PETE 310 Maria A. Barrufet

Transcription

1 Complementary Material Oilfield Brines Conversion to Fresh Water Lecture # 32? PETE 310 Maria A. Barrufet

2 Tentative Agenda Problem that triggered this research Strategy to solve the problem and make it a revenue source Terminology (Basic principles) Objectives and Tasks Engineering Design and Optimization Oil/water and reverse osmosis separation processes Data collection and analysis Process integration Future Discussions

3 Problems Increasing costs of disposal of waste brine from oil and gas production operations Permian Basin produces over 400 million gallons of water per day Equivalent to the daily use of water in the city of Houston Limited sources of fresh water for communities and industry Oilfield brines unacceptable for irrigation, industrial, or municipal use

4 Our Proposed Solution Reuse water on-site Convert oilfield brines to irrigation and fresh water Design and build portable units for water treatment Accommodate variation in input stream characteristics Plan for automated operation, reliability and safety

5 Not a simple desalination task Processing oilfield brines requires integration and adaptation of different technologies Suspended solids Emulsified oil (s) Multiple point sources Remote locations away from distribution networks Different types and concentrations of dissolved solids (TDS)

6 Total Dissolved Solids (TDS)

7 Generalized Brine Conversion Process Biocide/Chem. Oil Waste-b Oil Waste-a S-107 CX-101 Centrifugal Extraction Source Brine O1Coalescer / OS-101 Oil Separation S-106 S-108 P-9 / FSP-103 Flow Splitting Oil Waste-c Flow Splitting S-111 S-103 P-13 / CY-101 Hydrocyclone S-109 S-110 Organo Clay / OC Permeate S-104 Holding Tank / Vt S-112 Reverse Osmosis / RO Reject Disposal

8 Suspended/Dissolved Solid Separation Levels Micro Filtration (MF) (10-0.1μm) Bacteria, suspended particles Ultrafiltration (UF) ( μm) Colloids, macromolecules Nanofiltration (NF) (5e -3-5.e -4 μm) Sugars, dyes, divalent salts Reverse Osmosis (RO) (1.e -4-1e -5 μm) Monovalent salts, ionic metals Water

9 Natural Osmosis Principle Selective barrier Selective Membrane Osmotic Pressure Δπ = f r ( T,C)

10 Reverse Osmosis Principle OSMOSIS REVERSE OSMOSIS Head = Osmotic Pressure Semi-permeable Membrane Diluted Brine Initial Brine or pure water Water Flow Applied Pressure Concentrated Brine Water Flow

11 Membrane Configurations and Materials Spiral-wound module Hollow fiber module

12 Terminology Rejection Transmembrane pressure Feed, permeate, reject or concentrate rates For scale-up use fluxes (volumetric rate/area) R = TMP F 1 = CP / C F PF + P 2 R P P P J w = flux of permeate y P x C F C

13 Reverse Osmosis Governing Equations J w = D w C w ~ v w ( ΔP Δπ ) RTt kt ( r ) D = Δπ = f T,C w 6πμ r w p

14 Osmotic Pressure Osmotic Pressure vs TDS** Osm motic Pre essure (p psia) T = 200 F T = 100 F Δπ = f r ( ) T,C TDS %

15 Osmotic Pressure as a Function of Concentration (T = 70 o F) Component 2% 5% 10% 15% Sucrose (342) 24 * Glucose (180) Seawater NaCl (58.5) KCl (74.6) K 2 SO 4 (174.3) MgSO 4 ( ) Molecular weight in ( ) * Pressure in (psia)

16 Brine Characteristics Input Waste Product: TOC up to 5,000 ppm (dissolved and emulsified) TDS up to 100,000 ppm Desired Output: Water (TDS) < ppm Oil (TOC) < 20 ppm Technology: Coalescing media, Organoclay adsorption, centrifuge, NF, RO

17 Process Components and Streams Biocide/Chem. Oil Waste-b S-107 S-102 P-9 / FSP-103 Flow Splitting CX-101 Centrifugal Extraction S-105 Source Brine S-101 S-103 Organo Clay / OC S-104 Permeate Holding Tank / Vt S-112 Reverse Osmosis / RO Reject Disposal

18 Objectives Maximize permeate production Minimize waste volume (concentrated brine) Eliminate bottlenecks Enable semi-continuous operation (long batch cycles) Provide low-cost process, maintenance, and operation Minimize manual intervention (automate) Portable, reliable, controllable

19 Oil/Water Separation Coalescing media Oil adsorption in packed columns (organoclay pellets)

20 Oil Emulsion & Analysis

21 Measurement of Oil in Water Calibration Issues Different oil contaminants t require recalibration of the equipment Equipment response linear up to 1,000 mv Dilutions needed for water samples with high oil concentrations (>200 ppm) Time-consuming technique

22 Schematics of the Coalescing Media Coalescer Media Tank Pump Coalescer

23 3- to 10-Fold Oil Concentration Reduction 1600 [Oil l], ppm ppm 1600 ppm 3200 ppm 6400 ppm y = e x R 2 = y = e x R 2 = y = e 0.358x R 2 = y = e x R 2 = Q, L/min

24 Adsorption Experiments Packing organoclay column Flow loop and sample preparation Sample collection and TOC Analysis Modeling oil adsorption Bed dimensions and rate Breakthrough times

25 Organoclay Before & After Oil Adsorption

26 Sharp front indicates higher efficiency C i / Cf (oil co oncentrat tion rat tio) C outlet C inlet Experiment 12 C final / C initial Time (minutes)

27 OC Adsorption Modeling Negligible axial dispersion Process governed by mass-transfer resistance First-order kinetics Sensitivity analysis to residence time

28 Second Column Brings Outlet TOC Below Limit Oil Adsorption Performance Two OC Columns In Series, ppm utlet TOC O P-1 / GMF-101 OC Filtration S-115 P-2 / GMF-102 OC Filtration time, hours Column 1 Column 2 TOC Limit, ppm Feed TOC, ppm

29 Desalination (RO) 1.3 gpm (OC) Feed Permeate Blending / Storage Reverse Osmosis Recycle

30 RO System - Pilot Unit Used

31 RO Experiments - Specs SWC spiral TMP ( psi) A = 2 m 70 ft Recycle on/off Inlet TDS (0 40,000 ppm) Feed rate (6 14 GPM)

32 Recovery Decreases with Pressure, Increasing Flow Rate ction Feed = Pure Water Per rmeate rec covery fra gpm 8 gpm 10 gpm Transmembrane pressure, psi

33 Increasing Salt Further Decreases Recovery Feed = 30, mg/l NaCl Per rmeate rec covery frac ction Transmembrane pressure, psi 6 gpm 8 gpm 10 gpm

34 Increasing TMP Increases Salt Rejection Feed = 40,000 mg/l NaCl Salt reje ection, % gpm 8 gpm 10 gpm Transmembrane pressure, psi

35 Salt Rejection Improves at Lower Concentration Feed = 10,000 mg/l NaCl % Salt rejection, gpm 8 gpm 10 gpm Transmembrane pressure, psi

36 RO Data Summary TDS range from 0 40, ppm TMP range psia Feed rate 6 to 10 gpm Data points triplicate (yes 3 repetitions) Over 450 data points Uncertainty % in permeate concentration measurement and + 1.5% in rate measurement

37 Least Squares Regression Least Squares Regression g Permeate flux Permeate flux + + = 6 a TDS a 4 a TDS a 2 a TMP a J Permeate flux Permeate flux + + = F J 5 a TMP 3 a F J 1 a w J b b Total TDS rejection Total TDS rejection + + = 6 b F J TDS 5 b 4 b TMP TDS 3 b 2 b F J TMP 1 b R F F

38 Rejection Model Matches Real Data 100 Membrane: SWC NaCl Rejection % (Error Bars + 0.5% ) 99 icted Pred Experimental

39 Permeate Flow Model Matches Real Data 30 Membrane: SWC Permeate Flow as % of Feed (Error Bars + 1.5% ) 25 Pred dicted Experimental

40 Scenario 1: Constant-Feed TDS Propose desired permeate (freshwater) rate or daily production Select transmembrane pressure (greater than Δπ) Obtain required membrane area A m Select L / A Obtain required feed-flow flow rate

41 Operating Conditions Design / -w S) PAm 5.59 vw ( qp =15000 gal/day L/A=25 m v W Am (qP/(qF-qP P)k /(1-w S) (1 - ΔΠ/ΔP)

42 Begin Design Set up Operating Conditions: Pump specifications, q F, T, and Brine Composition Evaluate: r b, m w, w s, p, v w Set ΔP and desired q P (gal/day) Design Stages With obtained value for x-axis - (1-π/ΔP) and q P evaluate A m from left y-axis Propose L/A (m -1 ) Obtain q F from right y-axis No Is q F within allowed range No End Yes

43 Design Example Given process parameters and desired outcome TDS = 18,000 ppm T = 160 F TMP = 500 psia q P = 5,000 gal/day Solution Δπ = 192 psi Left axis Am=3953m m 2 Propose - L/A = 15 m -1 Right axis q F = 69,000 gal/day (7%)

44 Scenario 2 (more likely) For a variable salt concentration in the feed (caused by recycling of concentrate) Given membrane area, feed rate, and TMP Estimate permeate volume and batch time Design issues Number of units required Series/parallel configuration Partial/full recycle, make-up streams

45 Example Results From RO Design Initial TDS = 5,000 ppm 1 RO unit (A m = 70 ft 2 ) Flow rate from OC train is = 1.3 gpm Holding tank volume gallons Feed rate = 6 GPM TMP = 750 psia Full recycle

46 Example Results From RO Design Batch ends when Feed > 40, ppm 1.3 gpm (OC) V t > 75 gallons V t < Feed rate Feed Permeate Permeate TDS > 500 ppm Blending / Storage Reverse Osmosis Recycle

47 Transient Behavior Holding Pr roduction, Tank Volu ume, Gallons gal TDS, ppm Cumulative Cumulative Permeate & Instantaneous Production Permeate & Recovery Concentration Efficiency Inst - ppm Cum - ppm Time, hrs Volume Permeate Time, hrs Produced RE = P/( (P+R)

48 TMP analysis (600, 800, 1000 psia) Permeate Produc ced, gallons Specifications RO - SWC GPM - (70SF) time, hours d TDS, ppm Fee psia 800 psia 1000 psia Specifications RO - SWC GPM - (70SF) 600 psia 800 psia 1000 psia Specifications RO - SWC GPM - (70SF) time, hours Ho olding Tank Volu ume, gallons time, hours 600 psia 800 psia 1000 psia

49 TMP Analysis Recovery Effic ciency Permeate Fraction Specifications RO - SWC GPM - (70SF) time, hours Specifications RO - SWC GPM - (70SF) time, hours 600 psia 800 psia 1000 psia Increase size of holding tank Use two tanks Increase feed rate from OC train but resize OC columns 600 psia Increase number of 800 psia OC columns 1000 psia

50 RO Performance: Feed Rate Analysis Membrane Performance (TMP=1000 psia, Vt= gallons) 0.35 Permeate Fraction gpm 8 gpm gpm 12 gpm 0.15 Membrane Performance (TMP=1000 psia, 6GPM) Permeate e Fraction 0.30 time, hours time, hours Vt (50-150) Vt ( ) Vt ( )

51 Design Scenarios Batch Time (h) TDS (F) Permeate TDS(P) Recovery TDS (ppm) (gal) (ppm) Efficiency (initial) (ppm) Volume Holding Tank (N,C) Units Feed TMP (OC,RO) gpm psia ,75 2, ,75 2, ,75 2, ,75 2, ,75 2, ,75 2, ,80 2, ,150 2, ,150 2, ,150 2, ,150 2, ,150 4, , , ,300 4, ,300 4, ,300 4, ,300 4,

52 Scale-Up Issues S-115 S-110 S-114 P-1 / GMF-101 OC Filtration S-116 P-2 / GMF-102 OC Filtration S-102 P-3 / RO-101 Reverse Osmosis S-113 S-103 S107 S-107 P-10 / V-102 Storage S-117 P-9 / V-101 Holding Tank S-101 P-11 / FSP-101 S-104 Flow Splitting S-105 P-4 / RO-102 Reverse Osmosis P-5 / RO-103 Reverse Osmosis S-106 S-108 S-109 P-12 / V-103 Permeate S-119 S-112 S-118 P-6 / RO-104 Reverse Osmosis S-111 P-7 / GMF-103 OC Filtration P-8 OC Filtration

53 Future Work Experiments with other membrane materials at higher pressure Expand RO-model design for other membrane specifications Continue OC experimental design to accommodate different packing Analyze membrane-regeneration regeneration cycles Analyze scaling, fouling

54 Future Work Membrane fouling: Causes (scale, oil, ph, aging) Monitoring, cleaning frequency and agents Prevention (extend membrane life) Permeate Flux Cleaning Time

55 Future Work Oil/water separation with hydrocyclones High separation efficiency No chemicals or cleaning needed Low maintenance and operating cost No Moving Parts Recycle options

56 Vision 2020 and beyond Work with local, state and federal agencies to incorporate this new process into permitted operations Develop new and faster online sensors for TDS and for selected metals (biosensors, nano- sensors) Develop and implement control algorithms for continuous operation Analyze hybrid RO systems Wind power driven, solar power Evaluate beneficial uses of waste (road desalting, construction materials, landscaping)

57 Interdisciplinary Program

58 Financial Support DOE CONACYT (Mexico, A&M) GPRI (Marathon, Total Fina, ChevronTexaco) Polymer Ventures TWRI