PVT analysis of bottom hole sample from Well 3411 0-1 7 STAT01 L EXPLORATION 81 PRODUCTlON LABORATORY by Otto Rogne
stcrtoil Den norske stats oljeselskap as Classification I Requested by J,Hanstveit, LET Bergen Subtitle Co-workers Bodil Fjareide, LAB PVT analysis of bottom hole sample from Well 3411 0-1 7 EXPLORATION & PRODUCTION LABORATORY by Otto Rogne Prepared Approved /7 j,/ /-
CONTENTS Page INTRODUCTION 2 SAMPLING CONDITIONS 3 Bubble point check Fig. 1 Bubble point at ambient FLASH OF RESERVOIR FLUID TO STOCK TANK Molecular composition Extended molecular composition CONSTANT MASS EXPANSION Fig. 2 Relative volume DIFFERENTIAL DEPLETION Molecular composition of liberated gases Molecular composition of residual oil Fig. 3 Compressibility factor, Z Fig. 4 Fig. 5 Fig. 6 Fig. 7 Reservoir oil density Gas formation volume factor Solution gas, RS Formation volume factor VISCOSITY OF RESERVOIR FLUID Fig. 8 Viscosity
INTRODUCTION The present report gives the experimental results of a PVTanalysis carried out on a bottom hole sample from test no. 2 on well 34110-17, obtained by Stavanger Oilfield Services AIS on June 8, 1983. Sampling details are given on page 3. The quality of the sample was checked by measuring the bubble point at ambient laboratory conditions and found to be 388 barg (page 4 ), as compared to a reported field value of 380 barg at approx. ~ O C this was considered sat isfactory. A portion of the sample was charged to a high pressure cell at 0 reservoi r temperature (106 C) where the bubble point, re1 at ive volumes and compressibility were determined. These results are on page 7. To determine the reservoir fluid composition a portion of the fluid in the cell was flashed through a laboratory separator at 15O~ and atmospheric pressure. The 1 i berated gas and oi 1 were collected, measured and analysed separately by gas chromatography through C with decanes plus fraction. These results are on page 9 5. An extended reservoir fluid composition based on the above mentioned flash up to C and from C10 to C20+ on a TBP 9' distillation of stock tank oil, is given on page 6. The TBP dist i 1 lat ion is reported separately. The remaining sample in the cell was finally differentially liberated through a series of pressure steps with the results shown on page 8. The composition of the liberated gases are on page 9, and the composition of the gas free liquid remaining in the cell at atmospheric pressure on page 10. The gas viscosity were calculated from the gas density according to Lee et.at.
J.Pet.Techn., 997 (1966). A separate portion of the sample was charged to a high pressure rolling ball viscosimeter for viscosity measurements at 1 0 6 ~ ~ The. results are on page 11. SAMPLING CONDITIONS We1 1 Format ion Date Test Interval 34/10-17 Brent 08.06.1983 2 2880-2890 m RKB Sample no. Sample bottle no. sample type Sample depth 9 810698 Bottom hole '$3gl.6 m RKB Bottom hole pressure Bottom hole temperature 409 bar 106 OC Well flowed for approx. 45 min., then closed in for approx. 10 min. before sample being taken.
Well: 34110-17 BHS BUBBLE POINT AT ROOM TEMPERATURE (Bottle nr. 810698) Pressure Barg 521.8 498.4 485.9 466.4 434.6 408.0 388 384.0 362.5 334.6 307.0 237.0 226.6 Pump reading cm 3 155.459 153.825 152.825 151.910 149.109 146.949 Bubble point lab ( lgoc) = 388 barg Bubble point field ( 8'~) = 380 barg
We1 1 : 34/10-17 BHS FLASH OF RESERVOIR FLUID TO STOCK TANK CONDITIONS (Molecular Composition) Component Stock tank Evol ved ~eservoirf lui% oi 1 gas mol % mol % mol % weight % N i t rogen Carbond i ox i de ' Methane' Ethane Propane i- Butane n- Butane i- Pentane n- Pentane Hexanes Heptanes Octanes Nonanes Decanes plus Molecular weight 229. 23.9 66.3 GOR 339 3 3 Sm /m Formation vol. factor 2.00 3 3 m /m Density at bubble point : 0.599 g/cm3 Density of ST0 at 15O~ : 0.853 g/cm3 Gas gravity (air =1) 0.827 Molecular weight of ClO+ : 316 Density of ClO+ at 15 C : 0.881 g / cm3
We1 1 : 34/10-17 BHS EXTENDED RESERVOIR FLUID COMPOSITION Component mol % mol weight Density
CONSTANT MASS EXPANSION AT 1 0 6 ~ ~. Pressure Re1 vol Compressibility Y-factor Barg V/Vb 1/Bar... 503.0 0.9724 2.41E-04 485.7 0.9771 2.51E-04 465.1 0.9828 2.64E-04 443.2 0.9882 2.77E-04 427.1 0.9926 2.86E-04 412.1 0.9969 2.95E-04 Pb = 402.0 1.0000 3.01E-04 392.1 1.0054 4.70 382.0 1.0112 4.66 363.9 1.0234 4.47 343.6 1.0405 4.20 310.2 1.0719 4.12 269.7 1.1275 3.85 219.9 1.2391 3.46 168.6 1.4538 3.05 132.8 1.7335 2.76 121.6 1.8627 2.67 For P < Pb Y = 1.803 + 7.36E-03 x P For P > Pb V/Vb = 1.17434-5.6650E-04 x P + 3.3039E-07xPxP
DIFFERENTIAL DEPLETION AT 1 06' C Pressure Oi 1 form Solution Gas form Res oi 1 Compr Gas vol fact gar vol fact dens i t y factor viscosity barg Bod Rs Bg g/cm3 Z cp :: at 15 C Bod : Volume of oil at P and T per volume of residual oil Rs Bg at 15 C and atm P. : Standard m3 gas per m3 residual oil at 15 C : m3 gas at T and P per standard m3 gas
DIFFERENTIAL DEPLETION AT 106O C (Molecular composition of differentially liberated gas, mol%) NITROGEN 1.24 CARBONDIOXIDE 0.84 METHANE 70.12 ETHANE 9.44 PROPANE 5.36 i -BUTANE 1.06 n-butane 1.83 i -PENTANE 1.02 n-pentane 0.99 HEXANES 1.09 HEPTANES 1.39 OCTANES 1.99 NONANES 0.75 MOLE WEIGHT 31.20 29.38 26.58 23.47 22.22 21.84 25.04 44.62 56.67 GRAVITY (air = 1) 1.077 1.014 0.918 0.810 0.767 0.754 0.865 1.541 1.957
DIFFERENTIAL DEPLETION AT 1 0 6 ~ ~ (Molecular composition of residual oil) COMPONENT MOL% NITROGEN CARBONDIOXIDE METHANE ETHANE PROPANE i -BUTANE n-butane i -PENTANE n-pentane HEXANES HEPTANES OCTANES NONANES DECANES DENSITY AT 15 C MOLE WEIGHT
DIFFERENTIAL DEPLETION Gas formation volume factor
DIFFERENTIAL 'DEPLET'ION AT 106 DEG.C SOLUTION GOR
VISCOSITY OF RESERVOIR FLUID AT 106'~ Pressure (barg) Vlscosi ty (centipoise)