Heat flow analysis of Upper Assam Shelf

1. HEAT FLOW ANALYSIS OF PETROLEUM SYSTEM
IN UPPER ASSAM SHELF
Submitted by:
HEMA SRIVASTAVA
M.Tech (P.EX.)-Final year
2009MT0137
Indian School Of Mines, Dhanbad.

2. INTRODUCTION
The Upper Assam Basin is located in the alluvial covered
foreland shelf zone and contains several oil and gas fields.
Few oil and gas fields are also located in the Naga thrust area
of Assam-Arakan fold belts. Both these units constitute the
part of Assam-Arakan basin fall in northeastern India.
It is the polyhistory basin with distinct episode of tectono-
sedimentary evolution. The dynamic and violent geological
past of this basin is relate to rifting, northward movement,
emergence of passive margin setting and collision of Indian
and Eurasian plates leading to rise Himalayas.

3. Index map of Upper Assam basin

4. Generalized Stratigraphy of Assam shelf

5. Petroleum system
 The essential elements and processes and all
genetically-related hydrocarbons that occur in petroleum
system, and accumulations whose provenance is a single
pod of active source rock
Elements
Source Rock
Migration Route
Reservoir Rock
Seal Rock
Trap
Generation
Migration
Accumulation
Preservation
Processes

6. Heat transfer process
 Heat Conduction is the transfer of thermal energy by
contact according to thermal gradients. It is the primary
process in the lithosphere.
 Heat Convection is thermal energy transported via the
actual movement of a plastic solid or a fluid. It is the
dominant thermal transport mechanism in the liquid
outer core.
 Heat Radiation is thermal transport via electromagnetic
waves. It is not considered important in subsurface heat
flow.

7. Factor affecting the heat flow
Four factors primarily influence the flow of
heat through sedimentary layers and,
ultimately, to the seafloor.
It include the rate and type of sedimentation.
throughout the burial history.
Radiogenic heat production in the sediments.
subsurface fluid flow through sediments.
 crustal properties.

8. The primary objectives of the present study are
given below.
Heat flow calibration for six-wells of upper
Assam shelf using BHT and VRo data.
Thermal maturation of organic matter.
1D petroleum modeling for selected wells in
the study area.
Optimized heat flow for input petroleum
system modeling.

9. Petroleum System Modeling
 Petroleum system modeling is the quantitative
numerical modeling of petroleum system and it involve
the application of commercially available software to
access generation-migration-entrapment of petroleum.
Petroleum system modeling emerged more than 30
years ago with the development of 1D tool for the
numerical simulation of the burial, temperature and
maturity history of source rocks.
As computer capabilities increased the methodology
evolved into increasingly comprehensive 2D and 3D
basin modeling tools, developed primarily for enhancing
the petroleum systems analysis.

10. Data Input
 Log data of 6 wells have been considered from north Assam
shelf. In the present study, logger depth and bottom hole
temperature data were used for heat flow analysis.
 Loading the data including Lithology, HI, T.O.C, Base,
Thickness, B.H.T data, PWD, SWIT, heat flow value.
 conditioning the data i.e. BHT and logger depth data was
collected for petro mod.
 Editing the data.
 Simulating the data from Petromod
Methodology

11. PRESENT STUDY AND ANALYSIS FOR THE WELLS
Input data for 1D- modeling at well no. A1

12. Table: Input boundary conditions, BHT and VRo
values for the well A1
Sl.No.
PWD SWIT * Heat Flow
Age (Ma) (m) Age (Ma) (oC) Age (mW/m2)
1 0.00 0.00 0.00 21.02 0.00 46
2 0.01 5 0.01 20.02 57.00 46
3 0.50 5 0.50 20.02
4 1.80 5 1.80 20.17
5 6.00 10 6.00 20.63
6 12.00 5 12.00 21.23
7 16.00 15 16.00 21.67
8 34.00 10 34.0 23.70
9 37.20 30 37.20 24.00
10 53.00 50 53.00 28.00
11 57.00 10 57.00 28.79

13. Bottom Hole Temperatures:
Sl.No. Depth (m) Corrected Temperature (oC)
1 0 24
2 3500 80
3 3680 91
4 3700 100
5 4100 110
Vitrinite Reflectance
Sl.No. Depth (m) Vitrinite Ref. (%)
1 0 0.2
2 3750 0.42
3 3850 0.46
4 3900 0.49
5 4100 0.50
6 4210 0.51
7 4300 0.53
8 4400 0.53
9 4500 0.55
10 4700 0.56

14. Output for the well A1:
Depth-Temperature diagram
of well A1
Vitrinite reflectance plot of
well A1.

15. Boundary Conditions Of Well A1

16. Source rock maturity of well A1

17. Input data for 1D- modeling at well no. A2

18. Input boundary conditions, BHT and VRo values for the
well A2
Sl.No.
PWD SWIT * Heat Flow
Age (Ma) (m) Age (Ma) (oC) Age (mW/m2)
1 0.00 0.00 0.00 21.02 0.00 39
2 0.02 5 0.01 20.02 57.00 39
3 0.50 5 0.50 20.02
4 1.80 5 1.80 20.17
5 6.00 10 6.00 20.63
6 12.00 5 12.00 21.23
7 16.00 15 16.00 21.67
8 34.00 10 34.0 23.70
9 37.20 30 37.20 24.00
10 53.00 50 53.00 28.00
11 57.00 10 57.00 28.79

19. Bottom hole temperature
Sl.No. Depth (m) Corrected Temperature (oC)
1 3600 80
Sl.No. Depth (m) Vitrinite Ref. (%)
1 4100 0.45
2 4300 0.47
3 43500 0.49
4 4500 0.51
5 4600 0.54
Vitrinite reflectance

20. Output for the well A2

21. Boundary condition of well A2

22. Source rock maturity diagram of well A2.

23. Input data for 1D- modeling at well no. A3

24. Input boundary conditions, BHT and VRo values for
the well A3
Sl.No. PWD SWIT * Heat Flow
Age (Ma) (m) Age (Ma) (oC) Age (mW/m2)
1 0.00 0.00 0.00 21.02 0.00 48
2 0.02 5 0.01 20.02 57.00 48
3 0.50 5 0.50 20.02
4 1.80 5 1.80 20.03
5 6.00 10 6.00 20.46
6 12.00 5 12.00 21.08
7 16.00 15 16.00 21.54
8 34.00 10 34.0 23.59
9 37.20 30 37.20 24.00
10 53.00 50 53.00 24.95
11 57.00 10 57.00 26.10

25. Depth-Temperature plot of well
A3
Depth-Temperature plot of well A3

26. Transformation ratio of well A3.

27. Input data for 1D- modeling at well no. A4

28. Sl.No.
PWD SWIT * Heat Flow
Age (Ma) (m) Age (Ma) (oC) Age (mW/m2)
1 0.00 0.00 0.00 21.02 0.00 42
2 0.02 5 0.01 20.02 57.00 42
3 0.50 5 0.50 20.02
4 1.80 5 1.80 20.03
5 6.00 10 6.00 20.46
6 12.00 5 12.00 21.08
7 16.00 15 16.00 21.54
8 34.00 10 34.0 23.59
9 37.20 30 37.20 24.00
10 53.00 50 53.00 24.95
11 57.00 10 57.00 26.10
Input boundary conditions, BHT and VRo
values for the well A4

29. Sl.No. Depth (m) Vitrinite Ref. (%)
1 3800 .42
2 3900 0.44
3 3950 0.47
4 4100 0.44
5 4200 0.47
6 4300 0.51
7 4400 0.51
8 4500 0.53
9 4800 0.54
Vitrinite Reflectance
Sl.No. Depth (m) Corrected Temperature (oC)
1 0 24
2 3500 80
3 4100 110
Bottom hole temperature

30. Boundary conditions of well A4

31. Depth-Vitrinite reflectance plot
of well A4
Depth-Vitrinite reflectance
plot of well A4

32. Transformation ratio of well A4

33. Input data for 1D- modeling at well no. A5

34. Sl.No.
PWD SWIT * Heat Flow
Age (Ma) (m) Age (Ma) (oC) Age (mW/m2)
1 0.00 0.00 0.00 21.02 0.00 45
2 0.02 5 0.01 20.02 57.00 45
3 0.50 5 0.50 20.02
4 1.80 5 1.80 20.17
5 6.00 10 6.00 20.63
6 12.00 5 12.00 21.23
7 16.00 15 16.00 21.67
8 34.00 10 34.0 23.70
9 37.20 30 37.20 24.00
10 53.00 50 53.00 28.00
11 57.00 10 57.00 28.79
Input boundary conditions, BHT and VRo values for the well A5.

35. Boundary conditions

38. Input data for 1D- modeling at well no. A6

39. Sl.No.
PWD SWIT * Heat Flow
Age
(Ma)
(m) Age
(Ma)
(oC) Age (mW/m
2)
1 0.00 0.00 0.00 21.02 0.00 45
2 0.02 5 0.01 20.02 57.00 45
3 0.50 5 0.50 20.02
4 1.80 5 1.80 20.17
5 6.00 10 6.00 20.63
6 12.00 5 12.00 21.23
7 16.00 15 16.00 21.67
8 34.00 10 34.0 23.70
9 37.20 30 37.20 24.00
10 53.00 50 53.00 28.00
11 57.00 10 57.00 28.79
Input boundary conditions

40. Sl.No. Depth (m) Vitrinite Ref. (%)
1 3800 0.45
2 3900 0.46
3 4300 0.55

42. Burial History diagram (Maturity and Transformation Ratio)

43.  Thermal calibration of present day heat flow regime was made using
observed corrected BHT values from wells. The observed VRo values from
wells were also used to calibrate temperature and thermal history. The
subsurface heat flow was varied (keeping thermal conductivity and other
physical rock properties constant) to achieve best fit with present day BHT.
 The analysis for the six well’s data reveals low maturity of source rocks
and fractional conversion or transformation ratio (TR) are not more than
10%. The heat flow values range from 39 to 48 mW/m2. It is observed that
the early oil generation is seen in some of the wells and the sediments are
immature in the shelf part and likely to be matured for expulsion in the
subthrust part towards Schuppen belt area. 2D and 3D Petroleum system
modeling can be carried out using the above optimized parameters so
estimated for the six wells.