Study On Initiation And Propagation Of Hydraulic Fracturing Fracks In Radial Boreholes

Due to the increasing proportion of low permeability reservoirs in oilfield production,c onventional production methods can not achieve the effect of production.At present,conven tional perforation fracturing will result in passive situations such as low permeability of rese rvoir,large damage of reservoir,low production increase and short validity period.The eme rgence of radial drilling hydraulic fracturing has become a new way to increase oil producti on.However,it is generally believed that radial borehole fracturing starts at the end of the borehole.In the field implementation of oil field,some oil wells with radial drilling hydra ulic fracturing have unsatisfactory stimulation effect.The hydraulic fracturing crack could no t reach the target oil layer,which caused the oil field stimulation measures to fail.In this paper,the radial borehole hydraulic fracturing crack is cracked from the borehole wall.Bas ed on the principle of stress superposition,this paper analyzes the distribution of the stress field around the radial borehole and the influence of the crack initiation of the radial boreh ole hydraulic fracturing.The effects of drilling parameters on crack initiation and extension of hydraulic fracturing cracks were obtained by indoor large-scale hydraulic fracturing experi ments and numerical simulation experiments.Firstly,by analyzing the stress around the radial borehole,the stress field distribution model around the radial borehole is established,and the influence of borehole parameters o n the in-situ stress around the borehole is analyzed.The stress field will be solved in two parts: the vertical wellbore stress field and the radial borehole stress field.Each stress field can be divided into the stress field caused by liquid pressure,the original in-situ stress re distribution stress field caused by borehole and the in-situ stress field caused by fracturing f luid filtration.Secondly,the cracking model of the radial borehole hydraulic fracturing crack is establi shed by the radial borehole stress distribution model.From the borehole aperture,the azimu th of the borehole(the angle with the maximum horizontal principal stress),the difference of the ground stress,etc.,the influence of the crack initiation and propagation of the radial borehole crack is analyzed.Finally,the ABAQUS finite element extension software and hydraulic fracturing experi ment are applied to study the law of radial drilling parameters affecting crack initiation and propagation.Finally,the conclusion is drawn that the root cause of radial drilling initiation and propagation is analyzed by the derivation of the stress field around the radial drilling.When the drilling angle is greater than 45 degrees,the stress distribution on the wall of t he drilling hole will be abrupt,and the crack will crack from the wall of the hole;as the horizontal stress stress difference increases,the crack initiation position is closer to the verti cal wellbore.And the cracking pressure increases with the increase of the stress difference;when the diameter of the hole is larger,the crack initiation position is closer to the vertical wellbore,but the cracking pressure changes little;when the diameter of the vertical wellbo re is larger,the radial drilling The closer the cracking position of the hole hydraulic fractur ing is to the wellbore,the less the cracking pressure changes.