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2009 Operations
2009 marked the commencement of the drilling phase of the block’s
exploration programme. There are three play types postulated to be
present in the block: structural (anticlines – northern, central
and southern); stratistructural; and stratigraphic. The D9 joint
venture has initially focused exploration efforts in the north
west corner of the block covering an area of approximately 3,640
km2.
The first exploratory well in the D9 block, KG-D9-A1, was to
evaluate the prospectivity of the Middle and Lower Miocene sands
deposited in the lower slope regime in a distal toe thrust
structural play in the central anticline.
Observations from A1 Well Data
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In the interval 3,235–3,242 m from rotary table (‘RT’) from
the Early Pliocene section, observed resistivity up to 30 ohms
in the pilot hole where no samples could be collected.
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In the interval of 3,500–3,650 m ('RT') of Upper Miocene age,
several thin sandstone and siltstone units having thickness of
1–3 m were encountered with a total gas > 2 per cent with
mostly C1 component. The maximum resistivity of up to 3 ohms
was observed in the interval 3,510–3,515 m RT with total gas
of 1 per cent.
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The first target in the Middle Miocene level encountered
siltstone in the interval 4,160–4,185 m RT and 4,370– 4,500 m
RT with low resistivities and insignificant gas shows.
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The deeper target in the Lower Miocene section encountered
limestone in the interval 4,695–4,710 m
RT contrary to the expected (prognosed) coarse clastic. No
significant gas shows were observed in this interval.
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Inference from A1 Well Results
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In the Upper Miocene, the KG-D9-A1 well encountered several
thin sandstone units with good gas shows (C1 dominant)
suggesting the possibility of a biogenic source. Studies are
being conducted to identify the likely thick reservoir prone
areas based on the detailed sedimentological studies of
KG-D9-A1 well cores and cuttings, and D6 block subsurface
data. These reservoirs are likely to be on the flanks of
anticlines in the mini-basin set up.
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In the Middle Miocene, the KG-D9-A1 well encountered siltstone
with low resistivity and insignificant gas shows. This zone
needs to be thoroughly re-evaluated to identify the probable
reservoir entry directions.
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Tight limestone was encountered in the Lower Miocene level in
the well. The data suggests this limestone package was
transported from the shelf area to the north through a slope
channel system. This will be confirmed by side wall core and
cutting sample analysis data.
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The remaining prospectivity of all the anticlinal closures
(north and central) cannot be ruled out because presence of
effective reservoirs and biogenic source will make them viable
targets.
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The KG-D9-A1 well drilled into the Lower Miocene section did
not penetrate the Cretaceous and Palaeocene sections thus
their prospectivity remains unchanged.
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