Research Of Drilling And Well Completion Fluid Protecting Reservoir In Yanchang Group Of Xiqu Oilfield

The low frequency pressure pulse technology*making the wave energy produced by lowrfequency pressure pulse act on oil layer and oil layer, as well as its lfuid，produce physicaland chemical changes, is to improve oil layer seepage condition, remove reservoir jam, createthe environment benefiting crude oil flow and obtain the aim that oil wells production increaseand injecting volume of injection well increase. For further understanding of the mechanismof oil displacement and increasing production by low rfequency pressure pulse, in this articlemainly aiming at the effect the low frequency pressure pulse has on oil-water seepage in lowpermeability reservoirs, the detailed research is done, mainly through the pulse experiment ofreal sandstone microscopic model and the pulse expeirment of core single-phase oil andoil-water two-phase, the effect the low rfequency pressure pulse has on micro residual oildistirbution and displacement eiffciency and the iMPact it has on single-phase oil, the seepagecurve of oil-water two phase，displacement eiffciency，as well as the moisture content, areanalyzed and summairzed. On account of the property that its energy will constantlyattenuation when the low rfequency pressure pulse spread in actual oil layer, therefore, infinally mathematical model of the propagation of the low frequency pressure pulse in thereservoir is built and the one-dimensional model of the low rfequency pressure pulsepropagation is solved, combined with the solution of the one-dimensional propagation model,the propagation property of low rfequency pressure pulse wave in oil reservoir is discussed.Through the indoor experiment research and computation of mathematical model, thefollowing results are obtained:(1)The low rfequency pressure pulse has a great effect on displacement efficiency andresidual oil distirbution of the real sandstone microscopic model. After the low frequencypressure pulse function, the residual oil saturation is reduced and the average residual oilsaturation is reduced by2.95%, the displacement efficiency is improved and the aveargedisplacement efifciency is increased by6.6%.(2)The low frequency pressure pulse has a major effect on the permeability of coresingle-phase oil, when pressure gradient is low，the permeability of oil phase increase with alarger extent, when pressure gradient gradually increases, the pulse effect significantly is weakened and the increase extent of oil phase permeability is decreased gradually.(3)When the amplitude of the low frequency pressure pulse,2.95MPa-4.3MPa,is bigger, thelfow area of oil-water two phase become wider, the equal permeability point is higher, underthe condition of residual oil saturation the water phase relative permeability is bigger,coMPared with conventional flooding, the pulse function greatly broadens the channel of oiland water flow and improve the flow ability of the oil and water. When the amplitude of thelow frequency pressure pulse is bigger than4MPa, the displacement eiffciency within nowater peirod and the final displacement efifciency are both improved, the irsing speed ofmoisture content is also fallen.(4)When the low rfequency pressure pulse spread in oil layer, with the decline of oil phaseviscosity, the increase of reservoir permeability, the decrease of the pulse frequency, theattenuation speed of the low frequency pressure pulse amplitude is more slow, the effectivepropagation distance is further. Excellent results have been achieved inits practical application.