Summary
Clean gas, cleanly produced
Major deep-water discoveries off the coast of Angola’s Zaire Province
over the past 25 years have transformed this Sub-Saharan African
nation. In the town of Soyo, a newly built liquefied natural gas (LNG)
plant will process one billion cubic feet of clean gas a day. The plant
will process both associated and non-associated gas extracted from
four offshore sites.
The project is led by Angola LNG, a joint venture between Chevron,
Sonangol, ENI, Total and BP. In the first half of 2011, two appraisal
wells were completed in Block 2 to evaluate non-associated gas
content, quality and reservoir properties. Tenaris provided OCTG
technology and services that helped overcome specific environmental
and operational challenges.
Challenges
Need to protect the environment
Environmental care is at the heart of the Angola LNG project, which
was devised to reduce emissions produced by gas flaring and to
commercialize a new source of clean energy. The operator was
looking for products and practices that would help it minimize the
environmental footprint of the field’s production.
The Quiluma 4 and Maboqueiro 2 appraisal wells provided a timely
opportunity to evaluate the performance of tubes with Dopeless®
connections, which don’t require the use of thread compounds,
cleaning solvents or any other wet chemicals that could potentially
damage the environment.
Early CwD experience
Both offshore wells shared the same design. This specified that the
13 3/8" section would be simultaneously drilled and cased. Known
as “Casing while Drilling” (CwD), this is a technique that has not yet
been used extensively in Angola. Since such applications are known
to add stress to strings, the customer required a strong premium
connection capable of reliably resisting fatigue.
Solution
Zero discharge
In August 2010, a local team of engineers from Tenaris organized
a make & break demonstration of Dopeless® technology in the
capital, Luanda. This provided ALNG with the opportunity to see
Dopeless® technology first hand, since they would later use the
TenarisHydril solution on 9 5/8" casing strings for both of its wells:
the first time in the Angolan market.
The environmental benefits derived from the use of Dopeless®
connections stem from the fact that – unlike standard products,
which require liquid-based storage and running compounds – they
are completely dry. Dopeless® connections are coated with a dry
lubricant that is applied at the mill in a controlled industrial process.
During routine pipe inspections and pipe preparation operations,
Dopeless® connections eliminate three manpower-intensive stages:
the removal of storage compound and cleaning of pin & box
ends; the cleaning of connection protectors; and the reapplying of
storage dope.
Safer work areas
Besides eliminating the discharge of chemicals and lubricants into the
well, Dopeless® connections bring health and safety advantages by
avoiding slippery surfaces at the yard and rig site, a key consideration
in offshore operations. Additionally, less OCTG handling is required,
which leads to less accidents and faster running jobs.
Proven fatigue behavior
To deal with the additional operational demands of the CwD section
in both wells, the operator chose to make up the 13 3/8" strings
with TenarisHydril Blue® connections, which provided excellent fatigue
behavior. Thanks to the detailed product performance technical data
that Tenaris’s dedicated R&D laboratories produce for this premium
connection, and a local team that provided technical support from
the beginning of the project, the customer was able to validate early
on that the TenarisHydril Blue® connection would meet its specific
CwD demands.
Further field support
The tubular products supplied by Tenaris were not alone in contributing
to the successful casing of both wells. Following the shipping of the
OCTG to the ALNG yard in Soyo, a local field services specialist from
Tenaris offered onsite technical support. Services provided included
material reception, visual inspection of all pipes and running assistance.
Results
157 run, 0 rejected
A total of 157 joints with TenarisHydril Blue® connections
were run in the 9 5/8" section of the wells. These casing jobs were
successfully completed with zero rejects and no reported safety
incidents. Also, the 81 joints with TenarisHydril Blue® connections
met the needs of the Casing while Drilling application.
Angola’s first Dopeless® technology experience
In February 2011, the Quiluma 4 officially became the first
well in Angola to be partially installed with Dopeless® technology,
followed two months later by the Maboqueiro 2. The experience
has been followed with interest by other E&P companies operating
in the area.
ALGN provided Tenaris with very positive feedback about both
the performance of TenarisHydril Blue® Dopeless® connections and
the quality of its value-added services. The operator is considering
extending the use of the technology to the development of the
Block 2 field, which is expected to begin in 2013.