Deep Water?
In the oil and gas world, the
term deepwater can mean different things depending on the discipline. Geologists
generally define deepwater with regards to the depositional environment (Slatt
2013). In drilling and well construction, water depths greater than 500m is
generally considered as deepwater because the technology requirements above
this depth changes (Cuviller et al. 2000). There have been other
sub-classifications of deepwater referring to deepwater as depths between 500m
and 2000m and Ultra-deep water as depths greater than 2000m.
Deepwater Potential
The potential of deeepwater
reserves has been widely recognised. According to the International Energy
Agency (IEA) (2013), it is believed that deepwater reserves harbour about a
quarter or 300 billion boe of the remaining recoverable conventional oil in
offshore fields. Table 1 shows the ultimate recoverable resources for the major
producing deepwater regions.
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Table 1 Deepwater Resources for Major Producing Deepwater Regions |
Deepwater Reservoirs
Deepwater reservoirs are typically
comprised of loose unconsolidated sands depending on age, depth of burial and
lithology (Ostermeier 1995). Majority of these reservoirs are relatively young
geologically and belong to class of formations known as turbidites (Total
2014). Due to their relatively young geological age, deepwater reservoirs
generally have good porosities and can be prolific hydrocarbon producers. The
nature of deposition of turbidites (Figure 1) results in layers of relatively
uniform sands and hence good permeability (Research Triangle Energy Consortium
2010).
Deepwater Challenges
These deepwater fields can be
challenging in various regards, from the economics to the technological
aspects, to HSE. Some of these challenges are highlighted below.
- They require large investments
- Large volumes of hydrocarbon producing at high rates are required to offset the large investments
- Early sand production due to the poorly consolidated nature of turbidite reservoirs
- Well Intervention is expensive due to high rig costs.
- Reservoir compaction can occur due to the poor consolidation as the reservoir is depleted.
- Observations and data acquisition have to be done remotely.
- The HSE risks are exacerbated due to remoteness from land.
References
CUVILLER, G. et al., 2000. Solving Deepwater Well-Construction
Problems. Oilfield Review
INTERNATIONAL
ENERGY AGENCY, 2013. Resources to Reserves. International Energy Agency.
NILSEN, T. et al., 2007. Atlas of
deep-water outcrops: AAPG Studies in Geology 56.
OSTERMEIER, R.M., 1995. Deepwater Gulf
of Mexico Turbidites - Compaction Effects on Porosity and Permeability.
RESEARCH TRIANGLE ENERGY CONSORTIUM,
2010. Deep water completions urgently need innovation. [online] North Carolina:
Research Triangle Energy Consortium. Available from:
http://rtec-rtp.org/2010/01/25/deep-water-completions-urgently-need-innovation
SLATT, R.M., 2013. Deepwater Deposits
and Reservoirs-Chapter 11. Developments in Petroleum Science, 61, pp. 475-552
TOTAL, 2014. Understanding deepwater
reservoirs. [online] Paris, France: Total. Available from:
http://www.total.com/en/energies-expertise/oil-gas/exploration-production/strategic-sectors/deep-offshore/expertise/understanding-deepwater-reservoirs
Thank you very much Engr Bolomope. So which of d challenges do u consider major and which still has not been resolved. Plus, what solution would you propose to such a challenge?
ReplyDeleteThank you Tomilayo for your comment.
DeleteIn answering your question, I will highlight some of the major challenges but I will do so at a high level. Please note that this does not represent a hierarchy of importance as the specifics of each project should determine the most important challenge.
First, the high costs of deepwater projects can be a huge barrier especially in tough economic climates as we have today. Deepwater projects can run in excess of $5 billion. Advancement in technology and good project management can help to reduce this cost. Drilling costs for example can account for over 60% of CAPEX. Finding safe ways to reduce drilling costs can reduce total cost.
Secondly, the risk attached to exploration uncertainty is higher due to higher investments being at stake.
Another is the technological challenge. Many of these projects will require the application of new technologies in some aspects of the development. It is also common for these fields to be High Pressure and High Temperature (HPHT) fields. These projects also usually involve high complex processes.
Safety is another big issue. The Macondo disaster is a good example of the importance of safety. As seen with BP, the impact of such accidents can lead to large financial losses to the business. BP has been fined well over $50 billion for the Macondo incident.
Other important challenges include Logistics, lack of infrastructure, government regulations, etc.
I hope this was helpful.
reservoirsignals.com
ReplyDeleteHere's a comment from Facebook
ReplyDeleteDeep-water development challenges: Most importantly, relatively low probability of success of confirming a discovery.
Here's my reply on Facebook
DeleteMukhtar Afodun Thank you for your comment.
First, I used the term 'Deepwater' as opposed to 'Deep-water' cus it's preferentially used in the industry even though it may not be grammatically correct.
Secondly, I don't exactly understand what you mean by "probability of success of CONFIRMING a discovery" but i guess you imply exploration uncertainty. You are correct to say that this is a major challenge in Deepwater Developments because there's a lot of potential investment at stake. Whether this is the most important part of the development process will only lead us back to the classical argument about whose job is the most important. Geologist? Reservoir Engineers? Drilling Engrs? etc. I don't think that argument will ever end. It is safe to say that all aspects are important and can be critical to the success of the project.
Thanks again for the comment.