A Successful Field Trial of a New ASP Technology in a High Water Cut and High Recovery Degree Reservoir After Polymer Flooding in North China

Abstract

Large scale polymer flooding in Daqing Oilfield achieved great success. The average recovery degree of these oilfields after polymer flooding has reached 52.5%, and the average water cut has reached 96.0%. It is urgent to find an effective technical method for further EOR. Targeting the highly dispersed remaining oil in the post polymer flooding reservoirs, the continuous phase polymer solution in ASP technology was replaced by nano-micron particle polymer dispersion to realize optimization for EOR mechanism, so the ASP technology was upgraded. The field test, has been completed the slug injection, and achieved obvious EOR effect. The ASP slug design with HPAM solution as the main displacement phase was abandoned. A type of water dispersion of nano-micron particle polymer as the main displacement phase was designed to replace the "P" in traditional ASP slug, so that the flowing control mechanism of "P" was optimized. Through synchronous diversion and displacement, it can initiate and sweep the remaining oil dispersed in relatively small pores. A large three-dimensional physical model with the size of 60 × 45 × 4.5cm was made to simulate the real development history of water injection and polymer flooding of the reservoir, based on which, the performance of the upgraded ASP was modeled. Furthermore, the program was designed and optimized by numerical simulation. The physical simulation fitting experiment of the development history of water flooding and polymer flooding shows that the coincidence rate is 93%+. After polymer flooding, the upgraded ASP further improved the recovery by 15.2 percent. The optimized scheme of numerical simulation is to inject 0.5PV of new ASP slug. Under the precondition of the historical recovery degree of 55.8% and water cut of 98.44%, the new ASP is expected to improve the recovery by 7.9% within 10 years. At present, the field test of ASP slug injection has just been completed, and remarkable results have been achieved, The daily oil production has increased by 60%, and the water oil ratio has decreased from 61.9 to 38.4. The daily oil production of some producers has increased by 2 to 3 times, and the recovery has increased by 5.2%. The field trial proves that the oil displacement mechanism of nano-micron-particle-polymer ASP flooding chemical system is more advanced and the displacement efficiency is higher than that of the traditional ASP flooding, and the oil recovery can be further enhanced for similar reservoirs under extreme conditions after polymer flooding. The traditional ASP technology is expected to have great upgrading and developing.