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Topic 46: Is it safe to leave the abandoned oil and and gas wells?

Edwin Lawrance's picture

Usually
when the well reaches its economic limit the operator plugs and abandons it.
But the risks and hazards that can happen due to this are neglected. Gas leak
from one of the plugged wells of Elgin gas field shows that abandoned wells can
cause serious threats. With this incident which occurred recently shows that, accidents
can happen even if we have methods to completely seal or plug a well. No human
life was threatened by this accident, but oil and gas leaks from the abandoned
wells can cause serious environmental impacts. Reason for the gas leak in Elgin
field was due to the outdated plugging method used to seal the well by Total.
This gas leak in Elgin would be costing the operator, Total a great deal of
money which was estimated to be around 
GBP 94,0000 a day in lost production. All these unnecessary
expenditure and risk could have been avoided if Total had updated their method
of plugging and abandoning. From this it can be understood that the
things which are consider as of less priority can give a backlash. 

Comments

This blog refers to really important part of oil and gas industries. The abandonment of oil and gas wells is an issue which should be considered as very important aspect of the entire oil and gas exploitation chain, despite that it is one of the final parts. The most significant reason is that the reservoirs cannot be completely depleted during production phase. It is practically impossible to produce all the reservoir fluids, and hence, most of companies decide to abandon the wells when production rate falls below 5%. Some other companies consider even higher production rates as not economically viable any more.
When the abandoned well is located nearby the facilities where there still hydrocarbon production is in process, the hazards are low as there is personnel, who usually monitor the wellhead pressures and generally the conditions are under control. The real problems appear when the abandoned wells are in remote area where the access of people is rare. The practice of the abandonment is not just plugging the well, but filling it with fluid which at offshore facilities is usually sea water. This provides hydrostatic column pressure which is expected to keep the hydrocarbons produced at the bottom of the well. Although, there is high probability, that after some period of time the hydrocarbons’ flow into the well, will create significantly high pressure enabling hydrocarbon's upward direction (kick). A mud could perform better the prevention, but it is too expensive in contrast with no costly sea water at offshore locations.
I think that one possible solution to avoid dangerous circumstances would be the application of geothermal power exploitation systems instead of cementing the wells, which is probably the most effective way to seal a well applied so far. Geothermal applications would involve employees working in these areas, who would provide safety in terms of continuous monitoring and thus avoiding environmental pollution potential of abandoned wells. But in this case there are other aspects that should be taken into consideration.     

Fungisai N Nota's picture

Fungisai Nota BEng(Hons) MIET

Fungisai N Nota's picture

 I do not believe that it is right to leave a abandoned well
no matter   how well you protect it you should always
monitor it and make sure that there are no leaks that will come out from it. Well
there are high risk involved in one abandoning a well that is to the environment
the sea life and its surroundings the company should always carry and take responsibility
to make sure that the hazard is safe to all works of life.  This means the constant monitoring of the
hazard and with doing so then you minimize the risk of the problem   

Fungisai Nota BEng(Hons) MIET

c.ejimuda's picture

Edwin you have pointed out a grave issue that has been neglected in the Oil and gas industry. Operators are more concerned in making profit from the exploitation of oil and gas but, less concerned in the proper management of a depleted reservoir. However, it is important to point out that if a reservoir is depleted, there should be a proper method in sealing and abandoning the well. Recent studies have shown that the estimated hydrocarbon remains from abandoned wells  in the United States is about 2.5 million and about 20 – 30 million globally (Kotler, S. 2011).

Abandoned wells are primarily sealed and plugged with cement. However, the pressure of gases within a completely sealed well will build up over time.  Subsequently, these gases will affect the integrity of the cement plug as a result of the pressure build up.  This leads to a leak.   Some of the problems with an abandon well are as follows:

·         Release of Poisonous Gases to the Environment: As previously mentioned, pressure within a completely sealed well builds up over time and affects the integrity of the cement plug eventually causing a leak.  Poisonous gases from within the well can escape into the environment causing both health and environmental hazards in neighbouring areas.

 ·         The pressure build up can destroy the aquifer.

 ·         Marine habitats are affected as a result of the leak.

 ·         Well explosion: Explosion can occur due to the escape of volatile gases from within the well.  This can occur from leakage due to pressure build up or poorly sealed well.

In my opinion, abandoned wells need to be monitored and inspected periodically. New technology for the prevention of gas leakage need to be devised. Consequently, this will reduce environmental hazards caused by gas leakage.   

 

Reference:

Kotler, S (2011) ‘Abandoned Oil and gas Wells Are Leaking’ ZMagazine, April 1. Woods Hole, MA. [Online]. Available at: http://www.zcommunications.org/abandoned-oil-and-gas-wells-are-leaking-by-steven-kotler [Accessed 26 November 2012]

   

Chukwumaijem M Ejimuda

MSC Safety and Reliability Engineering.

Kelvin Osaro's picture

I just want to support what Chukwumaijem is say by adding that from research and development, it has been observed that abandoning oil and gas well after production can be hazardous to the environment. So, proper safety majors are provided to ensure that the wells are properly sealed. This safety majors are to ensure that properly sealed wells are monitored to avoid leakage of hydrocarbon to the environment [1]. The government should ensure that sufficient resources are available to properly plug abandoned well and also to consider ways of securing funds in order to treat and mitigate this wells. More so, regulators and decision-makers should ensure proper research on well integrity and isolation containment which will help to plan large scale injection projects [1]. A proper area of review (AOR) requirement for each seizure projects should be set up by regulatory bodies and standardized on a federal level instead of state level because liabilities arising from well leakage could be large.      

References
[1] http://sequestration.mit.edu/pdf/GHGT8_Ide.pdf

 

Neil Fraser James Carr's picture

Chuma, I agree with your points entirely, however, I would like to bring an additional perspective into this. Oil has been naturally seeping into our environment for as long as we were aware it exists. Looking at data on natural oil seepage it seems that the world has its own way of dealing with hydrocarbon releases with it being often a natural part of the geological make up of the planet. 

I do however agree that the dangers to our underground water and resources of poorly planned abandonments is serious but I would also like to point out that regulation and advice on well plugging has been in place since the 1970’s and is becoming far more advanced a concern for operators as no one wants profits from the 80’s eroded at 2015 rates of compensation.[1] 

Looking at the offshore installations and wells regulations 1996 it is clear that official guidance on the matter is “goal setting” [4] and is incorporated into the stages of well planning and I personally feel that with the bulk of wells being drilled post 1970’s and exploited to exhaustion the risk of abandoned wells in the north sea causing a serious risk compared with the natural seepage that occurs is very low.  

 

References:

[1]http://www.npc.org/Prudent_Development-Topic_Papers/2-25_Well_Plugging_and_Abandonment_Paper.pdf

[2]http://www.nap.edu/openbook.php?record_id=10388&page=191 

[3]http://www.livescience.com/5422-natural-oil-spills-surprising-amount-seeps-sea.html 

[4] http://www.legislation.gov.uk/uksi/1996/913/regulation/15/made 

c.ejimuda's picture

In my previous post, I wrote mainly on the problems of gas leakage and its consequences on marine habitat, fresh water aquifer and the release of poisonous greenhouse gases to the atmosphere.

I realise that one important problem that will eventually lead to the release of gases from abandoned wells is inadequate plugging and poor cement job.

One key question to ask is “how sealed and secure are abandoned wells? “According to AP report, well abandonment is done mainly with cement and metal plug (Kotler, S. 2011). Studies reveal that no matter the quality of the cement job, after a prolong period of time, the cement will crack and the plug used will fail. Also, if the cement is still intact, the plugging device over a long period of time can fail as a result of corrosion.  This eventually can lead to toxic gases and well fluids being released into the environment. In the United States, EPA study showed that over 17 percent of onshore abandoned wells were improperly plugged (Kotler, S. 2011).


Reference:

Kotler, S (2011) ‘Abandoned Oil and gas Wells Are Leaking’ ZMagazine, April 1. Woods Hole, MA. [Online]. Available at: http://www.zcommunications.org/abandoned-oil-and-gas-wells-are-leaking-b... [Accessed 26 November 2012]


Technology Subgroup of Operations and Environment Task Group 2011[Online]. Available at: http://www.npc.org/Prudent_Development-Topic_Papers/2-25_Well_Plugging_a... [Accessed 26 November 2012] 

 

Chukwumaijem M Ejimuda


MSC Safety and Reliability Engineering.

Neil Fraser James Carr's picture

The evidence points towards a high failure rate in abandoned wells which c.ejimuda stated however with these wells being antiquated abandonments the information is quite negative, modern drilling programmes and well planning and material quality control is of a more accomplished level due to advances to deal with HPHT deep water with specialist tools and equipment available for plugging and testing. It is also worth bearing in mind that wells are more likely to be abandoned appropriately to complete more profitable fields by preventing cross contamination into other production fields. Particular concern for the future should be the abandonement of shale gas resevoirs due to the drilling angles involved.

 

References:[1]http://www.npc.org/Prudent_Development-Topic_Papers/2-25_Well_Plugging_and_Abandonment_Paper.pdf (Accessed 26/11/2012)

[2]http://www.nap.edu/openbook.php?record_id=10388&page=191 (Accessed 26/11/2012)

Michail.Sevasteiadis's picture

As mentioned by my fellow students before, oil/gas well abandonment could hide some dangers related with the sealing of the borehole and there were some suggestions on how we can avoid them. At this point I would like to add some information which I believe that could help us understand better the reasons of a probable abandoned well leakage.

Examining the main characteristics of an oil well we can extract some valuable things in terms of sealing risk. Firstly, if a particular reservoir contains sufficient fluid amount through it, then this could flow to the surface without artificial means. The nature of the reservoir fuel also leads to different behavior and consequences if leaked. A significant factor for corrosion is the resence of sour fluids inside which increase the risk of a failure to happen over the years. Another parameter is the reliability and the expected lifetime of each used wellbore part like the casing, the tubing, etc. As for the cement plug, its integrity over time plays a significant role for a sealed well.

In sum, I believe that all these factors should be taken into account properly in order for the well to be abandoned while reducing the risk of a leakage.


References:
J.R. Nichol, S.N. Kariyawasam. Risk Assessment of Temporarily Abandoned or Shut-in Wells. US Dept of Interior, Minerals Management Service:2000.(http://www.wellintegrity.net/Documents/MMS%20Report%20on%20SI%20Wells.pdf)

t01sik12's picture

Unsealed or improperly sealed wells may threaten public health and safety. Therefore, the proper abandonment (decommissioning)
of a well is a critical final step in its service life. However, it is necessary to point
out that if a well is depleted, there should be a proper method in
sealing and abandoning the well. studies have shown that the
estimated hydrocarbon remains from abandoned wells are high.
Abandoned wells are primarily sealed
and plugged with cement. However, the pressure of gases within a
completely sealed well will build up over a period of time.

The main characteristics of an oil well we can extract some terms of sealing risk. particularly wells which  contains sufficient fluid amount through it, then this could
flow to the surface without artificial means. The nature of the well  also leads to different behavior and consequences if
leaked.
Without those plugs, there is little to prevent powerful leaks from
pushing to the surface, so these wells could be an even greater
environmental threat than wells that have been sealed and classified as
either temporarily or permanently abandoned.

Factors considered must be suitable prior to plugging the well so as to eliminate blow out in the future.

Ref.

1)   http://www.wellintegrity.net/Documents/MMS%20Report%20on%20SI%20Wells.pdf

2)   http://www.msnbc.msn.com/id/42690994/ns/us_news-environment/t/abandoned-...

 

Samuel.Kanu

 

Keqin Chen's picture

 In the decommission stage of the aging oil and gas field, generally the
oil and gas wells should be plugged first before abandoning them. After that,
nearly nothing will be done in most cases.

 

However, abandoned wells were not completely regulated for scant
monitoring and it is definitely not always safe after abandon and huge environmental
dangers and unexpected loss will be caused by this carelessness.  Brine, oil, greenhouse gases may be leaked
from abandoned wells. Aquifers and ecosystems will be damaged seriously. The polycyclic
aromatic hydrocarbons (PAHs) contained in crude oil may be toxic and manifest
years in the future
. [1]

 

Things seem to be worse now. According to the statistics of Florida State University
hydrologist who studies natural oil seeps: When Deepwater Horizon occurred,
they found four different abandoned wells in the same field that were all
leaking.

So satellite-based monitoring system should be established to examine
natural oil seeps in all over the world.

 

References:

 

1.     
 Abandoned Oil and gas Wells Are Leaking

http://www.zcommunications.org/abandoned-oil-and-gas-wells-are-leaking-by-steven-kotler

 

Keqin Chen


Msc of Oil and Gas Engineering

ID:51126368

sreehariprabhu's picture

After the production, most oil producers leave the well abandoned and doen't give much importance for the safe abandoning. Till date there is no known technology for efficiently seal the wells. This leads to many dangers of which the main is the environmental problems. We all know how bad the situation was when the Deep water horizon occured. Millions of barrels of oil leaked into the sea which caused many environmental problems. The sea was polluted and marine life was badly affected. A study shows that when an investigation on deep water horizon was conducted, they found four different wells which were abandoned on the same field were leaking. This shows the method adopted for the abandonment of wells were not safely done.

The method used to seal the well is by applying cement. But the main concern is that, if the cement is not applied properly or due to aging, it can cause shrinking or form cracks, which leads to leak. Other concern is that since most of these wells ar underwater, they may get collided with ships. Eventhough the wells are sealed, there is no monitoring carried out whether to know its leaking or not. If no proper sealing is done, it will lead the wells to leak leading to the release of methane which can lead to explosion.

So it is very important that a good safety method should be found out to cap and seal the wells effectively so that they may not lead to any leaks. Also a good monitoring system must also be applied to make sure the seals work efficiently. This can make the well abandonment safer.

http://www.zcommunications.org/abandoned-oil-and-gas-wells-are-leaking-b...

http://www.npc.org/Prudent_Development-Topic_Papers/2-25_Well_Plugging_a...

Sreehari Ramachandra Prabhu

Siwei Kang's picture

During the past decades, offshore oil and gas developed fast, and got much attention worldwide. However, with the increased aging oil and gas wells, one fact is ignored that abandoned oil and gas wells can be the biggest leakage risk, especially those unplugged effectively. In my opinion, two issues are unsolved.

The first one is that detailed provisions are introduced on how to deal with wells when the production license is expired, but there is no recommandation for wells which are not produced when the license is avaiable. In fact,  because of the high cost of concrete plugging and the convenience to reinstall the BOP, most of companies have chosen to install valves for future re-mining "go backward", instead of concrete plugging.

on the other hand, the proability of leakage in abandoned oil and gas wells still exists. Wells can regain the pressure due to near drilling wells operating or change of subsurface oil and gas layer. Therefore, it is neccessary to find a safer way to deal with the abandoned wells.

To sum up, with the increase of decommissiong offhsore structure, we still have a lot of work to do in the near future. 

Dear all,

 

Although there are advancement in Plug & Abandon process over the years, even a well P&A wells are prone to leakages due to 1. poor cement job 2. well without cement plug (other materials are used) 3. or not even plugged [1]. The issue at hand right now are, the well P&A before 1952 [1].

 

There are no long term visions of these aspect as most operators try to cut cost as the are plugging the well and to its won’t be economic to pour in resources to something that deem un-useful [2].

 

With decommissioning rate of 186 structures / years through to 2023, it is important to address the long term P&A effects to environment. Such recommendation should be made:

  1. To monitor after plugging and abandoning a well and making sure it is plugged with an acceptable leakages. [1]
  2. to design and implement good P&A methodologies. [3]
  3. to have a national regulatory body and fundings in making these wells’ P&A are well design and plugged.

 

Leakages will happened depending on the integrity of the P&A jobs and it will be wise to penalized such operators that are trying to minimize CAPEX. Furthermore, to minimize leakages as low as compare to natural leakage occurrence should be an industrial benchmark. Awareness policy from HSE department should be made as part of operators P&A policies and strictly adhere to it by not exceptions.

 

Regards,

Anas Abd Rahman

 

References:

1. Ide, T., S.J. Friedmann, H. Herzog, "CO2 Leakage through Existing Wells: Current Technology and Regulations," presented at the 8th International Conference on Greenhouse Gas Control Technologies, Trondheim, Norway, June (2006) Available from : http://sequestration.mit.edu/pdf/GHGT8_Ide.pdf

[Accessed on 24 November 2012]

 

2.Technology Subgroup, (2011), Plugging and Abandonment of Oil and Gas Wells, Operations & Environment Task Group, Working Document of the NPC North American Resource Development Study, Paper #2-25, Available from:http://www.npc.org/Prudent_Development-Topic_Papers/2-25_Well_Plugging_and_Abandonment_Paper.pdf

[Accessed on 24 November 2012]

 

 

3. Moritis, G., (2002) Offshore Abandonment: Issues and Practices, Oil & Gas Journal. [Online] July 15, 2002

faizakhatri's picture

Is it safe to leave the abandoned oil and and gas wells? The answer is obvious "no"there is a high risk if we cannot abandon aging  well which can be defined as the probability of a well bore or wellhead leak to the environment multiplied by a measure of its subsequent adverse consequences.multiplied by time  so as time pass reservoir fluid can may seep to surface having an adverse effect on the environment and may incident/accident occurs. Unplugged or poorly abandoned  wells are an environmental hazard as they provide pathways for natural fluid (oil /gas) to seep to the surface and cause fire  health hazard  and by well  plugging and abandonment (P&A),future environmental related  with fluid, contamination with ground water , or gas leakage issues can be avoided, minimized. Properly plugged well  to also prevent contamination of drinking water aquifers which is very important. for those areas where ground water use is important.so there is a need of proper planned P&A for oil and gas wells


Reference:

http://www.wellintegrity.net/Documents/MMS%20Report%20on%20SI%20Wells.pdf


http://www.npc.org/Prudent_Development-Topic_Papers/2-25_Well_Plugging_a...



Faiza khatri 


M.Sc oil and gas engineering

faizakhatri's picture

Is it safe to leave the abandoned oil and and gas wells? The answer is obvious "no"there is a high risk if we cannot abandon aging  well which can be defined as the probability of a well bore or wellhead leak to the environment multiplied by a measure of its subsequent adverse consequences.multiplied by time  so as time pass reservoir fluid can may seep to surface having an adverse effect on the environment and may incident/accident occurs. Unplugged or poorly abandoned  wells are an environmental hazard as they provide pathways for natural fluid (oil /gas) to seep to the surface and cause fire  health hazard  and by well  plugging and abandonment (P&A),future environmental related  with fluid, contamination with ground water , or gas leakage issues can be avoided, minimized. Properly plugged well  to also prevent contamination of drinking water aquifers which is very important. for those areas where ground water use is important.so there is a need of proper planned P&A for oil and gas wells


Reference:

http://www.wellintegrity.net/Documents/MMS%20Report%20on%20SI%20Wells.pdf


http://www.npc.org/Prudent_Development-Topic_Papers/2-25_Well_Plugging_a...



Faiza khatri 


M.Sc oil and gas engineering

Tianchi You's picture

It is obvious that the abandoned oil wells will increase the safety problems' rate if they are neglected. The abandoned oil&gas wells are estimated to be  20millions around the world, which means the potential hazard behind them may result in some unpredicted disasaters. For instance, according to Damascus Citizens for Sustainability, Over the years, numerous cases of methane and fluid migration have occurred near active drilling in proximity to historic fields. As a result, there were some homes exploded, lives were lost and the aquifers have been contaminated.


To sum up, I think there are several problems can be caused by the abandoned oil wells :

  • It can pollute the water supplies
  • If there is no billboard, once someone fell down into the abandoned wells, then it is impossible to climb out by himself.
  • It will become a threat to the wildlife animals
  • The abandoned wells may release the toxic gas which will be harmful to the environment


Reference:


http://www.damascuscitizensforsustainability.org/2012/04/risks-and-riche...


http://www.wisegeek.com/what-is-an-abandoned-well.htm


Regards,


Tianchi You


51233959


Oil&gas engineering

Abdulazeez Bello's picture

It is never safe to abandon wells without proper
mechanism in place to prevent leakages and pollution to the environment. As
crude oil reserve gets depleted most big companies sells of their assets to
smaller ones. One of the challenges encountered by these smaller operators during
well abandonment is the cost and procedure used during drilling operations.
Choices
made during  this process (drilling) can complicate
an abandonment operation and includes the following: the types of fluids left
in each annulus, hole cleaning and cement placement techniques, the type and
amount of cement used during drilling operations, pressures applied to the casing
strings during production operations and obstructions left in the wellbore
during its production life
.
Regulations relating to abandonment are mostly design by the host country
though not always enough and in some cases challenges arise. Companies are normally
held accountable for future leakages. The best way to guide against this occurrence
is putting in place mechanism to monitor abandon wells by owing both the
initial and present operators accountable and procedure used
must
stabilize the wellbore and its associated annuli for an extended period of time
when the geologic forces are able to re-establish the natural barriers that
existed before the well was drilled (kelm, 1999).

Abdulazeez Bello's picture

It is never safe to abandon wells without proper mechanism in place to
prevent leakages and pollution to the environment. As crude oil reserve gets depleted
most big companies sells off their assets to smaller ones. One of the challenges
encountered by these smaller operators during well abandonment is the cost and procedure
used during drilling operations.
Choices made during
 this process (drilling) can complicate
an abandonment operation and includes the following: the types of fluids left
in each annulus, hole cleaning and cement placement techniques, the type and
amount of cement used during drilling operations, pressures applied to the casing
strings during production operations and obstructions left in the wellbore
during its production life
.
Regulations relating to abandonment are mostly design by the host country
though not always enough and in some cases challenges arise. Companies are normally
held accountable for future leakages. The best way to guide against this occurrence
is putting in place mechanism to monitor abandon wells by owing both the
initial and present operators accountable and procedure used
must
stabilize the wellbore and its associated annuli for an extended period of time
when the geologic forces are able to re-establish the natural barriers that
existed before the well was drilled (kelm, 1999).

Reference
Kelm, H.C., Faul, R.R., ‘A “best practices” approach can reduce environmental
risk’, SPE Asia pacific oil and gas conference, Jakarta April 20-22 1999.
Onepetro [Online]. Available at [Accessed on 02 December, 2012]

 

 

charlesggeorge's picture

Some of the reports from The
Federal Environmental Protection Agency shows  that there are about 1.2 million abandoned oil
and gas wells nationwide  in USA and also
 some  200,000 of them may not be appropriately plugged.

Sometimes drilled to depths of a mile or more, oil wells typically tap into
sandy formations permeated with a brine that is up to four times saltier than
sea water and that is laced with radioactivity, heavy metals and other toxins.
The brain solution can flow up to the well shaft and it will leak into the fresh
water aquifers or sometimes reach the surface because of without extensive and
costly plugging of the oil and gas well.

 

ref :http://www.nytimes.com/1992/05/03/us/abandoned-oil-and-gas-wells-become-...

 

Charles George.

Craig Donaldson's picture

It is all well and good improving the plugging and sealing technologies but I think it is of equal importance to begin tracking all wells which have been sealed and thus abandoned. This would be done by way of a national database operated from within the oil and gas industry and not from the taxpayers' pocket. 


After a well has been sealed it should be checked for leaks within a set period say 3 months to ensure its initial integrity and then the well should be checked every 5 - 8 years later for leakage and re sealed when appropriate. Obviously the monitoring rate would depend on how difficult and costly it is to check wells for leakage but I'm sure a regulatory regime could be set up easily after the first few have begun monitoring and the process successfully documented.

Apparently production companies submit their paperwork after abandonment and then forget all about the well. This has to change and can only be done when strong regulation with commitment from government is implemented.

amaka.ikeaka's picture

Oil and gas wells usually undergo
permanent plug and abandonment at the end of their useful life cycle. The
plugging technique involves the use of setting cement to seal off all potential
leak zone points, fresh zone zones and the surface. An improperly abandoned
well cannot only be hazardous to the environment but also to our health and
safety. These abandoned and unplugged wells provide pathways for oil and gas to
contaminate the groundwater supplies or travel up to the surface. Most of the
wells that are posing a threat to the environment were drilled and abandoned in
the past when no regulation were in place to ensure proper cleaning and plugging
of wells when they were no longer in use. Research has shown globally that
about 20-30 million abandoned oil and gas wells exist, unfortunately this
problem has not been given much consideration by the industry and government,
as it has been growing for a while now, ever since the first oil wells were
drilled. Each abandoned well is an environmental accident waiting to happen and
could result in earthquakes, natural erosion, re-pressurization, groundwater
contamination etc. There's need for adequate attention to be paid to this
developing environmental calamity, as it posses a huge threat to our ecosystem.

 

Reference

http://ecohearth.com/eco-zine/green-issues/1609-abandoned-leaking-oil-wells-natural-gas-well-leaks-disaster.html

Azeezat's picture

As my
colleagues have mentioned above. I also agree on the point that it is not safe
to abandon a well offshore except if the operators follow the guidelines for abandonment
process which I know the cost of the abandonment won’t allow the operator to do
so. An abandoned well is a well which has been drilled, later abandoned or
permanently shut down due to  the
integrity of the structures been subject to ageing, not  viable for commercial and engineering reasons
or no longer required for its original purpose thereby  needs to be abandoned. Wells are abandoned
because the wells are no longer needed to support oil and gas development.. Abandonment
of the pipelines has engineering, safety and economic implication.

 

To ensure
the safe and effective abandonment of oil and gas wells, all operators must
follow a process that is defined and regulated by the HSE. The operators are
also responsible for all well-abandonment activities .There are a number of
general steps that are followed as part of the abandonment process

The first
step in Abandonment of a pipeline is to identify the project plan through the
integrity of the structure, then execution and implementation which involves decommissioning,
then the process of purging; cleaning of the pipelines needs to be adopted.

 

Abandonment
of the wells also poses a risk of hydrocarbon leaks as my colleagues have already
mentioned above, to add to this a well leak from an abandoned well can be caused
by many things, including damage during excavation, corrosion and improper
abandonment

The risk associated with an abandoned well is that if the
pipeline is abandoned it will deteriorate and may break up thereby having
impact on personnel and environment.

Reference

http://www.ercb.ca/directives/AbandonedWells_Primer_2012.pdf

http://www.hse.gov.uk/research/othpdf/500-599/oth535.pdf

http://www.ercb.ca/directives/AbandonedWells_Primer_2012.pdf

Savitha Haneef's picture

I agree to the comments that abandoned wells are unsafe.And new policies  and regulations should be made and followed.The worrying part is there are hundreds of thousands of wells which were abandoned before the regulations were put in place.Who is going to monitor them?Un fortunately, most of the nations do not keep a track of their  abandoned wells. And I am sure, we have plenty of leaking abandoned wells now all over the world destructing our eco system.

There is no known technology for properly sealing a well. The most used method is application of cement and cast iron plugs. But a faulty application and ageing of cement and corrosion of iron plugs leads to cracking and hence leaks.Abandoned wells leak oil, brine and greenhouse gases and can alter the ecosystem.Environmental injury is high incase of an oil leakage.The abandoned wells can repressurise leading to leaks as well.Oil & gas regulatory programs should ensure if wells are plugged properly and should be periodically inspected.In theory, abandoned wells can be renetered.But the mechanical difficulty and the high cost of dismantling and plugging the the abandoned wells is very high.So the oil companies overlook the leaks or even a possibility of leaks in their abandoned wells.

 Read more: www.ecohearth.com/eco-zine/green-issues/1609-abadoned-leaking-oil-wells-...

www.hydroquest.com 

 

Savitha Haneef

MSC Safety & Reliability Engineering

RossWinter's picture

As most people have mentioned above the practicality of plugging old wells after use is a complex process. However, especially in the older wells, the planning of how they are going to seal the wells up after use are an after-thought and can prove to be tricky, like in the Elgin field leak. The "offshore installations and wells regs 1996" state if wells are suspended or abandoned then they should be so in a "safe manner ... and there can be no unplanned escape of fluids from it or from the reservoir to which it led." In general these rules are very vague and can be interpreted differently between companies, therefore leading to different levels of safety in the abandonment procedures. 

Ross Winter Msc Renewable Energy

Edwin Lawrance's picture

From the views of all my
dear friends we can understand that abandoning an oil and gas well will cause
safety and environmental risks. To properly seal the well and to create a
monitoring system definitely will cost a lot, so why spend money on something
which is not productive and according to one of my friends comment we have
wells that are abandoned even before the laws came in to action. So what is a
possible solution for all these?

According to the studies
done by the Chinese Academy of Sciences in Guangzhou, there is a way to reuse
these wells. The way is to use them as geothermal power generators. These wells
are usually too deep to tap in to the geothermal energy, because rock
temperatures increase between 25-50 degree celsius for every kilometre of
depth. Here the proposed method is by utilising a pipe within a pipe method,
where water will flow down through one pipe gets heated up and is pumped
through the other one to drive a turbine on the surface. From a single well the
energy produced this way won’t be much but when we consider about the 2.5
million abandoned wells in USA alone, can create a large amount of clean
energy.

Liu Yishan's picture

I agree with Edwin's view about abandoned oil and gas wells. Since it is dangerous and expensive to abandon oil and gas wells, there could be better ways to reuse the abandoned wells. As Edwin said, the way is to use the abandoned wells as geothermal power generators. The power is generated by using hot fluids co-produced from oil and gas reservoirs.
A research by PetroChina studies on the reservoirs in which in-situ combustion technology is being used for enhanced oil recovery by air injection. They take DU84 reservoir in Shuguang oilfield and Ren9 reservoir in Renqiu oilfield for examples. The temperature in oil reservoirs under air injection with in-situ combustion could reach over 400°C for light oil reservoirs and over 600°C for heavy oil reservoirs. The oil reservoirs under such temperature conditions may be transformed as exceptional enhanced geothermal reservoirs (EEGS), compared to the normal EGS systems in Hot Dry Rock (HDR) formations. High temperature and high pressure steam can be obtained for power generation using water injection followed by air injection. The efficiency of power generation using the fluids from in-situ combustion reservoirs will be much higher than that by using hot fluids coproduced from oil and gas reservoirs. At the same time, the crude oil will also be produced by air injection.
Therefore, based on this theory, both the oil and geothermal industries will obtain benefits from the abandoned oil and gas wells.

Reference: Lingyu Zhang etc. Energy from Abandoned Oil and Gas Reservoirs, Society of Petroleum Engineers, 2008

Elle Allswell David's picture

An oil or gas well can be plugged and abandoned if it has been depleted to a point that it’s no longer economically viable or a problem with the well casing that cannot be repaired. 

Plugging and abandonment (P & A) regulations varies among countries. Plugging is done by either using a Mud (drilling fluid), Cement or by Mechanical methods. Technology Subgroup of the

Operations & Environment Task Group (2011) argued that plugging a well correctly helps in avoiding future environmental issues associated with fluids or gas leakage and thereby preserve savings otherwise eroded by remediation or litigation costs. Properly plugged wells will save operators lost production from fields that are candidate for high –technology recovery in the future for example the Elgin-gas field leak incidence in 2011.

When a well is plugged and abandoned it should be properly recorded and documented, this is because the field might still be re-entered in the future with modern technology such as chemical or CO2 flooding which will increase the Pressure in the reservoir which might eventually result in gas or oil migrating upwards from the plugged well as a result of the increase in Reservoir pressure which might result in the contamination of the fresh water aquifer or leakage of gas to the surface.

CONCLUSION: It is not save to  abandon a plugged oil or gas well but the operator of the field should send environmentalists from time to time to measure the gas content of the air within the vicinity of the field to determine if there is a leakage of natural gas or oil from the plugged well. In the case where a marginal field will be sold to smaller companies provision should be made in the contractual agreement on how the abandonment will finally be carried.

REFERENCES

Paper #2-25

PLUGGING AND ABANDONMENT OF OIL AND GAS WELLS

Prepared by the Technology Subgroup of the Operations & Environment Task Group

Available on: http://www.npc.org/Prudent_Development-Topic_Papers/2-25_Well_Plugging_a...

Felipe.Santana.Lima's picture

 

Production wells are man-made systems and as such will never be 100% safe, even after the end of their operational life time. This is a fact.

Finding alternatives to plugging and abandoning it is a valid exercise and if attractive options are envisaged obviously they obviously should be pursued. But by giving these wells a “posthumous mission”, are we really reducing the associated HSE risks? Would we solve the safety problem by transforming a production well into a geothermal system? Surely not, and likely the risks of an operative geothermal subsea system would be higher than those of a plugged subsea well.

I think this leads us to the economic and legal framework. The first question to be made is: is there any way of creating value with this or that well after producing oil or gas is no longer economically viable? If yes, the next question is whether the safety level of the new economic activity is acceptable. If the answer to the first or the second question is no, it probably means it needs to be plugged and abandoned anyway. Then there needs to be a legal framework that does not dictate exactly how the operator is to plug it, but one that gives full responsibility to the operator for engineering the safest practicable solution and holds them permanently accountable for any failure, at any time, and for all consequences of their solution.

 

Kyeyune Joseph's picture

Abandoned oil and gas wells are wells that have permanently ceased to serve their original purpose. If not plugged, these wells can act as sources of environmental pollution in the oil and gas industry mainly threatening the safety of underground sources of drinking water (USDW). Contamination usually comes from hydrocarbons, carbon dioxide, formation water or injected fluids such as polymers used to enhance oil recovery. It is worth to note that a large number of wells are abandoned not because they are depleted but because they are uneconomical to operate due to low product prices and environmental compliance cost [1]. The latter is more likely. These wells can serve as sources of contaminants into USDW. This is mainly through two ways: (1) Wells serving as conduits for migration of reservoir fluids and gases like carbon dioxide into USDW. (2) Water from highly saline aquifers migrating into fresh water aquifers. Surface pollution is also possible with abandoned wells.

Thus, it is not safe to leave abandoned oil and gas wells. Plugging prior to abandonment is necessary to avert environmental issues and can be done by: (1) isolating hydrocarbon bearing intervals (2) isolating over pressurised intervals (3) isolating fresh water sources (4) surface isolation. All such isolations are done by use of cement barriers in place that can remain intact for some time to finally allow natural balance that existed before the well was drilled to occur. Plugging process is based on type of fluids contained in the reservoir and mechanical condition of the well prior to abandonment [2]. These will determine type of cement, formulations as well as other interventions necessary to ensure effectiveness of the process. Plugging process is driven by cost and regulations thus some operators have not prioritised it and see it as a sunk cost. This is to the detriment of the environment!

References:
[1] Thomas, K.T. 2001, "Produce or Plug? A Summary of Idle and Orphan Well Statistics and Regulatory Approaches", SPE/EPA/DOE Exploration and Production Environmental Conference. Society of Petroleum Engineers, San Antonio, Texas, 26-28 February 2001.SPE 68695, available at onepetro.
[2] Kelm, C.H. & Faul, R.R. 1999, "Well Abandonment-A ‘’Best Practices” Approach Can Reduce Environmental Risk", SPE Asia Pacific Oil and Gas Conference and Exhibition. Society of Petroleum Engineers, Jakarta, Indonesia, 20-22 April 1999. SPE 54344, available at onepetro.

Harrison Oluwaseyi's picture

A well is abandoned when it
reaches the end of its economic production life with the available technology or
is dried. After abandonment, several procedures are taken to prevent leaks from
the wells. A recent survey in the US shows that in the past two centuries over
12million wells have been drilled, over hundreds of thousands of these wells
were not properly abandoned after their production life. There have been
several concerns about these wells like leaks of oil, gas and brine into
underground table water or migrating to the earth surface, leaks of hydrogen
sulphide, methane gas, pressure build up."In 2008, gas from an abandoned
well leaked into a septic system in Pennsylvania and exploded when someone
tried to light a candle in a bathroom, killing the person".

 Going through different papers and YouTube
videos, I would say that leaving oil and gas wells after reaching the end of their
production life without plugging them or taking the necessary steps to prevent
potential hazards from occurring is an inhumane act. My advice is thus government
and different operator companies should have a record of all drilled and
abandoned wells, the wells should be revisited over time to apply new plugging
techniques and technology available.

REFERENCES

1)http://ecohearth.com/eco-zine/green-issues/1609-abandoned-leaking-oil-we...

2)http://www.post-gazette.com/stories/news/us/danger-in-honeycomb-of-old-w...

3)http://www.andersenenviro.com/oil_well_abandonment.htm

4)http://www.youtube.com/watch?v=ytQ08PawhIY

Azeezat's picture

In view of the above discussion, I will add that if appropriate technology is used it might be safe to abandon well.

Cement plugs are normally used in the open hole section
and various positions in the casing of oil and gas wells to abandon them when
they become dry or uneconomic to produce. The casing is usually cut and
retrieved as deep as possible 

In the North sea, Health and safety Executive
Regulations (HSE) require that all strings of casing are cut 10ft or more below
the seabed, and that all structures above this point should  be recovered. Also any debris lying on the
seabed, within a 70m radius of the drilling location should be removed. Some of
the modern method used for these operations such as hydraulically operated
casing cutting tools are quite expensive and even value more than the recover
wellhead, hence some of the operators use explosive charges to severe the
wellhead below the seabed when the rig as moved off location.

The use of the explosives has some safety issues, such
as the transport, use and storage of explosives are also a concern, especially
offshore.

However, this is now been replaced with modern
technology and use of state of the art tools to carryout safe well abandonment
in compliance with the HSE regulations.

One of such technological innovation is  the use of Down hole Power Unit (DPU-I)  tool developed by Halliburton for the oil and
gas industries as a reliable, non-explosive alternative for setting packers and
plugs on E-Line.

 

References:

(1)Drilling engineering: heriot watt university

 (2)http://www.halliburton.com

Leziga Bakor's picture

In my opinion it is not safe to totally leave the abandoned oil and gas well. You can leave the well but it should be constantly monitored. When wells are abandoned, they are usually plugged. The plugs that are used to plug the wells do not have 100 percent reliability and as such can fail. Also there are factors that can affect the integrity of the plugs and make them fail earlier than expected.  The failure of the plug can occur after a very long time. This is why they have to be properly monitored so that if there is a failure it will be noticed quickly.
When a well is abandoned and production has stopped from the field, there is still the chance of the reservoir pressure to build up again after some time. If this happens, the reservoir fluids will be able to escape through the well and if the plugs used to plug the wells have failed, then it can result in hydrocarbon leakage.  For this reason I will say that wells that are abandoned should not be left but be monitored from time to time so that all changes will be noted.

Bassey Kufre Peter's picture

  A US report had it that there are currently
2.5 million known abandoned oil wells in America
 and an estimated 20-30 million globally[1]. Due
to the fact that there are no known technology for permanently or temporary
securing sealing these tens of millions
of abandoned
 oil and gas wells, leaving an abandoned oil and gas well
becomes an unsafe practice.
This practice is unsafe because of the
following reasons:

1.         Reliability
of Plugging Process:

The traditional method the
well is relatively unreliable due to the fact that the cement use in the
technique can crack or shrink  with
aging. Also if improperly applied the cracking or shrinking factor also comes
into play there by making these abandoned wells threats to the environment.

2.         Environmental contamination:

Due to the threat in
the plugging process discussed in 1 above, a 
crack sealing results in the release of brine or oil or greenhouse gas or sometimes all the three. Brine
and oil release poisons aquifers and the ecosystems .Greenhouse gases are also
release from the  well and these are
toxic gases that can cause damages to lives.

3.         Scant Monitoring:

The oil and gas onshore
and subsea operators and at times the Government  lacks or have an inadequate intervention
mechanism such as “abandoned well inspection team”  saddled with the responsibility of early
detecting leaks from abandoned wells and resealing  so as to prevent further dangers.

On a final note I will
say that the Government or regulators of the oil and gas downstream operations
should seriously enforce the regulation of having “abandoned well inspection team” that will be ”  saddled with the responsibility of early
detecting leaks from abandoned wells and resealing  so as to prevent further dangers.

REFERENCE:

[1].    http://ecohearth.com/eco-zine/green-issues/1609-abandoned-leaking-oil-wells-natural-gas-well-leaks-disaster.html

 Bassey, Kufre Peter
M.Sc-Subsea Engineering-2012/2013
University of Aberdeen.

Kelvin Arazu's picture

An abandoned oil and gas well primarily is a well that was discovered and confirmed not to be economically viable to produce by the operator. Well of this kind is usually abandoned mainly on economic facts.  They issue here as it relates to safety operation would be should the well be plugged? Yes! The reason being that oil and gas reservoir is referred to as a pressure bag for example likes of a balloon filled with air. 

If a wellbore is drilled into the reservoir therefore abandoning the well would be a threat to health and safety, hence hazardous. As there would be probability of the
hydrocarbon seeping to the surface, the possible impact to safety includes:

Water pollution: this will be the case when the hydrocarbon seeps at the surface at the sea bed polluting the water as this would affect aquatic life.

Saturation of light hydrocarbon gases that is C1-C3, as any source of ignition (lighting and others) can cause explosion.

In my own opinion, if an operator must abandon an oil and gas well, the well must be plugged to prevent hydrocarbon seeping to the surface.     

Kevin K. Waweru's picture

The Offshore Installations & Wells (design and construction, etc) Regulations of 1996 apply to most oil and gas activity on the UK Continental Shelf (UKCS). For well suspension and abandonment however, operators adopt a set of guidelines developed by the industry body Oil & Gas UK [1].

Although I am yet to see these guidelines, I expect they offer a consistent approach to this issue and may recommend the depth, intervals and materials to be used for plugging [1]. Water, cement and drilling mud have traditionally been the main ingredients used for plugging.

If an abandoned well were to leak and cause an unwanted environmental pollution incident, legal action could be taken against the well owners exposing them to a significant financial risk. The ensuing compensation and clean-up liability could potentially last a very long time. In addition, I am in agreement with my fellow student colleagues that abandoned wells should be regularly monitored.

1. http://www.oilandgasuk.co.uk/news/news.cfm/newsid/748

Kevin K. Waweru

MSc Oil & Gas Engineering

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