Influences Of Secondary Fracture Shapes On Production Of Fractured Horizontal Wells In Tight Oil Reservoirs

Horizontal wells in tight oil reservoirs will form complex interlaced fracture network of main and secondary fractures after fracturing,the distribution shapes of fracture network and different secondary fracture parameters are very important for post-fracturing development effect.The purpose of this paper is to study the influence degree of different secondary fracture shapes on production in fractured horizontal wells,and provide analysis basis for fracturing transformation of horizontal wells.Firstly,on the basis of fully investigating the secondary fracture shapes at home and abroad,we select orthogonal fracture network,branch fracture network,Y-like fracture network and H-like fracture network as the research objects,and design the SRV algorithm of each fracture networks.Secondly,through the numerical simulation,the optimum secondary fracture parameters of different fracture networks are analyzed.Then,the secondary fracture production evaluation system is established by the visual judgment method,the coefficient of variation method and the grey relative change rate association method,so that the influence degree of each parameter is quantitatively ranked.The advantages and disadvantages of different methods are compared and evaluated,and give advice on how to use the evaluation method.Finally,according to the field data,establishing the actual well model,and applied in the actual well model,which provides a reference for the actual fracturing of the unfractured horizontal well in this area.The results show that the development effect of the four kinds of fracture networks is: H-type fracture network > Y-type fracture network > orthogonal fracture network > branched fracture network,but the difference of yield increase effect is less than 6%.The quantitative ranking of influence degree of each fracture parameter on production is as follows: the secondary fracture segment > the secondary fracture conductivity > the half secondary fracture length > the secondary fracture angle.In the theoretical study,the orthogonal fracture network can be selected.In actual fracturing,increasing the number of secondary fracture segments,secondary fracture conductivity and fracture complexity are considered to increase production.