Laboratory investigations and application of a new technology to improve polymer flooding in the niger delta reservoirs

Polymer flooding has been one of the most important enhanced oil recovery (EOR) technologies at Niger Delta oil field. However it was observed that an ordinary polymer solution did not efficiently flood the reservoir as it flowed easily through macro pores and emerged in the oil zone after continuous injection. This led to water breakthrough by fingering. This phenomenon was observed at most of polymer injection areas in the Niger Delta. In this paper, the test on the suitability of a special crosslinker (CL-1) to improve the polymer flooding performance is presented. A research was carried out in the laboratory to see how the CL-1 crosslinker may improve polymer flood performance. The crosslinker was mixed with some polymers to obtain a gel. All the polymers used in test are HPAM. The cross/inking states of CL-i and the different samples Of PAM were evaluated against a number of physical parameters. The experiments showed that when CL-i was used in polymer flooding, the modified polymer system showed a better improvement in viscosity, thermal stability and salinity resistance. A distribution device was also success fully manufactured to accurately add the dosage of CL-i into polymer solution automatically. When CL-i was added and the polymer solution was injected into the injection well with low pressure, the moveable polymer gel with high viscosity was formed in the formation. This penetrated deeply into the micropores of the reservoir, blocking the macropores and preventing or minimizing further polymer channeling. This resulted in a better sweep of residual oil and improvement in wellhead pressure.The modified polymer system technology was applied to Iyobosa oil field in Delta State since May, 2015. The field has 15 injection wells and 46 production wells; well spacing is 300 metres, and the reserve in place is about 5145x104stb. There are 6 injection wells which remained low injection pressures even after seven months polymer flooding. The modified polymer flooding system was applied to these six wells mentioned above. A better performance resulted, with the injection pressure rising from 870psi to 1378psi. The daily oil production from the producers increased while the water cut decreased. Due to this success, the technology is now applied in some other polymer flooding areas.