Abstract:
The purpose of this dissertation is to define the subsurface geometry with the
help of seismic techniques in order to evaluate the present hydrocarbon and their reserve
estimation, which has been done by subsurface mapping using seismic data and its
incorporation with the well data. The Jabo Field lies in the Badin South block which is
present in the Lower Indus Basin of Pakistan. Here the stratigraphic sequence ranges
from Middle Jurassic to upper Paleocene. The study have undergone complex tectonic
deformations which can be classified under three major phases 1) Early Cretaceous
(Pre-Chiltan to Sembar) 2) Middle to Late Cretaceous (Basal Sand to Upper Goru) 3)
Post Paleocene (uplifting and doming). The study area is tectonically present in
extensional regime, normal faults forming horst and graben structures are found and it
holds all the major elements of petroleum system verified by a number of oil and gas
discoveries. Horizons marked and mapped were the Kirthar Formation, Ranikot
Formation, B-Sand, Middle Sand and Basal Sand. The shallow Kirthar and Ranikot
Formations were dipping towards East. Seismic lines were interpreted with the aid of
well data and time and depth maps were generated, wells were drilled up to B-Sand
level, but the map for Middle Sand showed presence of a lead which should be drilled
and tested for hydrocarbons. From the interpretation it can be seen that the main faults
are oriented in NW direction. For petrophysical well data from Jabo-05 was primarily
used as Jabo-01 had a flushed borehole and some log readings were not reliable. The
petrophysical analysis was carried out for B-Sand zone only and the results obtained
showed good effective porosity and hydrocarbon saturation. The volumetric analysis
revealed very good recoverable hydrocarbons. Showing that the B-Sand in this area is
an effective hydrocarbon producing reservoir.
