Challenges and Failures Encountered in the Development of

Challenges and Failures Encountered in the Development of

Direct-Push High-Pressure Jet Injection for Amendment

Delivery in Low-Permeability Zones

Jim Wragg, MSc. Geosyntec Consultants, Manchester, UK

Chapman M. Ross, M.S., P.E., Geosyntec Consultants, Acton, MA

Neal Durant, Ph.D., Geosyntec Consultants, Columbia, MD

William Slack, Ph.D., P.E., FRx, Inc. Cincinnati, OH

Peder Johansen, Capital Region of Denmark

Partners in Developing Technology

Peder Johansen

Mads Terkelsen

FRx Bill Slack

Doug Knight

Capital Region of Denmark

Injection Experts

Torben Jørgensen

Eline Begtrup Weeth

Kirsten Rügge

Neal Durant

Chapman Ross

Dariusz Chlebica

Introduction / Overview

In situ remediation of chlorinated solvents in low-permeability

zones is challenging due to:

Reagent delivery constraints and

Treatment rates controlled by CVOC back-diffusion from the

matrix.

Pneumatic and hydraulic fracturing are two methods of injection

that are commonly used to enhance delivery of treatment agents;

However, their radius of influence (ROI) is limited and often

controlled by heterogeneities in the target formation.

Problem Statement: Develop Better

Injection Technology to Treat Clay Till

Method development partially

funded by Danish government.

Why?

• 40% Denmark covered in

highly fractured clay till.

• Hundreds of chlorinated

solvent sites.

• Strong reliance on GW for

potable supply

Clay till + solvents = long-term source zones

Creative Thinking, Valued Solutions.

Conceptual Model – Treatment with DPT Jet Injection

Large Vertical

Fractures













Objective

High Pressure Jet Injection Mechanisms

How it works

Up 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.

Horizontal

Fracture

Conduits

Cavity

Plan View

High Pressure Jet Injection –

Pilot Testing Chronology

Initial DK

Pilot Test

DPT Proof of

Concept Testing

DPT Jet Injection

Testing – Phase I

DPT Jet Injection

Full Scale Trial

Year 2011 2012 2013 2014

Location Denmark US (SC) US (OH) Denmark

Geology Clay Till Saprolite Clay Till Clay Till

Delivery

MethodBlank PVC Well DPT (single line) DPT (dual line) DPT (dual line)

Jetting Fluid Water Water w/ Green Dye Water Water

Injection Slurry

Amendment Slurry

w/ Rhodamine WT

Dye

none

Cross-linked Guar Gel

Slurry w/ Rhodamine

WT Dye

Cross-linked Guar Gel

Slurry, mZVI and sand

(with various tracers)

Initial Jet Injection Pilot Test

Taastrup, 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

DPT Proof of Concept Testing

Travelers 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 wells

Is less susceptible to short-circuiting than injection into PVC

wells

Can emplace conduits/fractures across natural fractures.

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)

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 lines

Modification for use with Geoprobe® expendable drive tips

Design 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 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 evidence of fracturing activated by jetting alone.

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

Test Location JI-C: 6-Jet Nozzle

1.0 m

Observed

Dye

Horizontal

Fracture

Cavity

0.9 m

0.9 m

2.5 m

2.1 m

0.3 m

0.4 m

NObservations during excavation:

Largest dimension of cavity measured

0.7 m

Largest dimension of horizontal fracture

measured 1.8 m

Dye observed in naturally permeable

features (silty sand and gravel layers)

2.5 m from injection

This trial showed sufficient promise for the

client to commission a full scale trial in

Denmark

DPT Jet Injection Full Scale Remedial Trial

Møllevej, Niva, Denmark

2014

Full Scale Remedial Trial Denmark Design

700m2 Target Treatment Area

(TTA)

4m design ROI

21 injection locations with

121 individual injections

5-7 discrete injection depths

50 tonnes mZVI

25 tonnes sand

Cross-linked Guar Gel slurry

5

25

50

5 to 80 mg/kg

VOCs (mostly TCE)

Yellow/red shading

demonstrates

coverage across TTA

Gray/white shading

shows overlap

between injection

locations

Results demonstrate

effective distribution

using 4 m design ROI

Tracing Single Fractures

De

pth

belo

w g

rou

nd

su

rfa

ce

(m

ete

rs)

I-10Ground Surface

Injection Characterization Soil Borings

Injection

Location

Distance from the injection point (meters)

1

2

3

4

5

6

7

8

9

10

11

12

North South

12 0 2 41 3 5345

Distance 3 m

Thickness 3 mm

Distance 2.5 m

Thickness 5 mm

Distance 1.25 m

Thickness 11 mm

Distance 0.25 m

Thickness 8 mm

Distance 2 m

Thickness 6 mm

Distance 4.7 m

Thickness 1 mmInje

cti

on

To

oli

ng

Injection Characterization Soil Borings

Mapping Overlap w/ Multiple Tracers

4m ROI

Documented multiple

overlapping ZVI-filled zones

between injection locations.

Methodology

3D modeling (EVS software) used

to interpolate magnetic

susceptibility (MS) readings.

Interpolated MS readings >1x10-3

were generally co-located with

visual identification of ZVI-filled

fractures.

Distribution of Fractures – 3D simulation Modeling

Distribution of VOCs in Soil –

Baseline and 6 Months Post-Treatment

Nov 2014 (Baseline)

June 2015

3D Modeling Shows Decrease

in Extent of VOC Source

Post-Treatment

Distribution of VOCs in Soil –

Baseline and 6 Months Post-Treatment

Nov 2014 (Baseline) June 2015

Total Estimated VOC

Mass in Soil Decreased

by >50% in 6 months

Conclusions – Technique Development

Process

Initial Pilot very unpromising – didn’t give up!

Recognised fundamental flaw in the approach and

opportunity provided more robust DP tooling

Worked with experienced contractor to develop method and

equipment.

Project team funded proof of concept work

Client recognized that P of C was a game changer

Kept striving for a workable solution

Conclusions – Current state of development

DPT Jet Injection has been shown to be an effective delivery

technique for emplacing amendments in low permeability

formations.

Multiple lines of evidence should be used to provide

confidence in the amendment distribution achieved and the

resulting treatment

Membrane interface probe (MIP) results from 6 months show

qualitative decrease in VOCs compared to baseline,

18 month results show further, more substantial decreases.

Conclusions: Advantages over Traditional

Hydraulic Fracturing

Reduces overall injection time

Delivers more power to the formation

Jetting cuts across vertical fractures

Creates more predictable fracture forms

Works more reliably than traditional fracturing methods at

shallow depths

Documents

Challenges and Failures Encountered in the Development of