N2 Foam Flooding Combined with Gel Plugging for Enhanced Oil Recovery in High-Temperature Reservoirs: Laboratory Experiments and Numerical Simulations

Thehigh-temperature reservoir (105 degrees C) in the Liubeiblockof Jidong Oilfield, with severe longitudinal heterogeneity, has entereda high water-cut stage. After a preliminary profile control, the watermanagement of the oilfield still faces serious water channeling problems.To strengthen water management, N-2 foam flooding combinedwith gel plugging for enhanced oil recovery was studied. In this work,considering a high-temperature reservoir of 105 degrees C, a compositefoam system and starch graft gel system with high temperature resistancewere screened out, and displacement experiments in one-dimensionalheterogeneous cores were carried out. Through the three-dimensionalexperimental model and numerical model of a 5-spot well pattern, physicalexperiments and numerical simulations were carried out respectivelyto study water control and oil increase. The experimental resultsshowed that the foam composite system had good temperature resistanceup to 140 degrees C and oil resistance up to 50% oil saturation andwas helpful to adjust the heterogeneous profile in a high temperatureof 105 degrees C. The starch graft gel system had good injection performance,with a solution viscosity of 18.15 mPa center dot s, and its gel strengthcould effectively seal the high-permeability layer, with a gel viscosityof 34950.92 mPa center dot s. The displacement test results showed thatafter a preliminary implementation of N-2 foam flooding,N-2 foam flooding combined with gel plugging could stillimprove oil recovery by 5.26%. Compared with preliminary N-2 foam flooding, gel plugging could control the water channeling inthe high-permeability zone near the production wells. The combinationof foam and gel made N-2 foam flooding and subsequent waterfloodingdivert to flow mainly along the low-permeability layer, which wasconducive to enhance water management and improve oil recovery. Thismethod can be used as an effective technology to manage similar heterogeneousreservoirs.

Automated summary

In this study, we investigated the water management issues in a high-temperature reservoir of 105 degrees C. Through experiments and numerical simulations, we found that the use of a composite foam system and starch graft gel system can effectively improve water control and oil recovery in the reservoir, leading to better management and enhanced oil production.