Water Plugging and Acidizing Combination Technology on Fractured Water Breakthrough Oil Well in Low Permeability Reservoirs

Abstract

During the exploration in low permeability reservoirs, oil wells are usually abruptly flooded because of the connection between injection wells and oil wells through fractures and large pore canals, causing the productivity decrease in the integral block. In this research a combination plugging agent consisting of weak gel, strong gel and temporary plugging agent is used to plug fractures and large pore canals and improve formation homogeneity by multi-slug injecting. The basic performances of gel plugging agent and the solubility of the temporary plugging agent in different solvents were determined. Furthermore, the selective plugging ability of combination plugging agent and the feasibility of the new technology were evaluated. The results show that combination plugging agent can reduce the permeability of high permeability core more than 99%, while hardly reduce the low permeability core, and by subsequent acidizing treatment, the permeability of low permeability core was increased more than 30 times, while high permeability core have be increased only a litter. Field application has been conducted in Changqing oil field. All of the three pilot tested wells are getting a good improvement. After the application of the combination technology, oil production is increased by 2.7 t per day of each well. And water content is reduced by 42.9% on average. The effective time is more than 418 days. This technology has increased 3,260.4 tons of oil and obtained an obvious effect.