The Research On Effects Of Cement Sheath And Reinforce Fiber Strengthening To Gas Storage Well

As the trend of developing clean energy strongly in our country strengthens, Gas storage well as a new type underground gas storage device with the advantages of covering a small area, low fire radius, constant temperature storage, etc is getting a number of popularization and application. Along with the application of gas storage well and use time increasing, in the gas storage well inspection, manufacture and use of gas storage well it is found that gas storage well not only has the security hidden danger of the well barrel flying out, the well barrel up, well barrel up and down, but also generate a lot of economic loss of economic loss due to decompression and stop using. In order to ensure the safety of gas storage well and the economic benefit of step-down well and stop-using well, the research reports of gas storage well increase year by year, CSEI, DUT and other research institutions jointly drafted the gas storage well national standard also has entered the stage of approval, which can standardize the market order in a certain extent, and promote the development of the gas storage well.Strengthen the intension gas storage well is an important means to improve the security and effectiveness of gas storage well, cement sheath and fiber-reinforced can bring into play in the process of strengthening the intension gas storage well. Cement sheath as an important part of gas storage well, can limit the deformation of gas storage well and strengthen gas storage well; fiber-reinforced can increase the intensity ofdefects of tube well, it is an important means to restore normal use of step-down well and stop-using well, however, the research on the impact of cement sheath and fiber-reinforced taking to strength of gas storage well for a long time, and the related research is almost in a blank state. Based on the demand for the development of gas storage well and the urgency of the situation to restore the normal use of tep-down well and stop-using well, the main research contents and conclusions of the paper are as follows:(1) The paper built an underground gas storage well test well according to the actual construction of gas storage well, and measured the well barrel strain under different internal pressure before and after the cementing the well respectively, according to the test data,it mainly got the following conclusions:cement sheath has stronger strengthening effect to the axial well barrel, cement sheath can make circumferential stress and axial stress of well barrel reduce by16%and16%respectively after well cementation; the rise of internal pressure can strengthen the effect of the cement ring to the circumferential well barrel, but the axial strength effect is affected little by internal pressure.(2) It established finite element models of well barrel centered, hole diameter expansion and eccentric well barrel, and studied the influence of hole diameter expansion, eccentric well barrel on the strengthen effect of cement ring in combination with cement ring and stratum mechanics property parameters, it mainly got the following conclusions:high modulus of cement ring and high stiffness of stratum can improve the strengthen effect of cement sheath significantly, the strengthen coefficient of cement ring can be enhanced by0.13and0.09to0.36and0.4. The hole diameter expansion occurring on soft stratum can reduce the strengthen effect of the cement ring significantly, the decreasing amplitude is36%; eccentric of well barrel occurring on soft stratum can reduce the strengthening coefficient from0.22to-0.14, but if the decentered degree is less than33%, eccentric of well barrel has a little effect on strengthening coefficient, the decreasing amplitude of strengthening parameter only0.045.(3) It established the finite element model of single-point corrosion, local corrosion and uniform corrosion, and studied the influence of reinforce layer thickness and the size of the corrosion defects on stress of the well barrel and layer of Reinforcement,it mainly got the following conclusions:it can make the membrane stress of well pipe and the maximum stress reduced to less than the allowable stress and yield strength respectively for different corrosion types and corrosion depth by adding reinforcing layer thickness; the thickness of carbon fiber reinforcing layer is mainly determined by the depth of corrosion, under the same corrosion depth, the smaller hoop angle of defect, the smaller reinforcing layer number required, the gap of layer thickness to different types of corrosion is from0.5mm to1mm.