SINTEF Offshore Blowout Database

is a comprehensive event database for blowout risk assessment. The database includes information on 544 offshore blowouts/well releases that have occurred world-wide since 1955 and overall exposure data from the US Gulf of Mexico, Outer Continental Shelf and the North Sea. The blowouts/well releases are categorized in several parameters, emphasizing blowout causes. A user-friendly interface allows for customized search patterns. ExproSoft has been contracted to operate the Offshore Blowout Database from 1 May 2001 by SINTEF.

Participants

The Participants of the Project are:  

• BP Norge
• ChevronTexaco Exploration and Production Technology Company
• ConocoPhillips Norge A/S
• DnV
• ENI Norge A/S
• Lilleaker Consulting a.s
• Safetec AS
• Scandpower Risk Management AS
• Shell Research Limited
• StatoilHydro
• Total E&P Norge

Blowout descriptions in the database

The database contains 51 different fields describing each blowout/well release. In addition, the database allows for attachment of any electronic file(s) to the blowout description. The various fields are grouped in six different groups:

1. Category and location
2. Well description
3. Present operation
4. Blowout causes
5. Blowout characteristics
6. Other

Category and location
Includes information related to the incident category (blowout vs. well leak), offshore installation such as location, operator, installation name and type, and water depth.

Well description
Includes well and casing depths, last casing size, mudweight, bottom hole- and shut in pressure, GOR, formation age and rock type.

Present operation
Includes the phase (exploration drilling, development drilling, workover etc.), the operation presently carried out (for example casing running) and the present activity (for example cementing) .

Blowout causes
Includes external cause (stating if an external cause contributed to the incident), loss of the primary barrier, loss of the secondary barrier (describing how primary and secondary barriers were lost) and human error. It should be noted that the field regarding human error in general holds low quality information. Human errors are frequently masked. A field named North Sea standards highlights if the development of the blowout could have been avoided if North Sea type equipment had been used (for instance in other parts of the world a blind shear ram is not mandatory in surface BOP stacks).

Blowout characteristics
Twelve fields are included comprising flow path, flow medium, flow rate (low quality), release point, ignition type, time to ignition, lost production (low quality), duration, fatalities, consequence class, material loss and pollution.

Other
In the “other” screen five fields are included: control method, remarks (includes a description of the incident, data quality (includes an evaluation of the source data quality), last revision date and references.

Exposure data

The overall offshore drilling and production exposure data for the US GoM OCS, Norwegian, and UK waters is covered from 1 January 1980. In addition drilling exposure data for the Dutch Continental Shelf, the east Coast of Canada, Australian waters, Danish waters and the US OCS Pacific are included.

Search possibilities and reporting facilities

Almost any type of search may be performed to select specific blowout /well release event types. Search criteria may be established by selecting predefined codes, specific numeric values, specific free text, or any combinations of these. The predefined codes are spelled out to ease understanding.

The database program counts and presents the events satisfying the search criteria. The selected data may be viewed, printed or copied to separate files for further analyses, for example by database or spreadsheet programs.

The exposure data and the blowout data are not linked. Blowout frequencies can therefore not be established directly.

Some definitions

The following main definitions have been applied when classifying the blowouts/well releases in categories and sub-categories.

Blowout: A blowout is an incident where formation fluid flows out of the well or between formation layers after all the predefined technical well barriers or the activation of the same have failed.

Well release: The reported incident is a well release if oil or gas flowed from the well from some point were flow was not intended and the flow was stopped by use of the barrier system that was available on the well at the time the incident started.

Shallow gas: Any gas zone penetrated before the BOP has been installed. Any zone penetrated after the BOP is installed is not shallow gas (typical Norwegian definition of shallow gas).

Category and Sub-category

The categories and subcategories applied when classifying the incidents in the SINTEF Offshore Blowout Database are shown in Table 1.

Table 1 Main categories and subcategories for the incidents in the SINTEF Offshore Blowout Database

Main	Category	Sub category	Comments/Example
Blowout and well release	Surface blowout	Totally uncontrolled flow, from a deep zone	Totally uncontrolled incidents with surface/subsea flow.
		Totally uncontrolled flow, from a shallow zone	Typical the diverter system fails
		Shallow gas "controlled" subsea release only	Typical incident is that riserless drilling is performed when the well starts to flow. The rig is pulled away
	Underground blowout	Underground flow only
		Underground flow mainly, limited surface flow	The limited surface flow will be incidents were a minor flow has appeared, but typical the BOP has been activated to shut the surface flow
	Well release	Limited surface flow before the secondary barrier was activated	Typical incident will be that flow is through the drillpipe and the shear ram is activated
		Tubing blown out of well, then the secondary barrier is activated	Typical incident occurring during completion or workover. Shear ram is used to close the well after the tubing has been blown out of the well.
	Diverted well release	Shallow gas controlled flow (diverted)	All incidents were the diverter system functioned as intended.
	Unknown	Unknown	Unknown may be selected for both the category and the subcategory

 

Scope of data

Totally the database includes 544 offshore blowouts worldwide (February 2008). Data from the US Gulf of Mexico Outer Continental Shelf (US GoM OCS), Norwegian and UK waters are in general better documented than blowouts from other regions.

From 1 January 1980 through 1 January 2006, a total of 218 blowouts/well releases from the US GoM OCS and the North Sea were consolidated in the database. Table 2 shows an overview of blowouts occurrence by operational phase.

Table 2. Number of blowouts experienced during different operational phases.

AREA	Dev. drlg	Expl. drlg	Unk. drlg	Comp-letion	Work-over	Production		Wire-line	Un-known	Total
						External cause*	No ext. cause*
US GoM OCS	52	48		12	31	6	9	5	2	165
	31.5%	29.1%	0.0%	7.3%	18.8%	3.6%	5.5%	3.0%	1.2%	100.0%
UK, and Nor-wegian waters	7	30	2	3	6	1	1	3		53
	13.2%	56.6%	3.8%	5.7%	11.3%	1.9%	1.9%	5.7%		100.0%
Total	59	78	2	15	37	7	10	8	2	218
	27.1%	35.8%	0.9%	6.9%	17.0%	3.2%	4.6%	3.7%	0.9%	100.0%

*             External causes are typical; storm, military activity, ship collision, fire and earthquake.

Access to the database and reports

The database and annual report are confidential and only accessible for the project sponsors. The SINTEF Offshore Blowout Database is open to new participants. Some statistics from the database are presented in the following references:

Holand, Per:
"Offshore Blowouts Causes and Trends" Doctoral Dissertation, Norwegian Institute of Technology, Department of Production and Quality Engineering, Trondheim, Norway, March 1996

Holand, Per:
"Experienced Offshore Blowout Risk" presented at the IADC 1996 Well Control Conference of the Americas, Rio de Janeiro 31. July - 2. August 1996.

Holand, Per:
"Offshore Blowouts Causes and Control", Gulf Publishing Company, Houston Texas, 1997

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