Abstract: The United States is now energy self-sufficient due to the production of shale oil reserves. With more than half of it being tapped daily in the United States, these unconventional reserves are massive and provide immense potential for future energy demands. Drilling horizontal wells and fracking are the primary methods for developing these reserves. Regrettably, recovery efficiency is rarely greater than 10%. Gas injection enhanced oil recovery offers a significant benefit in optimizing recovery of shale oil. This could be either through huff and puff, gas flooding, and cyclic gas injection. Methane, nitrogen, and carbon (IV) oxide, among other high-pressure gases, can be injected. Operators use Darcy's law to assess a reservoir's productive capacity, but they are unaware that the law may not apply to shale oil reserves. This is due to the fact that, unlike pressure differences alone, diffusion, concentration, and gas selection all play a role in the flow of gas injected into the wellbore. The reservoir drainage and oil sweep efficiency rates are determined by the transport method. This research evaluates the parameters that influence gas injection transport mechanism. Understanding the process could accelerate recovery by two to three times.
Abstract: The UK has had its fair share of the shale gas
revolutionary waves blowing across the global oil and gas industry at
present. Although, its exploitation is widely agreed to have been
delayed, shale gas was looked upon favorably by the UK Parliament
when they recognized it as genuine energy source and granted
licenses to industry to search and extract the resource. This, although
a significant progress by industry, there yet remains another test the
UK fracking resource must pass in order to render shale gas
extraction feasible – it must be economically extractible and
sustainably so. Developing unconventional resources is much more
expensive and risky, and for shale gas wells, producing in
commercial volumes is conditional upon drilling horizontal wells and
hydraulic fracturing, techniques which increase CAPEX. Meanwhile,
investment in shale gas development projects is sensitive to gas price
and technical and geological risks. Using a Two-Factor Model, the
economics of the Bowland shale wells were analyzed and the
operational conditions under which fracking is profitable in the UK
was characterized. We find that there is a great degree of flexibility
about Opex spending; hence Opex does not pose much threat to the
fracking industry in the UK. However, we discover Bowland shale
gas wells fail to add value at gas price of $8/ Mmbtu. A minimum gas
price of $12/Mmbtu at Opex of no more than $2/ Mcf and no more
than $14.95M Capex are required to create value within the present
petroleum tax regime, in the UK fracking industry.
Abstract: Horizontal wells are proven to be better producers
because they can be extended for a long distance in the pay zone.
Engineers have the technical means to forecast the well productivity
for a given horizontal length. However, experiences have shown that
the actual production rate is often significantly less than that of
forecasted. It is a difficult task, if not impossible to identify the real
reason why a horizontal well is not producing what was forecasted.
Often the source of problem lies in the drilling of horizontal section
such as permeability reduction in the pay zone due to mud invasion
or snaky well patterns created during drilling. Although drillers aim
to drill a constant inclination hole in the pay zone, the more frequent
outcome is a sinusoidal wellbore trajectory. The two factors, which
play an important role in wellbore tortuosity, are the inclination and
side force at bit. A constant inclination horizontal well can only be
drilled if the bit face is maintained perpendicular to longitudinal axis
of bottom hole assembly (BHA) while keeping the side force nil at
the bit. This approach assumes that there exists no formation force at
bit. Hence, an appropriate BHA can be designed if bit side force and
bit tilt are determined accurately. The Artificial Neural Network
(ANN) is superior to existing analytical techniques. In this study, the
neural networks have been employed as a general approximation tool
for estimation of the bit side forces. A number of samples are
analyzed with ANN for parameters of bit side force and the results
are compared with exact analysis. Back Propagation Neural network
(BPN) is used to approximation of bit side forces. Resultant low
relative error value of the test indicates the usability of the BPN in
this area.