Dhaka city has been expanding rapidly by urbanization process to meet up the needs for increasing population in

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A sequence stratigraphic analysis was carried out on the sedimentary packages of parts of the Bengal Basin hydrocarbon province. This paper focuses on the identification of petroleum system of Srikail Gas Field within eastern folded belt of Bengal basin using sequence stratigraphic concept. Three strike and five dip seismic lines are used in this work and data analysis is done using Petrel 2015 software. Seismic line-2 (SK-2) of Srikail is good in resolution and is used here only for identifying potential petroleum system. Seven sequence boundaries were identified on the basis of onlap and reflection truncation. The result of the interpreted sequence boundary has revealed that all the elements which are required to generate a potential prospect are present in the study area. Fine grained sediments deposited during the rising and lowering of sea level might act as a potential source rock. Time contour maps of the study area have revealed that the NW-SE trending anticlinal Srikail structure is largely affected by shale filled channel in the crestal and western flank. The channel filled shale is later acting as a seal on north and western part of the structure. Erosional remnants truncated against shale fill canyon is acting as prospective reservoirs in the Srikail gas field. The NW-SE trending anticlinal structure and shale fill canyon help this sand as potential traps for hydrocarbon accumulation. Hence the petroleum system of the study area become very prospective in terms of hydrocarbon accumulation.

The Pourashava area of Manikganj, located in the central part of Bangladesh is treated as arsenic hotspot in the country as the outcome of various studies concludes that almost 80% of the domestic tube wells at this area exceed arsenic level of Bangladesh standard (50 µg/l) for drinking water. To enhance the potable water supply in the area, 15 geoelectric soundings survey using Schlumberger configuration with spreading AB/2 = 300 meters has been executed to decipher the subsurface lithology distribution and aquifers at different depths, to determine the lateral and vertical extent of aquifer at the area. Correlation of the analyzed VES results with primary and secondary borelogs, the subsurface sequence of the area is broadly divided into two geoelectric units. Firstly, the near surface geoelectric unit of resistivity less than 20.0 Ω-m represents the top soil composed of silty clay to clay. The thickness of this layer varies from 1 meter to 5 meters. The second geoelectric unit represents the sand layer and is characterized by a resistivity range of 21.0 to 190.0 Ω-m. This unit encompasses the very fine sand with variable thickness of 2 to 248m while resistivity is from 21.0 to 30.0 Ω-m, very fine to fine sand having thickness from 174-280m and geoelectric value ranges from 31.0 to 40.0 Ω-m, fine sand with resistivity from 44.0 to 50.0 Ω-m, fine to medium sand having resistivity from 51.0 to 70.0 Ω-m, medium sand and medium to coarse sand with resistivity value 75.0 to 110.0 Ω-m, and 140.0 to 190.0 Ω-m, respectively. The ultimate thickness of this unit could not be determined due to limited spread of survey but at least continues to a depth of 300 m. In the context of groundwater storage, the second geoelectric unit acts as the regional aquifer and is used for groundwater development in the Pourashava area for water supply.

Although reservoir characterization has been carried out by many researchers on the sedimentary package of the Bengal basin hydrocarbon province, integration of petrophysical and seismic sequence-based reservoir evaluation is rarely taken into account. This paper focuses on the identification of gas zones, reserve estimation and identification of new prospects in Srikail gas field within the eastern fold belt of Bengal basin integrating four wireline logs and 2D seismic data. Our study finds seven hydrocarbon-bearing zones (A, B, C, D, E, F and G) within the measured depth between 2429.5 and 3501 m. Petrophysical properties of seven hydrocarbon-bearing zones indicate that they are good quality reservoir sands. The gas horizons were mapped on seismic sections which reveal that the NW–SE anticlinal structure is largely affected by channels in the crest and western flank. The channels are infilled by fine-grained sediments which act as cap rock on northern and western parts of the structure. Thus, the anticlinal structure and fine-grained sediments make a potential trap for hydrocarbon accumulation and laterally and vertically well-distributed sequence remnants are the main reservoir rocks in this area. Volumetric reserve estimation of these sands provided a total gas initially in place as 552 billion cubic feet. Moreover, all the four wells are drilled in the southern block of the structure, and since there is a structural continuity from south to the north, it is highly recommended to drill a well up to 3000 m depth in the northern block to test its hydrocarbon potentiality. Overall, the outcomes of this study contribute new insights for reservoir characterization and identification of new prospects in an efficient way.