Study On The Mechanical Properties Of Packer Rubber Based On Nanofluidic System

Packer rubber is the main sealing element of packers.Failure of packer rubber occurs from time to time in the process of well completion,water injection and fracturing in oil and gas fields.High temperature and pressure packer rubber used in China mainly depends on foreign imports.In this paper,a new type of packer rubber material based on nanofluidic system is proposed.The honeycomb matrix nanofluidic packer rubber is made of a composite elastic materials composed of bionics honeycomb matrix skeleton encapsulating nanofluidic system.Nanofluidic system possesses unique pressure-volume,temperature-volume variation characteristics thus can promote the mechanical property of packer rubber.The mechanical properties of the new packer rubber are studied in the current work.In this work,MCM-41-water system and β zeolite-water system are chosen as filling formulas for the new type of packer rubber.The pressure-volume characteristics of the two chosen nanofluidic systems are tested on the built experimental platform.The influencing law of different loading rates on infiltration pressure,effective pore volume and the relative outflow rate of functional fluids are obtained.The mechanical properties of honeycomb skeleton structure using to support nanofluidic system are studied by applying ANSYS Workbench finite element analysis software.The influencing law of the ratio of diameter to wall thickness and the height on the structure mechanics of honeycomb are obtained,and a suggested optimum size parameters of honeycomb structure is given.According to the setting condition of packer rubber,the finite element simulation analysis of the traditional packer rubber and the packer rubber coupling nanofluidic system’s characteristics are carried out.The influencing laws of setting load on the compression distance and contact stress of the packers rubber are investigated.According to experiment,both MCM-41-water system and β zeolite-water system can be used as filling formulas for the new type of packer rubber.The pressure threshold of the MCM-41-water system is 22 MPa,and the pressure threshold of the β zeolite-water system is25 MPa.During experiment,the external pressure is between 0 and 70 MPa and the loadingrate is within the range of 0.3 to 1.0 mm/s.The experimental results show that fluid molecules take less time to enter nanopores with the increase of loading rate.What’s more,with the increase of loading rate,the entry time of the fluid molecules becomes shorter and both the infiltration pressure and the relative outflow rate increases.According to numerical simulation results of the honeycomb skeleton structure,the diameter length of honeycomb skeleton structure is optimized to be 4 mm,the ratio of diameter to wall thickness is 3,and the height is10 mm.Numerical simulation of packer rubber shows that the compression distance of the nanofluidic packer rubber is smaller than a traditional one under the same setting load.The sealing performance of nanofluidic packer rubber is better as its contact length with casing is relatively long,and the contact stress between the packer rubber and the casing is larger comparing to a traditional one too.Therefore,the nanofluidic packer rubber possesses better sealing performance thus can reduce the risk of annulus sealing failure.