Ravva - Cairn’s first development success story has been the bedrock of innovation, and the foundation of our success story in the country and the region. Ravva, which in Sanskrit and Telegu means “diamond” showcases the journey of growth that Cairn has been able to achieve in its business. Incidentally, Ravva is the only field in India to get such a unique name indicating the belief of the nation in it.

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RAVVA
Celebrating 16 Years of Technical Excellence
Innovating Development | Use of Seal tite to control leaks

2. Ravva | Innovating Development
Use of Seal tite to control leaks
Offshore oil and gas production systems are complex systems comprising wells, flow lines, a variety of
subsea and dry subsystems, production platforms and export lines. Hydraulic systems are extensively
used in offshore production systems, particularly for valves control and operation.
Failures in hydraulics systems may cause loss of
redundancy, loss of control and well shut-in with
economic losses and risks to system integrity and
environment. Leaks, mostly internal, represent one of the
most common failures in the hydraulic systems.
The conventional approach to repair these leaks makes
use of rig and/or support vessels. This can be time and
money consuming with the additional risk imposed on the
system under intervention. Having an alternative to
mechanical workover when repairing subsea leaks not
only clears the operator’s mind but it also clears the way
for greater production and profitability.
The well RB-1 in the Ravva field had dual completion
installed in it and the subsurface safety valve on one of
the strings developed a leak over the operating life. One
of the options to eliminate the leak was to do a workover
operation and replace the valve.
Normally, a workover operation is carried out in the well to
retrieve the completion string and replace the sub-surface
safety valve. But the sealant technology was identified
and applied to cure the leak to allow production from the
well until the workover campaign was planned. This
technology was being used for the first time in India.
The sealant consists of a super-saturated mixture of
short-chain polymers, monomers and polymerising
chemicals in a carrier fluid. There is a cross-linking reaction analogous to blood coagulating. As the
reaction proceeds, the polymerised sealant plates out on the edges of the leak site and, simultaneously
links across the leak site to seal the leak.
The resulting seal is an elastic bond across the leak. Basically, the liquid sealant molecules link together
to form a flexible solid when forced into a suitable flow restriction (leak site). The process is called
polymerisation. The rest of the sealant will remain fluid not clogging the hydraulic system or the well.
The sealant operation was carried out in two days and the control line was tested on the third day, which
displayed proper operation. The sealant used was quick, resistant, made in closed circuit, had no risk of
environmental contamination and required minimum tools and personnel for its application, thereby
avoiding loss of production.
However, the sealant is temporary with a life of two years and is economical, costing just 6% of the valve
change cost. As a result of fixing the leak, a workover was delayed by almost a year and subsequently
production from the well was regained.
Use of such techniques has helped in effectively managing well servicing and workover costs by better
planning, which makes Ravva one of the lowest cost producers in the world.