Melted Shallow Gas Hydrates Blowing Through Burst Disk Triggered Macondo

It now seems highly probable that the offshore oil and gas industry’s infamous and long feared Gulf of Mexico Gas Hydrates [GH] caused drilling blowout was ultimately the cause of the horrors which occurred at the Block MC252 Macondo well  in the GoM in April 2010. This potential trigger has been well documented in the technical literature for many years, although probably required the compounding sequence of drilling mistakes that happened as BP continually adjusted their threadbare well design “on the hoof”. The incompetence and arrogance of BP has become breathtaking in recent years and this hydrate melt blowout was a direct result of that. Wells have been drilled through frozen gas hydrate formations in the Gulf of Mexico before, and the potential hazards were understood. It would be very surprising if the 1st trial finding arrived at was not gross misconduct and wilful misconduct, but that remains to be seen. This is and will continue to be a highly politicised situation. The question that arises is: Should a technique of cementing together smaller and smaller steel pipes in much the same way as done a century ago on land continue to be used in drilling very deep wells in very deep water in such hazardous geological situations?

A number of individuals, including senior members of the Deepwater Horizon Study Group [DHSG] have believed for some time that there was some sort of “casing breach” higher up in the drillstring. If one reads the events surrounding the workings of the US federal Steven Chu led team when they were “embedded” in the BP Houston office prior to the attempted Top Kill, one can see that there was a strong suspicion/fear that a casing breach or fracture had occurred or that one of the three 16” casing “burst disks” had blown. There is a remarkable first hand witness account held by the DHSG written in the immediate aftermath. Reading that, it is obvious to anyone who has any understanding about what an expanding Gas Hydrate generated methane cloud would consist of and what it would look like spreading across and flooding a drilldeck that this was the trigger. The cold methane cloud was quickly followed by mud being siphoned up the inner drillstring followed by oil as the shoe track at the well bottom was blown to pieces under an immense suction force at reservoir level. The DHSG have produced work of great diligence and fair-mindedness, but for whatever political reasons, have stayed away from the potential hydrate/burst disk scenario, presumably since such a scenario is effectively “unprovable”.

A senior member of the DHSG e-mailed me on the 14th December 2012 in response to a broad outline of my views I supplied to him:

“Thank you for the updates.

I share your observations and conclusions.

The civil litigation trial (Phase 1 – developments to the blowout) is scheduled to resume February 25th. the Phase 2 (post blowout developments) trial is scheduled to start “late summer 2013). 

I do not think that much more of the developments, including the current surveys, will become public until the litigation processes force them to become public.

Thank you again for the insights and www links”

What is remarkable when one considers the geological context is that the words “Gas Hydrate”, “Methane Clathrate”, “Burst Disk” and “Shallow Water Flow” do not appear at all in any of the thousands of 1st trial transcript documents. When one considers where Macondo was drilled and its location in relation to the well known gas hydrate bearing zones in the Gulf of Mexico, this is odd to say the least, or perhaps not so odd.

BP could and should have used “Riserless Drilling” techniques which they helped to develop in the South Caspian sea, where they also had serious blowout problems..This would have allowed better control of the formation fracture pressures and was used by BP in similarly hazardous geological conditions at West Azeri and elsewhere in the South Caspian after an earlier blowout and other problems. This is detailed in a separate post.

The belief in some quarters is that the US Govt. will await judge Carl Barbier’s 1st decision on “Gross Incompetence and Wilful Negligence” after Part 1 and then Part 2 will be all about how much BP pay up, based upon best estimates of oil which flowed. The attempted COREXIT clean up was a disgrace which compounded the original incompetence and this dreadful attempt to “disappear” oil thus reducing future fines is well covered elsewhere.

The truth will out. It is far too important not to be. But we are all just tiny individuals struggling to make sense of a hugely complex event, which is why some parties hope that the complexity and obfuscation can continue.

There is a least now a vast amount of Public Domain information on the subject, and there are a handful of people around who have now figured out what went on. Mr. Dan Zimmerman is the person who first warned of what may happen offshore California, but his work was not listened to in 2009. However obtaining critical documents has been akin to getting blood from a stone. For example, the rather prescriptive Macondo “Shallow Hazards Assessment” report was only made available as a Court Exhibit in April 2013 [TREX-07502], see

Based upon information received and the opinions of a very few independent specialists it is now quite convincing that in addition to the seven major drilling and completions errors, the root geological “geohazard” cause of the blowout was drilling into uncontrolled Gas Hydrates on the shelf edge area. These are frozen gas beds in the seafloor 100’s of metres thick and expand considerably when warmed/melted, or cause pressure build-up if constrained. The situation was compounded by the presence of 6 distinct  Shallow Water Flow [SWF] sand units mapped at well known intervals, the somewhat unusual placing of burst disks in the 16″ casing and some shorter casing strings than planned leading to the GH stability zone and sub-zone being exposed directly to the 16″ uncemented casing. This all has shades of the MARS/URSA drilling problems some years ago (1998-1999), which Shell are of course well aware of. There will be people in a number of oil companies who are well aware of what happened there and there are a few publications on the casing crimping and buckling that led to abandonment.

The melted frozen gas hydrate most likely blew through the lowest Burst Disk (essentially a valve) which was unprotected/uncemented and open to the sand layer, due to the 16″ casing being stopped early about 950 feet shallower than planned. After the pressure reduction in the well caused by the final negative leak off test, he gas blew up through the so-called outer annulus direct to the drill deck. It is unlikely this gas did not come from reservoir level at 18,000 feet. That high velocity gas plume siphoned the oil up through the inner drillstring from depth later on ( a few minutes) and off went the flow for 87 days. The main evidence provided to explain why the blowout flowpath was internal and not via the annulus was the lack of hydrocarbons identified in the annular fluids. However only gas entered the annulus. The oil flowed through the drillstring as erosion inspections of the wellhead showed.

Having the lowest burst disk in the centre of a thick permeable sand layer, unprotected from the outer strata by casing or cement and in a highly likely hydrate depth zone was a huge error, probably not realised by anyone onboard at the time in all the horrible confusion.


If this is the case, and I think the evidence is fairly conclusive, then not only could deep drilling be stopped in GoM beyond a certain water depth, but also in deepwater regions around the world offshore West Africa and elsewhere. This in combination with the almost certain ban on exploration drilling of any sort in environmentally sensitive areas such as Alaska, the Antarctic Basin and elsewhere, will likely lead to a rocketing oil price in the coming years. BP has not come clean and there is possibly a degree of covering up going on. This does a disservice to the rest of the GoM oil industry and that secrecy will lead to problems for the other players when the truth actually does come out.

Bhopal and Exxon Valdez took years to come out and the same may be true here.

Why does it matter that the gas came from much shallower gas hydrate [GH] layers and not reservoir depth? Well, Alaska, amongst others, is a big hydrate area, which has been looked at for GH exploitation as an energy source, as has the Gulf of Mexico and other parts of the world. You can perhaps guess what might be going on here.

The description given on Page 5 of Peter Folger’s US Congressional Research Service document is almost certainly what happened at MC 252:


Solve Climate

Boing Boing

In These Times

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Lord Browne of Cuadrilla

Lord Browne of Cuadrilla

Not content with screwing up the GoM, Browne is now Chairman of Cuadrilla, all set to screw up much of Lancashire.

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BP Did Not Use Riserless Drilling at Macondo

BP Development of Riserless Drilling

Following severe and expensive drilling problems experienced by BP in 2003 at the West Azeri template in the South Caspian, a decision was taken to develop a system of riserless drilling in order to avoid such problems in the future. The company AGR Subsea developed a Tophole Drilling Package names Riserless Mud recovery System [RMR] which enables drilling the tophole section using weighted inhibited drilling mud, leading to improved hole stability, reduced wash outs, improved well control both with regard to shallow gas and shallow water flows [SWF].

A field trial was conducted in December 2004 following the establishment of a Joint Industry Project [JIP] was established funded by the Norwegian Research Council, Statoil-Hydro and AGR in order to qualify the RMR technology for use in up to 450 m water depths.

The RMR system was used on 15 wells at the BP West Azeri problem site (see previous) and in Deepwater Gunashli and Shah Deniz in the South Caspian. By mid-2007,  28 wells had been drilled on BP projects in the South Caspian using this technique, as well as at Sakhalin offshore Russia, specifically to avoid potential problems related to geohazards. By 2007, Shell E&P and the BP America Production Company had joined the original Demo 2000 JIP, with the specific aim to “develop, manufacture and perform a field trial of an RMR system for use in 5000 ft. of water depth in the GOM”.

Subsequently a large-scale field trial was conducted from a deepwater semisubmersible offshore Sabah, Malaysia, in September 2008. A joint industry group comprising AGR Subsea, BP America, Shell and the Norwegian Research DEMO 2000 [the original RMR JIP] program and supported by Petronas undertook this work. This group set out to advance subsea mud return technology from its established commercial market of shallow-water applications, 1,800 ft (549 m) or less, to deepwater depths and drilling requirements. Novel equipment and deployment methods were designed, developed, delivered, tested and proven to a demanding schedule.

The shallow water (< 450 m) version of RMR has been used commercially since 2003 on more than 100 wells worldwide. Statoil was the first operator in the GoM to adopt the RMR system, which has been used on the Discoverer Americas drill ship on the Statoil-operated Krakatoa prospect. The RMR system allows the circulation of mud, reducing the total consumption and discharges to sea to a quarter of the amount compared with conventional methods. The cost of mud and the transportation to the drill ship are significantly reduced and technology allows deeper drilling depths for shallow casing strings, again reducing the overall drilling time per well. Minimising the number of casing strings in deepwater drilling where you may run out of options.

Statoil currently has two drilling units in operation in the Gulf of Mexico. RMR technology has successfully been used by Statoil on the Norwegian Continental Shelf in 19 operations over the past years. As a partner with BP in the South Caspian and with BP America a partner in the successful development of the RMR technique, the question must be asked as to why it has not been adopted in the GoM by BP in general and at Macondo specifically, in view of the known severe potential geohazard related drilling problems that might be encountered at location, specifically related to shallow water flows , a weak unstable formation and gas hydrates, all common to the South Caspian.

 If the RMR system was not considered to be available or suitable for use at Macondo, for whatever reason, when it was used extensively by BP in the South Caspian and at Sakhalin then it is arguable that the Macondo well should not have been drilled where and when it was, using the outdated riskier conventional technique of cementing casing strings with a long riser. Could it be that BP in Houston were not fully aware of the RMR developments or rejected its use on cost grounds or as an “unknown step-out for the GoM”? BP are generally not as innovative as Statoil.

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Tony Hayward – Libya and Iraq Involvment

Two recent articles (20th September) by Tom Bawden of the UK Independent Newspaper on oil exploration in Libya and northern Iraq involving the newly formed Vallares investment vehicle, headed up by Tony Hayward, Nathaniel Rotchschild, ex-Goldman Sachs CEO Julian Metherill and mining metals and coal financier Tom Daniel are interesting in the context of events in recent years in those countries and as a piece of information to consider when wondering if the wars were partly aimed at preserving “Western” access to massive oil and gas reserves. However, how many people when reading of this feel a sense of disgust and revulsion that the former CEO of BP, having presided over the worst environmental disaster caused by mankind in the history of this planet should find it appropriate to be doing business in those countries. Presumably Mr Hayward has happily got some sort of a life back and he and his “managers” in BP felt that Macondo was just not really their fault at all, which could well be the case as they may have had no real idea of what was being done in their name and their shareholders names by the poor handful of overwhelmed BP employed individuals on the Deepwater Horizon and in offices in Houston for a few days during April 2010. Hopefully the new governments in Libya and Iraq will be able to judge the value of his and others involvement accordingly, coming so soon as it does after the hard fight to succeed in developing these fledgling democracies, at great cost in money and lives. This man’s conscience must be in shutdown, if indeed he ever had one.

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Macondo – Gas Hydrates, Shallow Water Flows and Burst Disks

Ignore the geology at your peril. As news comes through of probable seabed seepages of oil being observed again at Macondo, the only question will be whether or not these are reactivated “residual” seeps or the nightmare scenario of new flow paths through the shallow strata. Whichever it is, the latest events are clear evidence that the Macondo well casing was breached, a belief held by several commentators in the past.

Macondo MC 252 is in an area of well known severe geological hazards, including gas hydrates and weak shallow (< 5,000 ft) artesian pressurised sand layers which can cause casing distortion and even buckling collapse, high inflow of drilling fluids, washout and partial collapse of those layers due to rapid drilling disturbance.

This “geohazard” is known as “shallow water flow” [SWF] and the associated risks have been extensively reported in the technical literature, and were ranked and mapped by the MMS. [Mississippi Canyon SWFs]. They were well known by individuals within BP America. In addition, the potential presence of extensive layers of in-situ frozen gas hydrates [GH] along the Mississippi Canyon continental shelf edge is understood and documented. Furthermore, this well location was selected and drilled very close to a gas hydrate bearing mud volcano feature in order to maximise the potential for a positive result at Target Depth. A safer method, known as “Riserless Drilling” does not appear to have been considered and was probably seen as too costly.

Despite all the above, BP took the decision to continue to attempt to drill the one of the world’s deepest wells to date in a slapdash, corner-cutting, driving down cost, “maximise added” value fashion. These cut corners and lack of management control have been well documented to date.

With proper drilling design, control and cementing, wells have been completed under these conditions in the past. However the risks should always be thoroughly assessed, with appropriate prevention and mitigation techniques and controls in place. Such measures are also well documented based upon the past experiences of GoM operators, including BP. However, as well as designing a high risk “long string” well, the MC252 Exploration Well was designed with safety valves (known as “Burst Disks”) at shallow depths which were close to the levels of three known and mapped SWF sands, and in a GH prone area. This was part of the plan to convert the exploration well to production at a later stage. More savings.

Indications are that the drillstring at Macondo was fractured/damaged as a result of SWF drilling fluid fracture, washout and collapse over a certain depth interval. Severe problems and drilling mud losses were recorded at the time. The expanded pressurised melted hydrate gas may have blown through the damaged casing and weak pathways in the bad cement job following the final negative leak off test. Drilling mud was displaced by seawater within the drillstring over too great a depth, leading to reduced internal hydrostatic pressure and a sudden imbalance between the internal (fluid) and external (expanding gas in sand) pressures. The hydrate almost certainly would have been steadily melting around the casing due to heat given off by the curing cement, a problem well understood by Haliburton, explaining their concerns over the use of a nitrogen foam cement.

The recent very detailed DNV forensic report on the BOP failure as well as an internal highly detailed Transocean Report leads to the conclusion that any BOP would have failed even if it had been in perfect condition, due to the condition of the well, it’s out of vertical alignment and the sudden immense force of the gas and fluid flow.

The question that should have been asked to date is: where did that huge quantity of gas really come from? Calculations may show that the valve system at the bottom of the well is unlikely to have “somehow” failed as a result of pressure changes far up the drillstring, causing a sudden influx of a vast quantity of gas from the hydrocarbon reservoir some two and half miles below seabed to burst upwards through fairly dense drilling mud at such a high velocity.

Consideration of the temperature and pressure regime in the shallow hole section below seabed suggests that natural in-situ hydrates are very likely to have been present at the Macondo location over a depth interval of a few hundred metres below mudline. The heat generated as a result of cement curing is likely to have led to melting of section of this natural hydrate bearing zone some distance radially from the cement and a subsequent increase in pressure as the gas tried to expand within one or more of the known SWF sand
layers. The presence of channels at certain levels within the cement is likely to have permitted a pathway(s) to form along part(s) of the 16” casing. Due to possible earlier drilling disturbance of the known layers of SWF sands prior to the melting of the hydrates, the 16” casing may have been out-of-straight or even slightly buckled as a result of partial liquefaction and softening of the SWF sands (similar to that observed at the BP/Shell URSA in 1999 in the GoM). This loss of lateral support may have caused a crack or breach in the casing, or even a loosening or damage at the casing joint(s). This casing is suspected to have been of too low a yield strength for the well design. At the point during the negative leak-off test when the pressure differential became sufficiently high, it is now well documented and accepted that the three “burst disks” (essentially pressure relief valves) placed at certain points on the casing joints down the casing string probably blew out at their inwards blowing rated burst pressure of 1600 psi. At this point the large pressure drop occurring within the mud fluids in the annulus between the production casing and the 16” casing might have been sufficiently large to allow a rapid influx of trapped pressurised gas lying within the SWF sand(s) and in the pathways which had formed in the bad exterior cement job. Melted hydrate expands to approximately 64 times its original frozen volume. This gas build up may have caused a very high pressure jet to blow out one of the rupture disks in the 16” casing, if the pressure differential between the seawater filled production casing and the annulus on the other side were sufficiently high. This immensely powerful gas jet stream would have travelled very quickly up the production casing.

This subsequent upwards rush of gas would have caused a siphoning of seawater, mud and subsequently oil with it as the production casing shoe was blown due to the very high suction force exerted. Once the initial shallow blast of GH sourced gas blew the BOP, reservir pressures would have been sufficient to allow the flow of oil to be maintained.

Much detail has been written in formal reports, books and publications to date about the mechanics of what happened. However virtually nothing has been stated about the root “geohazard” causes – shallow water flows and gas hydrates, a horrible but all too feared combination.

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BP Knowingly Drilled Macondo MC 252 in High Risk Geohazard Area

The recently published National Commission Report to the President of the United States of America (11th January 2011) and BP’s own earlier Accident Investigation Report dated 8th September 2010 have focused almost entirely on the failings of equipment and processes on the drilldeck of the Deepwater Horizon, on the seafloor BOP and associated equipment and on the errors and mistakes made in drilling and cementing up of the close to completed well.
The fact is that BP were drilling at Macondo MC 252 in an area of well known and documented geological hazards (known in the industry as “Geohazards”). At Macondo these included such features as extensive beds of frozen gas (or methane hydrates) and a number of layers of artesian overpressured sands where the interstitial natural water pressures could cause casing collapse due to disturbance of those sands. This process is known as “liquefaction”, also known in the trade as “shallow water flows” [SWF]. The presence of gas hydrates and shallow water flows in this Mississippi canyon shelf edge zone is very well documented by the MMS, BP and other operators. As if that were not enough, having had some nasty failures at the MC 252 location, BP (not Transocean or Halliburton or Cameron or any other organisation) took the decision to continue to attempt to drill the world’s deepest well in a slapdash, corner-cutting, driving down cost, maximise added value fashion in a zone of salt dome features and severe faulting.
The word “geohazard” is not mentioned once in either of the above reports.
It is entirely possible that BP’s reasonable level of in-house expertise in this part of the GoM in such geologically risky conditions was overridden. Why one might well ask? Because the ultimate “paydirt” at MC252 was a prize of some 50 to 100 million barrels of oil (BP estimate), which for an extraction success ratio of 30% may have been worth 1500 to 3000 million US dollars. Small beer in relation to say, the Tiber prospect nearby but worth it all the same. This guesstimate is based on USD 100 a barrel. As the oil price continues to climb in the coming years, this black gold fortune was worth the risk for BP’s “management”. Worth ignoring their tiny teams of in-house technical experts, following the massive staff culls of the globalising megalomaniac cost slashing Lord Browne, post Amoco merger. The recent claims by new man Mr. Dudley that BP has fully and surprisingly rapidly absorbed the “Lessons Learned” from MC252 has a very hollow ring. This lip service phrase much used and abused within oil companies is usually taken with a massive pinch of salt. Public domain available documents and references describe in detail very close calls for BP and partners at Ursa (GoM) in the late 1990’s where several drillstring casings collapsed and buckled due to SWF problems. In the South Caspian Sea in 2003 several well casings were buckled at the AIOC West Azeri location which had to be abandoned and repositioned at huge cost due to a slightly different geohazard problem set (weak/unusual overburden clays, tophole overpressures, highly saline pore fluids, shallow gas and mud volcanoes). A further near miss occurred on a gas reinjection well at the next door Central Azeri Platform on 17th September 2008 when 211 personnel had to be evacuated following gas alarms. The avoidance of gas ignition was lucky. These expensive lessons were either learned and forgotten or ignored. More likely is that BP managers and senior individuals assumed they had been learned and that mitigation measures would somehow magically have been put in place by others. Or they simply accept the risks. There are many other such case studies. It is time for appropriate organisations and national governments to urgently check the activities of these arrogant corporate cowboys, at a time when we hear of BP partnerships in Russia, fresh exploration activities in Alaska and Australia and increasing plans to drill in deeper waters off high geohazard risk continental shelf edges. The culture of almost paranoid secrecy within BP has to be seen to be believed. Macondo is very likely still leaking hydrocarbons through a ruptured casing string at depth through seabed fissures and cracks. The hope has been that these will self-seal and stop. Try googling “B K Lim Macondo” and read his excellent and courageous detailed geohazard assessment.

“Human salvation lies in the hands of the creatively maladjusted” – Martin Luther King. – The GallowGlaich.

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