Shale Gas Extraction by Hydraulic Fracturing - seii.org · PDF fileEarthquakes triggered by gas gas production from unconventional deposits are less probable than from conventional

www.dmt.deNovember 2013 | Brussels | SEII Meeting | Hydraulic Fracturing | Slide 1

Shale Gas Extraction by Hydraulic Fracturing

Dipl.-Geol. Ralph SchlüterDMT GmbH & Co. KG, Essen, Germany

SEII, Brussels15.11.2013


EUROPEEUROPE?

Source: TIME Magazine


History and application of fracking

First fracture stimulation: 1949 in Duncan, Oklahoma;

Quelle: aoghs.org


Applied for about 70 years, in Germany for about 50 years

Objective: Permeability, which is not in the rock naturally, is produced by → use of horizontal drilling, application of perforating gun and frac fluids

Pro: Allows economic production of the resource→ producing remaining quantities and making up for production decline

Disposal in wells, depleted deposits or processing

Number of fracs in Germany since 1961

Frac-technology has been applied in Germany for 50 years to stimulate natural gas deposits

History and application of fracking


Gas from unconventional deposits

Difference between conventionaland unconventional deposits

Unconventional deposits are made up of reservoir rocks with very low permeability

conventional deposits

unconventional deposits

conventional structural traps

tight sandstone

shale

coalCoalbed Methane

Tight Gas

Shale Gas

Connected pores lend the rock its permeability

Source: Erdgassuche in Deutschland (ExxonMobil)

adapted from BGR


Tight gas3.500-5.000 m deepin impermeable sand- and limestone formations

Shale gas700 - 2.000 m deepOrganic matter is degraded in the shale under high temperatures, subsequent re-adsorption of the gas and inclusion in shale formations

Coal Bed Methane700 – 2.000 m deepDegradation of organic matter in coal occurrences


Source: STATOIL




The process in detail

Providing the basis:

Site investigation

Geological exploration of gas resources

Simulating the environmental impact of drilling and production

Providing the infrastructure, electricity, water, access roads,later, if necessary piping


Providing the basis:

Waste disposal

Collection system for sludge and pumped water (flowback)

Rigging up




Source: Wintershall

Drilling vertically until the targeted reservoir rock is reached (max. ≈ 5000 m deep)

Setting steel casing and cementing to prevent contamination

Branching and drilling horizontal leg (max. 1000 - 3000 m)

Completion of well and disposal of cuttings and drilling mud

Source: Canadian Association of Petroleum Producers


Site configuration during frac operation



Frac propagation along zones of weakness, e.g. bedding planes orpredefined fractures, perpendicular to the least normal stress direction

Under high pressure (200 – 300 bar, max. 1000 bar) a mixture of water, sand and chemical additives is pumped into the reservoir rock for a few hrs


Perforation


Water consumption depending on type of deposit: 500 to max. 5.000 m³

„Sand“ remains in the fractures and act as propping agent to maintain the enhanced permeability

Gas flows from the rock towards the well bore

Additives are required to reduce friction, prevent precipitation, corrosion and biofilms

Source: Golden rules for a Golden Age of Gas, IEA report

Source: Empire Energy Forum



Drillhole cluster (shale gas – Coalbed Methane)


Source: STATOIL


Frac dimensions and control

Frac dimensionse.g. at 2,500 m drilling depth max. frac height 450 m

groundwater aquifer (max. 500 m)

range of medium frac height

range of maximum frac heightdepth

Source: Risk Study Fracking / ExxonMobil


Frac dimensions and controlModelling of frac propagation

Frac‐propagation in different formations is not homogenous.

Upwards the fracs are limited by the barrier rock!

Viscosity of injection fluid has a high influence on frac geometry

Fracs can be controlled!


Frac dimensions and controlModelling of frac propagation

Salt level

Bottom anhydrite


Frac dimensions and control


971 m >> Wurmberg (Harz)

830 m >> Burj Khalifa

443 m >> Empire State Building

157 m >> Cologne Cathedral

Injection W

ell

Production W

ell

Leakage of chemicals on well site/ truck accident

Methane migration

Frac fluid in deep groundwaterRising frac fluid

Well leakageBlow-OutLeakage waste water pipeline

Well leakage

Rising waste water

Waste water in deep groundwater

Injection of frac fluid into the wellInjection of frac fluid into the deep undergroundConsumption of water and waste water disposalSeismic events – EarthquakesGas leakage and emissions

Environmental risks and respective pathways

Chemicals at the well site


Chemicals at the well siteMost probable risk scenario is a transport accident


Injection of water and frac fluidsWater requirements

Shale gas deposit

Locality depth of geological

formation (m)

Porosity %

Percentage TOM %

Amount of water per well

(m³)


Injection of water and frac fluidsApplication of different frac fluids

Rock brittleness Fluid system Frack geometry Fluid volume Amount of proppant High Low

Low High

SlickwaterSlickwater

HybridLinear Gel

FoamLinked GelLinked Gel

CO2/N2-Hybrid-Fluid Slickwater1982-2000 2000-2011 Natarp 1995 2000-2011 Damme 2008

Water [m³/frack] 785(302 - 2,336)

268(92 - 461)

61 303(37 - 459)

4,040

Liquid gas[kg/frack]

- - 40,875 45,589(32,684-73,218)

-

Proppant[kg/frack]

163,907(47,100 - 450,000)

98,629(18,900 - 184,625)

20,850 54,429(14,583 - 115,714)

196,000

Additive[kg/frack]

54,959(4,343 - 274,764)

7,346(2,803 - 18,058)

615 7,709(1,276 - 16,832)

6,624


Purpose and composition of frac fluid: Reduction of additives e.g. replacement of

biocides by UV radiation Alternative: Clean Fracking

Additives Purpose

Gelling Agent Increase viscosity

Foams Transport and settlement of sand

Acids Dissolving minerals

Corrosion Inhibitor Protection of installations

Breaker Reducing viscosity for flowback recovery

Biocide Prevention of bacteria growth

Fluid-Loss Reduction of fluid-loss into the host rock

Friction Reducer Reduction of friction in fluid

Frac fluids and flowback



New developments:

Gas Fracking with higher hydrocarbons replacing water (applied in the US)

Clean-Fracking (Austria) with water, bauxite sand and starch as propping agents (tests abandoned)



Dissolving mineral phasesSorption of additivesTransformation and degradation productsMobilisation of hydrocarbons

Equilibrating mineral phasesHydrocarbonsNaturally Occurring Radioactive MaterialGases

Formation water

potential spreading along flow paths

Vertical and horizontal transport of frac fluid can be modelled and are expected to be very limited


Frac fluids and flowbackWater recycling Part of the flow back will

be recovered; surface storage in tanks or ponds

untreated formation water

injection into depleted oil and gas fields

geology / chemistry

disposal in sewage plant

chemistry / HSE / saline load / safety values/

disposal in surface water system

chemistry / HSE / safety values/

Analysis of environmental impact of different methods

other methods of disposal


Frac fluid / formation water disposalWater recycling

Applying techniques to process flowback is still in the development phase

Flowback treatment on site separation of chemicals disposal of remaining

substances quality of treated waste water

≥ quality of formation water joint disposal / injection testing of applicability of

modern treatment plants

The concept of recycling formation water and flowback has yet to be proven

Production water

Flow

back

10 % to 30 % of the originally injected frack fluid


Need for action: Full disclosure of all substances applied regarding identity and quantities; Providing relevant physico-chemical parameters to assess their environmental

behavior; Site-specific detection and evaluation of the composition of the formation water

and flowback regarding drinking water relevant ingredients (salts, heavy metals, hydrocarbons, NORM) and regarding the additives used (primary substances) as well as their transformation products (secondary substances);

Collection and evaluation of the proportion of the back produced frac fluid; Evidence of the behavior and fate of substances in the site-specific

underground through life cycle assessment of the additives used; Integration of environmental criteria in the selection of appropriate additives,

and developing environmentally friendly frac fluids.

Citation NRW StudyPreliminary conclusion frac-fluids, formation water and flowback


Seismic events - Earthquakes

Seismic events / „earthquakes“ in connection with natural gas production from unconventional deposists are possible, but

Earthquakes triggered by gas gas production from unconventional deposits are less probable than from conventional deposits.

Combining monitoring and controling frac processes will probably allow to minimize the risk.

For newly developed deposits a dense monitoring network makes sense

Breaking length Magnitude Appearence, EffectMajor earthquakes 10 - 300 km 6 bis 9 Japan, Indonesien, ...

major to catastrophic damagesMinor earthquakes 100 m - 3 km 2 bis 5 also in Central Europe

no to minor damagesMicroearthquakes 1 - 30 m -2 bis 1 can be technically induced

not noticeable by menFracking -2 bis 0


Gas leakage and emissionsImpact of frac fluid on consolidated drilling cements

Salt precipitation can protect the surface from aggresive chemicals

Partly increase of mean compressive strength by post-hydratation

Mean compressive strength in N/mm²

Step 1 Step 2 Step 3 Step 4 Step 5


DMT’s services for unconventional gas depositsSafety in planning, exploration and operation

Geological consulting

2D- and 3D seismics

Geological modelling

Numerical modelling of ground-water and transport processes

Numerical simulation of gas flow

Monitoring of effects on ground-water quality and quantity

Monitoring of waste water disposal

Monitoring of gas leaks and surface gas emissions

Microseismic monitoring of frac propagation and seismic events


DMT’s services for unconventional gas depositsSafety in planning, exploration and operation

Geological consulting

2D- and 3D seismics

Geological modelling

Numerical modelling of ground-water and transport processes

Numerical simulation of gas flow

Monitoring of effects on ground-water quality and quantity

Monitoring of waste water disposal

Monitoring of gas leaks and surface gas emissions

Microseismic monitoring of frac propagation and seismic events


Need for action:

To allow a containment and detailed definition of development orproduction techniques, the geological conditions must be known first.

The currently communicated development concepts must be explicitly complemented by dealing with the accruing deposit water and flowback.

Further studies regarding cement aging and long-time barrier integrity of wells must be performed. The current state of the art in this respect must be examined for potential improvements.

Citation NRW StudyPreliminary conclusion exploration and extraction techniques


16. For deep wells that are drilled in the frame of exploring unconventional natural gas deposits without fracking (phase A), in our view no other requirements must apply than for wells not aiming at unconventional natural gas deposits unless they are planned to be fracked in the necessary subsequent phase B. The primary objective of these holes should here - from a water management point of view -be the exploration of geological, hydrogeological and hydrochemical conditions. Particularly for the coalbed methane deposits, which are significant for NRW clarity should be established whether the fracking technology must necessarily be used.

Citation NRW StudyFundamental recommendations


In September, the Federal Environment Agency had warned in its report of possible hazards of fracking for groundwater. BGR experts blame the Environmental Protection Agency ... of negligent examination. UBA has equated in its opinion erroneously groundwater with drinking water. On the subject of fracking, however, is not about aquifers near the surface, but to much deeper layers, the newspaper quoted from the statement. The near-surface groundwater for drinking water winning, however, “are mostly not in conjunction” with deeper layers of rock with gas reserves.The assumed hazard for groundwater by fracking in the UBA study is therefore far less relevant than shown. In addition, the consultants of the UBA had made inaccurate statements about possible hazards of thechemicals that would be used for fracking.

Federal authorities arguing about gas productionfrom Spiegel online


Production Marcellus Shale USA


Thank you for your attention!

Source: Energy Tribune


RESERVE


Status in Germany

In Germany applied for about 50 years

Objective: Permeability, which is not in the rock naturally, is produced by → use of horizontal drilling, application of perforating gun and frack fluids

Pro: Allows economic production of the resource→ producing remaining quantities and making up for production decline

Disposal in wells, depleted deposits or processing


In Germany large areas are bearing potential shale gas and coalbed methane deposits

New fields have been awarded for unconventional gas occurences

Major players are ExxonMobil, Wintershall, BNK Petroleum, 3Legs Resources, Dart Energy

Study of the independent group of experts is available (sponsored by ExxonMobil)

Studie North-Rhine Westphalia

Studie German Environmental Agency

Amendments to the mining law are discussed

Status in Germany


International positions

based on Golden rules for a Golden Age of Gas, IEA report

Advanced with considerable production: USA, Australia, CanadaUSA turning from gas importer to exporter, sharp drop of local gas price

„Emerging countries“China, India, Poland

Potential:Mexico, South America, South Africa, Russia

currently cautious or rejecting: Germany, France, Bulgaria, Romania, Czech Republic


International positions

Advanced with considerable production: USA, Australia, CanadaUSA turning from gas importer to exporter, sharp drop of local gas price

„Emerging countries“China, India, Poland

Potential:Mexico, South America, South Africa, Russia

currently cautious or rejecting: Germany, France, Bulgaria, Romania, Czech Republic


Composition and development of frac fluids


Wird Deutschland „Gasland“?


Citation NRW StudyFrac-Fluids

The selection of the frac additives is based in particular on the required viscosity for proppant transport, the pressure and temperature conditions in the reservoir, the mineralogical and geochemical composition and petrophysical properties of the target horizon, the hydrochemical composition of the formation water and the protection against installation corrosion.

The analysis of available data shows that per frac between <100 m³and >4,000 m³ fluids were used, whereas the amounts vary considerably depending on the fluid system used and the reservoir properties. ..... in more recent gel fluids, applied after the year 2000 per frac on average about 100 t of proppant and 7.3 t of additives (of which usually < 30 kg are biocidal products).


Need to action:

Evaluation of so far not accessible documents,

Field investigations (3D seismic, drilling without fracs),

Establishment of regional models,

if appropriate, comparison with the results of Exxon expert dialogue.

Citation NRW StudyPreliminary conclusion risk


Prior to the approval of a frac, the following tasks have executed:

Confirmation and localization of economically recoverable unconventional gas resources …..

Deduction of recovery strategies (individual holes / cluster well sites, with or without fracking, etc.) that will be needed to exploit them.

The existing WEG guide for well site design should be adapted to the requirements of a cluster well site.

Citation NRW StudyConclusions and recommendations


Vielen Dank für Ihre Aufmerksamkeit!

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Shale Gas Extraction by Hydraulic Fracturing - seii.org · PDF fileEarthquakes triggered by gas gas production from unconventional deposits are less probable than from conventional