A New Strategy for Heavy Oil Reservoirs Water Shut Off: Customized Blocking Strength to Implement Chemical Water Shut Off

Abstract High water cut is a main challenge which influenced the production of heavy oil reservoirs, and it is even worse for thermal recovery. There are many factors, such as reservoir development time, reservoir non-homogeneity, oil-to-water flow ratio, well network well type, production parameters, and water intrusion management also involves the above factors. It is the key issue to prevent and manage water shut off for the efficient development of heavy oil fields. The key point is to make the correct judge and choose the appropriate strategy. Firstly, the self-developed Intelligent Diagnosis Technology of Water-flooded Condition in Complex Reservoirs(FLIISTM) is used to identify quantitative identification and calculation of dominant seepage channels. Secondly,customized blocking strength was optimized, and different chemical agents were developed, such as thermosensitive reversible gel and thermo-stable foaming agent. At last,the water intrusion law was analyzed, based on the time to see water and the rate of rise of water content, constructed the water intrusion step by step to adjust the plugging design layout.The thermosensitive reversible gel was developed that it is a low viscosity fluid at a temperature lower than the transition point and is colloid when the temperature is higher than the transition point. The gelling strength grade H and the temperature resistance above 180 °C and controlled by adjusting the formula proportion, suitable for different reservoir temperatures. After the core is injected with thermosensitive reversible gel and formed into glue, the plugging rate reaches more than 99.7%. Thethermo-stable foaming agent itself is a surfactant, which can inhibit gas channeling in multiple rounds of thermal production and improve the effect of multiple rounds of thermal production. The temperature resistance can reach 350 °C, and the oil resistance can reach 30%. It owns good plugging and regulating performance, which still has high resistance factor after aging at 350 °C. After study thermo-stable foaming agent was used in the first round of A1, the water content in the initial stage of the measure decreased from 74% to less than 5%, the peak daily oil production was 53.9 m3/day, the oil increase was 8-10 times, the cumulative oil production was 4900 m3, the cumulative oil increase was 4100m3, and the validity period was about 5 months.The thermo-sensitive Gel relieved the mutual gas channeling effect during single well injection. Oil production increases by 40-60% after thermal recovery.