Discussions on developing hydrophilic sandstone reservoir by water injection-production

Most reservoirs of the south Dagang Oilfield are complex fault block pools with faults developed in the reservoir. The blocks are small and closed, the reservoir permeability is low and oil viscosity is high, which makes it difficult to displace oil by water flooding. Soon after injectors are brought into production, the injection pressure is increased rapidly. Meanwhile, the injectivity decreases dramatically, which leads to little benefit to corresponding oil wells. For this kind of reservoir, hydrophilic property of the sandstone could be used advantageously. According to the spontaneous imbibition expulsion mechanism of the sandstone, the higher recovery efficiency could be obtained by water injection-production. Wang 26-1 block of Wangguantun Oilfield is of low permeability, and Zi 19-14 block of Zilaitun Oilfield is of high viscosity, and both are hydrophilic complex block pools. On the success of pilot test, the development mode of water injection-production had been used in this way and oil production increment of the two blocks reached over 22,000 t.