SPE 122189Improving Water Injectivity in Barrancas Mature Field with Produced WaterReinjection: A team ApproachA.N.Cavalla...
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Produced water reinjection (PWRI) is one of the most usual ways of produced water reuse in mature fields with high water cut.
The relationship between water quality and injectivity decline in wells is well known and it is particularly important in mature
fields, such as Barrancas, an old field located in Mendoza –Argentina, with more than 40 years of water injection. In this
reservoir significant injectivity losses were recorded when fresh water was replaced by produced water in the 90´s.
Formation Damage mechanism is mainly caused by external cake. Particles are principally, iron sulfide, calcium carbonate,
and oil droplets.

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Spe international symposium

  1. 1. SPE 122189Improving Water Injectivity in Barrancas Mature Field with Produced WaterReinjection: A team ApproachA.N.Cavallaro, SPE, YPF SA., M. Sitta, I. Torre, G. Palma, YPF S.A. E.Lanza, Universidad Nacional de CuyoCopyright 2009, Society of Petroleum EngineersThis paper was prepared for presentation at the 2009 SPE European Formation Damage Conference held in Scheveningen, The Netherlands, 27–29 May 2009.This paper was selected for presentation by an SPE program committee following review of information contained in an abstract submitted by the author(s). Contents of the paper have not beenreviewed by the Society of Petroleum Engineers and are subject to correction by the author(s). The material does not necessarily reflect any position of the Society of Petroleum Engineers, itsofficers, or members. Electronic reproduction, distribution, or storage of any part of this paper without the written consent of the Society of Petroleum Engineers is prohibited. Permission toreproduce in print is restricted to an abstract of not more than 300 words; illustrations may not be copied. The abstract must contain conspicuous acknowledgment of SPE copyright.AbstractProduced water reinjection (PWRI) is one of the most usual ways of produced water reuse in mature fields with high water cut.The relationship between water quality and injectivity decline in wells is well known and it is particularly important in maturefields, such as Barrancas, an old field located in Mendoza –Argentina, with more than 40 years of water injection. In thisreservoir significant injectivity losses were recorded when fresh water was replaced by produced water in the 90´s.Formation Damage mechanism is mainly caused by external cake. Particles are principally, iron sulfide, calcium carbonate,and oil droplets.Water treatment and injection well chemical stimulation are two important contributions to oil lifting cost at Barrancas. Theaverage water quality is quite good between water treatment plant and wells. In spite of this, injection wells require regularacidic and non acidic stimulations to restore injectivity.To identify the causes, a team effort combining field experience, chemical and bacteriological analysis, laboratory and on sitecore flooding test was performed.Through this work, water quality performance between plant and down hole well at the level of perforated zones was analyzed.Oil and solids chemical dispersants were tested during core experiments to avoid fall of injectiviy.The experimental study has demonstrated that the use of dispersants could help to maintain water quality stability at the levelof case perforations. A pilot in a selected group of wells will be implemented. It is likely to be successful.Down -hole water quality is a critical parameter as well as the on site evaluation tests. Based on the outcome new experiencesand down-hole monitoring tool will be developed.The final goal is to improve water quality stability at the level of formation, prevent injectivity decline and reduce workingpressure.IntroductionThe injection of produced water (PWRI) is the main process implemented in YPF SA to recover oil in Argentina.This is one of the most important reasons for high volumes of water produced. This is particularly true when water cutincreases with the field maturity.The PWRI is an attractive option for improving oil recovery, and also to maintain pressure. Another important aspect is thatproduced water (PW) is an important source of minimizing environmental risks associated with water discharges. 1 94705Furthermore studies have shown that the injection of produced water induces formation damage by external and internal filtercake. These mechanisms cause loss of injectivity especially PWRI matrix. 2(Bennion)Injectivity decline is a complex phenomenon that depends on the quality of water, conditions of injection and reservoirproperties.The water quality required will be mainly a function of permeability and pore throats size distribution. Layers of smallthickness and low permeability require better water quality than the corresponding layers with high pemeability.The mechanism and extent of the blockage for a given period of time depends on the formation, type, concentration,composition, shape and size distribution of particles in suspension, in addition the flow rate and injection pressure.368977
  2. 2. 2 SPE 122189Deposition of particles –External cake formationThe relation between particle size and pore thoroat size distribution, is a key factor in establishing the mechanism ofdeposition of particles that occur in porous media.With the retention of particles in the pore throats starts to form a temporary cake on the face of formation. When it processreaches a certain thickness, the filter cake permeability government the decline of injectivity profile. In this step, the cakeporosity and permeability are sensitive to the pressure applied. 5 IAPGFactors affecting water qualityThere are many factors affecting the Injectivity.This category includes:- Suspended Solids.- Corrosion products.- Formation of precipitates inorganic / organic- Bacterial activity.- Content of oil.-H2S-souring 4 53987The H2S generation increases the corrosion rate. The FeS produced has a very reduce water solubility. It is: 0.00062 g / 100cm3. It can be deposited as scale on surface pipe surface facilities and injector well installation. Also the FeS suspension istransported by water, causing plugging. The oil in water agglomerates iron sulfide particles increasing plugging tendency.Barrancas, a mature oil field in Cuyana Basin, located in Mendoza province-Argentina (Figure. 1), injectivity losses. Thatprovides an example of injectivity losses related to a PWRI system . 569533.This is an field that has been producing for over 60 years mostly parafinic oil (25 °API). The hydrocarbon accumulations comefrom sandstones of the Barrancas Formation at 2500 meters of depth.Water flooding started in 1967 and during decades only fresh water was injected, but in the 90’s fresh water wasgradually replaced by production water (PWRI) with h i g h a v e r a g e o f salinity (Table 1) .It is a quite hot reservoir (originally 100 °C and 85°C after waterflooding).Along with the change to salt water (PWRI) began to increase the injection pressure to 20,000 kPa.Associated to waterflooding project w i t h PWRI appears the H2S biological souring (H2S up 200 ppmv) and the pluggingtendency of the injection water. When back flush samples were taken, these results have shown that iron sulfide species suchas: pyrite, marcasite and mackinawite are present.Lower proportion of calcium carbonate scale and oil has been found with iron sulfide particles in some injection wells.The analysis of the composition of solids by XRD (X-Ray Diffraction) and chemical analysis is shown in Figure 2. Solidssamples have been taken at different times, all of these shown that the most important solid present is iron sulfide. (See Table2; 3). Table 3 are samples taken during 2008.It requires frequent treatments acid (HCl 10% or 10% HCl + 2% HF) and chlorine oxides formulations to remove theformation damage, restore the injectivity and reduce wellhead pressure. In some cases stimulation frequency is less than twomonths. A typical injectivity decline curve is show in Figure 3.About 100 or more chemical treatments are performedannually.The negative results of this situation on economics are: sweep efficiency is reduced and oil production decline. The watertreatment cost, work overs, acidic and non acidic stimulations, facilities failures are increased .The high injection pressureproduces high energy consumption. As a consequence the lifting costs on the field also increases and lost of revenue occurs.A work plan including differents actions has been implemented, beside it the poor injectivity continue in this reservoir withpermeability range between 60- 100 mD. Water quality evolution vs depth has been included in the work plan.In this paper, a comprehensive laboratory and field tests studies were carried out at Barrancas field to identify and minimizethe causes de rapid injectivity decline encountered in this mature waterfloodingThe current work analyzes specifically the water quality evolution down hole. This is the main difference with previous onesfor Barrancas Field.Specific issues addressed included as a part of an integral water management program are:To examine and quantify the decline injectivity causesTo identify an strategy for reducing working pressures
  3. 3. SPE 122189 3To found the most cost effective solutionsIn the next section, previous related studies are summarized. In the section after that, the current procedures are described.Experimental results are presented and discussed in the last section.Diagnosis of Water Injectivity DeclinePrevious studies showed that the damage mechanism of particle deposition is mainly caused by formation of external cakeduring core fooding. Also in these experiments were conducted other tests such as pore throats and particle size and SEMFigures 4-a; 4-b show the particle deposition in porous media.The reservoir permeability varies between 60 and 250 mD for the cores tested. The average is estimated at 100 mD.The behavior of the stimulation was with the progress of pressure treatment validates laboratory experiences. Figure 5 shows atypical behavior between chemical treatments.The injectivity decline model (half life time) assuming external cake conclude that the time for injectivity decline betweenstimulations is similar to evolution observed in the field. It has been shown to integrate all the information that the cause ofloss of injectivity is formation damage by external cake. Water injection declines during the formation of external cake.In addition to looking for a new stimulation system more effective and less expensive than the acid treatment for removingiron sulfide, a program to improve the water quality to the plant output has been implemented. The results are shown in Figure6.Operational improvements have been observed between 2007 and 2008 year in all cases analyzed, which resulted in fewerevents per year.(See Figure 7).Monitoring water quality at the well head, also indicates that there was decrease of TSS but despite the improvementscontinued decline of injectivity.From the field observations, it was acknowledged that a program of bacterial control with biocides was carried out. At thesame time a plan has started to minimize operational problems to found the most effective solutions.In spite of the efforts, the injection wells need to be stimulated to restore injectivity. The multidisciplinary team presumes thatthe water quality is deteriorated with depth of the well causing the particles deposition and the reduced injection. As a first stepthe team has decided to understand the behavior of water quality down hole. The next section provides and approach that werefollowed to identifying and minimize the problems detected during decline injectivity due to solid depositions and plugging.Laboratory and Field Testing ProgrammeTo achieve the objectives, the following experimental work was conducted to determine:- Identify TSS variations, particle size distribution, SRB vs depth (between well head and perforations).- Perform Solid characterization- Study Chemical dispersant effect- Improve water quality stability- Reduce pressure injection- Collect information to: - Design a trial to verify laboratory tests results - Develop a down- hole monitoring tool porting a porous media (core)The tool porting is to identify differences in water quality between well head and well down at the level of perforations. Thistool would be applied to follow the improvements during chemical treatments.The tests were based on:-Physical and chemicals analyses: to know water chemistry, water quality, particles size, solids composition, membranefiltration in the field and during core flooding tests.-Pore throats size distribution:-Petrophysics-SRB bacteria accounts (Sulfate reducing bacteria)-Formation damage core flooding test: to examine the injectivity performance, the chemical dispersant effect, the permeabilityand pressure profile.Core samples were selected of representative layers from Barancas Formation (CRI). The reservoir permeability and porosity
  4. 4. 4 SPE 122189of the selected cores are shown in Table 4The pore throats size distribution are represented in Figure 8Experimental Core Flooding ProceduresA general core flooding procedure was followed for on site field tests and laboratory for all tests. These were designed tomonitor permeability changes, pressure profile, flow rate profile, under certain pressure and temperature reservoir conditions.The variations can be attributed to mechanisms as solids deposition or in the case were chemicals are added the variation canbe pressure stable or reduced.The steps are:- Saturate core with filtered formation water- Measure reference permeability simulating injection flow direction (filtered formation water)-Flow PWRI-Flow PWRI with chemicalsAll flow tests were performed at the Core test laboratory, LECOR, of the Universidad Nacional de Cuyo, Mendoza, Argentina.The core flooding equipment is schematically shown in Figure 9.During the chemical injection a pump for dosage wasincluded.Up to now four core flooding test were carried on: one on site close injection well and three in the laboratoryCore Flood 1On site, flow rate variation to examine water quality on site. The equipment was installed very close the injection well. SeeFigure 10Core Flood 2, to run a base line for permeability evolution (Kf/ki), and pressure injection profile when PWRI was injectedCore Flood 3, 4 were flooded with PWRI and two preselected chemical dispersants for prevention of Formation Damage andfollow the pressure evolution.Chemical dispersant InformationBoth are non ionic surfactant soluble in water. The application is extended to fresh water, salt formation water / sea water. Thistreatment promotes solids dispersion, clean perforations, clean the pipes, hydrocarbon dispersion and low injectionpressure.The dosage was recommend by the provider and tested in laboratory.ResultsPhysical and chemical analyses are shown in Tables 5-a, 5-b; 5-c. This information includes the variation a along the watersystem between Water Plant and injection well B-208. The TSS no presents an important increase , the most importantvariation belongs for sulfides. The filtration tests are shown in Figures 11-a and 11-b. Both present similar slope.A monitoring was implemented in B-118 and others wells, solids and particle size distribution is presented in Figures. Thisinformation evidence how the water quality properties are altered from well head until well down. SRB, TSS increases andsoluble sulfides are reduced. The biological activity increases total suspended solids. Soluble sulfides are converted ininsoluble sulfides.The oil in water is under specification but in the solid samples the oil content it is not in ppm order, It is in % p/p order.The oilwould be sticking to iron sulfides promoving an increase in particle size. These results are presented in Tables 6; 7 and figures12-a ; 12-b.Applying the rule “1/3-1/7” the comparison between particle size and pore thoroats distribution indicates that a filter cakewould be formed.Core 1-On site Field test: a significant volume of water was injected in this core . The permeability reduction was not severelyalong the time.(Figure 13).The visual observation have not shown an external filter cake.During this test the TSS measuredwas 6 mg/l.
  5. 5. SPE 122189 5The permeability profile: Core 2 Base LineCore 3-PWRI + Chemical “A”Core 4-PWRI + Chemical “B” is presented in Figure14.The TSS determined in PWRI for this coreflooding was 50 ppm.This TSS value represemts an example of down holecomposition.The change observed in injectivity result indicates the dispersant effect when the chemicals are injected.Theproducts are reducing agglomerated particles also avoid filter cake formation.In the Figure 15 the pressure evolution is shown. This graphic show how the increasing in injection pressure is attenuate.Summary of studiesResults presented in the previous section have given evidence that the water quality is deteriorated during the travel betweensurface and down hole. The poor water quality is attributed to bacterial activity, iron sulfides.The relation oil/iron sulfides requires further studies as the formation damage mechanism (internal cake) when particles aredispersed by chemical “A” and “B”. This effect could not been evaluated during the core flooding 3 and 4.Field TrialA field trial was designed and implemented to prevent decline of Injectivity based on core flooding results (core tests 3 and 4).The product selected was chemical dispersant called “A”. At the moment to prepare this paper the pilot is starting.TisTreatament combines PWRI and product “A.” A special monitoring plan was implemented to follow the product performancein the injectors. At the same time is in phase design is the dowhole tool sampler to port a porous media.Conclusions1-In this study was demonstrated the poor water quality down hole.2-The poor injectivity is produced by sulfides and bacterial activity when the PWRI travel from well head to perforated zone3- Base on the core flooding test the chemical dispersants avoid an external filter cake deposition.4-During the test the decline injectivity and injection pressure is stabilized when chemical dispersants are added to PWRI.5-This study has created new opportunities for understanding, monitoring and controlling water quality down hole.6-The treatment would be clean wellbore and pipes. It appears to promote injection pressure reduction and improve injectivitydecline.RecomendationsNomenclaturePWRI: produced water reinjectedPW: produce waterSEM: scanning electron microscopyXRD: X-Ray diffractionHCl: hydrochloric acidHF: hydrofluoric acidTSS: Total Suspended SolidsSRB: Sulfate Reducing BacteriaAcknowledgmentsThe authors wish to thank YPF S.A. for permission to publish this paper. Also they would like to acknowledge specially,
  6. 6. 6 SPE 122189Javier Sanagua, Director of Mendoza Norte business Unit.The authors are grateful to: Eduardo Curci, Santiago Bertagna, Raul Movio, Marcelo Escobar, Luis Farias, Dante Crosta, JuanCarlos Scolari from YPF S. A., for their valuable contribution and suggestions given during the study, also operative groupthat work in Barrancas Field. Universidad Nacional de Cuyo students for their contribution during field test. The students areJonatan Medina, Carlos Ferlaza, Marcelo Mascialino, Lucas Vasallo and Marcelo Parlante.Other contributions as from Fernando Gomez –Induser Group, Jorge Costanzo-ITBA, Fabian Sein CTA-YPF SA TechnologyCenter are acknowledged.References Cavallaro A., Curci E., Galliano G., Vicente M., Crosta D.,
  7. 7. SPE 122189 7 Leanza H., 2001, Design of an Acid Stimulation System with Chlorine Dioxide for the Treatment of Water-Injection Wells. SPE-Latin American and Caribbean Petroleum Engineering Conference. Buenos Aires. 2001. SPE-69533. Curci E., Cavallaro A., Galliano G., Gerrard P., 2000, Sulfur compounds in injection Waters, oild and gas: origing, measurement and importance, Compuestos de Azufre en Crudos, Aguas y Gases: Origen , Medidición e Importancia, Congreso de Producción Proction Congresss, IAPG. Iguazu-Argentina.Bennion, D.B.2001, An overview of formation Damage Mechanisms causing a reduction in the productivityand injectivity of oil and gas producing formations.Canadian International Petroleum Conference,Calgary,Alberta, CanadaCollins, IR et al, 2004,Laboratory and Economic Evaluation of the Impact of Chemical Incompatibilities inComingled Fluids on the Efficiency of a Produced Water Reinjection System: A North Sea Example,SPEInternational Symposium and Exhibition on Formation Damage Control, Lafayette, Lousiana, USA,February 2004cBennion, D.B. et al, Injection Water quality a key Factor to successful water flooding, Journal of CanadianPetroleum Technology, Volume 37, No.6, June 1998.F.A.H. Al-Abduwani et al, 2001, Visual Observation of Produced Water Re-Injection Under LaboratoryConditions. SPE European Formation Damage Conference, The Haghe, The Netherlands, May 2001-SPE68977
  8. 8. 8 SPE 122189 Value Barrancas Barrancas (typical) (peaks) pH 6.8 CO3-2 (mg/l) <1 HCO3- (mg/l) 400 Cl- (mg/l) 30,000 SO4+2 (mg/l) 1,300 Ca+2 (mg/l) 1,220 Sr+2 (mg/l) 45 Ba+2 (mg/lt) <1 Mg+2 (mg/l) 60 T.S.S. (mg/l) 2.5 10 HC (mg/l) <1 4 Table 1: Average Physicochemical PWRI composition-Barrancas field Parameter B-297 B-488 21.1 55.7 FeS (% p/p) 0.40 1.25 Extracted inDichloromethane (% p/p) Table 2: Solid samples taken in injection well installation (tubing and valves) B-487 B-487 B-487 B-487 B-487 Parameter S1 A S1B S2 SA S2 SB S3 17.3 48.8 57.9 35.0 50.4 FeS (% p/p) 2.40 0.54 1.57 0.76 1.84 Extracted in Dichlorometh ane (% p/p) Table 3: Solid samples taken in injection well installation during 2008 Core Well B-342 Porosity (%) Permeability (mD) 1-3-1 16.0 89.4 1-6-4 14.1 204.9 2-7-2 16.3 103.7 2-6-4 14.1 113.6 4-8-2 22.8 80.8 Table 4: Porosity and Permeability values
  9. 9. SPE 122189 9Parameter Value Method Parameter Value MethodpH 7 M.N. 4500 H-B pH 7 M.N. 4500 H-BConductivity 103.3mS/cm M.N. 2510 – Conductivity 105.3mS/cm M.N. 2510 –TSS 2.3mg/l NACE TM-01-73 TSS 2.8mg/l NACE TM-01-73Hidrocarbon < 0,1 mg/l Colorimetry Method – UV visible Hidrocarbon < 0,1 mg/l Colorimetry Method – UV visibleTotal Sulfide 5.1 mg/l M.N. 4500 S-2 E - Total Sulfide 7.5 mg/l M.N. 4500 S-2 E -Solube Sulfide 4.6mg/l M.N. 4500 S-2 E - Solube Sulfide 5.7mg/l M.N. 4500 S-2 E -Table :5a Output BV Water Treatment Plant Table 5-b:Output b-87 RepumpingParameter Value MethodpH 7 M.N. 4500 H-BConductivity 105,2 mS/cm M.N. 2510 –TSS 4,5mg/l NACE TM-01-73Hidrocarbon < 0,1 mg/l Colorimetry Method – UV visibleTotal Sulfide 14,7mg/l M.N. 4500 S-2 E -Solube Sulfide 13,5mg/l M.N. 4500 S-2 E -Table 5-c: B-208 Well Date: 01-09-08 Monitoring: Wells: B-355 y B-487 S.T.S. HC -2 -2 Muestra Fecha mg/l S (Total) mg/l S (Soluble) mg/l Fe mg/l mg/l BSR Ph Cond. B-355(1°Run Well head) 05-ago 2,8 25,2 19,8 1 0,1 … 7 102.7 B-355(2°Run-Well Head) 12-ago 4,2 12,4 12 1 0,1 <1 6,8 103.8 B-487(Down Hole Sample) 20-ago 249 11,7 4,3 175 0,4 5+ 7,3 107.9 B-487(Well head) 20-ago 10,5 12,6 12 3 0,7 3+ 7,2 105.3Table 6: water quality vs depthDate 10-11-08in situ sampleSamples: B-118 Well (Well head and down hole) -2 TSS. S (Total) HC Sample Date mg/l mg/l S-2(Soluble) mg/l Fe mg/l mg/l BSR Ph Conduct. B-118 (Well head) 31-oct 4 12,6 11,5 1,1 0,3 2+ 6,9 102,2 B-118 (down hole sample) 31-oct 84.1 23,1 4 253 0,5 4+ 7 102,7Table 7. water quality vs depth in
  10. 10. 10 SPE 122189 ESTRUCTURA CRUZ DE PIEDRA MENDOZA BARRANCAS BARRANCAS LUNLUNTA CARRIZAL 30 Km UGARTECHE UGARTECHE LOMA DE LOS ALTOS 21 Km LOMA DE LA MINA RIO TUNUYAN LA BREA PTO. MUÑOZ EL CARRIZAL DAM LOMA ALTA 340 MENDOZA LOMA ALTA SUR PAMPA PALAUCO PAMPA PALAUCO 17 Km Cº DIVISADERO LA VENTANA LOS CAVAOS MALAL DEL MEDIO CUYANA BASIN RIO GRANDE 23 Km CERRO FORTUNOSO CERRO FORTUNOSO VIZCACHERAS 10 KMFigure 1 : Field Location Barrancas Field Injection Wells Weight percent (%) SO4Ca Zn Pb CO3Ca Fe2O3 Si O2Figure 2: Weight composition of scale samples taken from different injections wells in 2000/2001. SPE S Fe 69533 Well number   INJECTOR WELL EJ2 Qi ( m3 / d ) 200 100 0 26- 20- 14- 11- 5- 30- 25- 19- 14- 8- 2- 27- 22- 16- 11- 5- DATE WORK OVER : 11/04/97 -STIMULATIONS: 04/30/98 Figure 3: FIGURE 1: WELL INJECTIVITY DECLINEFigure 3: Typical Injectivity decline curve in Barrancas Field
  11. 11. SPE 122189 11    Figure : 4-a-SEM before PWRI flooding Figure. 4-b-SEM afterPWRI flooding  400 S tim u la ti o n B e h a vi o r 350 35 6 P r e ss u r e  In je c t io n ‐ Flo w  Ra t e  E v o lut io n  v s t im e 300 2 250 m c P re s s u r e In j ec t i o n / g k - 3 94 2 08 2 102 10 a í 200 2 00 19 5 20 020 0 20 52 0 02 0 52 0 52 00 2 00 1 94 2 00 d / 1 90 3 17 8 m 1 7017 0 17 2 1 60 150 14 0 1 30 1 38 1 33 1 22 12 0 12 011 5 12 0 110 1 05 100 10 09 9 9 6 83 88 90 Fl ow  Ra te 60 50 50 4 4 4 5 3 8 42 50 30 30 St im u l at ion 20 20 10 0 0 0 2 1 2 8 2 2 5 2 9 0 1 0 2 0 6 1 2 1 6 2 0 2 4 2 6 0 3 0 7 0 9 1 7 2 1 2 0 3 1 0 5 1 3 1 9 2 3 0 2 … … … … … … … … … … … … … … … … … … … … … … … … … C a u d al f ec h ae s ión PrFigure 5:Injection Pressure and Flow rate profile between stimulations TSS-Total Suspended Solids SULFIDES 35,00 120,00 Year 2007 TSS 30,00 Year 2007 SULFIDES 100,00 Year 2008 TSS Year 2008 SULFIDES 25,00 80,00 20,00 mg/l Mg/l 60,00 15,00 40,00 10,00 20,00 5,00 0,00 0,00 E.BBV S.BBV E.B87 S.B87 SAT.23 SAT.26 B-208 E.BBV S.BBV E.B87 S.B87 SAT.23 SAT.26 B-208
  12. 12. 12 SPE 122189 SRB COUNTS OIL CONTENT 4,50 16,00 4,00 14,00 3,50 12,00 3,00 Year 2007 HYDORCARBONS 10,00 Caldos positivos 2,50 Year 2008 HYDORCARBONSPPM 8,00 2,00 6,00 1,50 Year 2007 BACTERIA-SRB Counts 4,00 1,00 Year 2008 BACTERIA -SRB Counts 2,00 0,50 0,00 0,00 E.BBV S.BBV E.B87 S.B87 SAT.23 SAT.26 B-208 E.BBV S.BBV E.B87 S.B87 SAT.23 SAT.26 B-208 Figure 6: Water quality parameters followed during 2007 and 2008 year EVENTS WELL PER YEAR BARRANCAS CRI Fm 5,00 4,60 4,50 4,00 3,67 3,50 3,21 EVENTS WELL PER YEAR 2,97 3,00 2,58 2,49 2,50 2,00 1,50 1,00 0,92 0,63 0,49 0,50 0,00 2006 YEAR 2007 YEAR 2008 YEAR Int. pozo año Estim.pozo año Eventos por pozo año Figure 7: Events per year Figure 8: Pore throats distribution
  13. 13. SPE 122189 13 FLOW EQUIPMENT Hydraulic Pump Overburden Circuit Stirrer Data acquisition system Formation Water Oven Injection Water Core Triaxial Cell Back Pressure Effluent Back Flow Circuit Collector Constant Rate Displacement PumpFigure 9. Core flooding euipment diagramFigure 10: on site core flooding testFigure 11a: figure 11-b:
  14. 14. 14 SPE 122189 Figure 12- a Figure 12-b DECLINE INJECTIVITY -TEST 1 ON SITE COREFLOODING PERMEABILITIY PROFILE (Kf/Ki vs vp) Well Location B-355 - Yac. BARRANCAS - Core Nº 4 - 8 - 2( B-342) 1,50 FILTERED FORMATION WATER(Ki) 1,00 Kf/Ki PWRI 0,50 0,00 0 1000 2000 3000 4000 5000 6000 7000 8000 PORAL VOLUM E INJECTED Figure 13: oni site core flooding test.   CORE FLOODING -TESTS :2; 3 AND 4 PEMEABILITY EVOLUTION (Kf/Ki vs PV) WELL: B-342 - BARRANCAS FIELD- CORE Nº 1-3-1 -- 2-6-4 -- 2-7-2 NOBP: 430 kg/cm2 - TEMPERATURE : 85 ºC 1,50 FILTERED FORMATION WATER(Ki) PWRI + PRODUCT B (250ppm) START PRODUCT INJECTION 1,00 Kf/Ki PWRI + PRODCUT A (250ppm) 0,50 PWRI- BASE LINE 0,00 0 50 100 150 200 PORAL VOLUME INJECTED (PV) Figure 14 : Permeability profile   CORE FLOODING -TESTS: 2; 3 AND 4 PRESSURE EVOLUTION VS PORAL VOLUME INJECTED Well: B-342 - Yac. BARRANCAS - CoreNº 1-3-1 -- 2-6-4 -- 2-7-2 NOBP: 430 kg/cm2 -- Temperature: 85 ºC 10,00 START PRODUCT INJECTION PWRI -BASE LINE 1,00 PRESSURE (Atm.) 0,10 PWRI + PRODUCT B (250ppm) PWRI + PRODCUT A(250ppm) 0,01 0 50 100 150 200 Poral Volume Injected Figure 15: Pressure Profile

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