Print this pageThermal Modelling and Hydrocarbon Generation History of the Kangra-Mandi Sub-basin of the Himalayan Foreland Basin, Himachal Pradesh, India
Mohan, Chander 1; Mukherjee, Basudev 2;
Verma, Narendra K.3
(1)Frontier Basins-HF Block, ONGC, Dehradun,
India. (2) Bengal-Purnea Basin, ONGC, Kolkata, India. (3) Frontier Basins,
ONGC, Dehradun, India.
A Tectono-stratigraphic model of the Kangra-Mandi sub-basin has
been constructed based on the surface geology , seismic data and well data. An
undisturbed Lambagroan syncline towards hinterland has been considered as
kitchen area, containing approximately ≈8900m(+) thick Tertiary sediments
deposited prior to the upliftment of Upper Siwalik ( 0.22 Ma). To account for
the complex tectonic history of the sub-basin , dating of major episodes of
upliftment and erosion has been integrated with the tectono-stratigraphic
model. Available data of Vitrinite reflectance from Subathu and Dharamsala
Formations have been calibrated to determine the maximum palaeo-temperature in
conjecture with the constructed tectono-stratigraphic model. Different kinetics
models have been tested and corroborated with the field data to arrive at final
kinetic model. Simulation with Variable as well as constant Heat Flow has
brought out similar results satisfying the basic data of Vitrinite reflectance
occurring at respective source beds in the model. The results bring out 21.8°C
/Km. as Palaeo-geothermal gradient which is on the lower side. Simulation with
kinetic model of Pepper & Corvi( 1995) predicts the present petroleum
system at gas generation stage. The source rocks of Subathu and Basal
Dharamsala , on attaining the burial depths in the range 4650m -5250m and
temperature window of 130°C - 140°C, started generating liquid hydrocarbon at
around 16Ma-14Ma(Langhian;Mid.Part of Lower Siwalik) and
14Ma-11Ma(Serravallian;Upp.Part of Lower Siwalik) respectively. Basal Subathu
and basal Lower Dharamsala source rocks are inferred at peak Oil generation
stage at ≈10Ma(Tortonian;Lr.Part of Mid.Siwalik) and 8Ma(Mid.Part of
Mid.Siwalik) respectively at burial depth of 5750m-6125m and temperature range
150°C-160°C with maximum kerogene transformation of 63% and 57% respectively.
Gas generation-Cracking in the sub-basin started at 9Ma and 6Ma(Upp.part of
Mid.Siwalik) at Subathu and basal Dharamsala levels at burial depth of 6500m
and temperature window 160°C-170°C.Total transformation(TR%) of Subathu and
Basal Dharamsala predicted at 0.22Ma are 94% and 86% respectively.
Coevalness of tectonic elements and generation history of the sub- basin indicates likely locales of hydrocarbon charging.
AAPG Search and Discovery Article #90135©2011 AAPG International Conference and Exhibition, Milan, Italy, 23-26 October 2011.