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A Timeline of Major Well Integrity Incidents

Major well integrity incidents highlight the need to assure well integrity to be in place within the oil and gas and petrochemical industry. Industrial incidents caused by failures and lapses in regular maintenance have irreversible damage to the environment and costly for operators. These incidents serve as an important reminder for companies to constantly review and improve safety protocols and equipment to prevent such incidents from happening. Here is a timeline of major well integrity incidents since 2004.


Moss Bluff Cavern #1 (August 2004)

In August 2004, Cavern #1 of the Moss Bluff natural gas storage in Texas, United States, experienced a major uncontrolled gas release and fire. Investigations revealed that a series of unusual events led to the incident: separation of the 8 5/8-inch well string inside the cavern; the breach of the 8-inch brine piping above ground; and the separation of the wellhead assembly above the cavern. The blowout initiated during de-brining of the cavern when gas entered the brine string, causing the pipe to burst at ground level. The following fire resulted, 21 hours later, in separation of the wellhead assembly and the uncontrolled loss of gas from the 20” production casing. The fire self extinguished about 6.5 days later, when all the gas was burned off. More than 6 sbcf of gas had been released.


Snorre A Well P-31A (November 2004)

The Petroleum Safety Authority Norway (PSA) characterized this incident as one of the most serious to occur on the Norwegian shelf. This is because of the potential of the incident, as well as comprehensive failure of the barriers in planning, implementation and follow-up of the work on well P-31A.

On 28 November 2004, an uncontrolled situation occurred during work in Well P-31A on the Snorre A facility (SNA). An uncontrolled gas blowout occurred on the seabed, resulting in gas on and under the facility. The work to regain control over the well was complicated by the gas under the facility which, among other things, prevented supply vessels from approaching the facility to unload additional drilling mud.  In total, the report revealed 28 non-conformities with the regulations, and several matters with potential for improvement Serious failures and deficiencies relate to:

  • Failure to comply with governing documentation
  • Deficient understanding and implementation of risk assessments
  • Deficient involvement of management
  • Breach of well barrier requirements


Montara Oil Spill (August 2009)

On 21 August 2009, Montara experienced a well control incident resulting in an uncontrolled release of oil and gas into the marine environment lasting 106 days. The Montara oil spill occured after a blowout and fire on the Montara wellhead platform. Investigations revealed that it was most likely that hydrocarbons entered the H1 Well through its 9⅝” cemented casing shoe and flowed up the inside of its 9⅝” casing. In total, approximately 64 000 litres of oil per day leaked from the well from 21 August 2009 until 3 November 2009, and approximately 6.7 million litres of oil leaked from the well.  The Montara oil spill is the largest offshore spill in Australian history.


Aliso Canyon Gas Leak (October 2015)

The largest gas leak in U.S. history, a leak in the Aliso Canyon gas storage field resulted in nearly 100,000 tonnes of methane and 7,300 tonnes of ethane being released into the atmosphere. The 112-day leak led to thousands of complaints of gas-related illnesses, force thousands of residents to evacuate from their homes for months, temporarily close two schools and impact businesses and property values throughout the region. Gas was escaping from a well within the Aliso Canyon’s underground storage facility in the Santa Susana Mountains. A lapse in the replacement of safety valves in several pipes in the facility led to the leak of a metal pipe in a breached 7-inch casing of injection well.


Managing Well Integrity through Design, Verification and Repairs is a 3-day training course held from 29 – 31 Oct 2018 (Kuala Lumpur), 18 – 22 Nov 2018 (Doha) and 3 – 7 Dec 2018 (Doha) designed for delegates to understand the WIM principal, barriers, conflicts in the organisation that threaten a lesser level of WIM construction or maintaining it. The course will cover key issues of well-completion design, construction, preventive maintenance strategies and more. For more information, please visit us at or contact us at


Interested to read more articles about Well Integrity?  Check out Well Integrity Management


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