Reservoir Fluid Study for Occidental de Colombia Rondon 1N Well RFL05097 Core Laboratories Venezuela, S.A. Calle 25 (Carretera Via El Mojan) Km 3 al lado dwe la Coca-Cola Tel +58 261 7574611, fax +58 261 7578684 The analyses, opinions or interpretations in this report are based on observations and material supplied by the client to whom, and for whose exclusive and confidential use, this report is made. The interpretations or opinions expressed represent the best judgement of Core Laboratories Venezuela, S.A. (all errors and omissions excepted); but Core Laboratories Venezuela, S.A. and its officers and employees assume no responsibility and make no warranty or representations as to the productivity, proper operation or profitability of any oil, gas or any other mineral well formation in connection with which such report is used or relied upon.
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Reservoir Fluid Study
for
Occidental de Colombia
Rondon 1N Well
RFL05097
Core Laboratories Venezuela, S.A.
Calle 25 (Carretera Via El Mojan) Km 3 al lado dwe la Coca-ColaTel +58 261 7574611, fax +58 261 7578684
The analyses, opinions or interpretations in this report are based onobservations and material supplied by the client to whom, and for whoseexclusive and confidential use, this report is made. The interpretations oropinions expressed represent the best judgement of Core LaboratoriesVenezuela, S.A. (all errors and omissions excepted); but Core LaboratoriesVenezuela, S.A. and its officers and employees assume no responsibility and make no warranty or representations as to the productivity, proper operationor profitability of any oil, gas or any other mineral well formation inconnection with which such report is used or relied upon.
Core Laboratories Venezuela, S.A.Km 3 Via El Mojan. Parcelamiento Buena VistaMaracaibo, Edo. Zulia-VenezuelaTel: 58 261 7574611Fax: 58 261 7578684Web: http://www.corelab.com
On May 20th of 2005, two wellhead samples were collected by Core Laboratoriesrepresentativesfrom the subject well and were delivered to our fluid laboratory in Maracaibo,Venezuela for performance of a reservoir fluid study.
Upon arrival at the laboratory, the samples were validated by measuring their bubble pointpressures at laboratory temperature; the selected sample was restored to reservoirconditions for subsequent PVT testing. Additional tests were required during the course ofthe study, preliminary results were provided to the client during the course of the laboratorystudy, as well. Final report is presented in the following pages.
It has been a pleasure to perform this study for Occidental de Colombia. Should anyquestions arise or if we may be of further service in any way, please do not hesitate tocontact us.
Occidental de ColombiaRondon 1N Well___________________________________________________________________________________________RFL05097
Table of Contents
Section A - Summary of PVT Methods and Data Page
Summary of PVT methods....................................................................................................... A.1-A.2Summary of PVT data.............................................................................................................. A.3
Section B - Summary of Samples Received and Validation Data
Well information........................................................................................................................ B.1Summary of samples received and validation data.................................................................. B.2
Section C - Compositional Analysis of Bottomhole Reservoir Fluid
Compositional Analysis of Reservoir Fluid to C36+.................................................................. C.1-C.2
Section D - Constant Composition Expansion
Single phase fluid properties at reservoir temperature............................................................. D.1Constant composition expansion at reservoir temperature...................................................... D.2Graphs of constant composition expansion at reservoir temperature...................................... D.3Constant composition expansion at different temperatures..................................................... D.4
Section E - Differential Vaporization
Differential vaporization data.................................................................................................... E.1Graphs of differential vaporization............................................................................................ E.2Differential vaporization data adjusted to surface conditions.................................................... E.3
Section F - Viscosity of Reservoir Fluid
Reservoir fluid viscosity data at Reservoir Temperature.......................................................... F.1-F.2
Section G - Separation Test of Reservoir Fluid
Atmospheric Flash test at 75 °F................................................................................................ G.1Molecular composition of evolved gas during atmospheric flash at 75 °F................................. G.2
Atmospheric Flash test at 140 °F.............................................................................................. G.3Molecular composition of evolved gas during atmospheric flash at 140 °F............................... G.4
Atmospheric Flash test at 180 °F.............................................................................................. G.5Molecular composition of evolved gas during atmospheric flash at 180 °F............................... G.6
Atmospheric Flash test at 200 °F.............................................................................................. G.7Molecular composition of evolved gas during atmospheric flash at 200 °F............................... G.8
Atmospheric Flash test at 220 °F.............................................................................................. G.9Molecular composition of evolved gas during atmospheric flash at 220 °F............................... G.10
Occidental de ColombiaRondon 1N Well___________________________________________________________________________________________RFL05097
Table of Contents, continued
Section H - Appendix
Data used in gas compositional calculations............................................................................ H.1Data used in liquid compositional calculations......................................................................... H.2Crude oil caracterization.......................................................................................................... H.3Crude oil distillation.................................................................................................................. H.4
Occidental de ColombiaRondon 1N Well___________________________________________________________________________________________RFL05097
Summary of Analysis Methods
Sample ValidationThe bubble point pressure at ambient temperature and free water content of each wellheadsample were determined as initial quality checks. From this quality control, the samples showedgood agreement with respect to the measured bubble point pressures and did not contain freewater. Therefore, the samples were deemed valid and were used to continue with testing
Heat TreatmentEach wellhead sample was heated to 200°F prior to subsampling for every PVT test to avoidwax or asphaltene deposition problems
Pressurized Wellhead Fluid CompositionApproximately 30 cc of pressurized fluid was flashed to atmospheric pressure at 120 °F andseparated into its respective gas and oil phases. The evolved gas and residual liquid wereanalyzed separately, using gas-liquid chromatography and recombined on a weight basis toproduce a C36+ weight percent composition. Calculations to mole% and the plus fractionsproperties are described below.
Gas CompositionsGas compositions were measured using a "one shot" Varian 3800 gas analyzer using methodGPA 2286. The gas chromatograph utilizes 3 columns to clearly identify all the elutedcomponents from N2, CO2 and C1 through C11+. The chromatograph is calibrated twice perweek using air and synthetic hydrocarbon gas with known compositions. The resultantcalibration data is checked statistically against previous calibrations prior to performing analyseson unknown samples.
Liquid CompositionResidual/stocktankliquid composition were measured using a Varian 3400 chromatograph. Thegas chromatograph utilizes a cold on-column, "sandwich injection" technique to ensure that arepresentative sample is injected and swept onto the column. The sample is run twice; first theoriginal fluid and then the same spiked with n-tetradecane. This allows the laboratory to take intoaccount any heavy end (C36+) losses that may have occurred, during the chromatographic runand make an accurate correction prior to reporting the liquid composition. The data obtainedfrom the gas chromatograph is in weight percent. Calculations to mole% and the plus fractionsproperties are described below.
The chromatograph is checked twice per week as well, using a gravimetric n-paraffin mixcontaining a range of pure components from C8 through C36 and a synthetic gas-oil mix(D2887) with known composition. The resultant calibration data is checked statistically againstprevious calibrations prior to performing analyses on unknown samples.
Occidental de ColombiaRondon 1N Well___________________________________________________________________________________________RFL05097
Summary of Analysis Methods (Continuation)
Calculation of Mole% Compositions and Plus Fraction PropertiesThe residue or stocktank liquid whole sample molecular weight and density are measured usinga cryscope unit and a PAAR densimeter respectively.
The mole% data is calculated using GPSA mole weight and density data, where individualcomponents are identified, from carbon dioxide through decanes. Katz and Firoozabadi data areused from undecanes through pentatriacontanes. The residue mole weight and density valuesare calculated so that the pseudo average mole weight and density are the same as themeasured values. This can lead to anomalous residue mole weights and densities where theKatz and Firoozabadi values may not be suitable for the isomer groups detected.
Other alternativesare to use an assumed C36+ molecular weight and density value, use a linearextrapolation technique for components from C10 to C35 to calculate the C36+ properties or toutilise distillation analysis to produce a C11+, C20+ or C36+ residual oil fraction and physicallymeasure the molecular weight and density.
Constant Composition ExpansionA portion of the wellhead fluid sample was charged to a high pressure visual cell and thermallyexpanded to the reservoir temperature of 225 °F. A constant composition expansion wascarried out during which the bubble point pressure and pressure-volume data for the singlephase and two phase fluid were determined. The density of the single phase fluid was alsodetermined by weighing measured volumes pumped from the cell at 5000 psig. Density data forother pressures were calculated using the volumetric data.
Differential VaporizationThis was carried out in a high pressure visual cell at reservoir temperature. At several pressurestages below the observed saturation pressure, the sample was stabilized. The gas evolvedwas then pumped out of the cell and its volume, compressibility and composition weredetermined. The final stage was carried out at atmospheric pressure when the residual liquidwas pumped out of the cell and its density was determined
Occidental de ColombiaRondon 1N Well___________________________________________________________________________________________RFL05097
Summary of Analysis Methods (Continuation)
ViscosityLive-oil viscosity was measured in a rolling ball viscometer at reservoir temperature. Viscositydeterminations were carried out over a wide range of pressures from above the reservoirpressure to atmospheric pressure.
The measurements were repeated at each pressure stage until five or more results agreed towithin 0.5% of the ball roll-time. The densities, obtained from the constant compositionexpansion and differential vaporization tests, were used in the calculation of viscosities incentipoise.
Separator TestsFive atmospheric flash tests at different temperatures each were carried out using a pressurizedtest separator cell. A portion of the wellhead sample, at a pressure above saturation pressure,was pumped into the separator cell and stabilized at ambient pressure and test temperature. Thgas evolved was pumped out of the cell and the volume and composition were determined. Thefinal stage was carried out at atmospheric pressure and ambient temperature and the density ofthe residual liquid was determined.
Crude Oil CaracterizationA set of atmospheric tests was also performed accordingly with ASTM methodologies and theirresults are presented in the Appendex.
Occidental de ColombiaRondon 1N Well___________________________________________________________________________________________RFL05097
Summary of Samples Received
Wellhead SamplesLaboratory
Sample Cylinder Sampling :- Bubble point :- Water SampleNumber Number Pressure Temp. Pressure Temp. Cut Volume
(psig) (°F) (psig) (°F) (%) (cm3)
1.1 436251D 305 100 310 76 0.2 890
1.2 897612C 305 100 305 76 0.2 890
Note:
Sample No.1.1 and 1.2 were selected for compositional and further PVT analysesOne 1000 cc plastic container with crude oil sample was also received to perform crude oil caracterization
(1) GOR in cubic feet of gas at 14.70 psia and 60°F per barrel of residual oil at 60°F.(2) Volume of oil at indicated pressure and temperature per volume of residual oil at 60°F.(3) Volume of oil plus liberated gas at indicated pressure and temperature per volume of residual oil at 60°F.(4) Volume of gas at indicated pressure and temperature per volume at 14.70 psia and 60°F.
* Evolved gas collected and analysed to Undecanes plus
(1) GOR in cubic feet of gas at 14.70 psia and 60°F per barrel of oil at indicated pressure and temperature.(2) GOR in cubic feet of gas at 14.70 psia and 60°F per barrel of stocktank oil at 60°F.(3) Volume of saturated oil at 508 psig and 225°F per volume of stocktank oil at 60°F.(4) Volume of oil at indicated pressure and temperature per volume of stocktank oil at 60°F.
* Evolved gas collected and analysed to Undecanes plus
(1) GOR in cubic feet of gas at 14.70 psia and 60°F per barrel of oil at indicated pressure and temperature.(2) GOR in cubic feet of gas at 14.70 psia and 60°F per barrel of stocktank oil at 60°F.(3) Volume of saturated oil at 508 psig and 225°F per volume of stocktank oil at 60°F.(4) Volume of oil at indicated pressure and temperature per volume of stocktank oil at 60°F.
* Evolved gas collected and analysed to Undecanes plus
(1) GOR in cubic feet of gas at 14.70 psia and 60°F per barrel of oil at indicated pressure and temperature.(2) GOR in cubic feet of gas at 14.70 psia and 60°F per barrel of stocktank oil at 60°F.(3) Volume of saturated oil at 508 psig and 225°F per volume of stocktank oil at 60°F.(4) Volume of oil at indicated pressure and temperature per volume of stocktank oil at 60°F.
* Evolved gas collected and analysed to Undecanes plus
(1) GOR in cubic feet of gas at 14.70 psia and 60°F per barrel of oil at indicated pressure and temperature.(2) GOR in cubic feet of gas at 14.70 psia and 60°F per barrel of stocktank oil at 60°F.(3) Volume of saturated oil at 508 psig and 225°F per volume of stocktank oil at 60°F.(4) Volume of oil at indicated pressure and temperature per volume of stocktank oil at 60°F.
* Evolved gas collected and analysed to Undecanes plus
(1) GOR in cubic feet of gas at 14.70 psia and 60°F per barrel of oil at indicated pressure and temperature.(2) GOR in cubic feet of gas at 14.70 psia and 60°F per barrel of stocktank oil at 60°F.(3) Volume of saturated oil at 508 psig and 225°F per volume of stocktank oil at 60°F.(4) Volume of oil at indicated pressure and temperature per volume of stocktank oil at 60°F.
* ASTM Data Series Publication DS 4B (1991) - Physical Constants of Hydrocarbon and Non-Hydrocarbon Compounds.
** GPA Table of Physical Constants of Paraffin Hydrocarbons and Other Components of Natural Gas, GPA 2145-96.
*** Journal of Petroleum Technology, Nov 1978, Pages 1649-1655. Predicting Phase Behaviour of Condensate/Crude Oil Systems Using Methane Interaction Coefficients - D.L. Katz & A. Firoozabadi.
Note :The gas mole % compositions were calculated from the measured weight % compositions using the most detailed analysis results, involving as many of the above components as were identified. The reported component mole % compositions were then sub-grouped into the generic carbon number components.
* ASTM Data Series Publication DS 4B (1991) - Physical Constants of Hydrocarbon and Non-Hydrocarbon Compounds.
** GPA Table of Physical Constants of Paraffin Hydrocarbons and Other Components of Natural Gas GPA 2145-96.
*** Journal of Petroleum Technology, Nov 1978, Pages 1649-1655. Predicting Phase Behaviour of Condensate/Crude Oil Systems Using Methane Interaction Coefficients - D.L. Katz & A. Firoozabadi.
Note :The residue mole weight and density values ( eg heptanes plus, undecanes plus, eicosanes plus) are calculated so that the calculated average mole weights and densities correspond with the measured values. This can lead to anomalous residue mole weights and densities where the Katz and Firoozabadi values may not be suitable for the isomer groups detected.