Development and Deployment of a Scale Squeeze Enhancer and Oil-Soluble Scale Inhibitor To Avoid Deferred Oil Production Losses During Squeezing Low-Water Cut Wells, North Slope, Alaska

Abstract

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThe paper outlines the experimental work that has been carried out to develop an effective treatment strategy for production wells, specifically those with electrical submersible pumps (ESP's) that suffered significant performance impairment at water cuts of less than 5% due to carbonate scale deposited within the ESP's. These Alaskan production wells had been treated for a couple of years using aqueous based scale inhibitor squeezes. Many of these treatments resulted in a significant 10% to 20% reduction in the oil production rate following the squeeze. The damage mechanism was investigated by coreflooding and revealed to be a combination of water block and relative permeability effects. Following the damage investigation coreflood, a second study was undertaken to investigate a chemical treatment to remove the damage already present within the near well bore and prevent further deposition of scale. The result of this test program was the development of a treatment strategy which used a solvent package followed by an oil soluble scale inhibitor. Field results of this type of treatment suggest that the wells treated with this chemical system did not suffer any reduction in oil production rate and were effectively protected from carbonate scale. Wells that had been damaged by the previous aqueous treatments could be stimulated and the lost oil production recovered. Reference is also made to the development of an improved aqueous based squeeze treatments for the treatment of higher water cut wells.

Avaliação de aditivos químicos para dissolver incrustação inôrganica de sulfato de bário em poços de petróleo

“…Segundo Jordan et al (2000), a utilização de grandes volumes de aditivos químicos em poços com baixa fração de água (até 10%) durante o período de retorno dos fluidos da produção, após o período de estagnação (shut in) pode resultar na formação de blocos de água e causar mudanças na permeabilidade relativa na região próxima ao poço produtor. Neste caso, deve-se utilizar um conjunto contendo o inibidor de incrustação, solvente orgânico com óleo cru para solucionar tal problema.…”

“…Estes tipos de tratamentos são empregados quando a fração de água alcança certo nível onde problemas de incrustação não poderão mais ser controlados economicamente por simples dissolução dos depósitos formados. Isso geralmente acontece quando fração de água produzida alcança frações superiores a 5 % (Jordan et al, 2000).…”

“…O processo de precipitação é função do tipo de inibidor, pH de aplicação e nível de íons bivalentes presente no meio. O mecanismo de precipitação pode oferecer certas vantagens sobre o processo de adsorção quando o sistema requer concentração mínima de inibidor acima de 15 ppm como destacado por Jordan et al (2000).…”