| Most onshore oilfields now use water flooding to supplement formation energy.However,due to the heterogeneity of reservoirs,there are large differences in permeability between different reservoirs and even in different plane orientations of the same reservoir.,the onshore oilfields led by Daqing Oilfield have entered the late stage of ultra-high water cut.After longterm liquid flow scouring in the area near the injection well,the formation clay minerals are stripped from the rock skeleton under the action of liquid flow,and are carried along with the liquid flow.Out of the surface,the permeability of the formation near the natural fractures is further increased,high-permeability bands are formed locally,the oil saturation in the highpermeability areas is further reduced,the contradiction between layers and layers is intensified,the problem of dominant channels is more prominent,and the injected water will Flowing along high-permeability layers and dominant seepage channels further increases the difference in seepage resistance between layers,intensifies inefficient and ineffective circulation,and leaves a large amount of remaining oil in the unswept area without being produced,which seriously affects the degree of recovery.Aiming at a series of problems caused by large fractured pores,this paper studies the formation mechanism of large fractured pores in the reservoir,and based on this,studies and evaluates the existing profile control agents,and develops a suitable for deep fractured pores.Granular profile control agent for profile control,the advantages and disadvantages of the profile control agent are clarified;for the shortcomings of the granular profile control agent,a new gel type profile control agent is developed.At the same time,it can also play a better plugging effect,thus forming a series of formula systems suitable for the plugging of large cracked pores.Finally,the performance of the formula system is verified through field test applications,which can improve the cost reduction.The related supporting process technology provides strong technical support.Firstly,the formation method of high water-cut fractured macro-channels in the formation was simulated by self-made equipment,and the pore structure,mineral composition,remaining oil distribution and remaining oil types of cores in different regions of fractured macro-channels were analyzed.The high-strength scouring experimental model of fractures is used to clarify the influence of scouring strength,scouring speed,scouring time and other factors on the clay minerals attached to the rock minerals in the formation.After consulting the information,a water-swellable rubber particle profile control agent system was synthesized and modified in the laboratory.This particle not only has excellent performance in injection performance,swelling performance,migration performance and degradation performance,but also has large cracks.The channel model experiment also verified that the particle has good sealing performance,but the particle has the disadvantage of not being resistant to erosion,and further research is needed to improve this situation.Aiming at the shortcomings of particle-type profile control agents,a multi-component complex polymer gel system was developed as a means to reinforce the water-swellable rubber particle system.At the same time,the gel formation of the system was observed by scanning electron microscope,and the retention effect of the gel on particles was analyzed microscopically;through fractured channel model experiments and flat core residual oil simulation experiments,the gel was The combination of glue and water-swellable rubber particles is used to verify the specific performance of the two.After proving that the composite system has good performance,the relevant injection process parameters are optimized,and the influence of different profile control radii and slug methods on the treatment effect is clarified.Conditions and reservoir physical parameters characteristic well pattern structure to evaluate the performance of the composite system.Finally,by applying the system in the target block,the problems of unbalanced production and serious low-efficiency circulation in some wells during the injection process are solved,and the water cut rise rate of the well group is greatly slowed down.It has been reduced to some extent,and good application results have been achieved,which provides a way of thinking for largescale application of deep profile control with high water-cut fractures and large channels,and provides strong technical support for cost-reducing and efficiency-enhancing supporting technology. |
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