The Study and Application of Seepage Reconstruction for Water Plugging in High Permeability Sandstone Reservoirs

Abstract

Abstract In the medium/high permeability sandstone reservoirs, long-term water flooding led to large pore channels formed in the reservoir, and the injected water quickly breaks into oil wells along the large pore channels, resulting in water cut increase rapidly and a significant reduction in water flooding efficiency. The traditional water shut-off by chemical or cement squeeze cannot reduce water cut for a long time and cannot increase oil production because they don't change the existing seepage characteristics of the reservoir. The seepage reconstruction is a combination of chemical water shut-off and fracturing technology. It involves innovation on intelligent water control materials and fracturing injection process. There are three plugging slugs, a strong plugging slug, a seepage reconstruction slug, and a tail plugging slug, should be filled into reservoir one by one. The strong plugging slug adopts inorganic polymer to shut-off the large pore by low speed injection. The seepage reconstruction slug is composed of 70-140 mesh quartz sand, 50-80um ceramist and intelligent water control materials with a ratio of 6:3:1, which is carried by low-concentration guar. The tail plugging slug is made of self-consolidated material to prevent sand returning from formation. The technology is used in G111-6 located in J oil field, which is successful in increasing oil production from 3.08bopd to 56.28bopd and reducing the water cut from 96.64% to 78%. The validity period was 492d, and the total oil production was 22624bbls. The technology of seepage reconstruction for water shut-off could effectively reduce the water cut and greatly increase the daily oil production. It effectively improves waterflood development efficiency of medium/high permeability sandstone reservoirs in high water cut stage. The innovation of this technology is the effective combination of fracturing technology and traditional chemical water shut off technology. The goals of water shut-off and oil increase are realized by innovative design of three plugging slugs. It provides a new approach for water shut-off in medium/high permeability sandstone reservoirs with high water cut.