Hydrocarbon Prospects of Balochistan Basin Revisited - Delineation of New Horizon for the Discovery of Hydrocarbons in Southwestern Part of Pakistan

Khan, Moin Raza ¹; Hisam, Noushaba ¹; Baitu, Abid Hussain ¹; Zaigham, Nayyer Alam ²
(1) Pakistan petroleum limited, Karachi, Pakistan.
(2) King Abdulaziz University, Jeddah, Saudi Arabia.

During the last five decades, several tectonic models were proposed by various researchers to explain the geologic setting viz-a-viz hydrocarbon potential of southwestern part of Pakistan, the Balochistan Basin, comprising Chagai Volcanic Arc, Kharan-Mashkhel-Panjgur Trough and the Makran Flysch Basin. In 1960s and then in last decade or so, several exploratory wells were drilled focusing particularly in offshore along the coastal areas of Makran accretionary prism. The wells drilled in 1960s were abandoned due to abnormally very high pressures, while those drilled in last decade did not find reservoirs. Simultaneously, most of the researchers proposed an active subduction of the Arabian oceanic plate beneath the Afghan Craton (block of continental landmass). The failure of exploratory drilling on the accretionary wedge in 1960s diverted the attention from further hydrocarbon exploratory activities in the region till late 1990s when exploration activities resumed in the same region, which again despite the drilling of three offshore wells did not yield positive results. However, Kharan-Mashkhel Trough (Forearc basin?) still remains unexplored. This calls for the reassessment of the exploration model for the Balochistan Basin. The results of present research study reveal the conducive environments by delineating the new horizon for the discoveries of hydrocarbons in the region. Based on present integrated geophysical analyses supplemented with detailed geological data, it is identified that the exposed or near-surface geologic trends are camouflaging the deep-seated geologic trends, which are entirely different in their tectonic style and other geologic characteristics. Considerably larger sedimentary basins have been identified in Kharan-Mashkhel-Panjgur region based on the analysis of the satellite gravity anomalies. Moreover, the results of the fault-plane solutions indicate the rifting nature of these basins indicating the possibility of tilted fault block traps. The results of the aeromagnetic and detailed geological data analyses demonstrate the presence of significant geothermal environments, which may have provided sufficient maturity level to relatively younger source rocks. However, the above needs to be confirmed by seismic survey results in Kharan Basin region. By integrating all the above factors, it is inferred that if unraveled appropriately, these basins may be the excellent targets for the hydrocarbon exploration in Pakistan in future.

AAPG Search and Discovery Article #90135©2011 AAPG International Conference and Exhibition, Milan, Italy, 23-26 October 2011.