It Is Suitable For The Development Of A Weak Gel System For Profile Control In Low-permeability Fractured Reservoirs

This paper investigates the weak gel used for enhanced oil recovery profile and studies the development history and current status of the gel.Under the condition that its application is successful,a WY block is used as the background condition to develop a kind of gel.It is suitable for the weak gel system used for profile control in WY block,and the performance evaluation of weak gel system,the mechanism of the gelation reaction of weak gel system,the microstructure research of weak gel system and the improvement of oil recovery.Through a large number of indoor simulation screening experiment,first in ZND-5,KYHPAM polymers,SNF and MO4000 four crosslinking agent Lord experiment contrast,stick through strong relationships,salt resistance,shearing resistance,temperature resistance performance test,optimizing the ZND-5 as a crosslinking agent Lord.Using citric acid/aluminum as crosslinking agent,the preparation conditions of citric acid root/aluminum ion ratio,reaction temperature,reaction time and pH value were optimized.In addition,through the experimental data and the actual situation,the crosslinking agent was selected and the stabilizer was selected for thiourea,with a quantity of 800mg/L.The sodium tartrate was selected by the retarder,and the dosage was 160mg/L.Finally,the formulation of weak gel system is obtained.This article also evaluated the temperature resistance,salt resistance,shear resistance,plugging property,breakthrough pressure,breakthrough pressure gradient,erosion resistance,and profile improvement ability of weak gels,combined with microscopic studies of AFM and ESEM,From the microscopic point of view,the mechanism of the change of the performance of the weak gel was explained,and it was concluded that the weak gel not only blocks the high-permeability reservoir and starts the low-permeability reservoir,but also plays a role in the displacement of the residual oil,and weak coagulation of small particles.After the glue enters the pores,it will break the balance of the internal force of the pore throat,forcing the residual oil to start,and it also has the function of microscopic displacement.Provides guidance for improving the recovery of weak gels.The displacement performance,plugging performance and profile control performance of the weak gel were studied by single-pipe displacement experiments,double-tube parallel experiments,and plane non-homogeneous physical model experiments.The experimental results showed that:single-pipe flooding experiments,double tubes In parallel experiments and plane non-homogeneous physical model experiments,weak gels all exhibited good performance;in the plane non-homogeneous physical model experiment,we also found weak gel properties in the residual resistance capacity established in the hypertonic layer.Excellent performance,because in the later water stage,the flow rate of the medium-penetration layer is always higher than the high-permeability diversion rate,and this ability has a decisive effect on the blockage of the hypertonic layer and the initiation of the middle and low permeability layers.