Structural Styles and Petroleum Potential of Miano Block, Central Indus Basin, Pakistan

Themain purpose of this research article is to evaluate the structural styles andhydrocarbon potential of Miano Block using seismic and well log data. The MianoBlock discovered in 1993 is located in the Central Indus Basin which is a partof an extensional regime exhibiting normal faulting, formed as a result ofsplit of the Indian Plate firstly from Africa and then from Madagascar andSeychelles. Tectonically, the Miano Block lies on the Panno-Aqil graben betweentwo extensive regional highs i.e. Jacobabad-KhairpurHigh and Mari Kandhkot High. Four migrated seismic lines were used for structuralenhancement; P2092-111, P2092-113 and P2092-115 (dip lines) and P2092-110(strike line). Time and depth contours were generated for four horizons,HabibRahi Formation, Sui Main Limestone, Ranikot Formation and Lower Goru Formationwhich showed the presence of horst and graben structures in the subsurface. Theinterpretation of horst and graben structures is based on a parallel set ofNS-oriented high-angle planar normal faults with dips either towards SE or SWwith majority of the faults dipping towards the SW. The faults are observed toexhibit slight disruption of strata with limited displacement to the order ofabout 50 m in Lower Goru Formation. Thus, horst and graben structures with NStrend in the study area are interpreted. The NS trend of these structures alongwith similar structural dip is inconsistent to the NW-SE orientation ofregional structures i.e. Panno- Aqil graben and theJacobabad-Kharipur and Mari-Kandhkot Highs indicating about the presence of asecond minor set of faults and complexity of deformation. In this setting,Maino-02 well was drilled with the primary target as B-Sands of Lower GoruFormation belonging to Lower Cretaceous age while secondary target was A-Sandsof Lower Goru belonging to the same age. The result of the petrophysicalanalysis supports two potential zones (zone 1 and zone 2) within the Lower GoruFormation. Potential reservoir zones were marked with average hydrocarbonsaturation of zone 1 calculated as 63.5% and that of zone 2 as 68.9%.