2. Unconventional
Oil
Crudes form the foundation of Petroleum Industry. They are
extracted from reservoir rocks.
Crude Oil can be classified on the basis of it’s density and ease of
flow.
Heavy Oil refers to crude that is too viscous to flow in pipeline
without dilution.
Conventional Oil are medium to low viscous crudes. They are found
in rocks that have enough permeability to let oil flow to the
wellbore.
3. What is Tight
Oil
Tight oil is a conventional-crude oil that is found within
reservoir with low permeability.
The reservoir rock has low permeability of around 0.1
mD and will not let oil flow easily to the wellbore.
Tight oil is low to medium viscous in nature.
Limestone and Sandstone generally contain tight oil.
They are now being produced because of advanced
technologies like horizontal drilling coupled with multi-
stage fracturing to stimulate flow of oil.
4. How is oil
stored and
released
Oil is stored in pores of rock. These are the empty space in
between the grains of rocks.
For the oil to flow to wellbore, the pores must be
interconnected to allow easy passage of oil. This property of
interconnectedness in rock is called permeability.
From such tight reservoirs, we get crude oil that is light in
nature, that means it is low viscosity fluid.
This makes it uneconomical and difficult to produce
compared to other crudes found.
5. Why Produce
Tight Oil
Tight oil is a smart alternate to already depleting
conventional oil resources.
The oil found in tight reservoirs is of high quality and
requires very little refinement on surface.
Current Tight oil reserves are estimated to multiply the
current production rates highly, if they can be produced
economically and efficiently.
6. The expected
Tight oil Reserve
We consume energy at the rate
of 8918 MTOE per year. At this
rate we will deplete all our
reserve in 40 years. If potential
tight oil reserves are produced,
they will solve this crisis for
years to come.
7. Where to find
Tight Oil Add a map, highlighting the areas where we find reserves.
Comment about the country currently exploiting the resource and
the effect it had.
At present USA has reserves
and the technology to produce
tight oil. This is a map of it’s
reserve.
10. Horizontal
Drilling
This means extending the
wellbore to horizontal
direction, to increase the
wellbore contact area with
reservoir, enabling more oil to
flow directly to wellbore
Once it becomes horizontal, the
horizontal length can extend 3-
4 kms.
11. Hydraulic
Fracturing
Once the wellbore is drilled, we
need permeability
enhancement techniques to
induce inflow of oil. This is
achieved by fracturing the
adjacent rocks in stages
hydraulically using fracture
fluids which are selected to suit
a particular wellbore
12. Hydraulic
Fracturing
One Section is isolated and then fractured hydraulically. Additives
in the fracturing fluid prevent closing of fractures.
First section is then closed and we move on to next section, which
is isolated from rest of wellbore and hydraulically fractured.
This is continued until desired length has been fractured, resulting
in improved permeability
If needed rocks can be fractured again to increase the permeability
when it has gone down with time and usage.
13. Micro Seismic
Micro tremors are used to induce cracks in rock.
They are monitored to ensure correct application using a variety of
techniques.
The real time measurements allow us to shape the fracture to
ensure optimum production
15. Water
Protection
The saline water and other
formation fluid including crude,
that is brought up to surface is
kept isolated from adjoining
shallower water table. The well
is covered in cement and steel
casing to provide total and fail
proof protection against
contamination.
16. Multi Well Pad
We can drill multiple wells from
one hole. This is economically
viable but needs more care to
operate and also has a smaller
footprint on environment.
17. Water
Consumption in
Hydrofracking
The projected total demand for
peak Marcellus Shale activity in the
same area is 8.4 million gallons per
day. This water is basically met
from surface water sources such as
lakes, rivers and municipal
supplies. However, groundwater
can be used to augment surface
water supplies where it is available
in sufficient quantities.
19. Other Effects of
Oil and Gas
Unconventional
Drilling
Due to use of seismic micro waves, many earthquakes in past have
been linked to drilling activities. Earthquakes occur more frequently
in injection wells vicinity.
The land once drilled is rendered useless which can not be used for
various purposes like once it could be.
Accidents like Oil-spill, Flares and Blowouts, harms the environment
in irreparable ways.
Factors like noise and dust add to total harm caused to nature.
Construction and explosion required hampers the soil and may
trigger geologic calamities.
20. Possible
Improvements
and Changes
Instead of using Micro seismic waves to detect the fracture, we can
use sensitive devices that can detect Radioactive substances to
very exact position if it is close enough. We can send RA tracers
along with fracking fluid to tell us the position of fracture and the
path fluid will take after fracture
The land rendered useless after the life of play is over, can be used
as underground CO2 storage facility plant. There can be many
alternative uses in the form of injection or storage wells.
Amount of water used in Hydrofracking is vital, since it comes from
fresh water sources. This water can be avoided by switching over to
GasFrac technique which utilizes propane gel to create fractures.
