Seismic sequence stratigraphic analysis of lower Goru sands, Miano block, middle Indus basin, Pakistan (T-1477) (MFN 3662)

Abstract

The Miano Field area lies at the eastern periphery of Jacobabad Highof the southern part of the Middle Indus Basin. It is producing gas from sandstone of Cretaceous Lower Goru Formation. To identify and demarcate additional possible hydrocarbon plays within Miano Field (Miano-01, 10 and 07) and the surrounding areas, sequence stratigraphic studies and structural interpretation have been carried out using well logs and 2D seismic lines.The synthesis of sequence stratigraphic studies indicate that the Lower Goru Formation in Miano area consists of four siliclastic of type-1 sequences each comprises late lowstand system tract with aggradational parasequence sets and transgressive system tract having retrogradational parasequence sets, developed on gently dipping slope. The associated high stand system tract and early lowstand system tract are probably deposited in east and west of Miano Field respectively. The schematic depositional model of Lower Goru Formation indicates that under favorable stratigraphic plays, the area east of Miano Gas Field may have substantial amount of hydrocarbons accumulations in late lowstand, high stand and transgressive system tract. Whereas basin floor fans, slope fans and facies of early lowstand system tract may be the potential stratigraphic targets in the west. The structural interpretation from seismic data indicates that the Miano area has experienced rifting and transtensional faulting in Mesozoic and Tertiary, respectively. As a result the present structure style is manifested by normal faults and negative flower structure. The study further indicates that the gas producing sand interval in “B” sequence of Lower Goru Formation represents the basal transgressive sand fed by its own associated source rock, deposited in the form of condensed section. This interpretation is contradictory to previous work of various authors, who associated this sand to incised valley fill, forced regressive wedge and tidal influence sands, charged by the shales of Sembar Formation through fault conduits. As the basal transgressive sands are generally associated with the excellent source rocks of condensed sections, these sand bodies are the prime targets for hydrocarbon exploration.