Study On The Effect Of Foamed Gel System As The Selective Water Control Technology

During oilfield development at present, there are always some problems such like leak-off,bottom water coning, fracture or high permeable channels existing between production andinjection wells and fingering phenomenon that occurred near the wellbore. Due to the poorstability of ordinary foam, gas channeling easily occurs in the injecting progress. As a result,the strength of ordinary foam profile control and water plugging is limited, plugging validityperiods are shorted. Foamed gel as a new method of profile control water plugging isproposed to solve the shortcomings of the ordinary foam system with weak profile controlability weak and short valid periods.Foamed gel is a mixed system with cross-linking polymer solution and surface active agent.After injecting gas, this solution forms foam through bubbling. When this foam systembecomes gel, it can effectively block the high permeability layers, forcing the subsequentliquid into the high oil saturation part to displace crude oil and improve the sweep efficiency.There are many factors impacting foamed gel blocking ability, through physical simulation,the influence of gas-liquid ratio, permeability, the flooding direction were studied on foamedgel plugging performance in porous medium. At the same time, we compared blocking abilityamong the polymer flooding, water-based foam flooding, gel flooding, foamed gel flooding.For the optimized foamed gel system, through physical simulation experiments, differentpermeability ratio, different injection methods and different sizes of the slug were studied onthe profile control law with double cores in parallel.This paper carried a series of experiments to study different factors’influence on the profilecontrol ability of foamed gel by an artificial cement core model. The research showed thatwith apparent oil and water selectivity, the foamed gel system’s water shut-off rate (99.8%)was significantly higher than its oil plugging rate (6.9%). The plugging performance of foamed gel in the porous medium increased first and then decreases with the increasinggas-liquid ratio, and increased with the increasing permeability. The core injected foamed gelwith positive water-flooding had higher plugging performance than that with reversewater-flooding. The diversion effect of foamed gel system first increased and then decreasedwith the increasing permeability ratio. The foam formed stably by gas and liquid flowingthrough the foam generator would get the best diversion effect. The injected slug either toolong or too short would adversely reduce the diverting effect of foamed gel system. Thisresearch can lay a theoretical foundation for the application of foamed gel system in profilecontrol and water shutoff technology.