General discussions of the systemic, societal and civilisational effects of depletion.
by ROCKMAN » Sun 06 Apr 2014, 18:22:18
Shorty - Your numbers seem to confirm my suspicions. I haven't seen anything about pressure maintenance via reinjecting the NG. Recycling NG production was proven decades ago to be the best way to max URR from such reservoirs. Maybe with so much capex sunk they got cheap. But as you say the proven models would have told them this was the way to go when they tested the discovery wells all those years ago. This is shaping up as one of the worst reservoir engineering f-ups I've ever seen. And I've seen my share. LOL.
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by rockdoc123 » Sun 06 Apr 2014, 22:37:49
seems to be some jumping to conclusions here that aren't warranted from the little bit of information available out there. Karachaganak is gas condensate but it is much more likely that Kashagan is volatile oil based on it's API (around 40) and the fact they have been saying oil rather than condensate in all reports from the companies involved. Volatile oil and Gas condensate behave completely different under reservoir depletion. Pressure maintenance is suggested in both but the end result of lowered pressure is different simply because of the different location of dew point on the solidus curve.
Also I noted from digging around a bit that it isn't corrosion per say that is causing the problem with the pipelines but rather stress corrosion cracking, which is completely different. Stress corrosion cracking is often related to the presence of water and the strength of the steel. Simple corrosion is easy to plan for, stress corrosion cracking less so. You can have stress corrosion cracking occurring in pipe that seems to be completely free of any normal corrosion.
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by shortonoil » Mon 07 Apr 2014, 12:15:56
Rockman said: "This is shaping up as one of the worst reservoir engineering f-ups I've ever seen. And I've seen my share. LOL."Now, don't be too hard on them. When this field was first investigated condensate reservoir modelling was still in its infancy compared to today. I see it like swimming in a vortex, once you get $10 - $20 billion in it, you can't get out!
rockman123 said: Also I noted from digging around a bit that it isn't corrosion per say that is causing the problem with the pipelines but rather stress corrosion cracking,Could be, but the problem with that appraisal is that it seems too simple. Stress cracking is usually associated with martensite production, and any mechanical engineer worth $0.15 per day would see that immediately. Solving that problem is just a matter of changing the material specs for the steel used in the pipe. Considering how much they've got invested in this mud hole they could have lain pipe all the way to the moon - and back, by now. I think Rock has the better take on the problem. With this kind of money at stake, above ground problems are going to get fixed. Below ground, not so easy, especially if you f--k'd up with initial reservoir modeling design.
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by ROCKMAN » Mon 07 Apr 2014, 14:10:51
shorty - “When this field was first investigated condensate reservoir modeling was still in its infancy compared to today." I don't know: when I was working for Amerada Hess about 35 years ago I worked on such a big reservoir in La state waters and they were doing a fine job of re-injecting the NG. Might not have had a good model back then but they knew how so seperate out the liquids and inject the NG.
But doc is right: without the details we're just guessing what’s going on. But given the monies and manpower involved such problems should not have developed IMHO. It’s not as though it were a marginal property and they couldn’t justify hiring the best in the world.
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by shortonoil » Mon 07 Apr 2014, 16:51:13
Rockman saidI don't know: when I was working for Amerada Hess about 35 years ago I worked on such a big reservoir in La state waters and they were doing a fine jobjob of re-injecting the NG.Rock you're talking about the stone age of reservoir simulation. The ECLIPSE 300 reservoir simulator can tell you how many hairs can grow on a barrel of field condensate! The stuff that Schlumberger has put together in the last few years makes ECLIPSE look like ancient history. This technology has come a long, long way in the last 10 years.
If Karachaganak turns out to be a 500,000 b/d field, from an expected 2 mb/d field we are never going to get the details; especially if it can be linked back to something like initially poor reservoir simulation. Kashagan has invested too much political capital into projecting the image that they were to be the next Saudi Arabia. You of anybody should know that in extractive resources you don't count your chickens before they hatch. Those baby chicks are as just as likely to turn out to be Goonie Birds, as chickens. I've seen a lot of outfits over the years spend a lot of money to find out that there was nothing there~
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by rockdoc123 » Tue 08 Apr 2014, 14:33:32
Just to clarify a few things.
As to what the problem is/might be the latest press information is still speaking of the problem being related to pipelines and not downhole casing corrosion/formation damage/phase changes etc.
http://www.reuters.com/article/2014/04/02/oil-kashagan-idUSL5N0MP4G820140402Some snippets worth noting:
$this->bbcode_second_pass_quote('', 'O')il company investigators have yet to announce conclusions about what went wrong at Kashagan in October, when onshore pipes carrying corrosive gases sprang leaks and brought offshore production in the Caspian Sea to a halt a month after start-up.
$this->bbcode_second_pass_quote('', 'I')t has now emerged that sulphur-laden sour gas burped out from the oil field during production last year may have weakened long stretches of processing pipelines, two sources said.
"The problem goes on for kilometre after kilometre, it's a systemic problem," an industry source briefed by Kashagan engineers told Reuters.
That defective stretch of pipeline runs mainly through hard-to-reach swampy terrain, making intervention costly and difficult.
$this->bbcode_second_pass_quote('', 'T')he consortium said only that toxic gas lay behind the problem. "Sulphur stress cracking was identified as the root cause of the pipeline issues," the spokesman said. "This process occurs if steel of high hardness is exposed to high concentrations of H2S (hydrogen sulphide) under high pressure in the presence of water," the spokesman said.
"This mechanism is not at all related to normal corrosion (formation of rust) but solely to the hardness of the steel".
And as to the issue of potential “retrograde condensate” dropout in the field, as I mentioned this is not a gas/condensate pool but rather an undersaturated very light /volatile oil and gas field. There are a number of papers that have alluded to this :
Ybray, D., Galiyeva, G., & Ibragimov, F. (2011, January 1). Raw Gas Injection Principles And Challenges In Kashagan Fields. Offshore Mediterranean Conference.$this->bbcode_second_pass_quote('', 'T')he reservoir fluid is a 43 °API light oil, with a GOR of about 2,850 scf/stb, mostly stored in the first medium. Notably, high sour gas content (16% H2S, 4% CO2) imply relevant HSE challenges for field management.
Albertini, C., Greta, L., Calabrese, M., Bado, L., Francesconi, A., & Tarantini, V. (2013, June 10). Kashagan Field Approaching Production Start-Up: Insight Into Reservoir Characteristics. Society of Petroleum Engineers. doi:10.2118/164831-MS$this->bbcode_second_pass_quote('', 'T')he Kashagan field is a deep, over pressured (initial reservoir pressure: 783 bar), isolated, carbonate build-up with a high-permeability, karstified and fractured rim and relatively low- permeability, stratified, platform interior. The field contains a 43-degree API light oil, with 15% H2S and 5% CO2, and contains more than 100 Tcf of associated gas.
One of the biggest challenges of the Kashagan field development is the management of huge volumes of highly sour associated gas. The consortium had essentially two options to address this challenge:
• A commercially unattractive, but technically not challenging, conventional choice of evacuating the sour gas to shore for treatment (H2S and CO2 removal) and sales; or
• A technically very challenging, but potentially economically beneficial, alternative of injecting the raw sour gas back into the reservoir.
This injection alternative, with its high discharge pressures and sour service, would extend the current capabilities of existing gas compression technologies. Nonetheless, it had the potential to significantly enhance oil recovery, as the
Kashagan oil and injected gas are first contact miscible at pressures well below the initial reservoir pressure. $this->bbcode_second_pass_quote('', 'T')he initial reservoir pressure (Р res init) exceeds the saturation pressure (Рs) by 50 МPа which ensures long-lasting stable production of the field