Fluid Accumulation Judgment And Methods Of Drainage Gas Production Of Horizontal Wells In Fractured Low Permeability Gas Reservoir

The development of fractured low-permeability gas reservoirs in horizontal wells will cause the water production in gas reservoir and gas well,which will cause gas wells to accumulate fluids at the bottom of wells,reduce productivity,and degrade oilfield benefits.Therefore,accurate identification of fluids in gas wells and take proper drainage Gas measures are the main points of current research.Aiming at this phenomenon,the fluid accumulation of horizontal gas wells in fractured low-permeability gas reservoirs is judged and a new internal spiral tool drainage gas recovery technology is proposed.First,the capacity equation method,that is,the newly established gas-water two-phase matrix-natural fracture-horizontal wellbore productivity equation for horizontal gas wells in fractured low-permeability gas reservoirs,is used to determine the fluid accumulation of gas wells,and the results are compared with the critical fluid-carrying flow method.It is proved that the accuracy rate of the capacity equation method reaches 80%.The productivity equation combines real gas state equations,and comprehensively considers stress-sensitive effects,startup pressure gradients,nonlinear seepage laws,nitrogen-water two-phase flow laws,and dualporosity medium structure.The accuracy rate of the equation in predicting the gas well productivity of a gas reservoir is 91.55%,and the influence law of natural fracture parameters on production capacity is given.Secondly,according to the characteristics of horizontal wells for fractured lowpermeability gas reservoirs,a kind of new internal spiral tool applied to the horizontal pipe section of a horizontal gas well was designed as a drainage gas recovery tool.The drainage mechanism of the tool and the sensitivity of the working conditions are studied.The flow state and fluid accumulation of gas-liquid mixed fluid in the wellbore before and after loading the inner spiral tool under different working conditions was simulated through a horizontal well indoor simulation experiment device.The experimental results show that the inner spiral tool can effectively reduce the fluid accumulation in wellbore,improve the flow pattern of mixed fluid in the wellbore and reduce production pressure drop.The deviation of pressure drop between the results of laboratory experiments and numerical simulation is within 10%,which meets the error requirements.Finally,the structural parameters of the internal spiral tool were optimized under different working conditions through orthogonal tests.An optimized plate for the structural parameters of the internal spiral tool was established,which gave the best internal spiral tool for ten example wells in a gas reservoir.It can provide optimized selection basis for the practical application of internal spiral tools.