Oil And Gas Produced Water Management And Beneficial Use In The Western .

Figures (continued)PageFigure 4Figure 5Figure 6Figure 7Figure 8Figure 9Figure 10Figure 11Figure 12Figure 13Figure 14Figure 15Figure 16Figure 17Figure 18Figure 19Figure 20Figure 21Figure 22Figure 23Figure 24Figure 25Figure 26xGeographic distribution of conventional gas wellsin the Western United States .Conventional and unconventional welldistribution by State .Produced water quantities by State in the WesternUnited States .Overlay of oil and gas producing basins and areaswith a potential for water conflict .Fresh water usage in the Western United States .Suitability of water for irrigation (adapted fromAyers and Westcot 1994) .Distribution of TDS for conventional basins .Distribution of TDS concentration for conventionaloil and gas .Distribution of TDS concentration for unconventionalCBM basins .Major cations and anions for produced water .Dominant salt types of produced water .Western United States oil and gas basins: dominantsalt type distribution.Geochemical fingerprints of conventional andunconventional basins .Western United States oil and gas basins: watergeochemistry .Radioactive oilfield equipment (USGS FactSheet 0142-99) .Conventional versus unconventional welldistribution in the TDS requirement categories foreach beneficial use .Western United States oil and gas basins: percentageof wells in various beneficial use categories.Conventional versus unconventional welldistribution in the irrigation requirementcategories for SAR .Western United States oil and gas basins: percentageof wells in SAR irrigation categories .Dead-end versus cross flow filtration .Schematic diagram of CDM produced watertreatment process .Base map with reference data and sources .Location of oil and gas producing basins and thetop 100 producing oil and gas wells in the WesternUnited States .1521222325304345454748485254596263656681919495

Figures (continued)PageFigure 27Figure 28Figure 29Figure 30Figure 31Figure 32Figure 33Figure 34Figure 35Figure 36Figure 37Figure 38Figure 39Geographic relationship between hydrologic unitsand petroleum basins.Potential water conflict and produced water generation .Areas of irrigated agriculture compared toproduced water generation .Selection of top 100 producing well in theDenver basin .Agricultural data within the study area .Oil and gas well location data within the study area .Irrigated land within the study area .Powder River basin example area .Location of oil and gas wells within 5-mile radius oftop producing well in the Powder River basin .Irrigated and nonirrigated agriculture within thestudy area .Uinta-Piceance basin example study area .Five-mile study radius for Piceance basin example .Surface discharge beneficial use option forUinta-Piceance study area .9596979899100100101102103103104104xi

1. Executive SummaryDue to increasing demand on fresh water sources, there is a need to develop newwater supplies in the Western United States. Large volumes of water producedduring oil and gas extraction, called produced water, are generated in droughtprone locations that are also experiencing an increase in population. Producedwater is a waste byproduct of the oil and gas industry; however, with appropriatetreatment and application to beneficial use, produced water can serve as a newwater supply in the Western United States.The Bureau of Reclamation (Reclamation) Technical Service Center gathereddata from publically available sources to describe the water quality characteristicsof produced water, performed an assessment of water quality in terms ofgeographic location and water quality criteria of potential beneficial uses,identified appropriate treatment technologies for produced water, and describedpractical beneficial uses of produced water.Produced water quality varies significantly based on geographical location, typeof hydrocarbon produced, and the geochemistry of the producing formation. Ingeneral, the total dissolved solids concentration can range from 100 milligramsper liter (mg/L) to over 400,000 mg/L. Silt and particulates, sodium, bicarbonate,and chloride are the most commonly occurring inorganic constituents in producedwater. Benzene, toluene, ethylbenzene, and xylene (BTEX) compounds are themost commonly occurring organic contaminants in produced water. The types ofcontaminants found in produced water and their concentrations have a largeimpact on the most appropriate type of beneficial use and the degree and cost oftreatment required.Many different types of technologies can be used to treat produced water;however, the types of constituents removed by each technology and the degree ofremoval must be considered to identify potential treatment technologies for agiven application. For some types of produced water, more than one type oftreatment technology may be capable of meeting the contaminant removal target;and a set of selection criteria must be applied to narrow down multiple treatmentoptions.Beneficial uses of produced water include crop irrigation, livestock watering,streamflow augmentation, and municipal and industrial uses. Produced water alsocan be placed in aquifer storage for future use. The type of beneficial use mostappropriate for a produced water application depends on the geographical locationof the produced water generation, the location of the beneficial use, and theconstituent concentrations in the produced water.1

Given the large volumes of produced water generated in the Western UnitedStates and the growing need for new water supplies, produced water has thepotential to augment conventional water supplies. Produced water, if managed asa resource rather than a waste for disposal, has the potential to be usedbeneficially.2

2. BackgroundProduced water is defined as the water that exists in subsurface formations and isbrought to the surface during oil and gas production. Water is generated fromconventional oil and gas production, as well as the production of unconventionalsources such as coal bed methane, tight sands, and gas shale. The concentrationof constituents and the volume of produced water differ dramatically dependingon the type and location of the petroleum product. Produced water accounts forthe largest waste stream volume associated with oil and gas production.2.1Petroleum Resource Formation and Production2.1.1 Conventional Oil and GasOil is formed from plant and animal material that accumulates at the bottom of awater supply such as an ocean, river, lake, or coral reef. Over time, this materialis buried by accumulating sediment and is pushed deeper into the earth’s surfacewhere the pressure increases from the weight of the overlying sediment and thetemperature increases due to heat from the earth’s core. Oil and gas reservoirs arecreated when hydrocarbon pyrolysis occurs in a confined layer of porous reservoirmaterial. The confined material restrains the fossil fuel in the subsurface, whilethe permeable and porous reservoir material allows for accumulation. Oil existsunderground as small droplets trapped inside the small void spaces in rock. Whena well is drilled into an oil reservoir, the high pressure that exists in the reservoirpushes oil out of the small voids and to the surface.2.1.2 Unconventional Petroleum ResourcesOil shale, gas shale, tight sands, and coal bed methane are consideredunconventional petroleum resources. Oil shale reservoirs are confined insedimentary formations. Oil shale formations do not convert hydrocarbons intocrude oil. Oil shale commonly is refined to produce a cleaner energy product forhigh grade fuel use. Tight sedimentary formations retain the hydrocarbonsrequiring energy and water intensive well development. Fracturing polymers incombination with water are injected at high pressures into the reservoir formation.Fracturing is necessary to produce sufficient effective aquifer conductivity toallow the production of economical quantities of oil and gas. The United Stateshas the largest oil shale deposits. The Green River formation in Wyoming,Colorado, and Utah contains the largest oil shale deposit in the United States.Seventy percent of the commercially attractive resource in the Green Riverformation resides on land managed by the United States Federal Government.Gas shale also is produced naturally from the shale formation. Gas is stored infractures, pore space, and adsorbed to the organic reservoir material. Gas shale3

was first developed by producing it from large fractures in the formations thatprovided sufficient gas flow for economic development. Recent advances in wellcompletion technology and artificial fracturing have increased the exploration ofthis resource. Shale gas has been produced for extend periods in the United Statesin the Illinois and the Appalachian basins. Due to recent advances in technology,the Barnett Shale in Texas also has been highly economical.Tight sands gas are an unconventional natural gas resource produced from lowpermeability compacted sediments. Similar to gas shale, advancements intechnology have increased the development of tight sands into an economicresource. Gas is tightly contained in the low permeability reservoir formation,and wells must be stimulated to produce from the reservoir formation. Tightsands basins in the United States overlap certain gas shales basins, but there is nocoincidence of tight sands in shale gas basins. Tight sands production occurs inthe Great Plains, Rocky Mountains, the Four Corners region, onshore gulf coast,and in Arkansas/Oklahoma.Coal bed methane or coal bed natural gas is an unconventional natural gasresource extracted from coal beds. Methane (CH4) is formed in the coal seam as aresult of both the bacterial processes (biogenic) and the chemical reactions thatoccur with high temperature and pressure during the bituminization phase(thermogenic). Methane from higher ranking coals is formed by thermogenicproduction, and lower rank coals produce methane by biogenic production.Additionally, the volume of gas increases with coal rank, depth, and reservoirpressure. Coal has a large surface area per volume, so that coal seams can containlarge volumes of gas. Coal seams are capable of containing six to seven timesmore gas than conventional gas reservoirs of comparable size (Taulis 2007).Because of the way in which coal is formed, large amounts of coal bed methaneexist at shallow depths. The shallow depths make drilling wells for coal bedmethane production relatively inexpensive. At greater depths, higher pressurecauses fractures in the coal seam to close, making the formations less permeableand more difficult for gas to move through the coal. Many of the coal bedmethane basins in the Rocky Mountain region, including the Powder River andthe San Juan basins contain subbituminous coals. Subbituminous coal is softenough that conventional well bores can be used, and the well is drilled to the topof the target coal seam.The Energy Information Administration publishes estimates of the provedreserves of coal bed methane. The proved reserves represent estimated quantitiesof coal bed methane (CBM) 1 that analysis of geological and engineering datademonstrate, with reasonable certainty, to be recoverable in future years fromknown reservoirs under existing economic and operating conditions (UnitedStates Energy Information Administration 2007). Actual coal bed methaneproduction data, formation testing, coal core analyses, and other data are used to14Also known as coal bed natural gas.

determine the economic production capacity of the coal formations. It is notnecessary that production, gathering, or transportation facilities be installed oroperative for a reservoir to be considered proved. Table 1 contains estimates oftotal and proved reserves for the major coal bed methane producing basins in theWestern United States. In general, as more data becomes available andtechnology advances, the estimated recoverable reserves of CBM increase.Between 2002–2007, the estimated total United States reserves increased by18 percent (%) based on historical data provided by the U.S. Energy InformationAdministration (USEIA).Table 1. CBM recoverable gas reserves and water qualityBasinPowder RiverRatonSan JuanUintaPiceanceCumulative1Production tion(million2barrels)Water toGas 1478,446460.0317581,995310.4241NA0.301.2NA – information not available1Un

Oil and Gas Produced Water Management and Beneficial Use . CBM coal bed methane, also coal bed natural gas CIP clean in place COD chemical oxygen demand . 7.3.2 CDM Produced Water Technology . 89 7.3.3 Veolia OPUS . 91 7.3.4 Altela Rain .