Performance And Preparation Of Liquid Gel Plug With Magnetorheological Fluid

Liquid gel is a temporary plugging agent for low pressure oil and gas wells,such as potential recovery,sand filling temporary plugging fracturing,horizontal well segmented temporary plugging and fracturing.In view of traditional temporary plugging agent which cannot provide sufficient strength,toughness and gelation time,a new temporary plugging agent based on magneto-rheological fluid?MRF?can make up for these disadvantages in principle and has a better application potential.MRF mainly consists of magnetic particles,carrier fluid,and additives.With a magnetic field,MRF varies from fluid to semi-solid phases and has a unique rheological characteristic.Therefore,a kind of MRF which has high settlement stability,good temperature resistance,simple preparation method and its fluid properties and magnetic rheological characteristic were studied.Finally,the temporary plugging effect of MRF on core is studied through laboratory experiments,which provides a basis for the feasibility study of its application in the field.Fe₃O₄ nanoparticles were prepared by chemical coprecipitation method and X-ray diffraction?XRD?and scanning electron microscope?SEM?analysis indicated Fe₃O₄ particles composition of high purity,smaller and narrow particle size distribution about 30 nm.By comparison,Fe₃O₄ nanoparticles are more suitable for the preparation of MRF than carbonyl iron powder.Through the orthogonal design experiment,a kind of MRF with good settlement stability was prepared and its component content as follows:magnetic particles Fe₃O₄ 65%,surface modifier RX 8%,thixotropic agent SiO₂ 3%,dispersant PVP 3%.The apparent viscosity of MRF decreases with the increase of temperature in the range of 25⁹5 C,and the settlement rate increases with the increase of temperature,and the change of viscosity and settlement is reversible.The rheological properties of the MRF study found that without magnetic field MRF is a shear thinning fluid Bingham;under magnetic field,MRF's apparent viscosity and shear yield stress decreases as the magnetic field increases significantly increased,can be as high as 75.265KPa,s and 74.453KPa respectively,and the relationship between shear stress with the shear rate meets the Bingham model,so this model can be used to obtain the fitting calculation of shear yield strength.Finally,the MRF for core plugging experiments showed enhanced plugging effect with magnetic field was better.Under 0.6T,the compressive strength is up to 15.81MPa,the plugging rate is higher than 97%,and the damage rate of permeability is lower than 5%.Compared with the traditional temporary plugging agent,the MRF temporary plugging agent has realized real time control,high efficiency and small pollution,which has a better application potential.