Study On Fracture Morphology And Optimization Design Method Of Fractured Horizontal Well In Low Permeability Interlaminated Reservoir

Along with the thorough development for horizontal well in peripheral low permeability oil field and its extending to the border of the oil field from the year 2007 to 2008,the Putaohua Reservoir had transformed from 2 or 3 thick layers to 4 or 5 thin layers,resulting in the complication of fracture cracking and extending state,insufficient understanding about fracture morphology and lacking in pertinence about optimization technology.In face with ultrathin layers and horizontal well fracturing of it,optimization design has encountered many problems.For example,in ultrathin sandstone,dirty sandstone and interbedded mudstone,artificial fracture is difficult to crack and extend,which will easily lead to the sanding profile unsatisfactory,reducing the effect.Among these,it hasn't formed a mature theory about fracture cracking and extending in thin interbed home and abroad.It also lacks standard for control and diagnosis,and imposes restrictions on apply and improvement of fracturing technology of horizontal well.Aiming at the characteristics of the bad thin interbed,we are badly in need of forming the fracturing scale optimization theory under different reservoir conditions,stabilizing and improving the fracturing effect of horizontal well.Facing with the horizontal well-vertical wells joint water injection,the target of fracturing segments optimization will be transformed to how to guarantee a long-term and efficient recovery.But the research of this aspect is blank.By tackling the problem,we have confirmed the extending discipline and influencing factor of artificial fracture in ultrathin reservoir,and this will lay the foundation for fracturing optimization of horizontal well in ultrathin reservoir;Aiming at the characteristics of thin interbed and well pattern development,we have formed the concept and method of optimization design on artificial fracture fracturing crossing formation and improving reserves employment vertically,the match between artificial fracture parameters and well pattern and the completion of injection-production relationship horizontally,thus we make it realized that the horizontal well gives a high and stable long-term yield;Combining the reservoir and well pattern,we make a personalized fracturing optimization design for block horizontal well,and have formed five different stimulation transformation patterns,maximizing its full play of horizontal well in development efficiency.According to the reservoir as well as well pattern characteristics of different block like Aonan,Zhaozhou et al.,the adaptive fracturing optimization design method and stimulation technique has been adopted.It's already verified by field trial of 110 well with 593 intervals that the development effect of low permeability reservoir has been improved with a design correspondence rate of 93.2%and 96.3%in successful cases,and the average initial production per fractured well goes to 9.5t/d,which is 5.3 times of fractured vertical well production in the same block.