Productivity Prediction And Optimal Design Of Multi-branched Fishbones

For low-permeability gas reservoirs with low permeability,poor connectivity and complex gas-water relationship,the current stimulation process is fracturing treatment.Fracturing horizontal wells can increase gas production in a short time,but fracturing cannot control the direction of crack propagation.It is impossible to determine whether cracks will penetrate each reservoir,and the gas-water relationship in the lower part of the reservoir is complicated.Fracturing cracks connect water bodies to cause the bottom water cone.Advance,resulting in a decrease in premature water production in gas wells.In order to avoid the above problems,the multi-branched fishbones naked hole completion technology is applied to the low permeability aqueous reservoir to increase production.Multi-branched fishbones naked hole completion technology uses hydraulic broken rock to form a plurality of stable small wellbore in the reservoir,increasing the bare area of the reservoir and the discharge passage,and the gas is more likely to flow radially into the main wellbore along the longer wellbore,and the hole Due to the “hydraulic pressure” effect,a large number of micro-cracks will be formed in the area,which will greatly improve the seepage capacity near the wellbore.This is a typical application method of jet stimulation technology.Moreover,the naked hole completion method reduces the pollution to the reservoir,and at the same time,it can effectively prevent the water raft and water cone phenomenon by controlling the arrangement orientation of the branch and controlling the branch extension length,which is more suitable for the development of low permeability aqueous reservoir than the horizontal well fracturing technology.According to the actual logging data of the target well area in a certain block of Sinopec,the deterministic modeling method is used to make the relevant structural model and reservoir attribute model.Aiming at the characteristics of multi-branched fishbones,considering the effects of stress sensitivity,starting pressure gradient and pressure loss,a coupling model of multi-branched fishbones seepage and horizontal wellbore pipe flow in low permeability gas reservoir is established,and the productivity model is established.Perform an iterative programming solution.Based on the actual stratum parameters of the target well area,the principle of orthogonal test design is applied to comprehensively analyze the primary and secondary order of the influence of various parameters on the multi-branched fishbones productivity,and further determine the multi-branched fishbones.The best combination of parameters in the well.At the same time,the multi-branched fishbones single well model after segmentation optimization is performed by numerical simulation software.The simulation calculation was carried out based on the established low-permeability gas reservoir productivity prediction model,and the multi-branched fishbones under the optimal branch morphology was used.A comparative analysis was made with the capacity of the field fracturing horizontal well.Research shows that: The number of branches in the branch morphology has the most significant effect on the productivity of multi-branched fishbones in low permeability gas reservoirs,followed by branch length,branch angle and branch spacing again,and branch diameter has the least impact on it.The best combination of factors for multi-branched fishbones was determined: the number of branches was 44,the branch angle was 60°,the branch length was 12 m,the branch spacing was 18 m,and the branch diameter was 40 mm.The results of capacity comparison analysis showed that the daily gas production and cumulative gas production of the optimized multi-branched fishbones after the pre-production optimization were significantly higher than that of the fracturing horizontal well,and the influence of the water layer on the gas well production was avoided as much as possible.