Experimental Study On Seepage Law Of YKL High Temperature And High Pressure Condensate Gas Reservoir

YKL gas reservoir belongs to high temperature and high pressure condensate gas reservoir.In the development process of the past ten years,Due to the implementation of the mist retrograde condensation control technology in the production process,the actual development effect is higher than the program expectation.Although some understandings and achievements have been made in the early stage,the phase characteristics of the hazy flow and the seepage mechanism are complicated,and the conditions and influencing factors are not clear.It is difficult to determine the conditions that the mist retrograde condensation control needs to meet.In addition,The field implementation of retrograde condensate control also lacks quantitative basis.For the problems in the development of YKL condensate gas reservoirs,the internal experimental evaluation method,fluid phase equilibrium theory,gas reservoir engineering,etc.are used to make the phase characteristics of the YKL gas reservoir,the fogging reverse condensate control conditions and the influencing factors.analysis.On this basis,the experimental study of indoor gas-oil two-phase seepage,combined experimental study of combined long core decondensation damage,experimental study of hazy flow core flow and analysis of the influence of reverse condensate control on gas well productivity were carried out.The study mainly achieved the following conclusions:(1)The phase study shows that the YKL condensate gas reservoir is a condensate gas system with medium to high gas-to-oil ratio and medium condensate type,and its expansion capacity is low.At the same pressure drop speed,as the pressure decreases,the fog-like features change from concentrated to shallow,and the time when the fog-like features exist is gradually shortened.As the pressure drop velocity increases,the fog-like features become more and more concentrated at the same pressure level,and the time when the fog-like features exist is longer and longer,but the pressure drop interval in which the fog-like features exist becomes more and more narrower.In addition,as the pressure drop rate increases,the degree of condensate recovery in the pressure zone where the mist flow exists is higher and higher,but the degree of natural gas recovery is not obvious;(2)Gas-oil two-phase seepage experiments show that for high and low permeability cores,the larger the displacement pressure difference,the higher the isotonic point and the shift to the right,indicating that the seepage resistance is reduced,which is conducive to oil and gas flow.The smaller the displacement pressure difference is,the gas permeability of the low permeability core is stronger than that of the high permeability core;the high permeability core is more aerobic than the low permeability core,and the smaller the residual oil saturation,the higher the oil displacement efficiency;(3)The anti-condensation pollution experiment shows that the proper increase of the pressure drop speed can help to reduce the reverse condensate damage in the near-well zone to a certain extent;(4)The flow experiments of the hazy flow core show that during the failure process of pressure drop rates of 1 MPa/h,2 MPa/h,3MPa/h and 4MPa/h,the cumulative recovery of condensate increases as the pressure drop rate increases.However,when the pressure drop rate is 3 MPa/h and 4 MPa/h,the cumulative output of condensate is not much different.The degree of natural gas production at the pressure drop rate of the four groups is not much different.The degree of recovery in the four experimental condensate stages has one thing in common.In the condensate stage,the degree of recovery first decreases and then increases and then decreases,and the corresponding gas-oil ratio increases first and then decreases and then increases;(5)The evaluation of the influence of the mist flow on the gas well productivity shows that at the appropriate pressure drop rate,the higher the pressure drop rate,the stronger the mist flow,and the lower the reverse condensate oil saturation in the near well area.The higher the degree of condensate recovery.