Kachi Onyeagoro, Frans Van der Vlugt, Steve Naruk, Mark Barton & Steve Jolley

Transcription

1 GEOLOGISTS AND RESERVOIR ENGINEERS SHOULD BE FRIENDS!!!! Kachi Onyeagoro, Frans Van der Vlugt, Steve Naruk, Mark Barton & Steve Jolley

2 INTRODUCTION STRUCTURAL AND SIMULATION STRATIGRAPHY AND SIMULATION STRUCTURAL, STRATIGRAPHY AND SIMULATION

3 High NTG Upper Sand (76%) INTRODUCTION GEOLOGISTS ARE ALWAYS HAPPY!!! Well 4 Well 5 Well 5 Low NTG Upper Sand (27%) Well 4 NO HISTORY MATCH!! Well 5 CAN T GET A HISTORY MATCH!!

4 INTRODUCTION RESERVOIR ENGINEERS WHEN HAPPY!!!! Case 1: Fault Tr =1, t = 14 yr RESERVOIR ENGINEERS WHEN UNHAPPY!!!! Case 2: Fault Tr =0, t = 14 yr THEY GET A HISTORY MATCH!! Or PREDICT.

5 DISCOVERY/APPRAISAL INTRODUCTION How we model!! I t s a t a n k o f s a n d! SRM w/ seismic-scale faults. Sheet sands EXPECT TO PRODUCE 15-30MBLS/D FROM MULTIPLE W ELLS 11,000 + Industry standard fault perms Manzocchi, 99; Petrel defaults. Fault Rx Perm (md) G o ug e co m p o sitio n 10,500 10,000 9,5 00 9,0 00 8,5 00 8, /05 /98 07 /24 /98 02 /0 9/ /2 8/ /1 5/0 0 Example typical well performance 1500 psi decline over 6 months 2500 psi decline over 2 yrs

6 11000 INTRODUCTION Field Performance Issues Why Did We Fail? Shell Exploration & Production FTPressure (psig) It s the stratigraphy It s the fault rock properties. It s differential depletion and compaction J- J- M- A- M- J- J- A- S- O- N- D- J- J- M- A- M- J- J- A- S- O- N- D- J- F- M- A- M- J- J- A- S- O- N- D- J- F- M- A- M- J- J- A

7 STRUCTURAL MODELING NIGHTMARES DO HAPPEN!!

8 STRUCTURAL AND SIMULATION Golden rule when modelling structurally complex reservoirs 1 km Ensure structure-seismic and geometrical consistency throughout seismic interpretation & static-dynamic modelling process

9 STRUCTURAL AND SIMULATION Build fault model with structurally validated geometries (seismic display in FAPS, but crossreference to Seisworks also direct link via Openworks). Import to TrapTester, QC and Edit Horizon-Fault Intersection

10 STRUCTURAL AND SIMULATION Importance of realistic fault geometry Static model Seismic domain fault polygons Dynamic model faults backloaded to Static model Geometry in dynamic model is a poor representation of seismic and static model Over 225 simulations runs no history match Huge number of ad hoc edits Even tried increasing permeability of layers increasing by 5 fold

11 STRUCTURAL AND SIMULATION Importance of realistic fault geometry Static model Seismic domain fault polygons Dynamic model faults backloaded to static model Geometry in dynamic model made representative of seismic and static model Only 70 simulations runs to achieve history match No major ad hoc edits required (e.g. no multipliers in reservoir permeability required)

12 STRUCTURAL AND SIMULATION Importance of realistic fault properties TMs calculated based on realistic fault properties (permeability and thickness) Note that large variation in TM along fault plane Variation in TMs realistic unlike when single TM per fault is used

13 STRUCTURAL AND SIMULATION Detailed structural, BHI and attribute analyses shows, additional, subtle faults Subtle faults Smallest resolvable fault block 10 acres Example subtle faults in horizontal well Faults in BHI logs

14 STRUCTURAL AND SIMULATION I m p o r t a n c e o f c o n s iidd e r iinn g m u ltl ti-i p h a s e f lol o w top reservoir no cross-fault flow cross-fault flow A b o v e p e t r o l e u m w a te r c o n ta c t tw o o r m o r e p h a s e s m a y b e p r e s e n t i n p o r e s p a c e Height above free-water level Petroleum saturation in fault zone Relative permeability 1 41 k rp k rw Petroleum saturation in fault zone 1 & 2 Im p o rta n t to ta k e i n t o a c c o u n t r e la t i v e p e r m e a b il i t y, w h i c h v a r i e s a s a f u n c t io n o f p h a s e s a tu r a t i o n ( i. e. h e i g h t a b o v e fre e w a te r le v e l) Capillary entry pressure modeling AT THIS POINT, WE HAVE BEATEN THE STRUCTURAL & FAULT ISSUES TO DEATH!!!!!!

15 STRATIGRAPHY AND SIMULATION PETREL TRADITIONAL CHANNEL MODEL, CHANNELS NOT STACKED IN GEOLOGIC ORDER ENSURE PETREL CHANNELS ARE STACKED IN GEOLOGIC ORDER

16 STRATIGRAPHY AND SIMULATION Sheet/Shoreface sands Use Available data to Distribute the shales

17 STRATIGRAPHY AND SIMULATION Channel sands Meander belt w ell Use Available data to Distribute the shales Show ing m eander belt and eroded holes Meander Belt Base Drape Interbed shales Copyright 2001 SIEP B.V. Channel Base Drape

18 STRATIGRAPHY AND SIMULATION Core Log calibration Channel base drape (blue) Convergent channel margin Channel base drape (blue) Channel base lag (orang e) Channel base lag (orang e) Channel base disconformity (red) Channel base disconformity (red) Channel base drape (blue) Channel base disconformity (red surface) Image log and core work flow for interpreting sub-seismic reservoir architecture P.T ANALYSIS Match 90_90_2 case, Match BU GEOCHEMICAL Europa L Sand: MDGC FINGERPRINTING Star Diagram SI EP B. V. Copyright 2001 K 10 1E Sk in Pi psia k.h Kh9730 md.ft k 139 md S - No Skin Flow 278 ft E - No Flow 285 ft N - No Flow 99.2 ft Boundaries Log-Log plot: dp and dp' [psi] vs dt [hr]

19 STRATIGRAPHY AND SIMULATION Ways to Study and Mitigate - Stratigraphy Focus on the Shale Architecture 1st Order 2nd Order 3rd Order Channel / Inter-channel Architecture Channel Base Drapes Channel Margin Mud Filled Channels Intra-channel Shales Infill Architecture

20 STRATIGRAPHY AND SIMULATION NORTH Turbidite stratigraphic architecture - 1 st order correlation appears layer cake Details from core, dip meter, seismic indicate channels and shale drapes Sheet Channel (ponded) (healed) A- 3 A- 1 ST A- 2O H ST1 A- 2S T BP 1 SOUTH Unit A Unit B Unit C Unit D Copyright 2001 t 2003 SIEP B.V. S IEP B.V.

21 Why Stratigraphic Compartmentalization - channel & Res ervoir p erform a nc e be ha viour Reservoir sweep Reduced recovery Dead ends, pockets of oil only connected via one path to producers/ energy source, bypa ssing M ore edges of reservoir, interaction with gravity Different W ater/ Gas breakthrough Fluid mixing, different flooding speeds through different paths Reservoir pressure Longer/ shorter path -> reservoir pressure distribution chang e STRATIGRAPHY AND SIMULATION Dead ends, pockets of oil only connected via one path to producer (Shale Drapes) Fluid mixing, different flooding speeds through different paths (Degree of Amalgamation) Edges of reservoir, interaction w ith gravity (Sinuosity) CB Drape

22 STRUCTURAL, STRATIGRAPHY AND SIMULATION Combined structural and strat features together account for performance SRM w/ subtle faults. Amalgamated Channels + Sheets Am a l. ch a n ne ls Sh eet (p on ded ) New fault perms function. Yields ~ HM in m ultiple w ells from 1 st principles 10 + Fault Rx Perm (md) logkf= f( Kh,Gouge comp) Simulated Bhp s Manzocchi 99 Copyright SIE 3 PB.V. S IEP B.V Actual Bhp s