| Steam injection is one of the effective methods to increase the recovery of heavy oil,however,due to the formation heterogeneity,the steam flowing in the high permeable layer can not effectively affect the low permeability layer,resulting in a large number of injected steam loss,and the volumetric sweep efficiency is reduced.Three-phase foam with solid particles has a high apparent viscosity,liquid film strength and stability,etc.Such as cement and solid particles can not only increase the foam stability and improve foam sealing strength,while the foam particles under high temperature conditions can be carried into the deep reservoir,achieving "permeable" plugging material.Firstly,Waring Blender method was used to optimize the concentration of blowing agent,suspending agent and consolidation agent.On the basis of evaluating the foaming ability and stability of three-phase foam,the suspension performance of polymer and modified starch gel as suspension agent is evaluated,and the formulations of two three-phase foam systems are optimized;Finally,the sealing performance and displacement efficiency of two three-phase foam systems are systematically evaluated by using different sand filling pipe models and artificial heterogeneous core models.For a three-phase foam system,the polymer suspension formulation is 0.3% SDS+0.3% suspension polymer + 0.5%~30% consolidation agent,and modified starch gel suspension formulation is 0.3%SDS+0.3% suspension modified starch gel + 0.5%~30%consolidation agent,the foaming volume is 600 mL and 450 mL respectively,and the half-life was 3h and 24 h respectively,both of the two systems have good suspension capacity for the consolidation agent with a concentration of up to 30%.The evaluation of plugging performance shows that the sealing rate of modified starch gel and polymer three-phase foam system can be adjusted in the range of 90%~95% and 80%~90%,andthe purpose of "permeability" can be achieved.In terms of oil displacement effect,the increase of EOR by starch gel three-phase foam system is 28.8% and 25% respectively at 5 times difference and 10 times difference,and the increase of EOR by polymer three-phase foam system is 22% and 15.7% respectively at 5 times difference and 10 times difference.The above research results show that the permeable three phase foam system can play a "controllable plugging permeability",reduce the steam channeling in high permeability layer,and make high permeability and low permeability layer relatively uniform advance,and effectively improve the oil displacement effect.Indoor evaluation results can provide data support in terms of the design and application in field implementation measures such as the utilization rate of steam. |
