Repairing Seawater Intake Basin With 100 MM$ Saving by Avoiding Production Cut and Optimizing Capex

Abstract

Abstract There was an immediate requirement for a low-cost fast-track solution to tackle the integrity threats of a Sea Water Intake Pumping Basin at an Offshore Island location. The intake basin, which is more than 40 years old and has gone through minor skin repairs 25 years back, houses all the fire water and cooling water pumps to meet the demand of 1 million barrel per day Oil Processing Plant with 7 nos 1-Million Barrel Crude Oil Storage Tanks. Sea Water Intake Basin is a box-type concrete structure divided into 7 Bays (compartments) separated by concrete walls or slabs wherein fire water and cooling water pumps are mounted. However, integrity condition of the basin was very alarming with half of the 300mm concrete thickness lost in most of the places of pump mounting slabs. As the intake basin is linked to two main systems of supplying cooling and fire water, failure of the intake structure would render the plant un-operational and lead to adverse impacts including plant shutdown. The conventional way of repairing the basin would call for the outage of 2 of 3 cooling water pumps for 4 days causing around 500000 barrels of daily oil production cut. As 2 fire water pumps are required to be available always, the repair work would also cause outage of 2 of 3 fire water pumps for 4 days, necessitating a temporary fire water arrangement at a cost of around US$10 million. The challenge was how to repair the intake basin by minimizing and/or avoiding production cut and, at the same time, ensuring uninterrupted supply of fire water during repair, and reducing project execution cost from US$17 million to the extent possible. A scheme was developed to avoid shutdown of critical pumps through use of buoyancy-assisted Temporary Support Structure and quick-setting concrete in dynamic condition as well as by optimizing plant parameters to reduce the cooling water demand. The scheme, executed at a cost of US$ 4.6 million, resulted in an overall savings of US$100 million. This paper presents the optimized scheme and execution methodology for the basin repair duly avoiding total shutdown of essential fire and cooling water pumps. Also, this paper highlights how in-house Technical Support can contribute towards "More Profitable Upstream" by providing a fit-for-purpose and cost-effective solution to Company's business needs.