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Flamborough Chalk Outcrops DrillItOrDie Plc.. Aims Provide detailed information to allow the distribution of permeability to be evaluated. Define the.

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Presentation on theme: "Flamborough Chalk Outcrops DrillItOrDie Plc.. Aims Provide detailed information to allow the distribution of permeability to be evaluated. Define the."— Presentation transcript:

1 Flamborough Chalk Outcrops DrillItOrDie Plc.

2 Aims Provide detailed information to allow the distribution of permeability to be evaluated. Define the most likely fluid flow model for the outcrop To demonstrate that GetRichQuick will not get rich, quickly or otherwise

3 Methods for data collection Sub-team 1 – jointing Fracture frequency for individual beds Fracture orientations Vertical connectivity of the fracture systems: In plan In section

4 Methods for data collection Sub-team 2 – faulting and fracturing Frequency of faults versus throw Clustering of faults Impact of faults – retard or enhancement of flow Fault timing relationship with joints

5 Jointing

6 Interpretation In section the joints and fractures are spatially dependant on the thickness of the bed Thicker beds have more distance between fractures and lower fracture density The fractures in thicker beds tend to continue through the surrounding thinner beds

7 Vertical connectivity Thinner beds are typically bound by clay rich layers above and below Stylolites present in thick beds and are laterally extensive prohibiting vertical permeability Governed by larger joints through thick and thin beds

8 Stylolites

9 Location 1: Plan view annotation of fractures Bed thickness = 20 cm 1m fault

10 Location 2: Plan view annotation of fractures 1m Bed Thickness = 30 cm

11 Location 3: Plan view annotation of fractures Bed Thickness = 29 cm 1m

12 Rose Diagrams Location 2Location 3 Thicker beds ~ 30cm N N Location 1 Thinner bed ~ 20cm N

13 Location 1Location 2Location 3 Fracture length vs area: 15.6m/m 2 5.9 m/m 2 5.5 m/m 2 No. of fracture junctions: 1301416 Connectivity (no. of connections / fracture length per m 2 ) 8.3 per m2.4 per m2.9 per m Fracture density and connectivity analysis Bed 20cm thickBed 30cm thickBed 29cm thick 1m 2

14 From fracture plan analysis… Near 100% connectivity in all chalk beds 20cm thick units have an 4x greater degree of fracturing as those measuring 30cm Dominant fracture orientation ~125° (+/-10°), sub-parallel to faults Fracture density increases around fault planes

15 Impact on fracture permeability Lateral fluid flow better in thinner chalk beds, but still active in thicker units General preferential orientation to fluid flow in SE-NW direction (fault controlled) Vertical fluid flow determined by fracture permeability of thicker units as smaller fractures (apparent in thin beds) do not translate

16 Implications for Reservoir Model Fracture analysis has shown that fluid flow will be dominantly horizontal in thinner beds which are heavily fractured Degree of vertical flow is controlled by larger joints that propagate through beds of various thickness Fractures and joints play a major role in the permeability of the chalk To maximise production:  Fluid flow will produce a higher yield laterally rather than vertically  Possible horizontal drilling may maximise flow out of reservoir

17 NE Brecciated Zone Releasing Faults. Displaced Limestone Beds. Typical short offset dextral faulting. Releasing Faults. SW 20 cm

18 Short offset faults Radial Fractures Fault bend Clay layer Clay layer thins towards bend from 3cm to 0.5cm Majority of faults contain fault bends and not extensional oversteps (fracture refraction) The beds around the fault bends are highly fractured

19 Longer Offset Fault The effect of larger displacements on a fault plane result here in a thin straight fault zone lined by clay These are likely to be barriers to horizontal flow Clay lining of fault Planed off fault bend

20 Large Offset Fault, example of fault gouge & a damage zone Calcite Precipitation filling highly fractured Damage Zone 2-3m wide gouge zone Damage Zone

21 Fault Morphology Two main fault trends W-E & ENE-WSW The amount of offset determines the likely role of the faults as fluid conduits or barriers. Short offset faults contain highly permeable fault bend zones. This suggests a refraction style of growth, this being the case the position of fault bends is determined by competency of the unit which it propagates through so that:  Clay layers & less competent chalk layers are more likely to result in fault bends concentrating fractures & flow  Thinner layers (more fractures) are less competent and may cause minor fault bends

22 Characteristics of small offset faults

23 Effects of Offset The large offset faults appear are likely to act as barriers unless their damage zones contain open zones i.e vugs that could concentrate flow through the fault gouge, however the extensive damage zone would likely form a barrier to flow over a production timescale Short offset faults increase permeability although there needs to be further research carried out into all the factors that determine clay smear along the faults

24 Incorporation of fault data into a reservoir model Definition of seismic scale faults & there spatial extent will allow for potential compartments to be identified. To maximise production  Drill through sealing compartmentalising faults  Utilise the dominant trend of intra reservoir small scale faults to maximise production

25 Limitations of Flamborough as an Analogue Uplift and erosion may affect the structural features recorded i.e the width of fractures could be significantly less, reducing permeability

26 Conclusions Large joints/fractures and faults determine level of vertical connectivity The majority of permeability is distributed horizontally We believe that the data collected and models proposed give us the best understanding to analysis the suitability of the outcrop as a reservoir


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