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
Multiphase Pump Installation Project

2. RAVVA – Celebrating 16 years of Technical Excellence
Pioneering Development
Multiphase Pump Installation Project
Multiphase pumping is a simple and economic technology that has replaced conventional methods of
producing oil and gas. Multiphase Pumps (MPP) are modified liquid pumps that are capable of pumping
various combinations of oil, water, gas and minor amounts of sand in the same pipeline without
separation. MPPs are the most commonly used devices to add energy to unprocessed fluids for long
distance transportation to the central downstream processing facilities, without requiring separate flow
lines, separators, heaters, intermediate storage tanks, gas flares, compressors, and separate pumping
facilities. Elimination of these equipments means a smaller platform and a more economical installation
can be used to boost the production (i.e., increase well fluid flow). In this way, even small fields in hostile
environments can be developed more economically. MPPs can thus handle low inlet pressure and have
the potential to reduce the back pressure on producing wells, leading to increase in production rate and
recovery efficiency.
Around 55% of the Ravva crude is produced from RA and RC wells. The produced fluid is brought to the
onshore terminal for crude stabilising and dehydration by a10” RA-RT line. Currently, about 30,000
barrels of fluid per day is evacuated through this line from the RA and RC platforms. This implies that a
high differential pressure is maintained in the pipeline to ensure this
high flow. Further production from the wells is restrained due to the line
back pressure on the producing wells. It has been observed physically
that the producing wells are unable to deliver any additional fluid into
this line due to the high back pressure.
As part of enhanced oil recovery (EOR), a study was conducted for the
procurement and installation of multiphase pumps. Lack of provision
for required power supply at the platforms, led to the installion of
multiphase pumps at the onshore terminal. The 10” RA-RT line is
connected to multiphase pump suction and the discharge fed to the
crude stabilisation units. Later the piping arrangement was modified
suitably to connect 12” RE-RT oil pipeline also to the MPP. At present,
either the RA–RT line or the RE-RT line can be connected to MPP
according to the process requirement.
Each multiphase pump skid consists of Bornemann Twin-Screw Pump
(Germany), 1300 KW HT motor, seal oil system, and associated
piping. The variable frequency drive for each equipment was
manufactured in Canada. These skids were transported to the Ravva
plant and installed at the terminal area.
Two ‘Twin Screw’ Multiphase Pumps with a total capacity of 36,000 barrels per day of liquid (at 50%
capacity utilisation) and 412,000 SCMD of gas are used to pump the well fluid from RA/RC-RT pipeline to
well fluid header at RT depending on the operating pressure of the separator trains. The power rating of
the pump is 1.3 MW. These Twin-Screw MPPs are capable of handling changing well flow conditions
during the entire lifetime as well as transient conditions, i.e. gas and liquid slugs during the short term.
Due to the working principle and the patented features, it handles 95% gas flow, e.g. during the start up of
wells, as good as 100% liquid flow due to the internal recirculation of liquid. The liquid flow especially can
be boosted without any time limitations. Bornemann’s MPPs are rotary positive displacement pumps and
are capable of handling liquid of low and high viscosity including liquid containing 100% gas. The rotating
element operates without contact so that these pumps can handle 100% gas.
During normal operation, these pumps are started and stopped manually using the remote push button
located at the plant PLC. The output from the suction pressure controller of the MPP is fed to a variable
frequency drive unit, which controls the speed of the pump to get the required flow rate as per the set
point provided at the plant PLC. Suction pressure and pump discharge temperature are monitored, which
can inhibit MPP operation with 100% gas volume (GVF) for a time longer than specified by the pump

3. RAVVA – Celebrating 16 years of Technical Excellence
Pioneering Development
vendor. Hence discharge temperature and the pump internal monitoring is vital, and appropriate shutdown
logic is necessary.
Low suction pressure alarms are provided in the individual pump suction line from RA-RT pipeline to alert
the operator at the control room. Further reduction of suction pressure (as indicated by suction pressure
transmitter and differential pressure transmitter across the pump) requires operator intervention to reduce
the flow rate set point (reduce pump rpm). Also, low suction pressure shall trip the individual pumps and
close the inlet shutdown valve. High discharge pressure trip is provided in the MPP discharge line.
Operator intervention will be required to monitor GVF in case the pump trips, due to long exposure to
100% GVF depending upon pump vendor specification. Indirect measurement of GVF will be the pump
discharge temperature. On high discharge temperature, the pump shall be stopped to protect the pump.
In the event of MPP tripping, interlock is provided to open bypass SDV to route the well fluid directly to
separators. Pressure in the RA-RT line will increase and the well fluid rate will come down. Pressure
Safety valve (PSV) on the discharge is provided to protect the MPP system against shut in pressure
peaks higher than 750 psi(g) .