PRODUCED WATER CHARACTERISTICS FOR TWO FIELDS IN THE PERMIAN

AND DELAWARE SHALE BASINS

J.M. Walsh, CETCO

Thursday January 19, 2017

The Produced Water Society Seminar 2017

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Sincere thanks to:

Ramesh Sharma, ConocoPhillips Greg McLelland – ConocoPhillips, Barkman-Davidson Tekla Taylor – independent consultant, Geochemisty Josh Hebert – CETCO, project planning & field work Gustavo Garcia – CETCO, field work Joey Rogers – CETCO, field work ConocoPhillips and Shell staff

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Produced Water Characteristics in two fields in the Permian and

Delaware Shale Basins Outline:

background

methods

results Geochemistry

conclusions

Not at liberty to identify the specific formations in this presentation.

Outline

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The four areas of design and operation all depend on the influent water characteristics and the required effluent quality. Water characterization becomes more important as the difference between influent and effluent becomes greater (true for shale).

Equipment Process

Chemical Treatment Operations

Fluid Characterization

Effluent Quality

Why Characterize the Fluids?

Ref: Walsh SPE 2008, SPE 2009, SPE 2010, Tekna 2011

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Which qualities / characteristics are important?

That depends on disposal / reuse options (required effluent quality):

Salt Water Disposal Well: injectivity

Reuse for hydraulic fracturing: injectivity, not

dissolved components (see Ref below)

Surface discharge: rigorous set of quality standards

How can we achieve the required qualities / characteristics?

Briefly discussed at the end

Important Water Qualities

Ref: SPE-163824 (2013):

Typical Process Flow Diagram

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General direction of flow This is a storage facility with unrealistic oil / water / solids separation

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Methods: on-site particle size analysis

(Jorin, Millipore) particle composition

(NACE TM0173 solvent test, DI water washed, TGA-DSC, SEM)

water chemistry

(on-site Hach & ICP digested samples)

on-site filterability

(Barkman-Davidson)

On-site measurements were made on “fresh” samples (i.e. no exposure to oxygen)

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Technology Pilot Unit / Sampling & Analysis

Jorin MZ4 field unit TSS filtration sample manifold

Sample Manifold

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Manifold features: PSV pressure gauge ball valves, needle valves flow rate via graduated cylinder eliminates shear

This system is used for: TSS 4-Filter Sieve test Barkman-Davidson Jorin feed

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Inside of the Analytical Trailer

scale

oven

Particle Size Measurements

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The next few slides provide data on the particle size. All measurements made on-site, on-line, “fresh” samples. Four measurement techniques were used:

Total Suspended Solids – 0.45 micron filter, NACE TM0173 5-Filter Sieve TSS measurement (20, 8, 2, 1.2, 0.45 micron)

Jorin Visual Particle Analyzer (ViPA) – particle count

Barkman-Davidson volume versus time – injectivity test

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The filter holder is connected to an on-line manifold with valves, a pressure gauge, and a graduated cylinder for measuring flow rate.

5-Filter Millipore Apparatus

5 filter holders stacked one on top of the other

water flow

Millipore size

(micron):

20

8

2

1.2

0.45 5 filter membranes

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5-Filter Millipore Apparatus

This apparatus catches suspended particles in five different size ranges. In theory, particles larger than 20 micron are caught on the 20 micron filter, particles smaller than 20 micron and larger than 8 micron are caught on the 8 micron filter, and so on. Filter cake will trap small particles on large pore filters.

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5-Filter Millipore Apparatus

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Barkman – Davidson Analysis

Volume of water (mL) passing through 0.45 micron filter paper versus square root of time (sec1/2). Feed pressure 20 psi. Steady flow rate (slope of red line) is due to filter- cake formation. B-D similar to NACE TM0173 or Silt Density Index (ASTM 4189-95). Drawbacks:

it only evaluates one impairment mechanism: filter cake buildup for quantitative results (injectivity improvement) it must be correlated to field data

Ref: J.H. Barkman, D.H. Davidson, SPE JPT (1972). J.R. Coleman, W.G. McLelland, SPE – 27394 (1994). W.G. McLelland SPE (2012, 2014, 2015, 2016)

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Barkman – Davidson Analysis for Conventional Fields

B-D Slope is empirically related to “injectivity” of produced water. These correlations are proprietary and will not be shown here.

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Results for produced water in the Delaware Basin:

particle size analysis

water chemistry

filterability (injectivity)

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Water Sample

Sample: 14-Aug 23:00

TSS Particle Size Analysis – mg/L versus N/L:

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Based on the 4-filter Sieve data the particle concentration (number of particles/mL) was calculated (right hand figure). There is a large number of particles in the range 0.45 to 8 micron.

Relation between mg/L and Number of particles/L

Jorin Particle Size Analysis - particle concentration

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Jorin does not accurately report results below 3 micron. Above 3 micron the Jorin agrees with the 4-filter TSS.

Jorin & TSS Particle Size Analysis – Number Average Particle Diameter

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This slide shows that the average (D50) particle diameter is about 1.3 micron. This means that half the particles are greater than 1.3 micron and half are smaller. Triangular points are from TSS 5-filter measurements. Line is from Rosin-Ramler.

D50 particle diameter is

read from here

1.3

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TDS Composition

Digested sample. Gas contains 2 mol % CO2, essentially no hydrogen sulfide.

Ref: SPE-163824 (2013) This study – Delaware Basin

Ref: R. Perry, R. Bosch, SPE ATW Dallas-Ft Worth (2013) R. Sharma, personal communication (2017)

Play iron (mg/L) Woodford 30 Wolfcamp 100 Haynesville 150 Eagle Ford 70

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Analytical Results – Unknowns Analysis

The following tests were carried out on the filter samples: XRF, XRD, FESEM, FTIR, XEDS Results are:

iron oxides and iron carbonate <1 to 3 micron precipitated NaCl (from drying) 1 to 3 micron silica (sand) 1 to 20 micron shale fines 1 to 10 micron

SEM SEM Frac Tank (iron)

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Analytical Results – Filter Material Solvent Wash

XRD analysis carried out on filter material Following the NACE-MR0173 method.

Roughly 9 to 20 wt% of filter material is soluble in DI water (NaCl); there is essentially no wax or asphaltene. Most of the sample is silica fines. There is significant iron.

XRD analysis carried out on filter material:

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Three settling stages of a sample

1 hour after sampling 1 day after sampling 2 days after sampling

Settling times indicate colloid chemistry (DLVO). Not intended for design purposes.

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Barkman – Davidson Analysis for Conventional vs Shale Field

conventional produced water shale well in Delaware Basin

According to the B-D Slope, this location will have injectivity problems – verified by operator.

B-D Slope is a measure of the rate at which water passes through a Millipore filter once a filter cake has built up. This can be correlated quantitatively to injectivity. A tight filter cake composed of small closely packed particles has a low B-D Slope value and indicates that injection wells will plug.

Good Injectivity

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Summary of Results for Delaware Basin:

Very small particles of iron

compounds, crushed sand

Limited presence of oily solids. No indication of organics adhered to solids

Low filterability (injectivity)

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Next: Results for produced water in the Permian:

particle size analysis

water chemistry

filterability (injectivity)

TSS Particle Size Analysis

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The above graph shows the number of particles per mL captured by the Millipore filter (5 Millipore are used with pore size: 0.45, 1.2, 8, 20, 60). There is a large number of particles in the range 0.45 to 8 micron.

30 Sample: 28-Sept 15:00

Original sample (left) and same sample with hexane added (right). Note that the contaminant is completely extracted into the hexane phase. This indicates that the solids are coated with oil.

Produced Water Appearance

31 Sample: 24-Sept 16:00

Note the droplets hanging just below the hexane/water interface. These hexane droplets are coated with oily solids that are interfacially active. The oily solids prevent coalescence with the hexane phase.

Produced Water Appearance

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Solids Composition – TGA-DSC:

Spent HF polymer – typical DSC ~ 300 to 400 C Kerogen – 400 to 500 C

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Solids Composition in Feed Water (NACE TM0173):

Carbonates are likely iron carbonate. HCl solubles are likely iron oxide compounds. No indication of sulfide. Acid insolubles are likely kerogen, shale, silica, clay. Data courtesy of Tom Tekavic, Shell.

insoluble acetic acid xylene HCl

Example filter

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Barkman – Davidson Analysis for Conventional vs Shale Fields

conventional reservoir Permian Basin

Low B-D Slope – low filterability (injectivity)

Geochemistry

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Is there a Geochemical source of iron?

Not at liberty to identify specific formations in this presentation. Geochemist (Tekla Taylor) has reviewed the specific formations and compared them to the known Geochemistry of these basins and found them to be consistent (water composition, iron, shale composition, carbonate content). Base of Rocky mountains with adjacent shallow sea marshes:

Igneous (volcanic) Rock (high iron content) Shales formed by Eolian (wind driven) processes which preferentially

transport very fine grains of silica, clay and magma into shoreline marshes and lagoons (same process as desert varnish).

Marsh vegetation trapped within the sediment, forming organic rich shale. Hydraulic fracturing and production:

Fine particles of shale rock & kerogen is then suspended in produced fluids via hydraulic fracturing. Also, high CO2 dissolves iron and other minerals.

Desert Varnish

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Summary & Conclusions: Delaware Basin field: small particles composed of iron compounds,

crushed silica (proppant sand), fine (fractured) shale particles without significant organic coating, clay, very poor filterability (injectibility).

Permian field: similar to above but with considerably more organics (spent polymer and kerogen).

Options to remove particles, for both types of fluid: • fine filtration; • oxidize the iron to create a filter floc (sludge blanket) or use a

high rate clarifier; • chemically precipitate the iron (Fentons, ozone, ClO2, peroxide); • coagulate / flocculate and settle / filter the solids; • electro-coagulate the solids and settle, float or filter

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The End

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Why are produced water characteristics important?

most produced water is disposed in SWD disposal costs (pumping, cleanout) depend on the

injectivity of the water

some produced water is recycled (injected into a shale formation) the success of the fracturing operation depends on

the water quality

Which characteristics / qualities are important? How can we achieve the required characteristics?

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Injection of Produced Water

Injectivity is a function of: Quality of the drilling and completion operations Porosity and permeability of formation – Karmen-Cozeny

approach Integrity of the formation (fines migration) Compatibility of injected water with formation & formation water Pore plugging characteristics of injection water

Produced Water Plugging Characteristics:

Core flush – fresh core, onsite, realistic pressures, expensive Measure TSS, Oil-in-Water, oil density – inexpensive, does not

correlate with injectivity Measure filterability