Calibrated Basin Modelling to Understand Hydrocarbon Distribution in Barmer Basin, India

Naidu, Bodapati N.; Kothari, V.; Whiteley, Nicholas J.; Guttormsen, Joel; Burley, Stuart
Subsurface and New Ventures, Cairn India, Gurgaon, India.

The Barmer Basin is a Tertiary intra-cratonic rift basin located in the western part of India with around 6000 m of sediment fill overlying Proterozoic basement. The main period of exploration began in 2000, with seismic being acquired over most of the basin and some 160 exploration and appraisal wells having been drilled to date. In addition, a vast amount of data has been collected on source rocks, oils, heat flow measurements and rock properties in both wells and outcrop sections. This data has been incorporated into a detailed petroleum system analysis.

An integrated approach was adopted for construction of a robust regional basin model which incorporates a set of gross depositional environment maps (GDE) for source (Barmer Hill and Dharvi Dungar), reservoirs (Fatehgarh, Dharvi Dungar and Thumbli) and seals (both intraformational and regional). Uplift/erosion estimates calibrated to apatite fission track and vitrinite reflectance data as well as paleobathymetry were used for burial history reconstruction. A calibrated heat flow model has been applied for building the 1D maturity models across the basin. Paleo-heat flow maps were calibrated to vitrinite and Horner corrected borehole temperature data. A regional pseudo-3D basin model with appropriate thermal scalars was constructed using calibrated 1D models across the basin. For the Barmer Hill Formation source rock specific kerogen kinetics data were used to define the source rock model. Original total organic carbon (TOC) and original hydrogen index (HI) were back computed from laboratory derived Rock-Eval data. The original TOC and HI mapping was governed by source rock GDE maps. The resulting regional pseudo-3D migration model was calibrated to the known discoveries and shows throughout the basin.

Results of the integrated basin modelling confirm the presence of multiple source units in the basin. The Barmer Hill Formation source rock is the main contributor of generated hydrocarbons. Source rock data analysis shows that northern Barmer Basin is enriched with oil prone lacustrine source facies whilst the southern Barmer Basin contains both oil and gas prone facies. The migration model indicates that local sub-grabens are able to charge the adjacent traps and that long distance migration is not required. The 3D basin model has provided critical insights to the spatio-temporal distribution of migrated hydrocarbons and helps predict type and physico-chemical properties of the fluids.

AAPG Search and Discovery Article #90155©2012 AAPG International Conference & Exhibition, Singapore, 16-19 September 2012