Bijupirá Field’s production system integrity required testing for fluid compatibility with system components and tuning of acid neutralizing processes.
Philip Bogaert, Shell Brasil E&P; Gustavo Cavazzoli, Daniel R. Perez, Cesar Guimaraes, Sascha Trummer and Bernhard Lungwitz, Schlumberger
Since reaching its plateau production in January 2004, the Bijupirá Field offshore deepwater Brazil has experienced significant production declines. Analysis of the causes suggested fines migration and possibly BaSO4 scaling. Shell and service company engineers selected scale removal and matrix stimulation treatments to reestablish productivity. These were performed from a dynamically positioned drillship using Coiled Tubing (CT) in the HoriZontal OpenHole Gravel Pack (HZOHGP). This article describes the process of laboratory testing, design, simulations and project execution. The combination of offshore, deepwater, gas lift, FPSO, drillship and CT formed the first intervention of its kind.
The field came on production in August 2003 and is both gas-lifted and waterflooded. In early 2004, oil production rapidly declined to near 15,000 bopd from an initial 50,000 bopd, in part because of increasing watercuts, but mainly from declining well rates. Most of this oil came from three wells: BJ-Q, BJ-T and BJ-S, which produced near dry oil with watercuts of less than 10% from 600-m long HZOHGP. Their oil production declined to 8,000 bopd from 40,000 bopd, Fig. 1.
By the end 2004, routine well and reservoir surveillance confirmed that declines were from well impairment. The downhole pressure gauges had failed and subsea interventions were too costly, so there were no real options to confirm the cause.
Several mechanisms were considered and a multidisciplinary team ranked their likelihood: swelling clay damage, scale formation, water holdup, emulsions and waterblock, salt deposition, organic deposits, fines migration and residual completion damage. The team concluded that the impairment was from migrating fines that plugged off sand screens and gravel pack sand.
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This article was adapted from a professional society paper for which World Oil was granted the right to print one time only. Therefore, to review the article, you should refer to the actual World Oil magazine in which it originally appeared.
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