159 / 2015-08-18 16:21:45

Study on Structural Styles and their Hydrocarbon Potential in Southern Sindh Monocline, Pakistan with the Integration of Seismic and Well Data.

Structural Styles ,Hydrocarbon Potential ,Sindh Monocline,Pakistan

Structural styles evolved in various tectonic settings are extremely important and most prolific in the accumulation of hydrocarbons. Variety of structural styles or broadly interrelated structures are associated with unified mechanism of their formation. The study area is the southern part of Sindh Monocline located in Lower Indus Basin of Pakistan. This area is characterized by extensional tectonic activities which are related to the rifting phases experienced by the Indo-Pakistan plate. Sindh monocline remained under extensive hydrocarbon exploration activities for more than 60 years by numerous indigenous as well as by multinational exploration companies by applying seismic method in order to investigate the subsurface for probable prospective geological structures. More than 100 wells have been discovered on the closure of structural traps but the comprehensive structure of many fields is still confusing and could not be achieved due to poor seismic data in early years and caused the failure of many wells.
This research work presents the study over the structural style and the hydrocarbon potential of Jabo field located with in Southern Sindh Monocline by the integration of 2D/3D seismic and well data. Seismic interpretation reveals that the Jabo structure is located at 8 km southwest of Raj-1 and 18km southwest of Tajedi field. The Seismic interpretation reveals that the structure of Jabo field is normal faults collectively forming horsts and grabens (Fig.1) which have provided basic elements of petroleum system. Grabens play main role for generation of oil into dry gasses and condensates due to deeper burial and higher temperature, oil in horsts remained unaffected and faults are providing migration pathways for hydrocarbons from source to reservoir rocks while the faults also providing the trapping mechanism for hydrocarbons. Wire line log interpretation results show that Turk shale and Badin Shale has source potential shown in composite logs of Jabo. Correlation of various wells of Jabo field showing the presence of effective reservoir (Lower Goru) with interbedded shales (Fig.2). Average porosity ranges from 8-20 % in Upper Sand. Results shows that source rock is associated both with Sembar Formation and Goru Formation. Regional studies shows that 0.6 -1.3% vitrinite reflectance is present in study area (Fig. 3)

Fig.1. Structural cross section along interpreted in PK85-964

Fig.2. Correlation between different wells of Jabo Field over Lower Goru Level.

Fig.3. Composite log with TOC value calculated at 0.9LOM in Jabo- 6