Direct Push High-pressure Jet Injection Method for Delivery of in Situ Remediation

Agents in Clay Till

Chapman Ross – Geosyntec Consultants

Co-Authors and Partners

Mads TerkelsenLone Tolstrup KarlbyCamilla Christiansen

FRx

Neal DurantChapman RossOwen Cadwalader

Bill Slack

Capital Region of Denmark

Hydraulic Fracturing Experts

Torben JørgensenLars Nissen

Problem Statement: Develop Method to Treat DNAPL Residual and Solvents Diffused into Clay Till

~40% of Denmark covered in highly fractured clay till

~1,500 chlorinated solvent sites in clay till in Capital Region alone

Result: many long term difficult to treat sources

High Pressure Jet Injection Mechanisms

How it worksUp to 690 bar (10,000 psi) water jetting erodes conduits in

clay in a chosen orientation.10.3 to 27.6 bar (150 to 400+ psi)

slurry introduced which creates hydraulic fractures extending from the ends and between the conduits.Slurry contains proppant/reactant

(sand, ZVI, etc) which holds fracture open and either enhances permeability or reacts with contaminants directly.

HorizontalFracture

Conduits

Cavity

High Pressure Jet Injection –Pilot Testing Chronology

Initial DK Pilot Test

DPT Proof of Concept Testing

DPT Jet Injection Testing – Phase I

Year 2011 2012 2013

Location Denmark US (SC) US (OH)

Geology Clay Till Saprolite Clay Till

Delivery Method Blank PVC Well DPT (single line) DPT (dual line)

Jetting Fluid Water Water w/ Green Dye Water

Injection Slurry

Amendment Slurry w/ Rhodamine WT Dye

noneCross-linked Guar

Gel Slurry w/ Rhodamine WT Dye

Initial Jet Injection Pilot TestTaastrup, Denmark, November 2011

Initial Denmark Pilot Test - Objectives - Taastrup, Denmark, November 2011

Deliver aqueous slurry ZVI via jet injection into PVC wells in fractured basal clay till formation at 3-7 meters below ground surface. Determine whether sub-horizontal, homogeneous distribution of remediation material is possible.Determine whether injection conduits can cut-across natural fractures. Determine how closely conduits can be induced at various depths.

Initial DK Pilot Test – Methods

Jetting through PVC casing and well grout caused many problems including injection short-circuiting

Initial DK Pilot Test - Primary Fractures

IW-1 IW-2

~2 m ~2 m

Initial DK Pilot Test– 3D Visualization of Primary Vertical Fractures

Initial DK Pilot Test – Summary of Results- Taastrup, Denmark, November 2011

Aqueous slurry containing zero valent iron (ZVI) was distributed into fractured basal clay till.Vertical fractures were observed 6-7 m across.Sub-horizontal, homogeneous distribution of ZVI was not achieved.

ZVI was distributed through primary and secondary sub-vertical and sub-horizontal fractures.Natural vertical fractures were not bypassed.

Failure ModeTOO MUCH KINETIC ENERGY LOSS

DPT Proof of Concept TestingTravelers Rest, South Carolina, July 2012

SC DPT Proof of Concept Testing - Objectives - Travelers Rest, South Carolina, July 2012

Determine whether DPT Jet Injection:Achieves a more controlled fracturing distribution, relative

to injection into PVC wellsIs less susceptible to short-circuiting than injection into

PVC wellsCan emplace conduits/fractures across natural fractures.

Determine whether injection into multiple nozzles simultaneously increases conduit length.

SC DPT Testing – Methods

Multi-port DPT Injection Tip

Dye mixing tank

Water blaster

Probe tip with nozzle inserts

SC DPT Testing– Excavation

Path of jet cutting across weathered rock

SC DPT Testing – Excavation

1.8 m

1.4 m

View from either side of the jet (parallel to jet-rod plane)

SC DPT Testing – 3D Visualization of Sub-Horizontal Fracture Form

(Dimensions in meters, Hach Colorimeter results in Pt-Co color units)

Conclusions – SC DPT Testing

Cavity size ranged from 0.3-0.9 m (conduits observed).Horizontal fracture widths ranged from 1.0 to 2.1 m across, often shifted off-center from injection point.Formed fractures that were perpendicular to geologic features.

DPT jet injection achieved more controlled fracture/conduit emplacement than jet injection into PVC wells.

DPT Jet Injection Development – Phase I August to December 2013

DPT Jet Injection – Phase I Tooling Design

Two new tooling designs were developed for field testing, improving on tooling used in the 2012 SC pilot test. Design modifications included:Separate water jetting and slurry injection linesModification for use with Geoprobe® expendable drive tipsDesign of 4-nozzle and 6-nozzle tips with differing slurry

line flow paths.

DPT Jet Injection – Phase I Tooling Design

DPT Jet Injection Tooling –Working Prototypes

4 Nozzle Design

6 Nozzle Design

Test SiteSchillig Farm - Alliance, Ohio

Clean test site identified in glacial clay till.Hand auger borings used to confirm presence of clay till. During pilot testing, advancement of geologic borings guided the selection of injection locations and depths.Soil borings identified the redox boundary and facilitated injection testing below this boundary.

http://www.dnr.state.oh.us/tabid/7143/Default.aspx (Canton Quadrangle)

Site MapSchillig Farm - Alliance, Ohio

Core 410 m

Core 3

Core 1

Core 2

JI-C

JI-B

JI-AExtent of

excavation

N

• 4 Geoprobe® borings for site characterization• 4 injection locations

• JI-A and JI-F in shallow soil – jetting only• JI-B and JI-C below redox boundary – jetting and slurry

injection

JI-F

Core 4

Site GeologySchillig Farm - Alliance, Ohio

0 to 0.4 m Topsoil and brown silty clay

Core 4

0.4 to 2.2 m Light brown to grey silty clay, some layers silt and fine sand

2.2 to 4.5 m Dense grey silty clay, trace sand and gravel

Target depth for injections: 2.2 – 3.8 mRedox Boundary

Depth Interval Soil Description

Detailed Operating Parameters

Test Location JI-F: 6-Jet Nozzle

Star-shaped cavity with six individual conduits eroded by each jet

0.9 m

0.3 m

Test demonstrated effectiveness of conduit formation:No venting or daylighting of fluids during prolonged

jetting (> 2 minutes) at a depth of only 1.1 m bgsNo evidence of fracturing activated by jetting alone.

Test Location JI-B: 4-Jet Nozzle

3.3 m

Redox Boundary

Injection in dense, grey clay till below redox boundary

Gravel Layer

Observed Dye

Test Location JI-B: 4-Jet Nozzle

HorizontalFracture

1.0 m

Cavity0.4 m

1.4 m

1.4 m

0.7 m

3.2 m

NObservations during excavation:Largest dimension of cavity

measured 1.8 mLargest dimension of horizontal

fracture measured 2.0 mDye observed in naturally

permeable features (sand & gravel layer) 3.2 m from injection

Test Location JI-B: 4-Jet Nozzle

Collapsed Cavity

Conduit eroded to 1.4 m away from jets

Test Location JI-B: 4-Jet Nozzle

Horizontal fracture formed in grey clay till between sub-horizontal sand and gravel layers.Fracture achieved despite proximity to highly permeable features.

Gravel Layer

Fine Sand/Silt Layer

Test Location JI-C: 6-Jet Nozzle

1.0 m

ObservedDye

HorizontalFracture

Cavity

0.9 m0.9 m

2.5 m

2.1 m

0.3 m

0.4 m

N

Collapsed Cavity

Observations during excavation:Largest dimension of cavity measured 0.7 mLargest dimension of horizontal fracture measured

1.8 mDye observed in naturally permeable features (silty

sand and gravel layers) 2.5 m from injection

Test Location JI-C: 6-Jet Nozzle

Created sub-horizontal fracture in dense glacial clay till.Fractures propagated from edges of cavity.

Successfully demonstrated controlled cutting of conduits with no surface venting with both tooling designs.4-jet design achieved an X-shaped cavity with four clearly defined conduits; horizontal fractures were formed both between the conduits and extending outward from the conduit tips.

Summary of Findings

6-Jet Design

Maximum fracture widths in Phase I testing likely limited by moderate slurry injection volumes (95 liters/injection).

6-jet design performed better at preventing slurry line clogs during tooling advancement. Developed procedure for preventing nozzle clogging during advancement.

Controlled Conduit Cutting

Observed Dye

HorizontalFracture

Cavity

Next Steps

Phase II testing of DPT Jet Injection method at a contaminated test site in Capital Region later this year.Refinement of injection procedures to:

Increase conduit lengths and uniformityIncrease horizontal fracture widths

Injection of zero-valent iron slurry into a clay till source zone and performance monitoring to evaluate treatment effectiveness.Evaluation of method performance in fractured clay till.

Questions?

Pressure Logs

Slurry pressure monitored at well head during injection.Head loss in 3-inch rod minimal

pslurry = pfracturing

Datalogged at ½ HertzTrend of pressure consistent with propagation of horizontal hydraulic fracture.

Breakdown

Net inj start

Declining trend

Shut-in