Structural and Petrophysical Evaluation of Sanghar North Block Using Seismic and Well Data

Abstract

Six scionic lines and a well are used to explore the hydrocarbon potential of Sanghar area, Lower Indus Basin, Sindh by the help of structural and petrophysical analysis. Land Mark Resoures (LMKR) provided 48-fold 2D seismic reflection data by the permission of Directorate General of Petroleum Concession (DGPC). The seismic sections were analyzed structurally to assess the suitable trap. The petrophysical analysis was carried out for the reservoir characterization. The analyses revealed the general style of deformation and the timing of deformation leading to the formation of a trapping facility for hydrocarbons. The petrophysical analysis furnished that the Lower Goru Formation is the main reservoir in the area and having the suitable attributes for a prospect. The area is under the Extensional Tectonic Regime which produced the Normal faulting in the region. Major Horst and Graben structures are formed due to process of rifting. The seismic sections are of lines 0/886-SGR-346, 0/886-SGR-347, O/886-SGR-389, 936-SGR-120, 20017-SNJ-02 and 20017-SNJ-20. The reflectors were marked due to prominent reflection on the seismic sections. Root mean square and interval velocities are used for the calculation of average velocities to convert the given time into depth. The reflector Top Lower Goru is marked due to its prominent reflection on the seismic sections due to data quality. The depths of reflectors are found by using velocities and one-way travel time. For the structural interpretation of the area, time and depth contour maps are generated. Well data of CHAK63 #1 was used to mark the thickness of the individual formations on the geoseismic section. The hydrocarbon potential of CHAK63-01 is calculated by evaluating their petrophysical analysis of the Well logs. Average values of porosity for each productive zone ranges from 18.15 to 20%; average values of water saturation is 31%, and average values of hydrocarbon saturation is 68%. The total reservoir rock volume is calculated to be 1729.7 acres and the total volumetric recoverable gas reserves are 140.3 Billion Cubic Feet (BCF) of CHAK63-01. Whereas new productive zone has 741.31 acres total reservoir rock volume and its total volumetric recoverable gas reserves are 60.13 Billion Cubic Feet (BCF).