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Enhance Gravity Inversion Result Using Integration of Time-lapse Surface and Borehole Microgravity
The document discusses enhancing gravity inversion results by integrating time-lapse surface and borehole microgravity surveys, focusing on basic theory, forward and inverse modeling, as well as analysis and conclusions. It emphasizes the importance of joint inversion for improved sensitivity and vertical resolution in determining density contrast distribution. Recommendations are made for applying joint inversion to real data and exploring other inversion methods and models for better optimization.
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Enhance Gravity Inversion Result Using Integration of Time-lapse Surface and Borehole Microgravity
- 1. Enhance Gravity InversionResult Using Integration of Time-lapse Surface and Borehole Microgravity By: Andika Perbawa(1)(2), Wawan G. A. K(3) (1)Medco E&P Indonesia (2) Formerly Geophysical Engineering ITB (3) Geophysical Engineering ITB The Bali 2010 International Geosciences Conference and Exposition, Bali, Indonesia, 19-22 July 2010
- 2. Background BasicTheory Forward Modeling Inverse Modeling Analysis Conclusions Recommendations
- 3. Time-lapse microgravitysurvey Supporting production management, Monitoring fluid movement. Acquisition At least two gravity measurements (Kadir, et. al., 2003). Limitation in vertical resolution. Time-lapse borehole microgravity survey Enhance the signal sensitivity, Sharpen vertical resolution. Inversion Understanding distribution of density contrast.
- 4. Background BasicTheory Forward Modeling Inverse Modeling Analysis Conclusions Recommendations
- 5. (Plouff, 1976) 2 1 2 1 2 1 ,, )log()log(arctan,, i j iijkiiijki ijkk ii k k ijkrqpz yRyxRx RZ yx ZGg rqp 222 kjiijk zyxR kji ijk 111 Where: ∆ρ=(+)
- 6. ∆gmgal mgal 1st measurement 2ndmeasurement = = TLSM TLBM Density contrast t1 t2 ∆t=t2-t1 µgal µgal ∆g
- 7. ρmatrix (gr/cc) ρoil(gr/cc) ρwater (gr/cc) Φ 2.65 0.85 1 27% ρb= (1-Φ) ρmatrix + Φ (So*ρoil+Sw*ρwater) 1st Condition (100% oil) ρb(1) = (100% - 27%)2.65 + 27%(100%*0.85 + 0%*1) ρb(1) = 2.16 gr/cc 2nd Condition (100% water) ρb(2) = (100% - 27%)2.65 + 27%(0%*0.85 + 100%*1) ρb(2) = 2.2 gr/cc ∆ρ=ρb(2)-ρb(1) ∆ρ=2.16-2.2 ∆ρ=0.04 gr/cc (Schön, 1995)
- 8.
- 9. Relationship betweendata and model parameter: Damp least square inversion solution: dGGGm mGd TT 1 dGIGGm TT 12 (Grandis, 2008) m : density contrast G : geometry factor matrix ε : damping factor I : identity matrix d : gravity anomaly
- 10. Background BasicTheory Forward Modeling Inverse Modeling Analysis Conclusions Recommendations
- 11.
- 12. (a)3D view (b)mapview (c)Cross section Body anomaly location (black rectangle)
- 13. Separate into twobodies ∆ρ(-) ∆ρ(+)
- 14. Background BasicTheory Forward Modeling Inverse Modeling Analysis Conclusions Recommendations
- 15. Actual Model TLSMInversion TLBM Inversion Joint Inversion Δρ (gr/cc) Actual model Δρ (gr/cc) TLSM Inversion Δρ (gr/cc) TLBM Inversion Δρ (gr/cc) Joint Inversion
- 16. Actual model Surfaceinversion Borehole inversion Joint inversion
- 17. Actual model Surfaceinversion Borehole inversion Joint inversion
- 18. Actual model Surfaceinversion Borehole inversion Joint inversion
- 19. Actual model Surfaceinversion Borehole inversion Joint inversion
- 20. Background BasicTheory Forward Modeling Inverse Modeling Analysis Conclusions Recommendations
- 21. Δρ (gr/cc) Actual model Joint inversion Boreholeinversion Surface inversion
- 22. -0.04 -0.03 -0.02 -0.01 0 0.01 0.02 0.03 0.04 0 100 200300 400 Density Profile at Layer 1 -0.03 -0.02 -0.01 0 0.01 0.02 0.03 0.04 0 100 200 300 400 Layer 2 -0.03 -0.02 -0.01 0 0.01 0.02 0.03 0.04 0 100 200 300 400 Layer 3 -0.03 -0.02 -0.01 0 0.01 0.02 0.03 0.04 0 100 200 300 400 Layer 4 Layer 4 Origin Layer 4 from surface inversion Layer 4 from All Borehole inversion Layer 4 from Join Inversion Initial model TLSM TLBM Joint (∆ρ) (∆ρ) (∆ρ) (∆ρ)
- 23. Δρ (gr/cc) Actual model Joint inversion Boreholeinversion Surface inversion
- 24. -0.03 -0.02 -0.01 0 0.01 0.02 0.03 0.04 0 100 200300 400 Density Profile at Layer 1 -0.03 -0.02 -0.01 0 0.01 0.02 0.03 0.04 0 100 200 300 400 Layer 2 -0.03 -0.02 -0.01 0 0.01 0.02 0.03 0.04 0 100 200 300 400 Layer 3 -0.03 -0.02 -0.01 0 0.01 0.02 0.03 0.04 0 100 200 300 400 Layer 4 Layer 4 Origin layer 4 from surface inversion Layer 4 from all borehole inversion Layer 4 from join inversion Initial model TLSM TLBM Joint (∆ρ) (∆ρ) (∆ρ) (∆ρ)
- 25. RMS error (gr/cc) surfaceinversion borehole inversion joint inversion 0.010 0.006 0.005
- 26. Background BasicTheory Forward Modeling Inverse Modeling Analysis Conclusions Recommendations
- 27. Time-lapse BoreholeMicrogravity Forward modeling : good vertical resolution. Inverse modeling : increase sensitivity to detect density contrast. Joint inversion shows the best result to determine density contrast distribution.
- 28. Background BasicTheory Forward Modeling Inverse Modeling Analysis Conclusions Recommendations
- 29. Apply jointinversion for real data. Try other inversion methods to optimize the result, Try other models (more complex), Analyze how much optimum boreholes that we need and the distance between them,
- 30.
- 31.
- 32. Detail inversion resultof TLSM
- 33. Inversion using 1borehole Δρ (gr/cc)
- 34. Inversion using 1borehole ±75 meter radius
- 35. Error distribution ofiteration TLSM Inversion Error TLBM Inversion Error Joint Inversion Error
- 36. Resolution :1-20 µgal Gas-oil ± 2 µgal Gas-water ± 5 µgal Oil-water 0.7-3 µgal Accessable casing up to 5½ inch. 14 degree from vertical. (Nabighian, et. al., 2005) Instrument Instrument of boreholegravitymeter. (Goodell, R. R., 1964).
Editor's Notes
- #2 bAss.wr.wb. Good morning ladies and gantleman.. Glad to see u here.. And thanks for coming to attend in my dry run presentation with title “Enhance Gravity Inversion Result Using Integration of Time-lapse Surface and Borehole Microgravity”.
- #3 This is outline that i propose Start from .... And recommendations
- #5 This is outline that i propose Start from .... And recommendations
- #6 Gravity attraction in vertical direction caused of prismatic body in subsurface shown as equation fom plouff, 1976......
- #9 This is the schematic TLBM anomaly. Actualy, what is time-lapse microgravity anomaly? TLM is like this... There are 2 measurement in certain time interval... And we measure the differences gravity anomaly from a both of measurement. This is the final condition (2nd measurement) This is the initial condition (1st measurement) Then this is the density differences (density contrast) The density contrast thats we call body gravity anomaly... Then this is the TLBM response in borehole.
- #10 To understand about contrast density distribution in our body, we hate to invert gravity anomaly by using inversion step. In this paper i use damp least square inversion method.
- #11 This is outline that i propose Start from .... And recommendations
- #12 This is a model that i create... This model looks like anticline with 4 way dip structure. From 4 ways there are injection activity represented by red colour (positive anomaly) While in the crest of anticline there is production activities that represented by blue colour (negative anomaly) Injection produce positive anomaly because it increasing density of pore fluid reservoir. From original oil replaced by water which is higher density. Production produce negative anomaly because it decreasing density of pore fluid reservoir. From more oil to less oil which is makes density decrease.
- #13 This is the forward modeling of TLSM. Usually, The gravity anomaly distribusion of TLSM is quite similar with distribusion of contrast density. But, in this model is different. Why? It could be caused by small geometry of body. My body is around 0.12 KM square. Is too small for being the field. Then this is the challenge for geophysicist if we get the problem like this. The important thing in this picture is i cannot measure the accuracy in vertical direction. We just know the distribution in lateral direction. So, to handle this problem TLBM can answer that.
- #15 This is outline that i propose Start from .... And recommendations
- #21 This is outline that i propose Start from .... And recommendations
- #22 This is northing line section of contrast density distribution. Joint inversion gives the best result among them
- #23 Joint inversion have the best fit to initial model than another inversion method
- #24 This is easting-line section of contrast density distribution. Joint inversion gives the best result among them
- #25 Joint inversion have the best fit to initial model than another inversion method
- #26 This is RMS error of density distribution over three inversion method. And joint inversion has the lowest error than TLSM or TLBM.
- #27 This is outline that i propose Start from .... And recommendations
- #29 This is outline that i propose Start from .... And recommendations
- #32 Last sentences i would like to share is. When the man brains is thinking about oil and gas exploration, it simple and cheap if we optimize our production field first, Monitoring is a way to make sure is our injection works well or not... Then, time-lapse microgravity born to answer that. Again, thank you for coming here... And its time for discussion and answer-question time.