Oilfield nanoparticles: Synthesis, characterization and application.

Why nano?• Nanoparticles is able to effectively transport ina reservoir/formation;• Nanoparticles offer us the potential applicationin oilfield scale treatment, with enhancedmobility and performance.

Background information:Common Methods of nanoparticles Synthesis• Co-precipitation process• Mechanochemical reaction• Hydrothermal• Surfactant template and sol-gel techniques• Precipitation in microemulsion• Microwave processing

Previous work of Dr. Heather ShipleySorption of DTPMP to Metal Oxide Nanoparticles1000(a) 20 nm Iron Oxide (b) 145 nm titanium oxide (anatase).55305425q (mg/g)10010w/o Caw/ CapIP535251pIPq (mg/g)2015105w/o Caw/ Ca15000 10 20 30 400 2 4 6 8 10C (mg/L)C (mg/L)(a) Adsorption of DTPMP to Iron Oxide (b) Adsorption of DTPMP to anatase

Previous Work of Dr. Dong ShenSynthesis and transport of Ca-DTPMP NanoparticlesCa-Phn in DIW Ca-Phn in PPCA Ca-Phn nanofluidC/Co/%100755025Breakthrough in sandstone media00 3 6 9 12 15volume/mlDTPMP (mg/L)1000010001001010.10.01Overflush with calcium brineOverflush with KCl brine0.1 1 10 100 1000 10000pore volume(a) Breakthrough in calcite (b) Flow back in calcite with 1%KCl

Background information: Surfactant• Surfactant (surface‐active‐agent): a substance that hasthe property of adsorbing onto the surface of thesystem and of altering the surface propertyremarkably. (M. J. Rosen)• Cationic surfactant: The surface‐active portion of themolecules bears a positive charge;Tetradodecylammonium bromide

Background information:• Anionic surfactant: The surface‐active portion of themolecules bears a positive chargeSodium dodecyl sulfate• Non‐ionic surfactant: The surface‐active portion ofthe molecules bears no apparent ionic charge.Tween 20 (Polyoxyethylene (20) sorbitan monolaurate )

Synthesis route for nanoparticles:Step 1 Nucleation• 4Ca 2+ + DTPMP Ca 4 H 2 DTPMP• 4.5Zn 2+ + DTPMP Zn 4.5 H 1 DTPMP• The metal‐Phn precipitate was fabricated upon contactwith each other, followed by surface coating withsurfactant, inhibiting the further nucleation and crystalgrowth.

Synthesis route for nanoparticles:Step 2 Surface coating with surfactantA surfactant‐assisted synthesis route was developed to formMetal‐Phn nanoparticles, without external energy input.

Synthesis schematicSyringePumpVariable conditions include:TemperatureTitration speedpHCa vs. Phn mass ratio24mL PhosphoatepH=9.150mL 80 o CCaCl 2/ZnCl 2and surfactant• The metal-Phn precipitate was formed instantaneouslyupon injection of phosphonate under constant stirring;• Optimal synthetic condition was chosen asLow injection rate, 80 o C, pH=6.5 and M: Phn=4.5

AgendaNano-SynthesisCharacterizationTransport inCalcite columnConclusions• Solid characterization:•Instrumental analysis ( BET, XRD & FT-IR)• Electron microscopic image (TEM & SEM)• Slurry stability

X-Ray Diffraction: Ca-Phn800Ca-DTPMP XRD spectrumIntensity (counts)600400200031.845.556.5 75.50 20 40 60 80 1002 thetaX-ray diffraction indicated of the microcrystalline structureof fabricated Ca-Phn particles

X-Ray Diffraction: Zn-Phn600Zn-DTPMP XRD spectrumIntensity (counts40020031.6845.556.575.400 20 40 60 80 1002 thetaX-ray diffraction indicated of the microcrystalline structureof fabricated Zn-Phn particles

Fourier transform infrared spectroscopyAbsorbance0.60.50.40.30.20.10-0.1-0.2-0.3996109014601660FT-IRCa-Phn-A1 (surf)Ca-Phn A2 (No surf)Ca-Phn-B2 (70C, w/ surf)Ca-Phn C2( w/ surf)0 1000 2000 3000 4000 5000Wave number(cm-1)• 1660 cm‐1: surfact adsorbed hydroxyl group;• 1460 cm‐1: C‐H bending in –CH2‐ groups;• 1090 cm‐1: phosphonate P‐O‐Metal;• 996cm‐1: P‐C stretching vibration

BET surface area analysisPorous structure ofsolid Metal‐Phn can berevealed by the BETsurface area of around30 m 2 /g

Scanning electron microscopeCa‐DTPMP w/TTAB Zn‐DTPMP w/SDS80 o C 80 o CSEM image shows the porous structure of theobtained metal-Phn nanoparticles

Transmission electron microscopyCa-Phn NanoparticlesCa-Phn no surfactant room T Zn-Phn no surfactant 80 o Cw/ TTAB w/ TTAB w/ Tween23 o C 80 o C 23 o C

Transmission electron microscopyZn-Phn Nanoparticlesw/ SDS w/TTAB w/Tween80 o C 80 o C 80 o CCa-DTPMP suspension w/TTAB Zn-DTPMP suspension w/SDS

Elemental analysis5Effect of pH on Zn-P ratioZn:P ratio of precipitate4.543.532.53 5 7 9 11Intial pH of NaDTPMPAs for Ca-Phn, under near neutral pH, Ca: Phn=4.5:1;As for Zn-Phn, ratio of Zn to Phn depends on the slurry pH

Slurry Stability: Ca-DTPMPw/o TTAB w/ TTAB w/TTAB and PPCA1% KCl 2% KCl 2% KClAfter two weeks of static stabilization, Ca-Phophonate withTTAB surfactant shows higher stability in up to 2% KCl.

Slurry Stability: Zn-DTPMPNo SDS w.SDSw/SDS w/SDSNo KCl no KCl 1% KCl 2% KClZn-Phosphonate particles can be stable under up to2% KCl over weeks, even without surfactant

AgendaSynthesis andprevious workcharacterizationTransport inCalcite columnConclusion Dispersant and Salinity effect Breakthrough Flow back

Transport Experiments• Breakthrough experiments: Nanoparticles wereinjected into a test calcite columns, which is 7.5cmlength with porosity of 0.41 to test the mobility ofnanoparticles in porous media.• Inhibitor return experiments: Nanoparticles areinjected halfway into a calcite column, followed byan overflush solution, 18 hours shut-in, and inhibitorreturns are monitored by injecting a calcite saturatedbrine (60,000 mg/L TDS, 1000 mg/L Ca, pH 5.6) tomonitor the inhibitor return.

Mechanisms of particle collisionSedimentationInterceptionDiffusionCCoη221/3 2/30= R N +3 A R + 4. 04APe−G ss= exp{ −23(1 −ε ) αη4Rc0L}Classic filtration modelYao, et al 1974Solution chemistry like salinity will increase the removalefficiency, making more nano particle removed by the calcite.

Mechanisms of particle collision• Straining• Filter ripening• Enhance colloid removal by:• i) reducing porosity;• ii) colloid‐colloid interaction is more adhesive thancolloid‐collector interaction

M-Phn Breakthrough in porous media100Ca-DTPMP through porous mediaC/Co755025Calcite media (106-250 um)Ottawa sand (250-500um)00 1 2 3Pore Volume• Nanoparticles of Ca‐DTPMP showed good mobilityin both sand and calcite porous media• Flow rate is 55 ft/day

Schematic of Nanoparticle Return in CalciteInjection SimulationCalcium or KCl brineP0.25 PV of Ca-DTPMPnano particlesProduction Simulationflow directionPSampling vialflow directionSynthetic brineSynthetic brine: 58,000 mg/L NaCl, 1000 mg/L Ca 2+ ,915 mg/L HCO 3-in 1 atm P CO2

Nanoparticle Return setup:• Return flow rate: 55 ft/day;• Temperature:70 o C• Brine composition: 1M NaCl, 0.025 M CaCl 2, 0.015 NaHCO 3;

Nanoparticle Return setup:

10000Nano-particle return curve:Ca-DTPMPReturn curve of Ca-DTPMPNano-particles in 1%KCl1000DTPMP mg/L1001010.10.1 1 10 100 1000 10000Pore Volume• The return curve of squeeze simulation indicated of the retention andlong term flow back performance of Ca-phosphonate particles;• The flow back phosphonate concentration of higher than 1 mg/L cankeep up to 1700 PV;

Nano-particle return curve:Ca-DTPMP1.2-53DTPMP (mg/L)0.80.4Ca-DTPMP return-LogIP-54-55log(Ion Product)01000800 1300 1800 2300 2800 3300Pore Volume• DTPMP can be detectable at up to 3000 pore volumes;•After 1000 PV, log (Ion Product)= -54, indicating that thesolid retained in column transformed to crystalline structurewith a low solubility-56

1000Nano-particle return curve:Zn-PhosphonatePhosphonate (mg/L)100101Zn-DTPMPZn-BHPMP0.10.1 1 10 100 1000 10000Pore Volume• The return curve of squeeze simulation indicated of the retention andlong term flow back performance of Zn-phosphonate particles;• The flow back phosphonate concentration of higher than 1 mg/L cankeep up to 1000 PV and can be detected up to 3000 PV.

AgendaNano-SynthesischaracterizationTransport inCalcite columnConclusions

Conclusions• A simple and economical method was employed toproduce metal-phosphonate nanofluids by means ofsurfactant-assisted synthesis for oilfield scale control;• The physical and chemical properties of the obtainednanoparticles have been carefully evaluated. Theproducts meet the criteria of forming stable suspension at70 o C and up to 2% KCl over weeks;• The potential application of fabricated nanoparticles ininhibitor treatment in oil fields was tested by laboratorysqueeze simulations, where the nanoparticles can beplaced at distance away from the injection port andreturned slowly as flow back with synthetic brine.

Future work:• Modify the Metal‐Phosphonate nanoparticles withmore uniform particle sizing and enhanced retentionand long‐term flow back performance in oil‐bearingformations;• Fabricate nanofluids containing nanoparticles as“carriers” to deliver phosphonate inhibitors toreservoir materials to place phosphonates at distancefrom the injection.