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

Abstract

The main purpose of this research article is to evaluate the structural styles and hydrocarbon potential of Miano Block using seismic and well log data. The Miano Block discovered in 1993 is located in the Central Indus Basin which is a part of an extensional regime exhibiting normal faulting, formed as a result of split of the Indian Plate firstly from Africa and then from Madagascar and Seychelles. Tectonically, the Miano Block lies on the Panno-Aqil graben between two extensive regional highs i.e. Jacobabad-Khairpur High and Mari Kandhkot High. Four migrated seismic lines were used for structural enhancement; 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 Formation which showed the presence of horst and graben structures in the subsurface. The interpretation of horst and graben structures is based on a parallel set of NS-oriented high-angle planar normal faults with dips either towards SE or SW with majority of the faults dipping towards the SW. The faults are observed to exhibit slight disruption of strata with limited displacement to the order of about 50 m in Lower Goru Formation. Thus, horst and graben structures with NS trend in the study area are interpreted. The NS trend of these structures along with similar structural dip is inconsistent to the NW-SE orientation of regional structures i.e. Panno- Aqil graben and the Jacobabad-Kharipur and Mari-Kandhkot Highs indicating about the presence of a second 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 Goru Formation belonging to Lower Cretaceous age while secondary target was A-Sands of Lower Goru belonging to the same age. The result of the petrophysical analysis supports two potential zones (zone 1 and zone 2) within the Lower Goru Formation. Potential reservoir zones were marked with average hydrocarbon saturation of zone 1 calculated as 63.5% and that of zone 2 as 68.9%.