| The offshore oilfield represented by BZ34-1 oilfield is characterized by strong heterogeneity,small layers,large permeability difference,large interlayer pressure difference and prominent contradiction in the interlayer.In the process of water injection development in this kind of oilfield,water injection wells are often vulnerable to injecting water,so acidizing is needed to remove plugging and improve the water absorption capacity of single well.In the process of acidizing,the acid liquid always gives priority to the high permeable layer,which causes a series of problems,such as the intensification of the water absorption section of the water injection well,the early water appeared in the oil well,and even the water logging.Meanwhile,for the reservoir with strong water absorption,it is necessary to control its water absorption,so as to avoid injection water advancing along the high permeability layer,resulting in ineffective circulation of injected water.Therefore,such wells not only need to take acidizing to get blockage removal,but also need to take profile control technology to improve the water injection profile.Simple acidizing and profile control can not simultaneously increase injection and reduce the contradiction between layers.Based on the analysis of the reservoir characteristics of BZ34-1 oilfield,based on the analysis of the blockage composition and the very poor permeability of the reservoir,from the point of view of the simultaneous realization of blockage removal and profile control,this paper puts forward the technology method of selection well and layer by the technology combined blockage removal and profile control,and carries out the study on working fluid system and process method for combined blockage removal and profile control of water injection well.(1)Through the analysis of the influence factors of the effect of the technology combined blockage removal and profile control,the Pehrson correlation coefficient method is used to calculate the correlation coefficient between the factors and the injection ratio.The weight of each factor is determined by the fuzzy analytic hierarchy process.The method of variable weight is used to deal with the lack of well parameters,so that the decision results are more objective and reasonable,and the selection of the work well layer is instruct.(2)The study of high efficiency acidizing blockage removal fluid system was carried out with the idea of "low injury and deep penetration",and a high efficiency acidizing blockage removal fluid system with better slow speed and corrosion resistance was optimized and compared with the performance of polyhydric acid system.High efficiency acidizing blockage removal fluid system has good compatibility with formation fluid and low corrosion rate,it can effectively chelate metal ions and prevent two or three times damage,and has good plugging effect.(3)The formulation of the water-plugging profile-control agent system is optimized,and its properties are evaluated.At the same time,through the double core flow simulation experiment,it is proved that the high efficiency acidizing blockage removal fluid system and the water-plugging profile-control agent system have good improvement effect on core permeability at the time of "solution and the adjustment" process work together.(4)Combined with on-site construction,the process and key parameter design method of the technology combined blockage removal and profile control in water injection well is put forward.The research contents and research results completed in this paper provide strong technical support for effectively solving profile adjustment of injection wells in BZ34-1 oilfield.At the same time,it also provides a reference for other water injection well technology combined blockage removal and profile control research. |
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