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FRACTURING

WATER SOURCING, FLOWBACK, RE-USE, DISPOSAL, AND RELEASE TO ENVIRONMENT

• The numbers on this graphic show increasing time.

1. Water acquisition: water is purchased and transported to the site.

2. The frac job is done. Chemicals are added, and the fluid pumped into the well.

3. The water comes back out of the well (flowback) along with water that was in the formation naturally (produced). It is stored in pits or tanks.

4. The water is transported offsite, treated, and usually injected in disposal wells.

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http://www2.epa.gov/hfstudy/hydraulic-fracturing-water-cycle

WATER PROCESS FLOW

WATERSOURCING

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SOURCING

WATERFLOWBACK

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FLOWBACK

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FLOWBACK

WATERDISPOSAL BY INJECTION

INJECTION WELLS

• After you get permits, the most simple disposal method

• Very common

• Central plant may have pumps that push water through a flowline network to the wells

• The water may be hauled in trucks

• Wells will usually be perforated, and have a packer

• Most states require a yearly test to make sure the water is going in the intended zone

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• Depending on the jurisdiction (usually the state):– Permits are required for the

individual wells

– Permits may be required for an overall “project”

– Permits may be required associating producers with particular injectors

• Some states more strict than others

INJECTION WELLS

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TYPICAL STATE UIC AUTHORITY

• UIC - Underground Injection Control

• EPA may delegate authority to the states for injection

Graphic from US EPA website

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PRIMACY: TWO EXAMPLE STATES

• Primacy – or primary enforcement authority – The authority to implement the UIC Program. To receive primacy, a state, territory, or tribe must demonstrate to EPA that its UIC program is at least as stringent as the federal standards; the state, territory, or tribal UIC requirements may be more stringent than the federal requirements. (For Class II, states must demonstrate that their programs are effective in preventing pollution of USDWs.) EPA may grant primacy for all or part of the UIC program, e.g., for certain classes of injection wells.

• California has a shared program with EPA

• Ohio has full primacy

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http://water.epa.gov/type/groundwater/uic/glossary.cfm#primacy

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WATER DISCHARGE TO THE ENVIRONMENT

“SURFACE DISCHARGE”

WESTERN STATES

• The discharge of oil field produced water into surface waters is allowed in states west of the 98th meridian if the water is used for agriculture or wildlife propagation (40 CFR (Code of Federal Regulations) 435 subpart E).

• Notice that it’s green east of the 98th meridian, and brown west of it.

– Shallow groundwater to protect or no?

– Need for water great enough to allow surface discharge?

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NPDES – SURFACE (NOT INJECTION WELLS)

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• National Pollutant Discharge Elimination System (NPDES) permit program controls water pollution by regulating point sources that discharge pollutants into waters of the United States

• You have to check the particular permit for water cleanup requirements

• Typically for discharge to streams:

– Oil and grease in 10’s of ppm

– TDS in low 1000’s of ppm

NPDES ADMINISTRATION VARIES BY STATE.

• EPA is a federal regulator

• They delegate authority for certain programs to state/tribal regulators in some cases

• Affects water discharges to streams

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WATERRE-USE

WATER PROCESSING

• We will first look at a state of the art system that has:– Both sources of water

• Produced

• Frack

– All three destinations for water• Re-use

• Discharge to environment

• Injection

• Then we will look at components of the process

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STATE OF THE ART: ANTICLINE DISPOSAL FACILITY

• Water is brought in from frack flowback sites and production

• Processed for re-use – Frack jobs

– Discharge to river

• Concentrated brine from RO is injected in a disposal well

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Photo courtesy of High Sierra Water Services

EQUIPMENT & PROCESSESSO, HOW DO WE DO THAT?

JARGON – WHAT’S “SCALE”?

• Scale is buildup of minerals in pipe

• Can happen in surface equipment or downhole

• Have to remove using acid or “mechanically”

• Problem may not be obvious –pipes are not see-through, and you can’t go downhole

– Causes pumps to have to work harder, using more electricity

– In boilers, can reduce heat transfer efficiency

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FWKO TREATER

WASHTANK

WEMCO

PRODUCEDWATERTANK F

ILT

ER

S

SOF

TE

NE

RS

FILTERED WATER TANK

SOFT WATER TANK

DISPOSAL WELLS

94% WaterEmulsion

30% WaterEmulsion

First stage separation (primary)

Second stageseparation

Third stageseparation

Solids Removal

Calcium and Magnesium Removal

ADVANCED WATER PROCESSING - EXAMPLE

RO

PL

AN

T

BENEFICIAL

REUSE

Salt Removal

Wash Tank/Clarifier Tank• After primary separation in the

FWKO, the water is fairly clean• The wash tank serves to reduce

the oil in water (OIW) content to the “hundreds of ppm” level

• The WEMCO then reduces the OIW to less than 5 ppm

• You may see the term “wash tank” used to refer to other equipment too

• Tank shown has “water leg” to regulate water level in tank

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WATER PROCESSING

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FLOTATION CELL (WEMCO)

• WEMCORemoves oil from water

• If inlet oil concentration is 100 ppm, outlet concentration of 5 to 10ppm can be achieved.

• Needed if downstream process requires low oil content.

• NPDES permits may allow higher concentrations

• (National Pollutant DischargeElimination System )

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• Osmosis: the diffusion of molecules from a place of higher concentration to a place of lower concentration until the concentration on both side is equal

• Reverse Osmosis: high pressure filtering thru a filter with extremely tiny holes

REVERSE OSMOSIS

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