Minnelusa Core Analysis and Evaluation Project

Transcription

1 Minnelusa Core Analysis and Evaluation Project Collaborative work of EORI with the Minnelusa Consortium and C&PE faculty members, Professors: Alvarado, Morrow and Piri Prepared for The EOR Commission and Technical Advisory Board Meeting Reza Barati 07/26/2012 Laramie, Wyoming

2 Outline Introduction Objectives Core protocol Thin section analysis Water and oil properties Wettability index measurement, low salinity and sequential water flooding Relative permeability measurements Capillary pressure measurements Summary Future work Acknowledgements 2

3 Introduction Core was collected from a Minnelusa well 120 ft of core was collected, ~58 ft of which was from Minnelusa (B sand ) 83 core plugs were taken, 20 of which were sent by the company for cleaning and porosity and permeability measurements Core was slabbed and described by the company The slabbed part of the core is donated to the Geology and Geophysics Dept. at UW and the rest is donated to EORI 83 core plugs were also donated to EORI 3

4 Objectives Improve the geological model of this field by measuring rock properties like porosity and permeability Generate Special Core Analysis (SCAL) for core plugs representative of different observed lithological-facies for this well to improve reservoir descriptions and simulations for this field and other Minnelusa fields Evaluate future application of EOR/IOR in this field and other Minnelusa fields Provide consortium with a valuable set of data for Minnelusa 4

5 Core Analysis Protocol Core plugs scanned Thin section analysis Cleaning the plugs: 6 plugs were flushed and extraction was used for the rest Selection of core plug triplicates for different lithofacies (three) Core plugs representative of each zone distributed between the groups Core plugs saturated and aged in brine for 10 days Oil flood to establish irreducible water saturation Age at 94 C for 30 days 5

6 Core Analysis Protocol, cont d Pore network modeling Pc for law salinity and high salinity floods AP, ASP and A blends for EOR core flooding tests Optimize the use of alkali to reduce precipitation of scales Anhydrite dissolution effect on water flooding Unsteady-state relative permeability 6

7 Thin Section Analysis Anhydrite cemented SS (#1-110, k He =0.225 md, f=7.7 %) Anhydrite nodules (#1-83) Fig.1 Thin section analysis done by Peigui Yin: The LHS image shows the anhydrite cemented SS and the RHS image shows the anhydrite nodules observed in some core plugs. Black spots are oil stained dolomite cement. 7

8 Thin Section Analysis, cont d Dolomite cement (#1-64, k He =0.069 md, f=3.5%) Sandy dolomite (#1-63) Fig.2 Thin section analysis done by Peigui Yin: The LHS image shows the sandstone with dolomite cement and the RHS image shows the sandy dolomite observed in some core plugs 8

9 Thin Section Analysis, cont d Permeable SS (#1-74, k He =280.5 md, f=23.7%) Fig.3 Thin section analysis done by Peigui Yin: A permeable SS observed in some of the core plugs 9

10 Thin Section Analysis, cont d

11 Porosity and Permeability Measurements Fig.5 Gas porosity and permeability (Morrow s group) and shifter sonic log vs. depth Fig.6 a) Porosity-average CT# correlations for 20 cleaned core plugs (red squares) and 53 uncleaned core plugs (green triangles). b) Core porosity vs. sonic transit time. 11

12 Water Properties Table 1 Water composition of the produced brine and the brine used in the experiments. Cations and anions Water analysis report (mg/l) Used in the experiments (mg/l) Na K Ca Mg Ba Sr Fe Mn Si SO Cl HCO TDS ph Table 2 Brine density, viscosity and surface tension measured at 60 C (Morrow s group) Density (g/cm 3 ) Viscosity, cp 0.55 Surface tension, mn/m 70.2 IFT against crude oil, mn/m

13 Viscosity, Pa.s Crude Oil Properties Table 3 Asphaltene content of the crude oil (Piri s group) Table 4 Crude oil density and surface tension measured at 60 C Sample No. Crude oil (gr) n-heptane (cc) Asphaltene content of crude oil (%) (Morrow s group) Density (g/cm 3 ) Surface tension, mn/m Average C 35 C 45 C 55 C 65 C 75 C 85 C C Shear rate, s -1 Fig.7 Crude oil viscosity versus shear rate at C (Alvarado s group) 13

14 Wettability Index Measurements Fig.8 Wettability index measurement procedure (Morrow s group) Core 86b Core 84b Core 79b received solventcleaned core measure dry properties saturate with brine; pressurize to 1000 psi with brine for 2+ hours; soak in brine for 10 C & 15 psig; cool to room temperature; measure brine-saturated properties; received uncleaned/as is saturate with oil; pressurize to 1000 psi with oil for 12+ hours measure oil permeability; age with crude oil at 95 C & 1000 psig for 30+ days; cooled to 60 C then set for imbibition; heated to 95 C for imbibition (2 months); cooled to 60 C then waterflood for about 90cm 3 at 2 cm 3 /min solvent-clean with alternating toluene and methanol flooding until effluent is clear (very light yellow tint is possible after 20 PV flooding but accepted as clear enough) Table 5 Wettability index measurement results (Morrow s group) core 86B core 84b Core 79b Initial condition cleaned uncleaned uncleaned Dry properties : porosity (by helium) Klinkenberg C Brine-saturated properties: porosity C Oil-saturated properties: porosity C Initial-water properties: S wi oil C oil C Imbibition test: oil produced during imbibition oil produced during waterflood index (I w ) Dry properties : porosity (by helium) Klinkenberg C 18.6% md 16.2% md 20.5% ~20-42 md ~65-85 md 2.05 cm cm % md 12.3% n/a 10.5% 2.0 md 18.8% (?) 5.8 md ~ cm cm % md 12.3% n/a 12.6% ~ md ~0% (?) ~ md ~17-25 md 2.35 cm cm % md measure dry properties 14

15 Wettability Index Measurements, cont d t D = 2 Lc 2 K σ φ μ w 1 + μ o μw Fig.9 Oil recovery caused by spontaneous imbibition versus dimensionless time (Morrow s group) Fig.10 Oil recovery caused by forced imbibition and pressure drop versus PV of injected brine (Morrow s group) 15

16 Low Salinity and Sequential Water-Flooding Results Fig.11 Low salinity and sequential waterflooding procedures (Morrow s group) Core 86b Core 84b Core 79b measure dry properties saturate with brine; pressurize to 1000 psi with brine for 2+ hours; soak in brine for 10 C & 15 psig; cool to room temperature; measure brine-saturated properties; secondary waterflood with brine; tertiary waterflood with 20x diluted brine; re-establish Swi by oil flooding and rewaterflood with diluted brine (5 consecutive times) measure oil permeability; age with crude oil at 95 C & 1000 psig for 30+ days; saturate with oil; pressurize to 1000 psi with oil for 12+ hours cooled to 60 C then set for imbibition; heated to 95 C for imbibition (2 months); cooled to 60 C then waterflood for about 90 cm 3 at 2 cm 3 /min solvent-clean with alternating toluene and methanol flooding until effluent is clear (very light yellow tint is possible after 20 PV flooding but accepted as clear enough) measure dry properties Table 5 Low salinity and sequential waterflooding results (Morrow s group) core 86B core 84b Core 79b Initial condition: re-cleaned cleaned cleaned Dry properties: porosity (by helium) Klinkenberg C Brine-saturated properties: porosity C Oil-saturated properties: porosity C Initial-water properties: S wi oil C oil C Waterflood test: oil produced during secondary WF oil produced during tertiary WF S or,swf1 S wi,swf2 oil produced during SWF2 S or,swf2 S wi,swf3 oil produced during SWF3 S or,swf3 S wi,swf4 oil produced during SWF4 S or,swf4 S wi,swf5 oil produced during SWF5 oil produced during SWF6 S or,swf6 Imbibition test oil produced during imbibition oil produced during waterflood index (I w ) 18.3% md 17.2% md 30.0% ~19-20 md ~31-53 md 17.2% md 15.0% 92.4 md 23.2% ~25-29 md ~ cm cm % 51.9% cm % 54.8% cm % 59.2% 4.8 cm 3 8.0% 62.1% 4.8 cm 3 SE or,swf5 N H S A N wi,swf6 C E D 5.1% 62.6% O I L R E C O V E R Y I N S T I T U T E 4.85 cm 3 4.3% 0.55 cm cm % md 17.4% ~ md 0% ~ md ~32-33 md 1.02 cm cm

17 Low Salinity and Sequential Water-Flooding, cont d Fig.12 Residual oil saturation after different cycles of sequential waterflooding (Morrow s group) Fig.13 Initial water saturation after different cycles of sequential waterflooding (Morrow s group) 17

18 Relative Permeability Measurement Setup Fig.14 HPHT relative permeability measurement setup. L) HT ovens. M) 2-liter accumulators. R) HT cells and Qizix pumps. (Piri s group) 18

19 Relative Permeability Measurement Setup, cont d Fig.15 HPHT relative permeability measurement setup. L) core flooding setup. M) HT cells and Qizix pumps. R) Back pressure regulator. (Piri s group) 19

20 Relative Permeability Measurements Core# 1-100b: K air = 112 md Near zero pressure drop after saturating and aging with brine Core#1-98b: K brine =95.39 md K air =69.5 md Fig.17 Water permeability measurement for core#98b (Piri s group) Fig.16 CT scan image of core#1-100b (Piri s group) 20

21 Capillary Pressure Measurements- Setup Fig.18 CPCS -355Z Reservoir Condition Capillary Pressure system (Alvarado s group) The CPCS -355Z Reservoir Condition Capillary Pressure system measures drainage and imbibition capillary pressure in conjunction with electrical resistivity measurements using 2T and 4T electrode configurations at 5 different frequencies The system uses a membrane technique with an upstream oil-wet membrane and a downstream water-wet membrane 21

22 Capillary Pressure Measurements- Procedure Pump B is connected to the upstream end to drive oil injection during drainage and pump A controls the downstream pressure During imbibition, pump B acts as back-pressure control and pump A injects water from the reservoir Resistivity is measured at 100 Hz, 1 khz, 10 khz, 20 khz and 100 khz and manually collected due to instrumentation problem, so the data will show gaps All the pressure and volume data are collected automatically and as frequently as several times a minute 22

23 Capillary Pressure Measurements- Core#1-115: L: 36.68mm D: 37.86mm Absolute Permeability: 66.95mD Porosity: 15.61% Pore Volume: 6.45cc Primary Drainage Fig.20 Primary drainage capillary pressure and resistance measurement for core#1-115 at reservoir pressure and temperature (Alvarado s group) Fig.19 CT scan image of core#1-115 (Piri s group) 23

24 Capillary Pressure Measurements- Primary Drainage, cont d Table 6 Primary drainage capillary pressure versus water saturation for core#1-115 at reservoir pressure and temperature (Alvarado s group) Sw Pc, psi Table 7 2T resistance of the core#1-115 at reservoir pressure and temperature versus water saturation (Alvarado s group) Sw 2T-100Hz 2T-1K Hz 2T-10K Hz 2T-20K Hz 2T-100K Hz

25 Capillary Pressure Measurements- Primary Drainage and Secondary Imbibition The entry pressure was overestimated and as a result, the shoulder was not obtained. This is being resolved in the second test. A power outage occurred as the negative capillary pressure was about to obtain Fig.21 Primary drainage and secondary imbibition capillary pressure for core#1-115 at reservoir pressure and temperature (Alvarado s group) 25

26 Summary Thin section analysis showed three main features: High quality sand Anhydrite cementation Dolomite cementation Wettability indexes were measured for a cleaned core and two uncleaned cores and showed weakly water-wet properties Low salinity waterfooding on a core plug did not show incremental oil Sequential waterfloowing showed significant reduction in the residual oil and increase in initial water saturation 26

27 Summary, cont d HPHT relative permeability measurement setup was installed and tested Aging and primary drainage was performed for one core but not finished One core showed very high permeability after water saturation Primary drainage and the positive part of the secondary imbibition capillary pressure curves were measured for one core Capillary pressure for a similar core but with low salinity brine is being measured 27

28 Future Work Morrow s group: Anhydrite dissolution studies Wettability index for oil Oil and water Amott indexes for two other core plugs representative of different lithologies Piri s group: Relative permeability measurement for three representative core plugs Relative permeability measurement for a core plug using low salinity brine 28

29 Future Work, cont d Alvarado s group: Capillary pressure and electrical properties measurement for two other representative core plugs Capillary pressure and electrical properties measurement for a core plug using low salinity brine 29

30 Acknowledgements C&PE faculty members: Norman Morrow Mohammad Piri Vladimir Alvarado C&PE researchers and students: Amirhossein Alizadeh Mortaza Akbarabadi Mahdi KazemPour Nina Loahardjo Winoto Winoto Xiao Wang EORI Peigui Yin Minnelusa Consortium 30