Experimental Study On Deep Profile Control And Flooding Of Amphoteric Polymer Gel In DH-4 Block

The reservoirs in DH-4 block are highly heterogeneous and complex in pore structure,resulting in a large amount of remaining oil and irreducible oil.These present in the reservoir have been difficult to replace in the current medium and high water cut stage,and other methods have been used to increase oilfield production and extend the life of the oilfield,and to the maximum extent.Improving oil recovery in the field has become an important research topic at present.The amphoteric polymer gel has controllable glue forming time,high plugging strength,long effective period and slow migration to the deep part of the formation.Therefore,it is necessary to carry out in-depth research on the formulation concentration optimization and indoor performance evaluation of the composite ion-type flooding system for DH-4 block,the indoor optimization of the injection parameters and the oil displacement mechanism of deep profile control and flooding.The results show that,through the indoor performance evaluation experiment,amphoteric polymer gel is preferred for the first time,wherein the polymer concentration range is 600¹000mg/L,the crosslinking agent concentration range is1600²000mg/L,and the stabilizer concentration range is 200³00mg/L;The influencing factors of the drive system were analyzed.At the temperature of 45.8°C,the viscosity retention rate of the 30th was 86.1%,and the viscosity of the 90d was still6500mPa·s.The viscosity can still reach 4000mPa·s or more at 2000r/min;G?is greater than G??at low frequency 1Hz,indicating that the elasticity of the system is greater than the viscosity.Through the injection experiment of the flooding system,it is preferred that the optimal injection speed of the control system in the 10cm core is 0.1mL/min,and the permeability of the adjustment system with the polymer concentration range of800¹000mg/L is specified.The injection performance of the core of 200⁴00×10^-3?m²is better.The artificial three-layer heterogeneous core is used to carry out the oil displacement experiment.The optimum injection volume is 0.3PV,and the optimal concentration of the polymer in the system is 800mg/L.The injection method is composite slug injection.Then,the three-tube parallel experiment is used to evaluate the effect of heterogeneous rectangular core in the presence of“separation layer”.In the subsequent water flooding stage,the cumulative split rate of the low permeability layer increased by 8.6%,and the recovery rate increased by 5.82%.Finally,the micro-lithography model,the visual oil displacement device and the three-layer heterogeneous core are used to carry out the oil displacement experiment.The visual display of the macroscopic flooding process and the analysis of the residual oil in different stages,it is further clarified that the regulation and drive system can expand the volume of the movement.Improve the displacement efficiency and realize the mechanism of side-by-side drive.