Produced Water Reinjection at Wellpads: Leverage Terminal Liquid Handling & Accelerate Oil Production from MBA Fields

Mehta, Nirav (Cairn Oil and Gas, Vedanta Ltd) | Ray, Rimjhim (Cairn Oil and Gas, Vedanta Ltd) | Kapadia, Gautam (Cairn Oil and Gas, Vedanta Ltd)

OnePetro 

Abstract

Oil, water and gas separation at wellpads with improved technology and compact design has significant advantage for increasing liquid handling from group gathering wellpads and accelerating oil production from fields. Cairn, Oil & Gas vertical of Vedanta Limited is the Operator of RJ/ON block in India with major fields Mangala (M), Bhagyam (B) and Aishwariya (A). Mangala field (75% of MBA production) is the largest onshore oil discovery in India and Bhagyam-Aishwarya fields together contribute to ~25% of the total MBA production. The MBA fields are on water + polymer flood and gradual increase in water production is challenging to process the same oil production volumes. Future field development plans in these fields requires debottlenecking of liquid handling constraints.

The current paper depicts the fast track modifications planned in various fields and its implementation carried out in Aishwariya field which was limited for produced fluid handling due to capacity constraints at the centralized processing well-pad 8 (AWP-08). These modifications were aimed towards localized produced water treatment and reinjection of 30,000 barrels per day (bpd) into the existing injection manifold at Aishwarya Wellpad. In the first stage, produced water is separated from 3,000 ppm to 300 ppm OIW and in second stage from 300 to <100 ppm OIW with <5 ppm TSS. The existing vessels were retrofitted and modified in field with internals like inlet device, calming baffles, coalescing pack, overflow weir and oil bucket. This enabled additional residence time suiting the given fluid characteristics and efficient separation of the produced fluids. This resulted in accelerating oil production from the field by ~2,000 bopd by opening more shut-in wells and leveraging terminal liquid handling capacity. And with the future ESP upsizing and more infill wells coming online, there is further potential to gain additional oil upto 3000 bopd. The execution of Project commenced in Sep-17 and was commissioned in Dec-17 in a record 3 months’ time period including engineering which helped in monetizing early oil production benefit. Based on the success of the local pad separation in Aishwariya field, similar scheme is planned to be implemented in Mangala & Bhagyam wellpads and other small fields with high water production.