample collection.
• ASTM D5847: Practice for Writing Quality Control Specifications for Standard Test Methods for Water Analysis - Ensures robust QC processes.
• ASTM E200: Practice for Preparation, Standardization, and Storage of Standard and Reagent Solutions for Chemical Analysis - Preparation of accurate reagents.

Practical Value

Implementing ASTM D3875-15(2023) for the determination of alkalinity in brackish water, seawater, and brines supports:

• Better management of water resources in petroleum recovery
• Enhanced operational efficiency by preventing scaling and optimizing reagent use
• Improved consistency and reliability in water sample analysis
• Confidence in results through rigorous quality control measures

This standard is integral for laboratories, water treatment facilities, and energy companies aiming to ensure precise water analysis and maintain compliance with international norms.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D3875 − 15 (Reapproved 2023)
Standard Test Method for
Alkalinity in Brackish Water, Seawater, and Brines
This standard is issued under the fixed designation D3875; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 4. Summary of Test Method
1.1 This test method covers the determination of alkalinity 4.1 An electrotitrator or pH meter is used to determine the
in brackish water, seawater, and brines. amount of acid necessary to reach pH 8.1 and 4.5, respectively.
The pH values approximate the points where the hydroxide and
1.2 The values stated in SI units are to be regarded as
bicarbonate ions are neutralized.
standard. No other units of measurement are included in this
standard.
5. Significance and Use
1.3 This standard does not purport to address all of the
5.1 Alkalinity as carbonate and bicarbonate of saline water
safety concerns, if any, associated with its use. It is the
is very important in chemical waterflooding or tertiary recov-
responsibility of the user of this standard to establish appro-
ery processes for recovering petroleum. Alkaline waters offer
priate safety, health, and environmental practices and deter-
better wetting to the formation rock and improve oil release. As
mine the applicability of regulatory limitations prior to use.
an additional benefit, ions that provide alkalinity adsorb on
1.4 This international standard was developed in accor-
rock surfaces occupying adsorption sites and decrease the loss
dance with internationally recognized principles on standard-
of recovery chemical by adsorption. Determination of alkalin-
ization established in the Decision on Principles for the
ity in waters used in tertiary recovery processes is therefore
Development of International Standards, Guides and Recom-
very important.
mendations issued by the World Trade Organization Technical
5.2 An alkalinity value is necessary in the calculation of
Barriers to Trade (TBT) Committee.
carbonate scaling tendencies of saline waters. It is also neces-
2. Referenced Documents
sary to determine the alkalinity if the ionic balance of a water
analysis is to be used as a check of the reliability of the
2.1 ASTM Standards:
analysis.
D1129 Terminology Relating to Water
D1193 Specification for Reagent Water
6. Interferences
D2777 Practice for Determination of Precision and Bias of
Applicable Test Methods of Committee D19 on Water
6.1 Anions other than bicarbonate, carbonate, or hydroxide
D3370 Practices for Sampling Water from Flowing Process ions that form weakly dissociated acids that participate in
Streams
hydrolysis reactions may also contribute to the alkalinity as
D5847 Practice for Writing Quality Control Specifications may some organic materials. The user of this test method on
for Standard Test Methods for Water Analysis
determining the alkalinity is cautioned that all the effects of the
E200 Practice for Preparation, Standardization, and Storage anions entering into hydrolysis reactions are combined and
of Standard and Reagent Solutions for Chemical Analysis
reported as an equivalent amount of a single substance or two
postulated ions. Included in the reported value is the alkalinity
3. Terminology
resulting from the presence of borate, silicate, sulfide, and
3.1 Definitions—For definitions of terms used in this test phosphate. The effect of borate on the alkalinity value is
method, refer to Terminology D1129.
considered negligible for waters with pH values of 7 or less.
7. Apparatus
This test method is under the jurisdiction of ASTM Committee D19 on Water
and is the direct responsibility of Subcommittee D19.05 on Inorganic Constituents
7.1 Electrotitrator or Standard pH Meter with suitable
in Water.
electrodes. Maintenance and standardization of electrodes and
Current edition approved April 1, 2023. Published April 2023. Originally
pH meter should follow manufacturer’s instructions because
approved in 1980. Last previous edition approved in 2015 as D3875 – 15. DOI:
10.1520/D3875-15R23.
performance can be affected by improper treatment.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
NOTE 1—Automatic titrators with combined pH electrode are found
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on useful to increase reliability and save time. The use of an automatic titrator
the ASTM website. is recommended in the procedure.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D3875 − 15 (2023)
7.2 Buret, 10-mL micro. 11. Calculation
11.1 Results of the titration offer a means for the stoichio-
8. Reagents
metric classification of the three principal forms of alkalinity.
8.1 Purity of Reagents—Reagent grade chemicals shall be The presence of the ions may be indicated by the relationships
shown in Table 1 (Note 3). Using Table 1, make the following
used in all tests. Unless otherwise indicated, it is intended that
all reagents shall conform to the specifications of the Commit- calculations:
tee on Analytical Reagents of the American Chemical Society,
NOTE 3—The presence of interferences (see 6.1) may produce errors in
where such specifications are available. Other grades may be
these relationships.
used, provided it is first ascertained that the reagent is of
11.2 Bicarbonate:
sufficiently high purity to permit its use without lessening the
HCO , mg/L 5 A × N × 61 × 1000 /M
~ !
accuracy of the determination. 3
where:
8.2 Purity of Water—Unless otherwise indicated, reference
to water shall be understood to mean reagent water conforming
A = millilitres of acid,
to Specification D1193, Type I. Other reagent water types may
N = normality of acid, and
M = millilitres of sample.
be used provided it is first ascertained that the water is of
sufficiently high purity to permit its use without adversely
11.3 Carbonate:
affecting the bias and precision of this test method. Type II
CO , mg/L 5 A × N × 30 × 1000 /M
~ !
water was specified at the time of round-robin testing of this
11.4 Hydroxyl:
test method.
OH , mg/L 5 A × N × 17 × 1000 /M
8.3 Sulfuric or Hydrochloric Acid, Standard Solution (not ~ !
exceeding 0.1 N)—See Practice E200 for preparation and
11.5 Results of titrations to specific end points may alterna-
standardization of acid.
tively be reported as follows: The alkalinity to pH ___ at
___,°C = ___ meq/L (epm).
8.4 Buffer Solutions (pH 4, 7, and 10). These pH buffers are
available from many chemical suppliers.
12. Precision and Bias
9. Sampling 12.1 The precision of this test method within its designated
range may be expressed as follows:
9.1 Collect the sample in accordance with Practices D3370.
S 5 0.005X12.8
T
10. Procedure
S 5 0.0076X10.375
O
10.1 Standardize the pH meter at a pH close to that of the
where:
samples. Normally this would be pH 7 for oilfield waters.
S = overall precision,
T
However, depending on the source of the sample, it may be as
S = single-operator precision, and
O
low as pH 4 or as high as pH 10. Check the meter periodically
X = concentration of alkalinity determined, mg/L.
with three buffers. Standardize the meter to 7 with pH 7 buffer
Because of the instability of solutions prepared for alkalinity
and check its response at 4 and 10 with pH 4 and pH 10 buffers
determinations, no statement of the accuracy of these measure-
(within 0.1 pH unit). This is important. Serious errors can result
ments is practical. In determining the precision, six operators
if only one buffer is always used.
from five different laboratories analyzed three samples in
10.2 Make this analysis immediately after determining the
duplicate on the same day.
pH in order to minimize errors due to decomposition of the
bicarbonate of the sample. Transfer an undiluted sample,
usually 50 mL to 100 mL, into a beaker.
Supporting data have b
...