1、 SEPTEMBER 2006 SPECIAL NOTES API publications necessarily address problems of a general nature. With respect to particular circumstances, local, state, and federal laws and regulations should be reviewed. Neither API nor any of APIs employees, subcontractors, consultants, committees, or other assig
2、nees make any warranty or representation, either express or implied, with respect to the accuracy, completeness, or usefulness of the information contained herein, or assume any liability or responsibility for any use, or the results of such use, of any information or process disclosed in this publi
3、cation. Neither API nor any of APIs employees, subcontractors, consultants, or other assignees represent that use of this publication would not infringe upon privately owned rights. API publications may be used by anyone desiring to do so. Every effort has been made by the Institute to assure the ac
4、curacy and reliability of the data contained in them; however, the Institute makes no representation, warranty, or guarantee in connection with this publication and hereby expressly disclaims any liability or responsibility for loss or damage resulting from its use or for the violation of any author
5、ities having jurisdiction with which this publication may conflict. API publications are published to facilitate the broad availability of proven, sound engineering and operating practices. These publications are not intended to obviate the need for applying sound engineering judgment regarding when
6、 and where these publications should be utilized. The formulation and publication of API publications is not intended in any way to inhibit anyone from using any other practices. Any manufacturer marking equipment or materials in conformance with the marking requirements of an API standard is solely
7、 responsible for complying with all the applicable requirements of that standard. API does not represent, warrant, or guarantee that such products do in fact conform to the applicable API standard. Cover photo: A produced water-impacted plot (left) contrasts with an adjoining salt-flat remediation p
8、lot (right) where the thriving halophyte, marsh hay cordgrass (Spartina sp.), was planted as plugs about five years previously in the Smackover oilfield of south Arkansas. Photo courtesy of David J. Carty, GreenBridge EarthWorks All rights reserved. No part of this work may be reproduced, stored in
9、a retrieval system, or transmitted by any means, electronic, mechanical, photocopying, recording, or otherwise, without prior written permission from the publisher. Contact the Publisher, API Publishing Services, 1220 L Street, N.W., Washington, D.C. 20005. Copyright 2006 American Petroleum Institut
10、e1 Strategies for Addressing Salt Impacts of Produced Water Releases to Plants, Soil, and Groundwater CHARLES J. NEWELL AND JOHN A. CONNOR GROUNDWATER SERVICES, INC. PURPOSE OF THIS GUIDE The exploration and production (E GO TO PAGE 4 Source: API Publication 4663 TECH TIP: See Page 17 for definition
11、s of EC, CEC, TDS, ESP, and SAR . IF THESE SOIL CONDITIONS RESULT FROM PRODUCED WATER RELEASE. RULE OF THUMB IS: Case 2 Case 3 Case 4 A RELEASE WILL MOST LIKELY NOT HARM SOILS AND/OR PLANTS MOST LIKELY NOT CLEARLY WILL NOT BE A SOIL FERTILITY ISSUE Source: API Publication 4663 WILL NOT CLEARLY WILL
12、NOT BE A SOIL FERTILITY ISSUE Source: API Publication 4663 WILL NOT Affected Soil EC 16 mmhos/cm Affected Soil ESP 22% (SAR 20) OR CASE 1 Produced Water TDS 100 bbls AND Produced Water With Chloride Greater Than 100,000 mg/L Depth to Groundwater 10 ft AND AND OR OR CASE 1 2CASE 3 2CASE 2 2SEPTEMBER
13、2006 4 DECISION CHART FOR SOIL / PLANT IMPACTS Evaluating Impacts - SOIL For those sites where produced water impacts to soils requires a corrective action, the following decision chart can be used to select appropriate remedial measures. More detail on specific technologies is provided on pages 7 8
14、. Decision Chart for Salt-Impacted Soils (Adapted from API Publication 4663)SEPTEMBER 2006 5 DECISION CHART FOR SOIL / PLANT IMPACTS (Continued) Evaluating Impacts - SOIL Decision Chart for Salt-Impacted Soils - Continued (Adapted from API Publication 4663)SEPTEMBER 2006 6 NATURAL REMEDIATION OF SOI
15、L IMPACTS Responding to Impacts - SOIL ACCEPTABLE PRECIPITATIONRATES SOIL TYPE SEEDING RATE SEEDING DRILL DEPTH GRASS HABIT Min (in/yr) Max (in/yr) L-M-H U.S. PLANTING SEASON (lbs/ac PLS drilled)(inches) Alkali Sacaton Bunch 8 18 L-M-H Summer 1/51/4Basin Wildrye Bunch 9 Irrigation OK L-M-H Late Fall
16、/Spring 5 1 Western Wheatgrass Sod 10 20 M-H Early Fall/Spring 8 1/2- 1 Beardless Wildrye Sod 20 Irrigation OK M-H Late Fall/Spring 8 3/4Tall Wheatgrass Bunch 5 20 L-M-H Spring 8 1/2- 2 NOTES: This table only presents a few of the grasses that can be used for revegetation. A number of other grasses
17、(such as Bermuda grass) are presented in API Publication 4663 and other literature. SOIL TYPE: L = LIGHT - sands, loamy fine sands, sandy loams M = MEDIUM - silty loams, loams, very fine sandy loams, sandy clay loams H = HEAVY - clay loams, silty clays, clay PLS = Pure Live Seeds. Natural Remediatio
18、n In-situ Chemical Amendment Mechanical RemediationOPTION B. Plant Salt-Tolerant Vegetation OPTION A. Monitored Natural Revegetation Approach: Allow natural revegetation to occur over 1-to 3-year time period and monitor the revegetation process. The affected area should be monitored for barren zones
19、 and stressed vegetation over time. If monitoring shows revegetation process is too slow, consider other methods. This method works best with sandy soils and soils containing limited clay. In some cases adding mulch, fertilizer, and water (see Option B, below) can speed up revegetation. Approach: Pl
20、ant halophytic vegetation that is suitable for the climate and the soil conditions and that can tolerate elevated salinity (see table below for examples of halophytic grasses). Add mulch and fertilizer as necessary: Mulch Rule of Thumb: Till in 2 to 4 inches of mulch over affected area (less for coa
21、rse soils, more for fine-grained soils; about five 60-lb bales of hay for every 1000 sq. feet). Fertilizer Rule of Thumb: Add about 28 pounds of 13-13-13 fertilizer for every 1000 sq. feet. (For more detail, see API Publication 4663) (Dont add too much fertilizer in a soil; fertilizers can act like
22、salts.) Watering Rule GENERALLY DO NOT ADD WATER BY ITSELF IF SALT IMPACT HAS of Thumb: ALREADY ENTERED SOILS CONTAINING CLAY. IF YOU ARE GOING TO ADD WATER, FIRST ADD CHEMICAL AMENDMENTS (see next page). For more detailed information on mulch / fertilizer addition, see API Publication 4663. Soil Re
23、mediation Alternative 1: Natural Remediation Concept: Use plants and natural water flushing to restore salt-impacted soils. This option is preferable in cases where remediation equipment can create additional soil damage (such as wetlands). EXAMPLES OF GRASSES THAT MAY BE USED FOR REVEGETATION Halop
24、hyte-assisted natural remediation Photo Courtesy of David Carty SEPTEMBER 2006 7 IN-SITU CHEMICAL AMENDMENT OF SOIL IMPACTS Responding to Impacts - SOIL Calculation Method 2: Amount of Gypsum Based on Strength of Produced Water Release Formula: Calculation Steps: 1. Calculate lbs of gypsum to add us
25、ing formula shown above. 2. Note that sodium typically comprises 20-35% of the TDS concentration, and can be estimated as (0.2 to 0.35) x TDS (mg/L). Add Gypsum or Other Amendment Approach: 1) Improve drainage, if necessary. 2) Calculate how much gypsum to add using Calculation Method 1 or Method 2
26、(below) or use this Rule of Thumb: Add 13 pounds of gypsum per 100 sq. feet of impacted soil 3) Add chemical amendments to affected soil. Solid Amendment: Incorporate from surface to depth of 1 to 2 ft using plow. Make sure amendment is in powdered or granular form. Liquid Amendment: Apply over soil
27、 surface with or without mechanical incorporation. 4) Adding mulch and fertilizer may enhance rapid restoration (see page 6). 5) Use perimeter berms to contain rainfall or use sprinkler irrigation in affected area to increase infiltration and leach salts (sodium) from affected soils. Rules of Thumb:
28、 ADD CHEMICAL AMENDMENTS BEFORE IRRIGATION OR A PERIOD OF HEAVY RAIN. Pulse flooding (watering with a few inches of water every few days) can reduce water requirements by half. A final top dressing of gypsum or mulch can protect the soil surface from dispersing after a rainfall or water event. See p
29、age 5 for amount of supplemental irrigation that is needed. Install erosion controls, if necessary. Calculation Method 1: Amount of Gypsum Based on Soil ESP, CEC Formula: Calculation Steps: 1. Perform calculation for 0 to 1 ft layer. 2. Perform calculation again for 1 to 2 ft layer. 3. Add lbs per s
30、q. ft. numbers together. 4. Multiply lbs of gypsum per sq. ft. by area of spill in sq. ft. to get lbs of gypsum. 5. If soil pH is 8.5, then may need to add sulfur or alternative chemical to decrease pH. See API Publication 4663. Natural Remediation Mechanical RemediationIn-situ Chemical Amendment ES
31、P - 5 x CEC x 0.00078 No. of lbs of gypsum to add per square foot of impacted soil = sodium concentration x 6.94 x volume spilled x 0.00019 No. of lbs of gypsum to add to affected area=(in %) (in meq/100 grams) (in pounds) (sodium concentration in mg/L) (volume spilled in bbl; 42 gallons per bbl) (i
32、n pounds / ft2) Addition of Chemical Amendment Photo Courtesy of David Carty TECH TIP 1: If soil pH is between 5.5 and 8.5, and if chloride or nitrate will not impact groundwater, you can replace gypsum with: Calcium Chloride CaCl2:2H20 at 0.85 pounds per pound gypsum requirement Calcium Nitrate Ca(
33、NO3)2 at 0.95 pounds per pound gypsum requirement TECH TIP 2: Adding more than the calculated amount of calcium will not hurt the soil. Calculation Method 1: Amount of Gypsum Needed Based on Soil ESP and CEC Calculation Method 2: Amount of Gypsum Needed Based on Sodium Concentration in Produced Wate
34、r ReleaseSoil Remediation Alternative 2: In-Situ Chemical Amendment Concept: Add a calcium-containing compound, such as gypsum, which serves to replace sodium (which changes the structure and porosity of clays in salt-impacted soils) with calcium and restores the structure of the soil. (See page 19.
35、) SEPTEMBER 2006 8 MECHANICAL REMEDIATION OF SOIL IMPACTS Responding to Impacts - SOIL OPTION C. Road Spreading OPTION D. Soil Washing OPTION E. Off-Site Disposal Approach: Spread salt-affected soil over a large area and mix with unaffected soils to reduce the salt concentration to an acceptable lev
36、el. Use front-end loader or backhoe for small spills; use dozers, trackhoes for larger spills. Use the following method to calculate the required area and thickness for land spreading: Formula 1: (in square feet) (Volume in cubic feet. EC in mmhos/cm) Formula 2: (in feet) (Volume in cubic feet. Area
37、 in square feet) Approach: Construct burial vault that may have one or more of the following features (Source: API Publication 4663): OPTION B. Burial Approach: Check with regulatory agencies to determine how road spreading may be performed. If acceptable, apply salt-affected soils so that salt does
38、 not damage the road bed, roadside vegetation, or significantly affect runoff water (same as with land spreading). Approach: Use soil washing contractor to mix water with salt-affected soil to decrease salinity. Collect rinse water for treatment or disposal. Note this option is likely to be more cos
39、tly than other options. Approach: Excavate and transport salt-affected soil to approved landfill as an exploration and production waste. Transport manifests may be required by some regulatory agencies. Fill excavation with clean fill and plant appropriate vegetation. Natural Remediation In-situ Chem
40、ical Amendment RemediationMechanical Remediation Soil Remediation Alternative 3: Mechanical Remediation Concept: Mechanical Remediation refers to a number of remediation techniques that involve mechanical mixing, spreading, or relocation of the affected soil. OPTION A. Land Spreading Topsoil Layer o
41、f gypsum Clean soil with clay Place capillary barrier of plastic, gravel, or rock above salt-affected soil Layer of sandIf possible, top of salt-affected soil should be at least 6 feet below surface soil. If possible, bottom of salt-affected soil should be at least 5 feet above seasonal high water t
42、able. Mound topsoil and vegetation Volume of salt-affected soil to be spread x (spill soil EC) (receiving soil EC) x 2.6* (final soil EC goal) (receiving soil EC) Area required for spreading =Thickness of salt-affected soil to be spread on received soil Volume of salt-affected soil Area required for
43、 spreading 6 ft 5 ft * This equation assumes 1.3 times expansion factor and a 0.5 foot mixing thickness. SEPTEMBER 2006 9 PRODUCED WATER AND GROUNDWATER Evaluating Impacts - GROUNDWATER Chloride Transport Pathway Chloride associated with a produced water release to the surface can impact surface soi
44、ls and be transported to underlying groundwater. The transport process can be separated into four separate steps as shown below. This guide provides a Planning Model (see below and pages 10-14), that can be used to evaluate this migration process. Information on Beneficial Uses of groundwater is pro
45、vided on page 15. A summary of key parameters that influence chloride transport to groundwater are shown on page 21. Using the Planning Model Results of this modeling are combined with other site-specific information to determine the potential effects on groundwater. To use the Planning Model, perfo
46、rm the following steps: Step 1: Estimate Mass of Chloride using volume and chloride concentration of a produced water release, OR Estimate Mass of Chloride using the area of produced water release (area of affected soil) and the chloride concentration of the soil (page 10) Step 2: Estimate Chloride
47、Loading Rate to Groundwater using the Annual Precipitation, (page 11) Step 3A: Estimate Increase in Chloride Concentration in Groundwater at the Release Point using the width of the release area, (page 12) Step 3B: Refine the estimate from Step 3A using site-specific information (either the site loc
48、ation, or more detailed hydrogeologic info), (page 13) Step 4: (Optional) Estimate the Increase in Chloride Concentration in Groundwater at a Downgradient Point using the distance from the release area (and other parameters), (page 14) Key assumptions and limitations of the Planning Model include: 1
49、) salts are mixed evenly throughout the soil; 2) the percentage of the rainfall that infiltrates through the soil to groundwater is proportional to the amount of rainfall; 3) the recharge rate is the 80thpercentile of recharge rates from data compiled from API Publication 4643; 4) almost all the salts in affected soils can be flushed out with 12 inches of recharge (from API 4663); 5) no capillary effects, evaporation, or other transport
