Vanessa Hebert - PhD thesis Papa Ousmane Mangane - PhD thesis

Transcription

1 Multiscale characterization of the carbonated porous media 3D X-ray core tomography analysis Vanessa Hebert - PhD thesis Papa Ousmane Mangane - PhD thesis Club 3D Meeting 25 th Mars 2010

2 Miocene carbonated reservoir: Campos experimental site Reefal carbonate site (Mallorca) Campos experimental site West Mediterranean map (L. Pomar, 2004) Campos site Lagoon Reef Slope Cap Blanc cliff Lagoon Mallorca island structural geology Reef Slope Multi scalar description of the porosity structure: - karstic intervals identification (size, shape, connectivity ) - fine characterization of macropore structure (moldic, vuggy), micropore (inter- intraparticular) - hydrodynamic y parameters evaluation for fluid displacement prediction

3 Focus on heterogeneities from µm to 100 m scale Identification of individual pores and porosity quantification from: Cores analyses Thin sections probing Plug measurements RX tomography In-situ borehole data Geophysical measurements and borehole wall images X-Ray tomography volume reconstruction measure porosity distribution More details than with petrophysical micro analysis on core plugs and borehole wall image analysis.

4 Summary For complex carbonated reservoir: Microtomography image analysis by Avizo 6: calibration pore network quantification pore network qualification X-Ray result statistics Multiscale study: integration of X-Ray tomography analysis for different scan resolution scales (CT scans and X-Ray micro-scans) by Avizo 6. range of resolution from 190 to 0.42 µm/pixel

5 Data: low resolution CT scans X-ray computed tomography images resolution : 2 LR full core (100 m long) in 3D (MC10 & MC11) : 190 μm/pixel from CSTJF RX scanner (Pau) 625 µm 190 µm Macro- mesopores and matrix phase quantification 2D CT scan images in MC11 well ( m) 3D scans analysis allows better understanding the petrophysical variations

6 Data: High resolution scans X-Ray microtomography images resolution : 49 HR plugs in 3D (diameter : 2 mm & 9 mm) at scales 5 from ESRF ID19 beam line (Grenoble) μm/pixel µm 0.42 µm MC10 2D porosity variation heterogeneity Ф 5 µm = 10.5 % Ф 0.42 µm = 13.4 % Ф 5 µm = 9.2 % HR MC10_ µm/pix (24.84 m) D = 0.8 mm (ESRF) HR MC10 _ 5 µm/pix (24.83 m) D = 9 mm (ESRF) HR MC10 _ 5 µm/pix (24.83 m) D = 9 mm (ESRF)

7 X-Ray tomography analysis of reservoir properties µm mm scale

8 Calibration of LR X-Ray scan Calibration from real plugs : comparison over 33 plugs linear relation Ф calib = a * mean gray value + b MC10 3D X-ray plug (77.27 m) Plug X-Ray porosity = 20 % Calibrated X-Ray porosity = 38 % The micro-porosity is intrinsec into the matrix due to the CT scans resolution. But the X-ray density is influenced by it. Calibration takes in account the microporosity it in addition to the observed macro- mesoporosity. MC10 Core volume ( m) Macro- microporosity visualization

9 Porosity extraction / quantification (1) Vl VolumeEdit: EditManual let Extraction ti of virtual it plug Plug LabelField: Measure of the volume of pores 1. Estimation of the bulky volume of virtual plugs: Threshold h MaterialStatistics i i 2. Segmentation of fluid and matrix phases: LabelField (threshold) MaterialStatistics Estimation of virtual porosity Ф = (Volume of pore/ Bulky volume of plug) * 100 Only meso and macro porosity is estimated from this virtual method. The micro porosity can be just visualized through dark grey zone and be extracted?

10 Porosity extraction / quantification (2) Labelling: Manual Extraction different porosity origins (moldic / vuggy) qualification 3D dissolved mold reconstitution (in red) 2D core slice (xy view): dissolved mold picked X-ray porosity = 11 % MC10 ( m) 2D core slice (xz view) 2D core slice (yz view) Qualitative method of porosity extraction with a complete information of pore origins BUT long manual work.

11 Reservoir parameters quantification: matrix structure Dolomite proportion calibration Microporosity Dolomite CT core voltex _ 78 m (190 µm/pixel) Microporosity and dolomite visualization linear relation parallel to the Calcite calibration relation Calcite / Dolomite proportions deducted Dolomite / Calcite proportion evaluation

12 Reservoir parameters quantification: well structure Calibrated porosity profile along well (from virtual plugs every 5 cm) Virtual plug sampling Porosity extraction from virtual plugs Calibrated porosity profile from mean gray value extraction per slice (x,y)?? High spatial resolution (value every 625 µm) 3D quantification: Create a high resolution and continuous petrophysical logs

13 Reservoir parameters quantification: phases proportion Material quantification according grayscale histogram (LabelVoxel) 91,16 m - CT core voltex and phase surfaces (190 µm/pixel) Macro- Mesopores 91,23 m - Dolomite Dolomite and macro- mesoporosity structure extraction Dark gray value in matrix range due to microporosity presence. The 3D distribution of the macro- and microporosity gives information about the connectivity of the structure. Comparison of estimated Dolomite volumes with estimated dissolved material.

14 Multiscale analysis from core and plug scans µm scale

15 Resolution influence on 2D porosity Influence of resolution Influence of 2D scan orientation MC10 2D images (61 m): cemented area with no vuggy porosity Resolution effect: visualization of different pore sizes and so variation of the 3D Segmentation: qualitative and quantitative microporosity quantification. method of porosity extraction with a complete information of pore geometry characteristics.

16 Multiscalar phases extraction Volume3D distribution in different samples - 61,7 m Virtual plug and ROI sampling Macro- microporosity distribution Phases labelisation from CT core scan - 62 m Phases surface Reconstruction For each element Virtual plug

17 Multiscalar porosity study Porosity quantification from core to plug X-Ray Core scan Core (half sliced) with real plug X-Ray Core voltex Virtual plug (190 µm/pixel) Plug A Porosity profile from CT scans No microporosity resolution porosity

18 3D porosity extraction: individual labelling LatticeAccess on 4 Go sample 3D median filter 200 MC m (0.42 µm/ /pix) 200 µm µm Thresholding 200 µm Pore separation 200 µm

19 3D porosity extraction: volume reconstruction Extraction of representative pore structure Slice 200 Merged scans with resampling 84 µm Slice 0 Connectivity (blue colour) : propagation through sample volume by incrementing grayscale value of the dark matrix (e.g. matrix with microporosity) MC10 plug _ 61,7 m (0,42 µm/pix) Porosity surface view (blue colour) Skeleton Pore 3D volume distribution MC10 plug _ 61,7 m (0,42 µm/pix) Pore cluster network (colours) in 3D voltex (B&W)

20 Multiscalar phases evaluation 3D cube (125 cm 3 MC m (190 µm/pix) ) 3D plug (15 cm 3 ) CT core scan (2500 cm 3 ) Calibrated porosity from (Ф calib = *mean gray value )

21 First results : First results and perspectives volume reconstruction: qualitative pore network skeleton: meso-micro porosity distribution / connectivity multi scale comparison 190 μm/pixel (LR CT scans) 2.12 μm/pixel 1.06 μm/pixel (HR X-ray scans) 0.42 μm/pixel better correlation with the petrophysical micro analysis on core plugs than with the borehole wall image analysis heterogeneous/homogeneous pore network at different scales Perspectives : HR scans calibration enhancement variogram distribution pore cluster separation others parameters : tortuosity, permeability

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