Cairn Oil & Gas in Joint Venture with ONGC, is the operator of contract area RJ-ON-90/1 in the state of Rajasthan, North West India. MBA fields (Mangala, Bhagyam and Aishwarya Field) comprise of more than 565 wells. Produced liquid from these wells is transferred to Mangala Processing terminal (MPT) where liquid from each of these wells is collected and processed. MPT processes ~11,00,000 BLPD and separated water is re-used for water injection for pressure maintenance and power fluid for jet pump artificial lift. This requires stringent separation procedures to maintain injection water quality.
With the terminal operating at the limit of its processing capacity and high field water cut, maintaining oil production with high liquid handling posed a big challenge.
The objective was to prove the concept of addressing liquid handling constraint and optimizing oil production by utilizing standalone separation and pumping systems. It was anticipated that bottlenecking in the lines was causing high backpressure on the wells which led to substantial decrease in well liquid production. A network model was created which confirmed this. This paper describes the approach used to establish a standalone set-up for header pressure reduction and increased liquid handling using surface well test and pumping facilities.
The network model indicated that for an increase of 1 bar pressure in production header, there was a substantial loss in oil production from each network of MBA field. For example in Mangala Cluster A, this resulted in ~ 400 BOPD of loss in oil production.
Later an idea was developed to take out ~10,000 BPD liquid from production header line of a network and the same was separated using standalone well test & pumping spread. It was planned to pump oil back into production header and use the produced water for Jet Pumping application and remaining water to be pumped in nearby injector. The entire operation was planned with 2 standalone surface well test spread and pumping units.
Post achieving success in Mangala field the same idea was implemented in Aishwarya field where the main objective was to knock off the gas from the system along with liquid reduction from the production header which ultimately reduced the back pressure on each of the well in the pad.