Page 30 - Fundamentals of Gas Shale Reservoirs

10 GAS SHALE: GLOBAL SIGNIFICANCE, DISTRIBUTION, AND CHALLENGES

shales, whilst the latter are terrestrial shales prone to Type III 1.5.17.1 Baltic Basin (Lithuania) The Baltic Basin in
kerogen. With the exception of the Cambay Basin shales, all Lithuania has an estimated TRR of 23 Tcf of shale gas, and
of the shales have high clay content. However, the Cambay is associated with the same Silurian age marine shale target
Basin shales are very deep (13,000 ft), only marginally that is attracting attention in Poland, hence has similar char­
mature (Ro 1.1%), and only have moderate organic richness acteristics. However, the shale is less mature within Lithuania
(TOC 3%). That said, they are very thick (500 ft), hence the (Ro 1.2%) but is also at a much shallower depth (6,700 ft, as
GIP concentration is relatively high. opposed to 12,000 ft). There has been no significant explo­
EIA (2011a) noted that as of 2011, there was no previous ration activity in Lithuania to date.
or specific planned shale gas exploration activity, although
the National Oil and Gas Companies have identified the 1.5.17.2 Lublin Basin (Ukraine) The Lublin Basin in
shales in the Cambay Basin as a priority area. Sharma and Ukraine is an extension of the Lublin Basin in Poland, and
Kulkarni (2010) note that there was an accidental shale gas has an estimated TRR of 30 Tcf. The shale characteristics
strike in well DK#30 within the Cambay Basin, in which are similar, although the average TOC is estimated to be
hydraulic fracturing was undertaken and which yielded approximately 2.5% instead of 1.5%. However, all explora­
3
200 m /day. tion interest in this basin to date has focused on Poland, not
the Ukraine.
1.5.15 Pakistan
1.5.17.3 Dnieper-Donets Basin (Ukraine) The Dnieper‐
Pakistan has a moderate estimated TRR of 51 Tcf of shale Donets Basin in central Ukraine has an estimated TRR of
gas, associated with the Southern Indus Basin. The target 12 Tcf. The target shale is relatively thin (100‐ft thick), deep
shale is of marine origin and was deposited in a foreland (13,000 ft), and is within the wet to dry gas window (Ro
basin. Although the net thickness is large (300–450 ft) and 1.3%). There has been no significant shale gas exploration
the clay content is low, the average organic content is only within this basin to date, although there is interest in
moderate (TOC 2%) and the target zones are deep (11,500 Ukrainian shale gas.
and 14,000 ft). The target zones are considered within the
wet gas to dry gas window (Ro 1.15–1.25%).
There is no information regarding any shale gas explora­ 1.5.18 Germany and Surrounding Nations
tion activity in Pakistan. Also, Pakistan’s natural gas produc­ The North Sea‐German Basin extends across northern
tion and consumption are in equilibrium, with growing Germany, Belgium, and the West Netherlands. There is an
proven conventional reserves. estimated TRR of 25 Tcf of shale gas, within three different
prospective shale formations. All of the shales are of marine
1.5.16 Northwest Africa origin and were deposited in a rift basin during the

The nations of Morocco, Algeria, Western Sahara, and Carboniferous, Jurassic, and Cretaceous. The shales are rec­
Mauritania share coverage of the prospective Tindouf Basin, ognized source rocks in the region, but have only recently
which is the most significant basin for shale gas in the region. been identified as having shale gas potential.
It has an estimated TRR of 50 Tcf of shale gas, whilst the All three shales are quite thin, at between 75 and 120 ft,
only other identified basin for shale gas (Tadla Basin) has a and have medium clay content, good organic content, and
TRR of 3 Tcf. maturity within the wet to dry gas window (Ro 1.25–
The target horizon in the Tindouf Basin is associated with 2.5%). The Wealden shale (TRR of 2 Tcf) is the shallowest
a thin zone of “hot shale,” limited to approximately 50‐ft (6,500 ft), whilst the Posidonia and Namurian Shales are
thick, as such the GIP concentration is very low. However, at depths of approximately 10,000 and 12,000 ft,
the shale does have good organic richness (average TOC of respectively.
5%), appropriate clay content, and good maturity. However, ExxonMobil has undertaken considerable shale gas
the limited vertical thickness and formation underpressure exploration in Germany. However, in recent years, there
are likely to be the limiting factor. has been legislative uncertainty surrounding hydraulic frac­
turing, with a temporary ban imposed during 2012, which
has since been lifted (Bloomberg, 2012).
1.5.17 Eastern Europe (Outside of Poland)
Outside of Poland, the shale gas potential of Eastern Europe 1.5.19 The United Kingdom
has not been explored to the same extent. However, there are
three main basins—which may have potential and which The United Kingdom has an estimated TRR of 20 Tcf of
have TRR data—the Baltic Basin in Lithuania, the Lublin shale gas, within the Northern Petroleum System (19 Tcf
Basin, and the Dnieper‐Donets Basins in Ukraine. All three TRR) and the Southern Petroleum System (1 Tcf TRR),
associated prospective shales are of marine origin. both of which are marine‐associated shales deposited in