# BAKKEN WATER OPPORTUNITIES

ASSESSMENT – PHASE 1

Final Report Summary

(for the period of June 19, 2009, through March 15, 2010)

Prepared for:

Karlene Fine

North Dakota Industrial Commission

Oil and Gas Research Council

600 East Boulevard Avenue State Capitol, 14th Floor Bismarck, ND 58505-0840

Contract No. G018-036

Prepared by:

Daniel J. Stepan Richard E. Shockey Bethany A. Kurz

Nicholas S. Kalenze

Robert M. Cowan

Joshua J. Ziman

John A. Harju

Energy & Environmental Research Center University of North Dakota 15 North 23rd Street, Stop 9018

Grand Forks, ND 58202-9018

2010-EERC-04-03 April 2010NDIC DISCLAIMER

This report was prepared by the Energy & Environmental Research Center (EERC) pursuant to an agreement partially funded by th e Industrial Commission of North Dakota, and neither the EERC nor any of its subcontractor s nor the North Dakota Industrial Commission nor any person acting on behalf of either:

(A) Makes any warranty or repr esentation, express or impl ied, with respect to the accuracy, completeness, or usefulness of th e information contained in this report or that the use of any information, apparatus, method, or process disclosed in this report may not infringe privately owned rights; or

(B) Assumes any liabilities with respect to the use of, or for damages resulting from the use of, any information, apparatus, method, or process disclose d in this report.

Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the North Dakota Industrial Commission. The views and opinions of authors expressed here in do not necessarily state or reflect those of the North Dakota

Industrial Commission.

DISCLAIMER

This report was prepared as an account of work sponsored by an agency of the United

States Government. Neither the United States G overnment, nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or re presents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States G overnment or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.

This report is available to th e public from the National Techni cal Information Service, U.S. Department of Commerce, 5285 Port Royal Road, Springf ield, VA 22161; phone orders accepted at (703) 487-4650.

EERC DISCLAIMER

LEGAL NOTICE This research report was prepared by the EERC, an agency of the University of North Dakota, as an account of work sponsored by North Dakota Industrial

Commission. Because of the resear ch nature of the work perfor med, neither the EERC nor any of its employees makes any warranty, express or implied, or assumes any legal liability orresponsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or othe rwise does not necessarily consti tute or imply its endorsement or recommendation by the EERC.i TABLE OF CONTENTS

LIST OF FIGURES ............................................................................................................... ......... ii

LIST OF TABLES ................................................................................................................ ......... iii

PROJECT SUMMARY ............................................................................................................... .. iv

INTRODUCTION .................................................................................................................. ........ 1

OBJECTIVE ..................................................................................................................... .............. 1

RESULTS AND DISCUSSION ..................................................................................................... 2

Task 1 – Current Water Use Practices .................................................................................. 2

Task 2 – Flowback Water Characteristics ............................................................................. 5 General Description of Hydraulic Fracturing .............................................................. 5 Flowback Water Quantity ............................................................................................ 8 Flowback Water Quality ............................................................................................ 10 Task 3 – Current Water-Handling Costs ............................................................................. 17

Task 4 – Review of Flowback Water-Recycling Technologies .......................................... 17

Thermal Treatment .................................................................................................... 18

Membrane Treatment ................................................................................................. 22 Task 5 – Flowback Water Treatment Technology Assessment .......................................... 23 Task 6 – Recommendations for Phase 2 Project Deployment ............................................ 24

Task 7 – Information Dissemination Activities .................................................................. 26

REFERENCES .................................................................................................................... ......... 27

BAKKEN FRAC FLOWBACK WA TER SALINITY-VERSUSTIME PLOTS................................................................................................................. App endix A

CUMULATIVE FLOWBACK PLOTS FOR HYDRAULIC

FRACTURE EVENTS WITH KNOWN IN JECTION VOLUMES ......................... Appendix A-1

CUMULATIVE FLOWBACK PLOTS FOR HYDRAULIC FRACTURE

EVENTS WITH ASSUMED INJECTION VOLUME OF 23,000 bbl ..................... Appendix A-2

BAKKEN FRAC FLOWBACK WA TER SALINITY VERSUS TIME DATA PLOTS .................................................................................................... Appendix B

CHARGE BALANCE ERROR ..................................................................................... Appendix C

WATER USE FACT SHEET ........................................................................................ Appendix Dii LIST OF FIGURES

1 Existing and proposed water depots as of March 2010 ......................................................... 3

2 Locations of Bakken oil wells where frac flowback data and information were

used in the assessment ....................................................................................................... .... 6

3 Cumulative flowback of oil and water for a typical hydraulic fracture event ....................... 8

4 Conductivity and TDS versus flowback water volume, Producer A .................................. 11

5 Salinity versus flowback water volume, Producer B .......................................................... 11

6 Salinity versus flowback water volume, Producer C .......................................................... 12

7 Salinity versus flowback water volume, Producer E ........................................................... 12

8 Major ion distribution fo r wells in Table 4 ......................................................................... 14

9 Changes in specific constituent concentra tion in frac flowback water versus time ............ 16

10 Applicability of various desalination technologies ............................................................. 16

11 AltelaRain process diagram ................................................................................................ 19

12 Aqua-Pure mechanical vapor recomp ression technology pro cess diagram ........................ 20

13 212 Resources vapor compressi on process flow diagram ................................................... 21

14 Frac flowback water storage impoundment ........................................................................ 23

15 Pretreatment system consisting of coagulat ion/flocculation, settli ng, and filter press ....... 24

16 Aqua-Pure Nomad 2000 mechanical vapor recompression unit ......................................... 25

17 Water samples: frac flowback, treat ed water, and MVR concentrate ................................. 25iii LIST OF TABLES

1 Summary of Data Types Collected ....................................................................................... 7

2 Summary of Flowback Quantity for Producers A, B, C, and E ............................................ 9

3 Summary of Flowback Quantity for Producer D ................................................................ 10

4 Flowback Water Chemical Analytical Results on Three Select Wells ............................... 13

5 Analytical Results for Producer A, Well 2, Samples Versus Time ..................................... 15

6 Water-Handling Costs ....................................................................................................... .. 17iv BAKKEN WATER OPPORTUNITIES ASSESSMENT – PHASE 1

PROJECT SUMMARY

The Energy & Environmental Research Center (EERC) Northern Great Plains Water Consortium (NGPWC) identified a potential opportunity to econom ically treat and reuse water that is used in hydraulic fracturing operations in the Bakken oil formation in North Dakota. The Bakken Water Opportunities Asse ssment project was undertaken with funding provided by the

North Dakota Industrial Commission Oil and Gas Research Council, the North Dakota Petroleum Council, and the U.S. Department of Energy. The project compiled information on the current water use practices for hydraulic fractur ing (frac) in the Bakken play, collected and analyzed frac flowback water data from five different oil producer s operating at va rious locations in the Bakken, assessed potentially applicable mobile fracture water -recycling technologies, worked with industry to disseminate info rmation about the project, and developed recommendations and plans for a Phase 2 evaluation.

Traditional sources of freshwater for hydrau lic fracturing include glacial and bedrock aquifer systems, surface waters, and municipal s upplies. The continued use of these sources to satisfy the increasing demand for freshwater will not be practical if future demands are to be met. The largest source of freshwater in the Bakken play is Lake Saka kawea, but access to this supply and its proximity to future drilling and fracturing activities make the lake less desirable as a longterm supply.

Treatment and recycling of frac flowback wate r was investigated as a means to reduce the demand for freshwater and provide a supplemental supply near drilling and fracturing activities.

The character of the frac flowback water with respect to both quantity and quality presented significant challenges for widespread water-r ecycling opportunities. A relatively small percentage (17% to 47%) of the water used in hydraulic fracturing in the Bakken is typically recoverable in a reasonable time (2 to 10 days). Further, the dissolved solids levels in the frac flowback water increase rapidly and to levels as high as 220,000 mg/L. These factors provide significant challenges for developing cost-effectiv e treatment strategies, even with the most robust technologies. While there will certainly be niche opportunities us ing certain technologies to recycle frac flowback water, widespread r ecycling will not likely be economically viable.

The regional and national importance of providi ng sufficient volumes of water for such an extremely high-value use cannot be overstated. Th ese water supplies will need to come from a variety of resources. One opportunity is to upgra de marginal-quality groundwater resources to satisfy a portion of the demand. An evaluation of a membrane technology for the treatment of nonpotable groundwater to supply water for hydraulic fracturing in the same geographic area is being conducted as a Phase 2 Bakken Wa ter Opportunities A ssessment project.1 BAKKEN WATER OPPORTUNITIES ASSESSMENT – PHASE 1

INTRODUCTION

Water is the most critical limiting resour ce throughout the world. Sufficient quantities of good-quality water are needed fo r several competing uses, incl uding energy production, growing and processing high-value crops, industrial manufacturing, and expanding populations. The Northern Great Plains Water Consortium (NGP WC) is a partnership between the Energy & Environmental Research Center (EERC), the U.S. Department of Energy (DOE), and key stakeholders representing oil and gas compan ies, power generation utilities, industry, municipalities, and other entities interested in addr essing critical water issues in the north-central United States. The primary goal of the NGPWC is to assess, develop, and demonstrate technologies and methodologies that minimize wate r use and reduce impacted water discharges from a range of energy technologies, includ ing coal combustion, coal gasification, coalbed methane, and oil and natural gas production.

The NGPWC identified a poten tial opportunity to economica lly recover and reuse water that is used in the oil field to pressurize and fracture oil-bearing formations to increase permeability and enhance the flow and recovery of oil. In North Dakota’s Bakken play, water used in hydraulic fracturing ranges from appr oximately 10,000 to 60,000 barrels (bbl) (0.5 to 3 million gallons), depending on the number of stages in the fracture. Multistage fractures, which require more water than single-stage fractures , are increasingly being employed in the Bakken Formation because they generate fractures more effectively.

Relatively low-total-dissolve d-solids and bacteria-free water is required for hydraulic fracturing. Typically, the freshwat er comes from glacial and bedr ock aquifer systems, surface waters, and municipal supplies. The use of municipal supplies can have a profound effect on small community water supplies, many of which have a relatively low treatment capacity. The additional demand on shallow groundwater syst ems can also have a significant impact, particularly on small glacial channel aqui fers that have lo w recharge rates.

Recycling the water used to hydraulically frac ture oil wells could have a positive effect on available resources, conserving th e supply for other beneficial uses . Fracture water is typically hauled to the well site in 7500- to 8000-gall on (180- to 190-bbl) tanker trucks. Once the formation fracturing is completed, the water flows back (frac flowback) as the pressure in the

well is released. After sand removal and oil r ecovery, the frac flowback water is typically disposed of via deep-well injection. Transportation costs, particularly for long haul distances, can

be excessive for both freshwater and flowback water. Treatment and reuse of frac flowback water may be an extremely attractive economic alte rnative to disposal vi a deep-well injection.

OBJECTIVE

The overall goal of th e project was to provide industry with data and information on the technical and economic potential to recycle frac flowback water. Specific Phase 1 objectives2 included 1) gathering data on curr ent water use practices, 2) investigating flowback water quality with respect to time and location, 3) assessing cu rrent water-handling costs, 4) assessing the use of water-recycling technologies and evaluating technical and econom ic suitability for application to Bakken Formation flowback water, 5) evalua ting the current state of existing water-recycling technologies, 6) developing plans for a full-scale field evaluation at a host Bakken location, and 7) information dissemination.

RESULTS AND DISCUSSION

Task 1 – Current Water Use Practices

There are different types of fracture fluids used in the Bakken play, and each has a

different formulation. While fractur e fluids can range from water to slickwater to gels, they require freshwater as a makeup fluid. This ensures the ability of individual producers to develop consistency in the composition of the fractur ing fluid and the desi red fracture results.

Common freshwater acquisiti on points for frac fluid ma keup are from existing water depots and municipalities. Figure 1 depicts the location of existin g and proposed water depots, as well as the permitted (or requested) water allocati on at each location. While some municipalities have extra capacity to provide water to the oil industry, they must first request an industrial permit from the North Dakota State Water Commissi on (SWC), and it should be noted that the additional available capacity would still not meet all of the industry needs.

In response to the increasing demand for fr eshwater, SWC has received numerous permit applications for additional groundw ater appropriation for withdrawal s at existing water depots as well as permit applications for new water wells. Prescribed permitting procedures require a published public notice, followed by a 30-day comment period. New permit applications are being contested by environmental groups, which re sults in significant de lays in the overall permitting process. Permits that would normally be issued within a 70- to 90-day period are taking in excess of 9 months.

SWC is also concerned about mining of fres h groundwater resources, sp ecifically surficial glacial aquifers (which are of limited extent in western North Dakota) and the Fox Hills–Hell Creek Aquifer. The Fox Hills–Hell Creek Aquifer is a widespread, reliable artesian aquifer. Because it is artesian and flows at the surface, it provides a valuable supply of water for remote

areas with no elec tricity for pumping. However, over the past several decades, the hydraulic pressure of the formation has been declining as a result of the large number of wells that are withdrawing water from the formation (Honeyman, 2007). SWC estimates that at the current rate of decline in hydraulic pressure, wells screened in the Fox Hills–Hell Creek Formation will stop flowing within the next 100 years (Honeyman, 2007) . Because of the low recharge rate of the Fox Hills–Hell Creek Aquifer, SWC is reluctant to permit new appropriations for withdrawals from this formation, particularly for industrial use.3 Figure 1. Existing and proposed water depots as of March 2010 (Source: North Dakota St ate Water Commission).4 With the exception of the Missouri River syst em, most surface waters in the Bakken region do not provide a reliable source of water because of seasonal flow variations. Sufficient flows exist only in the spring of the year, during periods of snowmelt. Given the concerns over mining of surficial aquifers, groundwater-permitting issu es, and the relative lack of surface water supplies in many areas of the state, SWC is en couraging the oil industr y to seek withdrawals from the Missouri River System for use in Ba kken development. Howeve r, there are several issues related to using Lake Sakakawea water, key among them being access to the lake and proximity of the resource to drilling locations.

While SWC handles water appropriations from the lake, permission for access at a particular point of diversion must be granted by the U.S. Army Corps of Engineers (Corps). This creates additional delays in accessing the resource because having to obtain permission from multiple agencies can slow the permitting process. In addition, it is not yet clear where access to the lake may or may not be allowed because of the potential disturbance of cultural sites and/or threatened and endangered specie s. SWC is working with the Corps and the U.S. Fish and Wildlife Service to identify corridors of access to the lake for industrial purposes and to publish access maps. It is unclear at this time when these maps will be available.

It is interesting to note that in late 2 009 and early 2010, several permit applications were submitted to SWC for allocations exceeding 1000 acre-feet from Lake Sakakawea. These requests are primarily to supply wa ter to the oil industry. The larg est requested appropriation of 24,000 acre-feet was made by International West ern Company, a Texas-based company, which has identified four proposed points of divers ion on Lake Sakakawea (each at a requested appropriation of 6000 acre-feet) from which it is planning to pump water in to a series of small reservoirs interconnected by underground pipelin e (International Wester n Company, personal communication, February 2010). The reservoirs will be strategically located near areas of drilling activity, including locations south of Tioga, northwest and southwes t of New Town, and north of Dodge.

The city of Dodge is also in the process of applying for a permit to allow its additional water capacity to be used for the oil industry. It currently estimates that it has an additional capacity of nearly 1500 acre-feet from the appropriation that it receives via the Southwest Pipeline project.

While there are some projects in the works that will improve the availability of freshwater resources for use in Bakken development, in th e near-term, there appears to be a significant water shortage. The Missouri River System ha s more than enough water available for Bakken development, but preferred access points to the lake are still undefined by the Corps. Additionally, there will be high costs associated with long tr ansportation distances from the lake to new drilling locations. Given the current need for water, coupled with high water acquisition, transportation, and disposal costs, nontraditional options for water supplies may be viable, such as municipal wastewater treatment or tr eatment of nonpotable gr oundwater resources.5 Task 2 – Flowback Water Characteristics

Task 2 was designed to identify informati on and collect new data regarding the quantity and quality of Bakken play hydrau lic fracture flowback water. Th e hope was that sufficient data

could be collected to evaluate the effect of geographic, ge ologic, and hydraulic fracture characteristics (e.g., water frac, gel frac, slickwat er frac, length of shut -in) on the quantity and quality of water recovered. These quantity and quali ty data could then be used to help assess the potential for treatment and reuse of the wate r in additional hydrau lic fracture events.

Five different companies that practice hydrau lic fracturing in the Ba kken participated in this assessment by providing frac flowback water information and data from a total of 89 wells (Figure 2). While the data were extensive, they were not comprehensiv e. Table 1 presents a summary of the data collected. The data varied in detail with respect to quantity and quality, with portions of the data set lacking the information critical for a detailed and accurate assessment but adequate for use as a basis in making generalized conclusions. Wa ter samples from several frac

flowback events were sent to a contract laboratory for detaile d chemical analysis to document water quality changes over time and flowback volume. EERC personnel attended the flowback event from one long-shut-in time hydraulic fracture event. Very little flowback water was recovered during the flowback period, and the sy stem was quickly converted from flowback to production mode because the well was producing mostly oil. Samples collected during that flowback period were also submitted for detailed chemical analysis.

This section of the report presents represen tative data concerning flowback water quantity, flowback water quality, and a generalized inte rpretation of what the quantity and quality information collected suggests re garding the potential for Bakken hydraulic frac flowback water

treatment and reuse.

General Description of Hydraulic Fracturing

After wells have been drilled, a well fiel d service company comes in with large waterholding tanks and pumps. Water is brought in (usu ally by tanker truck) to fill the water tanks. This water is mixed with sand (proppant) and chem icals (e.g., surfactants, gels, oil) and injected at a high flow rate and pressure into the fo rmation in order to hyd raulically fracture the formation. This opens channels in the formation and increases the near-field porosity to provide flow paths for the oil. The fluid pumped into th e formation may be pumpedin all at once (singlestage fracture) or in several stages (multistage fracture) over a period of one to several days (up to five is common). The fluid is then shut in for a period of time before it is allowed to flow back. The length of time from finishing the fracturi ng process to the start of flowback can be as short as 4 hours (no shut-in) to as long as 30 days. The most common shut -in procedures seem to be none, overnight, and ove r-the-weekend shut-in times.

After the shut-in period is over, the fractur e fluid is allowed to flow back out of the formation. In the Bakken, this typically occurs without the need for pu mping because of the formation pressure and residual pressure associ ated with fracturing operations; hence, pumping in the Bakken is not required. The material that comes out of the well during flowback includes residual proppant (sand), water (enr iched in dissolved salts from the formation), oil, and gas. The6 Figure 2. Locations of Bakken oil wells where frac flowback data and information were used in

the assessment.7 Table 1. Summary of Data Types Collected

Company Frac Fluid

Volume Flowback

Volume Flowback Salinity or

TDS Detailed Chemistry Location ClosedIn Time

or Frac

Water

Contact

Time Number

of Wells

A Estimated Versus

time Salinity Yes X

B Known (three of five wells) Versus

time TDS 1 X 5

C Estimated Versus

time Salinity

and TDS Yes X 30 days

D Known Total and

initial

volume to

TDS

cutoff Only as

cutoff at

TDS = 60,000

ppm X 62 in 10

areas

E 2 Known Versus

time Salinity X 4 hours

to 7 days 4

E 3 Unknown Unknown TDS Major ions,

hardness X 7

1 Total dissolved solids.

2 Service Provider A perfor med hydraulic fracture.

3 Service Provider B perf ormed hydraulic fracture.

sand and gas are typically separate d from the oil and water in a cy clone or gravity separator, and the gas is utilized on-site, sent to a gas-pr ocessing facility, or flared. The oil and water are separated in an API (American Petroleum Institute) oil–water separator. The water is collected in a pit and/or in fracture tanks used to hold the water prior to the fracture event. The water collected during flowback is the focus of this investigation. The oil is sent to the production separators (heater–treaters) for the removal of any remaining water and collected in tanks in preparation for shipping to a refinery. Because th e Bakken Formation has little to no free water, any water collected over time with the oil might be considered flowback because its origin was likely the fracture event. However, operationally, the period of flowback is considered over when the well operation switches to a normal producti on mode. The actual fraction of water in the produced fluid that is consistent with the end of flowback might vary from operator to operator but, commonly, it can be considered to occur wh en the liquid well produc t contains less than

25% water.8 Flowback Water Quantity

Flowback consists of both water and oil. In itially, frac flowback is water, but the amount

of oil in the flowback increases over time. The relative amount of oil in the flowback typically dictates the length of flowback operations and, thus, the corresponding period of time when water recovery may be feasible based on the rela tive amount of water in the flowback. Figure 3 presents frac flowback data from a selected well. The figure shows cumulative total flowback (oil plus water), cumulative water flowback, cu mulative oil flowback, the volume of frac water not recovered, and the percent of oil in a grab sa mple of flowback versus time. In the example, 12,775 bbl of water was injected during hydraulic fracturing, and the duration of the flowback period was approximately 45 hours , at which time the well was switched to a production mode. At that point, the total flowback contained 63% oil and 37% wate r. The water recovered during the flowback period represented 33% of th e total used in the fracturing process.

Flowback quantity data, similar to those pres ented in Figure 3, were obtained for a total of 12 wells from data provided from four of the participating producers. Th e volume of freshwater used in the fracturing was known for seven of t hose wells. For the other five wells, a frac water volume of 23,000 bbl was assumed. Plots of these data (similar to Figur e 3) are provided in Appendices A-1 (known frac fluid volume) a nd A-2 (assumed 23,000 bbl frac fluid volume). Additional flowback quantity data were provided for 62 additional wells, but the nature of those data did not allow for a similar analysis. Data from these wells will be discussed later.

Figure 3. Cumulative flowback of oil and water fo r a typical hydraulic fracture event. Flowback continued until the proportion of oil in the fluid being produced was 63%. At that point, 33% of the injected water had been recovered.9 Table 2 summarizes the flowback water quan tity data, including fracture fluid volume, the duration of flowback, and percent water recovery at the end of flowback, as well as statistical information (maximum, minimum, mean, median, st andard deviation) for four of the producers. The observed flowback periods rang ed from around 2 days to as long as 10 days, with a median time of almost 2 days and an average of 3 days. During the first 24 hours of flowback, the amount of water recovered ranged from as little as 3% to as much as 26%, with a median value of 12%. At the end of the flowback period (as i ndicated by the end of fl owback data collection by the producer), flowback water re covery ranged from 5% to 41% of the fracture water injected,

with a median value of 17%.

Table 3 summarizes flowback water recovery information from data provided for 62 wells from a single producer. These data were originally provided as barrels of water recovered that had TDS levels of less than 60,000 ppm and barrels of water at th e end of the flowback period and the duration of flowback. The flowback peri od for this producer ranged from nearly 31⁄2 to almost 18 days, with a median flowback period of just over 91⁄2 days, much longer than those reported by the other producers. Th e percentage of water recovered ranged from 7% to 75% of the original fracture water injected, with a me dian value of 47%, which was also higher than typical values of the other pr oducers. The water recovered with TDS <60,000 mg/L represented 0% to 39% of the injected volum e, with a median of 5%. Five of the 62 wells produced no water with salinity levels under 60,000 ppm, and the median well produc ed only 974 bbl of water at less than 60,000 mg/L of TDS, whic h represented 5% of the inject ed water volume for that well. Overall, of the 1,088,590 bbl of water inject ed during fracturin g operations, only 10.5% (114,172 bbl) was recovered at a sa linity of less than 60,000 mg/L.

Table 2. Summary of Flowback Quantity for Producers A, B, C, and E

Producer Well Fracture Fluid

Volume Length of

FlowBack Water Recovered

in 24 hours Cumulative Water

Recovered bbl hours % of injected % of injected
A 1 23,000 124.0 3 13 2 23,000 120.0 4 9 B 1 19,105 95.0 25 41 2 19,007 95.5 23 33 3 19,106 93.5 22 36 C 1 23,000 36.5 4 5 2 23,000 33.5 7 8 3 23,000 37.5 4 5

E 1 8326 36.0 16 21 2 12,775 45.2 25 33 3 52,000 44.0 4 6 4 13,065 36.0 26 30

Minimum 33.5 3 5

Maximum 124.0 26 41

Median 44.6 12 17

Mean 66.4 14 20

Standard Deviation 36.0 10 1410 Table 3. Summary of Flowback Quantity for Producer D

Fluid Pumped, bbl Duration of Flowback, days Flowback Water

with TDS <60,000 mg/L , % Total Flowback Water Recovered,

% Minimum 10,966 3.42 0 7 Maximum 36,333 17.75 39 75

Median 17,476 9.58 5 47 Mean 17,587 9.92 12 45

Standard Deviation 4417 3.21 12 16

In general, the volume of wate r recovered in the flowback is significantly less than what was originally anticipated. The reason for the low initial water recovery is not readily understood, but can be attributed in part to the fo rmation being oil-wet (little to no free formation water), and the water being retained in the frac ture and pore space and in spaces where salts were dissolved by frac water. Based on the available da ta, it was not possible to develop a correlation between flowback water recovery and shut-in tim e, nor was it possible to develop any correlation

between well location and the amount of flowb ack water recovered. While the water may be recovered over a long period of time with continued oil producti on, the amount of water that can be readily recovered and recycled in a timely ma nner is typically a relativ ely small percentage of the original water used to fracture the forma tion. This will significantly impact the widespread economic viability of frac flowback water recyc ling in the Bakken play. The low recovery of water, however, will reduce the overall cost fo r disposal by reducing th e total volume requiring disposal.

Flowback Water Quality

Oil producers typically measure frac flowback water quality in terms of salinity using a refractometer. Salinity and/or conductivity levels of flowback water versus time were provided by four of the five participating producers, a nd one of the producers provided data in terms of water recovered with salinity le vels less than 60,000 ppm. Select ed samples of frac flowback water over time from two of the producers were submitted to contract laboratories for a more detailed chemical characterization. A third producer provided concentration data for major ions.

Figures 4–7 illustrate dissolved solids content of the flowback water versus flowback water throughout the flowback period. Figure 3 presents the data in terms of specific conductance and

TDS concentration calculated as the sum of me asure ion concentrations , and the other figures show salinity values. There is a wide range in the concentration of dissolved salts in the frac flowback water, not only betw een different producers, but am ong different wells of a single producer (Figure 7). These data show that the flowback water salinity values typically range from 60,000 ppm to over 200,000 ppm. Values around 100,000 ppm are typi cal, and levels greater than 200,000 ppm are not uncommon. Very little frac flowback was shown to have salinity levels less than 60,000 ppm. Additional plot s of salinity versus time of flowback are provided in Appendix B. The data in Appendix B ar e from the same flowback events as the data in Appendix A.11 Figure 4. Conductivity and TDS versus flowb ack water volume, Producer A.

Figure 5. Salinity versus flowback water volume, Producer B.12 Figure 6. Salinity versus flowback water volume, Producer C.

Figure 7. Salinity versus flowback water volume, Producer E.13 Detailed chemical composition data were co llected on selected flowback water samples from three of the producers participating in the project. Characterization results from representative samples collected at a time around 3500 bbl of cumulative total flowback are listed in Table 4, with the major ion concentr ations compared graphically in Figure 8. All analyses were confirmed to have charge balance errors (CBE) of less than ±5% (see explanation of CBE in Appendix C). Sodium chloride (NaC l) is the dominant salt comprising 91.1%, 89.8%, and 95.0% of the TDS in the Producer A, C, a nd E well flowback waters , respectively. Calcium is present at concentration ranges between 7540 and 13,500 mg/L. Other ions detected at concentrations of 1000 ppm or greater in at least one sample are magnesium, potassium, strontium, and sulfate. Boron, bicarbonate, and iron were each detected at concentrations above 100 ppm in at least one sample. The pH was found to be mildly acidic, ranging from 5.47 in the sample from Producer E to 6.53 in the sample from Producer A.

Table 4. Flowback Water Chemical Anal ytical Results on Three Select Wells

Producer/Well A/2 C/2 E/ Total Flowback, bbl 3688 3283 Unknown Water Flowback, bbl 2090 1611 Unknown Charge Balance Error, % 1.74

− 0.752

− 0.220 Cations/Conc. mg/L mg/L mg/L Calcium (Ca) 8010 13,500 7540 Barium (Ba) 7 24.6 0 Magnesium (Mg) 630 1440 1750 Iron (Fe) ND 1 72 120 Potassium (K) 3140 5770 0 Sodium (Na) 47,100 62,700 74,600 Phosphorus (P) ND 0.03 NR 2
Silica (Si) 7 6.41 NR Strontium (Sr) 518 1010 NR Boron (B) 192 39.9 NR Manganese (Mn) 4 10.2 NR Copper (Cu) ND 0.21 NR Molybdenum (Mo) ND <0.2 NR Zinc (Zn) 2 11.3 NR Aluminum (Al) ND <1 NR Anions/Conc. mg/L mg/L mg/L

Sulfate 680 300 1000 Chloride 90,000 133,000 133,000

Bicarbonate 122 140 610

Other Measurements

pH 6.53 5.62 5.47 Specific Gravity 1.0961 1.155 1.14 Specific Cond., mS/cm 205 220.8 NR TDS (calculated), mg/L 150,000 218,000 219,000

1 Not detected,

2 Not reported.14 Figure 8. Major ion distribution fo r wells in Table 4.

Table 5 presents detailed chemical characte rization data over time during the flowback period from Producer A, Well 2 (Figure 3). Figure 9 shows the changes in specific ion concentration and illustrates increasing concentr ation with time during the flowback period.

The very high TDS levels in the Bakken frac flowback water will present a significant treatment challenge. Figure 10 presents inform ation on the applicability of desalination technologies over a range of TDS concentrations. Traditional desalination technologies such as reverse osmosis (RO) typically are capable of treating waters with TDS levels up to 40,000 mg/L. Thermal treatment technologies such as mechanical vapor recompression (MVR) are more applicable to treating high-TDS waters, such as t hose found in certain Bakken flowback situations, particularly if MVR is coupled with pretreatment to reduce the c oncentration of divalent ions typically associat ed with scaling. Even with pr etreatment, the very high sodium chloride in Bakken flowback water will require sp ecial consideration of metallurgy for treatment components. Expensive metals such as titanium that are resistant to corrosion and chloride stress corrosion will be required for high-temperature thermal recove ry processes tr eating chloride

Bakken flowback water.15 Table 5. Analytical Results for Producer A, Well 2, Samples Versus Time

Sample No. 1 2 3 4 5

Total Cumulative

Flowback Water, bbl 54 487 633 2778 3688

CBE, % 5.35

− 1.54 1.03 0.418 1.74 Cations/Conc. mg/L mg/L mg/L mg/L mg/L Calcium (Ca) 105 3496 5350 6740 8010 Barium (Ba) <1 2 5 6 7 Magnesium (Mg) 36 290 425 537 630 Iron (Fe) 3 8 40 ND ND Potassium (K) 28 1816 2466 2790 3138 Sodium (Na) 540 22,285 33,225 40,980 47,080 Phosphorus (P) 18 2 2 ND ND Silica (Si) 12 16 16 8 7 Strontium (Sr) 4 225 351 441 518 Boron (B) 1 102 147 174 192 Manganese (Mn) <1 3 4 4 4 Copper (Cu) ND ND ND ND ND Molybdenum (Mo) ND ND ND ND ND Zinc (Zn) ND ND ND 1 2 Aluminum (Al) ND ND ND ND ND Anions/Conc. mg/L mg /L mg/L mg/L mg/L

Sulfate 627 688 742 719 681 Chloride 500 45,000 64,000 80,000 90,000

Bicarbonate 244 229 183 151 122

Other Measurements

pH 7.11 6.98 6.92 6.66 6.53 Specific Gravity 1.0010 1.0495 1.0696 1.0860 1.0961 Specific Cond., mS/cm 3 102 149 182 20516 Figure 9. Changes in specific constituent concentrat ion in frac flowback water versus time.

Figure 10. Applicability of various desalination technologies.17 Task 3 – Current Water-Handling Costs

Cost data were provided by several of the participating producers. The reported costs of current water handling for hydraulic fracturing can vary significantly, depending on acquisition costs, transportation costs (including wait time), and disposal costs. Ta ble 6 lists a range of current water-handling costs for Bakken fracture water. The cost to purchase raw water ranged from $0.25/bbl up to $1.75/bbl, and the cost of tran sporting that water to the fracture location ranged from $0.63/bbl up to an estimated $5.00/bbl. Transportation costs re presented the highest level of variability in water acquisition costs an d depend on several factors, including trucking charges, haul distances, and wait time. Trucking charges were reported to range from $110 to $150/hr, and the charges that are incurred during wait time are included in the overall transportation costs. Th e costs for deep-well injection rang ed from $0.50/bbl to $1.75/bbl. Again, transportation costs were the most significant cost for disposal, and the higher overall transportation costs were associated with long wait times to unload at a disposal facility. It is unlikely that water-handling costs would consistently be as high as $16/bbl, but considering that transportation costs represent anywhere from 56% to 84% of the total water-handling costs, an assessment of the economic potential of frac flow back water recycling is justified. Recycling could reduce the overall transportation and dispos al costs through a reduc tion in the amount of water that would require disposal.

Table 6. Water-Handling Costs Cost, $/bbl Acquisition Costs Raw Water $0.25–$1.05 Transportation $0.63–$5.00 Disposal Costs Transportation $0.63–$9.00 Deep-Well Injection $0.50–$1.75

Total Costs $2.00–$16.80

Task 4 – Review of Flowback Water-Recycling Technologies

A review of available literature and Internet searches revealed that frac flowback waterrecycling technologies were in various stages of development. These technologies, however, were being evaluated for use in treating frac flowback from natural gas-bearing shale formations

such as the Barnett and Marcellus shales. Beca use the Bakken Formation contains oil-wet rock with little to no free water, the chemical com position of the flowback water is very different from the natural gas shales. Ba kken flowback waters are more highly concentrated with salts than are comparable gas formations. Preliminary Bakken flowback water data collected early in the study showed relatively low concentrations of sa lts in the flowback water, albeit at relatively low volumes, but there still appeared to be a limited opportunity for recycling.

Treatment of Bakken flowback water will require extremel y robust technologies built on highly mobile platforms. Based on the characte r of the Bakken flowback water, the most18 applicable technologies include thermal or membrane processes coupled with pretreatment to reduce levels of scale-forming constituents. Pretreatment will be required of any technology treating Bakken frac flowback water.

Thermal Treatment

Thermal treatment uses heat to distill high-salt-content water to steam, which is condensed into clean water. The process also produces a lower-volume concentrate, or brine stream. Thermal treatment processes have high energy i nput requirements, which would normally make it economically impractical for the treatment of frac flowback water. However, the use of associated gas that would normally be flared early in flowback operations to power thermal treatment processes makes distilla tion an economical alternative.

Several companies offer thermal treatment processes for the treatment of flowback and produced waters. Thermal treatment technology vendors in this assessment included

AltelaRain SM , Aqua-Pure, and 212 Resouces.

AltelaRain

AltelaRain desalinates and decontaminates water using a low-pressure, low-temperature countercurrent-flow evaporati on/condensation process (Figure 11). Altela claims this configuration provides 3 gallons of treated water from the same amount of heat energy that would normally be required to produce 1 gallon of water through a 300% energy reuse. Individual Altela treatment units process about 8 barrels per day (bpd), but units can be deployed in parallel when treating larger volumes of wate r (Veil, 2008). The standa rd Altela system ARS4000 is delivered in a single, porta ble 45- × 8-foot shipping containe r and has been used to treat 4000 gallons/day (~100 bpd) of produced water in New Mexico. Altela systems can operate on low-grade waste heat or wellhead natural gas. Th is reportedly lowers Altela’s operating costs relative to high-pressure, high-el ectricity-cost technologies such as RO and mechanical vacuum compression (MVC). The system reportedly uses no pressure, high temperatures, filters, or membranes, allowing it to be manufactured from plastics rather than metals. The applicability of the technology to Bakken flowback water is very uncertain.

Aqua-Pure

Fountain Quail Water Management (FQWM) is a technology serv ice provider that developed the Nomad mobile ev aporator platform based on A qua-Pure’s patented process (Figure 12). The following process descrip tion was taken from Aqua-Pure’s Web site (www.aqua-pure.com, 2010):

Mechanical Vapour Recompression (MVR) Evaporation is an energy efficient process that produces pure distilled water from wastewater containing dissolved solids. With evaporation, pure water is boiled from wastewater and can be later

condensed as distilled water. The disso lved solids remain in solution and are removed from the system as concentrat ed blowdown. In an MVR Evaporator, a19 Figure 11. AltelaRain process diagra m (www.altelainc.com, 2010).

compressor is used to add the energy requi red to boil water. The feedwater passes through two preheat exchangers where sensible heat is absorbed from the distillate and concentrate products leaving the syst em. The feed then passes through a deaerator column where dissolved gases are vented. The feed then passes into a recirculation loop where con centrate circulates through an evaporator exchanger and a vapour/liquid separator. A portion of the concentrate is boiled to steam in the evaporator exchanger and separated from the liquid in the separator vessel. A compressor draws the steam off the separato r and boosts the pressure, which results in an increase in temperature. The steam is driven through the opposite side of the evaporator exchanger where it condenses to dist illed water, releasing its latent heat to the boiling concentrate. The distilled wa ter is then pumped through the preheat exchanger where remaining sensible heat is transferred to the incoming feed. Concentrate is continually pumped from th e recirculation loop out of the unit to prevent the solution from reaching satura tion. The concentrate also passes through a preheat exchanger where remaining sensible heat is transferred to the incoming feed.

Producing distilled water from direct-f ired distillate requires 1000 BTU/lb of heat energy. Due to the sophisticated heat exchanger configuration in MVR20 evaporation, distilled wate r can be theoretically produ ced with only 25-28 BTU/lb, 1/40th the energy.

The Nomad 2000 MVR units are designed to produce 2000 bpd of treated water from nominally 2300 bpd of feedwater. The systems are portable, with each consisting of three skids that can be transported with tr actor–trailers. The Nomad system uses available wellhead natural gas as an energy source so no th ree-phase power is required. Th e Nomad can also be monitored and controlled remotely via cell phone.

212 Resources

212 Resources owns and operates the platfo rm technology that employs patented vapor compression flash evaporation systems. 212 Resources claims to have solved the fouling/scaling operational concern through a minimum-fouling, minimum-scaling, high-ve locity evaporation system. Each unit contains a specially designed heat exchanger along with a high-powered pump to cycle water under pressure at many times the ev aporation rate. A process flow diagram for the 212 Resources vapor compression system is s hown in Figure 13 (www.212resources.com, 2010). Figure 12. Aqua-Pure mechanical vapor recompression technology process diagram (www.aqua-pure.com, 2010).21 Figure 13. 212 Resources vapor compression process flow diagram (www.212resources.com, 2010).

While thermal processes are capable of produc ing a high-quality effluent, there remains a concern regarding the treated water yield that is actually possible when tr eating high-TDS waters

like Bakken flowbacks. Pretreatment of these wa ters will enhance thermal treatment processes by both reducing the levels of scale-causing constituents and, ultimately, providing highertreated water yields.22 Membrane Treatment

Membrane technologies are much younger in de velopment than thermal technologies and were developed primarily for commercial and municipal water supplies in the 1970s. As the name implies, membrane treatment removes disso lved minerals, such as salts, from solution using filtration through a semipermeable memb rane. The three main types of membrane treatment include RO, electrodialysis (ED), and nanofiltration (NF).

Of the membrane technologies commonly employed for seawater desalination, RO accounts for about 81%, while ED and NF account for 11% and 8%, respectively. RO is a membrane-based technology that employs dynamic pr essure to overcome the osmotic pressure of the saline feedwater. RO uses thin, semipermeable membranes to separate the feed stream into two streams, a low-TDS permeate and a high-TDS concentrate. Pressure forces pure water through a membrane that rejects dissolved salts.

ED is one of the three common membrane proc esses in desalination an d is primarily used

to treat brackish water. ED involves the selective movement of ions through a membrane in response to a direct electric cu rrent. Electric energy is consumed in proportion to the quantity of salts to be removed. Economics usually limit it s application to feed waters of less than 10,000 mg/L TDS. The electrodialysis reversal (EDR ) process is based on the same principles of electrochemistry as ED. The fundamental differen ce is that during the EDR process, the polarity of the cell is periodically reverse d, usually three to four times an hour, to alter the flow of ions across the membrane. This action improves the tole rance of the technology to treat scaling-prone or turbid feedwater. EDR has largely replaced ED in the United States and in some overseas markets. EDR has a permeate recovery capacity and a salt rejection rate of 90%. A significant disadvantage of EDR treatment is the cost, which is approximately twice that of RO (Hanson, E., GE Osmotics, personal communication, 2008).

NF is a membrane process that primarily re moves divalent salt ions (such as calcium, magnesium, and sulfate) from solution, but not m onovalent ions (such as sodium and chloride). As a result, NF is most commonly used for wa ter softening and for nondesalting applications, such as removal of organic compounds.

The use of membrane filtration for treating Bakken frac flowback water will likely have limited application. However, the Texas A&M Univ ersity Global Petroleu m Research Institute (GPRI) has developed an advanced membrane treat ment process for the de salination of oil field brine. GPRI licensed the technology and reached a long-term agreement with M-I SWACO to commercialize the technology. David Burnett, Direct or of GPRI, indicated that the process can

desalinate waters with less th an 40,000 ppm TDS, much lower le vels than are found in Bakken

flowback water.

Ecosphere Technologies, Inc., has develope d the OzonixTM mobile frac flowback water treatment system. The advanced oxidation system uses a combination of ozonation, ultrasound, electroprecipitation, centrifugation, f iltration, and RO to improve th e quality of frac flowback and produced water. The water is first filtered to remove suspended solids and then treated in the Ozonix unit which employs ozone, ultrasound, a nd electroprecip itation technolo gies. In the23 presence of an ultrasonic cavitation field, oz one decomposes into two hydroxyl radicals and oxygen gas. The hydroxyl radical oxi dizes organic compounds and ki lls bacteria in the water. The electroprecipitation causes some chemical species to come out of solution, and the precipitated material is removed in the centrif ugal separation, media, and cartridge filtration units. The final processing step is RO, which re moves nearly all remain ing dissolved solids.

Task 5 – Flowback Water Treatment Technology Assessment

Based on the review of existing frac flowb ack water treatment technologies and evaluation factors, including 1) stage of de velopment; 2) demonstrat ed application of oil field compatibility; 3) mobility; 4) robustness, particularly consid ering climate extremes in North Dakota; and 5) discussions with producer s, technology vendors, and indus try experts, the EERC focused

continued assessment efforts on thermal treatment processes and, in particular, the Aqua-Pure MVR process. In April 2009, EERC staff visited site s near Decatur, Texas, in the Barnett shale region where Devon Energy was using FQWM a nd its Aqua-Pure technol ogy to recycle frac flowback and produced water.

Devon collects frac flowback water and tran sports it by tanker tr uck to a centralized facility location, where it is unloaded into aboveground storage imp oundments (Figure 14). Suspended solids are allowed to settle during storage. Flowback water is pumped from the storage impoundment to a pretreatme nt process that consists of flocculation, coagulation, gravity settling, and dewatering. Figure 15 shows the pretreatment system. Coagulants are used to produce a chemical flocculant that is removed in an inclined plate settler. Supernatant from the settler is pumped to the Nomad MVR units. Unde rflow from the settler is pumped to a filter press that dewaters the flocculated solids. Water from the filter press is also conveyed to the

Figure 14. Frac flowback water storage impoundment.24 Figure 15. Pretreatment system consisting of coa gulation/flocculation, sett ling, and filter press.

Nomad MVR units (Figure 16). The Nomad MVR un its operate as described in the previous section. During the site visit, FQWM was treati ng water that was a blend of frac flowback and produced water. The feedwater had a TDS le vel of around 60,000 mg/L. With a throughput of 2300 bpd, each unit was able to pr oduce approximately 2000 bpd of high-quality treated water. Figure 17 is a photograph of system feedwater, treated water, and concentrate from the MVR

units.

Continued discussions with FQWM focused on the timing of a poten tial demonstration of the Nomad MVR technology at a Bakken host site. At the same time, active data collection and assessment activities were provid ing information that suggeste d less of an opportunity than originally envisioned for widesp read frac water-recycling opport unities in the Bakken play. That, coupled with the marginal economics of recycli ng frac water in the Barnett shale, led the EERC

to refocus research efforts on a more promising opportunity.

Task 6 – Recommendations for Phase 2 Project Deployment

The purpose of this task was to develop detailed plans for the field evaluation of the most technically and economically sound mobile frac flowback water-re cycling process. The Phase 1 frac water-recycling feasibility assessment, ho wever, documented significant challenges for demonstrating cost-effective treat ment and recycling strategies , even with the most robust available technologies. While there will cert ainly be niche opportunities using certain technologies to recycle frac flowback water, widespread recycling will not likely be economically viable. The increasing demand for lim ited supplies of freshwater in western North Dakota, the often long distances between freshw ater sources and well sites (and associated25 Figure 16. Aqua-Pure Nomad 2000 mechan ical vapor recompression unit.

Figure 17. Water samples: frac flowback (left), treated water (center), and MVR concentrate (right).26 transportation costs), and the time constraints associated with obtaining new permits to pump from fresh groundwater sources all create sign ificant challenges to the oil industry.

The regional and national importance of providi ng sufficient volumes of water for such an extremely high-value use cannot be overstated. Th ese water supplies will need to come from a variety of resources. One opportunity is to upgra de marginal-quality groundwater resources to satisfy a portion of the demand. An evaluation of a membrane technology for the treatment of abundant supplies of nonpotable groundwater has been proposed as a Phase 2 Bakken Water Opportunities Assessment project. The EERC is teaming with an o il industry partner to investigate the treatment of moderately saline groundwater fr om the Dakota Formation with pretreatment and RO technology. The proposed pilot-scale demonstra tion will treat up to 215 gpm of groundwater to produce approximately 160 gpm of permeate, assuming an estimated 75% recovery rate.

Task 7 – Information Di ssemination Activities

Throughout the course of this project, the EERC has worked proactively with industry sponsors to inform the public and others abou t water issues and opportunities in the Bakken. These activities have ranged from general discussions with citizens, to presentations at town hall meetings, to technical presentations and at nati onal meetings and conferences. The following is a listing of the venues where Bakken Water Opport unities Assessment dissemination and outreach

activities have b een conducted:

• DOE National Energy Technology Laboratory (NETL) Water/Power Nexus Workshop, Pittsburgh, Pennsylvania, October 27–28, 2008

• NGPWC Kickoff Meeting, NETL, Pitts burgh, Pennsylvania, October 29, 2008

• Series of townhall meetings in western North Dakota’s oil country – November 12–13,

2008

• Milestones and Challenges, 45th Annual Jo int North Dakota Water Convention and Irrigation Expo, Bismarck, North Dakota, December 2–5, 2008

• North Dakota Petroleum Council Annual Meeting – Medora, North Dakota, September 1–3, 2009

• North Dakota Solid Waste and Recycl ing Symposium – Minot, North Dakota, September 17, 2009

• Great Plains Energy Expo – Bismar ck, North Dakota, November 9–10, 2009

• Water Resource Opportunities Meeting – Bismarck, North Dakota, December 10, 2009

• Oil and Gas Research Counc il Meeting – January 20, 201027 In addition, the EERC developed a NGPWC Water Use Fact Sheet that presents a comparison of water use for hydraulic fracturing to more traditional water uses such as centerpivot irrigators and municipal uses, along with unit conversion factors to illustrate the relative magnitude of water use in various activities . The fact sheet can be found in Appendix D.

REFERENCES

Honeyman, R.P., 2007, Pressure head fluctuati ons of the Fox Hills–Hell Creek Aquifer in McKenzie County, North Dakota: North Dakota State Water Commission Water Resources Investigation 43, Project File 1442, 130 p.

Veil, J.A., 2008, Thermal distillation technology fo r management of produced water and frac flowback water: Argonne National Labor atory Water Technology Brief 2008-1, U.S. Department of Energy Office of Fossil En ergy, National Energy Technology Laboratory, 12 p.

# APPENDIX A

BAKKEN FRAC FLOWBACK WATER SALINITYVERSUS-TIME PLOTS

# APPENDIX A-1

CUMULATIVE FLOWBACK PLOTS FOR

HYDRAULIC FRACTURE EVENTS WITH

KNOWN INJECTION VOLUMESA-1-1 CUMULATIVE FLOWBACK PLOTS FOR HYDRAULIC FRACTURE EVENTS WITH

KNOWN INJECTION VOLUMESA-1-2A-1-3A-1-4

# APPENDIX A-2

CUMULATIVE FLOWBACK PLOTS FOR

HYDRAULIC FRACTURE EVENTS WITH ASSUMED INJECTION VOLUME OF 23,000 bblA-2-1 CUMULATIVE FLOWBACK PLOTS FOR HYDRAULIC FRACTURE EVENTS WITH ASSUMED INJECTION VOLUME OF 23,000 bblA-2-2A-2-3

# APPENDIX B

BAKKEN FRAC FLOWBACK WATER SALINITY

VERSUS TIME DATA PLOTSB-1 BAKKEN FRAC FLOWBACK WATER SALINITY VERSUS TIME DATA PLOTSB-2B-3B-4B-5B-6 Note: This figure contains data for sample s of Bakken frac flowback water that were analyzed for both TDS and electri cal conductivity. This relationshi p was used to coordinate the conductivity and TDS axes on th e plots presented for Producer A flowback water. The magnitude of a conductivity to TDS conversion factor depends on the particular distribution of ions in a given water. The literature reports values ranging from 510 to 970 mg/L TDS/(mS/cm).

The value calculated for the Bakken flow back water was 728 mg/L TDS/(mS/cm).

# APPENDIX C

CHARGE BALANCE ERRORC-1 CHARGE BALANCE ERROR

Aqueous solutions must be electrically neutra l. The sum of all negative charges must equal the sum of all positive charges. An indicator of the quality of a water analysis is the charge balance error (CBE). CBE is calcula ted based on the following formula:

The cations and anions in the above equation have units of milliequivalents per liter (m). This value is then multiplied by the valence of the ion (z).

CBE may be negative or positive, dependi ng on whether anions or cations are more abundant in the analysis. For instance, a negative CBE value indicates that the water sample has a higher concentration of anions than cations. A CBE of ±5% is acceptable for most groundwater samples (Freeze and Cherry, 1979). If the CBE exceeds 5%, it may be because of an anion or cation not included in the analysis , an error in the analysis, or a data recording error. Produced water flowback after hydraulic fracture is high ly brackish. Brackish wate r can often lead to a higher CBE than normal groundwater. However, in the case of these three samples, the CBE was very small, an indication likely all of the cations and anions in solution have been accounted for.

REFERENCE

Freeze, R.A., and Cherry, J.A., 1979, Groundwat er: Englewood Cliffs, New Jersey, PrenticeHall, Inc., 604 p.

# APPENDIX D

WATER USE FACT SHEET

# EER C

E n e r

g y & E

n v i

ro n m e n t a l R e

s e a r

c h C

e n t

e r ® Putting Research into Practice 

# Northern Great Plains Water Consortium

The Demand for Water 

# W ater is the most critical limiting resource throughout the world. Sustainable economic growth requires a reliable supply of water for energy, agriculture, and a growing population. Water is necessary for urban development, power production, growing and processing high-value crops, oil and gas development and processing, and industrial manufacturing. Satisfying all of these competing needs requires a better understanding of water resources and new approaches to water management. Energy, agriculture, industry, and municipalities all urgently need a scientifically valid basis upon which to make management and regulatory decisions related to water use and quality.

The Energy & Environmental Research Center (EERC) is developing a partnership between the U.S. Department of Energy (DOE) and key energy-producing entities in the northern

Great Plains to address issues related to water availability, reducing freshwater use, and minimizing the impacts of facility and industry operations on water quality. The key goals of this partnership, called the Northern Great Plains Water Consortium (NGPWC), are:

• To evaluate water demand and consumption from

competing users in the northern Great Plains region, including energy production, agriculture, industry, and domestic/municipal users.

• To assess, develop, and demonstrate

technologies and methodologies that minimize water use and reduce wastewater discharge from energy production and agricultural processing facilities.

• To identify nontraditional water supply sources

and innovative options for water reuse.



### Thinking Outside the Box to
Address Water Issues

As the United States continues to pursue economic development and the population increases, demand for ever-increasing amounts of energy to support that growth will require water. In areas

where water resources are limited or become scarce because of overallocation and/or drought, competing interests for water could limit energy development and production. With the vibrant oil, gas, and utility interests in the region, potential water reuse synergies among energy-related industries should be explored. For example, thermoelectric power generation is second only to agriculture as the largest domestic user of water, accounting for approximately 40% of all freshwater withdrawals in the United States, as illustrated in the figure above. A portion of that cooling water effluent could be used in other industries, perhaps even prior to cooling, to capitalize on the waste heat. Significant volumes of water are also used in the drilling and completion of oil and gas wells. Wastewater from other industries could be used to supply water needed for drilling operations, and options may exist to treat and reuse the produced water from oil and gas operations. Finding innovative solutions that expand water resource options for the energy industries in the region is one of the key goals of the NGPWC. 

## Water Use Fact Sheet

3 9

. 7 % 4 0

. 1 %

1 2

. 7 %

5

. 8 %

1

. 1 %

0

. 7 % T h e r m o e l e c t r i c P o w e r

I r r i g a ti o n

P u b l i c S u p p l y

I n d u s t r i a l U s e

A q u a c u l t u r e

D o m e s ti c
, L i v e s t o c k

,
a n d M i n i n g

The major users of freshwater within the United States (aquaculture is the farming of aquatic organisms).

EERC BK32528.AI

Ag-Related Processing

Electric Utility

Industrial

Petroleum- and Natural
Gas-Related Facilities

NGPWC region showing the locations of key energy, agricultural, and industrial facilities.

EERC . . . The International Center for Applied Energy Technology SMThe NGPWC is a partnership of key public and private water users in the northern Great Plains region. New members are
welcome. To learn more, contact:

**Bethany A. Kurz** , Senior Research Manager, (701) 777-5050

**Daniel J. Stepan** , Senior Research Manager, (701) 777-5247

**John A. Harju** , EERC Associate Director for Research, (701) 777-5157

**Gerald H. Groenewold,** EERC Director, (701) 777-5131 Approximate Volumetric Equivalents

barrels gallons acre-feet cubic feet cubic meters

1 42 0.000129 5.6146 0.15897

7758 325,851 1 43,560 1233

23,810 1,000,000 3.1 133,681 3785

Approximate Flow Equivalents

barrels per day (bbl/day) million gallons per day (Mgd) gallons per minute (gpm) cubic feet per
second (cfs) cubic meters per
second (m 3 /s)

23,810 1.0 694.4 1.55 0.04381

34.3 0.00144 1.0 0.0022 0.00006

100 0.0042 2.9167 0.0065 0.000184

Water Use Comparisons

Use gallons
(millions) barrels
(thousands) acre-feet cubic meters

Typical Daily Use for a 50,000-Person Midwestern City 10 238.1 30.7 37,850

Daily Pumping Volume for a Center-Pivot Irrigator for 130 Acres (irrigated portion of 1⁄4 section) 1.008 24 3.1 3815

Average Daily Water Withdrawal for Once-Through Cooling at a 400-MW Coal-Fired Power Plant 365 8691 1120 1,381,525

Water Used to Fracture the Formation for an Oil Well in
the Bakken Formation ( one-time use ) 0.5–1.0 11.9–23.8 1.5–3.1 1893–3785

Proposed Maximum Daily Volume of Water Imported for the Red River Valley Water Supply Project 77.56 1,847 238 293,556 

### Putting Regional Water Use in Perspective

The various industries and water users within the region often use different units of reference when referring to water consumption and discharge. To gain a perspective on the relationship between municipal, industrial, and agricultural water use, it is helpful to compare some common units and examples of water use among the

sectors.

EERC BK32526.INDD 1/10 Sponsored in Part by the U.S. Department of Energy

N A T I O N A L E N E R G Y T E C H N O L O G Y L A B O R A T O R Y 

### Interested in Joining?

The EERC is actively seeking charter members to complement DOE funding and to help direct the program’s efforts. The NGPWC is currently engaged in Phase I of the program, wherein future program efforts and demonstration projects will be selected and prioritized. Phase II of the effort, scheduled to begin in 2010, will focus on demonstrating the water minimization and beneficial reuse strategies and technologies prioritized in Phase I. Conversion Factors

1 cubic foot = 7.4805 gallons
1 gallon = 3.785 liters

1 cubic meter = 1000 liters
1 acre = 43,560 square feet

U n i v e r s i t y o f N o r t h D a k o

t a G r

a n d F

o r k

s