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Study of Imbibition Mechanisms in the Naturally Fractured Spraberry Trend Area Yan Fidra Petroleum and Chemical Engineering Department New Mexico Institute.

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Presentation on theme: "Study of Imbibition Mechanisms in the Naturally Fractured Spraberry Trend Area Yan Fidra Petroleum and Chemical Engineering Department New Mexico Institute."— Presentation transcript:

1 Study of Imbibition Mechanisms in the Naturally Fractured Spraberry Trend Area Yan Fidra Petroleum and Chemical Engineering Department New Mexico Institute of Mining and Technology

2 Outline Introduction Laboratory Experiments Modeling Conclusions Recommendations

3 Outline Introduction –Problem statement –Literature review –Objectives –Overview of the study Laboratory Experiments Modeling Conclusions Recommendations

4 Problem Statement Lack in understanding of upscaling laboratory imbibition experiments to field dimensions - Low rock permeability that represent real thing - Static and dynamic process - Reservoir conditions Wetting behavior

5 Literature Review  rock characteristics (Mattax and Kyte, 1962; Torsaeter, 1984; Thomas 1984; Hamon and Vidal, 1988)  fluid properties (Iffly et al., 1972; Cuiec et al., 1990; Keijzer and De Vries, 1990; Ghedan and Poetmann, 1990; Schechter et al., 1991; Babadagli, 1995; Al-Lawati and Saleh, 1996)  low permeability of Chalk reservoir (Torsaeter, 1984; Bourbiaux and Kalaydjian, 1990; Cuiec et al., 1990)  wettability (Anderson, 1986; Hirasaki, et al, 1990; Zhou et al., 1995; Buckley, et al, 1995)  aging time and temperature and initial water saturations (Zhou et al., 1993; Jadhunandan and Morrow, 1991)  scaling of imbibition data (Mattax and Kyte, 1962; Lefebvre du Prey, 1978; Ma, 1995; Zhang et al, 1996)

6 Objectives To investigate wettability of Spraberry Trend Area at reservoir conditions. To upscale the laboratory imbibition results to field-scale dimensions. To investigate the contribution of the capillary imbibition mechanism to waterflood recovery. To determine the critical water injection rate during dynamic imbibition.

7 Overview of the Study Static imbibition Dynamic imbibition Field dimension Determine rock wettability Upscaling Determine laboratory critical injection rate Fracture Capillary Number Scaling equations Capillary pressure curve

8 Outline Introduction Laboratory Experiments –Static Imbibition Tests Verify the effect of P & T on recovery mechanisms Determine rock wettability index –Dynamic Imbibition Tests Investigate the effect of injection rate on recovery mechanism Determine critical injection rate Modeling Conclusions Recommendations

9 Static Imbibition Experiments Materials Experimental apparatus Results

10 Porous Media Fluids Crude Oil Synthetic Reservoir Brine (TDS = 130,196 ppm) Berea sandstone Low permeability Spraberry rock Materials

11 Schematic Diagram of the Static Imbibition Process in Laboratory core oil water Imbibition model with one end closed 1.5” X ” Core Synthetic brine beaker 138 o F

12 Experimental Set-up for Imbibition Tests under HPHT BV NV PR Graduated Cylinder Brine Tank High Pressure Imbibition Cell N 2 Bottle (2000 psi) Air Bath BV = Ball Valve NV = Needle Valve PR = Pressure Regulator Top View Inlet for creating tangential flow Side View core

13 Brine PumpOil Pump Air Bath Core holder Confining pressure gauge Graduated cylinder Oil tankBrine tank Flooding Apparatus

14 Effect of Pressure and Temperature on Static Imbibition Rate and Recovery using Berea Sandstone

15 138 o F 70 o F Effect of Temperature on Static Imbibition Rate and Recovery using Spraberry Reservoir Rock

16 Cleaning Spraberry core plugs Dean Stark Extraction Chloroform Displacement Drying (2 days) Evacuation (24 hours) Weight Evacuated Spraberry brine Measure brine density and viscosity Saturation of core samples Ionic equilibrium (3 days) Porosity calculation  Brine permeability  Recheck the porosity Oil viscosity, density and IFT measurements Oil flooding Establish Swi i Aging core samples in oil Aging time (days) at reservoir temperature Aging time (days) at reservoir temperature No aging time Imbibition tests (21 days) at reservoir temperature Imbibition tests (21 days) at reservoir temperature Imbibition tests (2 months) at ambient condition Brine displacement at room temperature Brine displacement at reservoir temperature Brine displacement at room temperature Results Experimental Procedures for determining WI using Spraberry Cores

17 Displacement A B Static imbibition Amott Wettability Index 0 1 Water-wet moreless

18 Static imbibition A Oil Recovery Curves Obtained from Static Imbibition Experiments at Reservoir Temperature Spraberry cores

19 Displacement A B Staticimbibition Total recovery vs aging time shows that 7 days aging time is adequate to start the experiments Spraberry cores

20 Displacement A B Static imbibition Wettability index vs aging time for different experimental temperatures Spraberry cores

21 Dynamic Imbibition Experiments Schematic of displacement process Experimental apparatus Results

22 MATRIX BLOCK FRACTURE Water Oil + Water Oil saturated matrix Imbibed water Capillary imbibition Viscous flow Oil produced Schematic Representation of the Displacement Process in Fractured Porous Medium

23 Matrix Fracture Artificially fractured core Air Bath Core holder Brine tank Confining pressure gauge Graduated cylinder N 2 Tank (2000 psi) Ruska Pump Experimental Apparatus for Dynamic Imbibition Tests

24 Oil Recovery from Fractured Berea Cores during Water Injection using Different Injection Rates

25 Unfractured core Fractured core Oil Recovery from Fractured Spraberry Cores during Water Injection using Different Injection Rates

26 Injection rate versus oil-cut curve for Berea and Spraberry cores

27 Outline Introduction Laboratory Experiments Modeling –Static imbibition data Investigate Pc from matching of experimental data. Scale up of static imbibition data. –Dynamic imbibition data Obtain Pc curves from matching of experimental data. Scale up of dynamic imbibition data. Conclusions Recommendations

28 Modeling of Static Imbibition Numerical Analysis of Static Imbibition Data Scaling of static imbibition data Results

29 Matching between Laboratory Experiments and Numerical Solution Capillary Pressure Curve Obtained as a Result of Matching Experimental data Numerical Analysis of Static Imbibition Data

30 Scaling of Imbibition Data “ Concept of Imbibition Flooding Process” ( Brownscombe, 1952 ) Water Matrix Fracture Invadedzone Oil production Oil production by water imbibition water oil Capillary force fracturematrix Matrix fracture fluid exchange mechanism Viscous force To investigate the contribution of a static imbibition process to waterflood recovery

31 Imbibition A Complete Oil Recovery Curves Obtained from Imbibition Experiments Spraberry cores No aging

32 Oil Recovery Curves in Terms of Dimensionless Variables

33 Averaging of imbibition curves

34 Equations for Scaling of Static Imbibition Data C = ;

35 Rock Properties of Upper Spraberry 1U Unit

36 L s = 3.79 ft h = 10 ft Recovery Profile Upper Spraberry 1 U Formation (Shackleford-138) 1U

37 Effect of Matrix Permeability and Fracture Spacing on Oil Recovery

38 Modeling of Dynamic Imbibition Data Numerical analysis of dynamic imbibition data to obtain capillary curves. Concept of fracture capillary number. Upscaling of dynamic imbibition data to determine critical water injection rate.

39 Matching Between Experimental Data and Numerical Solution Berea Core Spraberry Core Cumulative water production vs. time Cumulative oil production vs. time Cumulative water production vs. time Cumulative oil production vs. time

40 P c Curves Obtained as Result of Matching Experiment Data Spraberry core Berea core P c from Numerical Model and Laboratory Experiment

41 Field Units : Lab Units : Fracture Capillary Number AmAm w dz AfAf Capillary force (  cos  A m ) Viscous force (v  w A f ) h

42 Injection Rate versus Oil-cut

43 Dimensionless fracture capillary number versus oil-cut

44 Upscaling of Critical Injection Rate

45 5U (N32E) 5U (N80E) 1U (N42E) Fracture orientation O’Daniel Pilot Layout

46 Estimate Critical Water Injection Rates for Wells in O’Daniel Pilot Area

47 Outline Introduction Laboratory Experiments Modeling Conclusions Recommendations

48 Conclusions Wettability Determination –Performing the imbibition tests at reservoir temperature and displacement tests at room temperature indicate that WI is 0.3 to 0.4. –Performing both imbibition and displacement tests at the same temperature (i.e., reservoir temperature or at room temperature) lowers the WI in the range of 0.20 to 0.25; thus, the temperatures during the experimental sequence affect wettability index determination. –Comprehensive experimental data clearly demonstrates that Spraberry reservoir rock is a very weakly water-wet system.

49 Conclusions (cont’d) Static Imbibition –Effect of pressure is much less important than the effect of temperature on imbibition rate and recovery. –Performing the imbibition tests at higher temperature results in faster imbibition rate and higher recovery due to change in mobility of fluids, expansion of oil, and change in IFT. –The final recovery due to imbibition using Spraberry cores varies from 10% to 15% of IOIP, depending on aging time.

50 Conclusions (cont’d) Scaling of static imbibition data –The contribution of the imbibition mechanism to oil recovery is up to 13% IOIP, depending on rock properties and wettability. –Degree of heterogeneity in the matrix and natural fracture system controls the efficiency of Spraberry waterflood performance.

51 Conclusions (cont’d) Dynamic Imbibition –As the flow rate increases, contact time between matrix and fluid in fracture decreases causing less effective capillary imbibition. –The capillary pressure curve obtained from dynamic imbibition experiments is higher that of the static imbibition experiments due to viscous forces during the dynamic process.

52 The limiting value of fracture capillary number for an efficient displacement process in this study was found to be and for Berea and Spraberry cores, respectively. Beyond this range, the displacement process is inefficient due to high water-cut. Conclusions (cont’d)

53 Outline Introduction Laboratory Experiments Modeling Conclusions Recommendations

54 Necessary to correlate the static and dynamic tests in order to achieve proper upscaling. The capillary pressure curve obtained from dynamic imbibition experiments using artificially fractured core can be used as input data in naturally fractured reservoir simulations instead of using mercury injection capillary pressure curves.

55 Acknowledgement I would like to express my sincere appreciation and gratitude to my advisor Dr. David S. Schechter and My committee members Dr. Robert L. Lee, Dr. H.Y. Chen and Dr. Donald Weinkauf for their advice and time spent on this thesis. To PRRC for the financial support through research assistantship grant. To my fellow students and the entire staff of the PRRC for their kindness and assistance.

56 Thank You … Happy Thanksgiving

57 FEET U (N32E) 5U (N80E) 1U (N42E) Fracture orientation


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