【摘要】：壓裂泵作為油氣田增儲上產(chǎn)的重要壓裂設(shè)備,要求其具有性能穩(wěn)定和工作可靠等特點,但壓裂泵液力端閥箱破裂失效事故頻發(fā),工作壽命和利用率普遍偏低,已嚴重影響壓裂工藝效率,成為提升壓裂裝備整體性能的瓶頸之一。為確定閥箱失效模式、裂紋擴展機理和查找失效原因,本論文結(jié)合了材料學、斷裂力學、金相學、有限元技術(shù)和強化處理工藝等理論,對報廢閥箱從實驗檢測到理論分析等角度出發(fā),深入開展了閥箱的疲勞損傷機理和疲勞壽命預測研究,主要進行的研究工作如下：(1)通過廣泛查閱、檢索國內(nèi)外文獻資料,深入調(diào)研分析了現(xiàn)有壓裂泵的性能和使用情況,全面系統(tǒng)地了解、掌握和研究了國內(nèi)外壓裂泵的技術(shù)發(fā)展動態(tài)。經(jīng)過對閥箱失效模式、失效準則的研究以及綜合現(xiàn)場失效數(shù)據(jù)分析,認為疲勞開裂是閥箱最主要和最危險的失效模式；(2)對閥箱材料進行了化學成分檢驗、金相觀察以及硬度測試一系列理化檢測試驗�；瘜W成分檢驗表明,閥箱材料中含有較多的耐腐蝕和耐磨損合金元素,針對閥箱易腐蝕、易磨損等惡劣服役條件,起一定的緩解作用：金相觀察說明閥箱熱處理工藝較合理,材料基體組織為回火索氏體和鐵素體,未發(fā)現(xiàn)夾雜物、組織偏析、氣孔等先天性缺陷；硬度測試闡明,工作介質(zhì)對閥箱材料有腐蝕作用,閥箱內(nèi)腔表面附近區(qū)域材料的硬度值下降明顯,易形成腐蝕缺陷而誘發(fā)裂紋萌生；(3)開展了失效閥箱裂紋的斷口定性分析,確定了閥箱開裂為疲勞所致。宏觀形貌觀察表明閥箱裂紋為非連續(xù)性生長,且直線型裂紋居多。微觀形貌分析揭示,斷口表面上的疲勞條紋以脆性方式擴展；(4)建立了閥箱有限元模型,引入全壽命、裂紋萌生、裂紋擴展等方法進行疲勞壽命預測,仿真結(jié)果表明：裂紋萌生預測結(jié)果與閥箱實際損傷情況吻合較好,即閥箱內(nèi)腔相貫線處和閥座座孔錐面為疲勞薄弱區(qū)域,且閥箱應(yīng)力集中峰值已接近疲勞極限,閥箱的高交變應(yīng)力是閥箱疲勞損傷的直接原因；(5)綜合探討了自增強技術(shù)、表面強化工藝、表面加工精度以及材料選擇等各種提高閥箱疲勞壽命的措施和效果,研究表明自增強和噴丸技術(shù)能有效提高閥箱疲勞壽命,建議選用強度較高且韌性良好的材料作為閥箱坯料；(6)通過閥箱材料拉伸力學性能測試、常規(guī)疲勞測試、腐蝕疲勞測試等試驗,掌握了閥箱材料的基本力學性能,獲得S-N曲線,以及腐蝕對疲勞壽命的影響效果。試驗測試數(shù)據(jù)表明在613Mpa應(yīng)力水平下,腐蝕能降低50%左右的疲勞壽命。總之,通過本論文的研究工作,確定了閥箱的失效模式、失效機理和失效原因。建立了閥箱不同疲勞壽命預測方法。從閥箱選材、結(jié)構(gòu)改進和制造強化工藝方面,探討了提高閥箱疲勞壽命的措施。為壓裂泵閥箱研制提供了一些新的思路和研究方法。因此,本論文的研究工作具有一定的實際應(yīng)用價值。
[Abstract]:Fracturing pump is an important fracturing equipment for increasing reservoir and production in oil and gas field. It is required to be stable in performance and reliable in work. However, the fracture failure of hydraulic end valve box of fracturing pump is frequent, and its working life and utilization ratio are generally low. It has seriously affected the efficiency of fracturing process and has become one of the bottlenecks in improving the overall performance of fracturing equipment. In order to determine the failure mode of valve box, crack growth mechanism and find out the failure reason, this paper combines the theory of material science, fracture mechanics, metallography, finite element technology and strengthening treatment technology. In this paper, the fatigue damage mechanism and fatigue life prediction of end-of-life valve box are studied from the point of view of experimental detection and theoretical analysis. The main research work is as follows: (1) through extensive reference, the domestic and foreign literature is retrieved. The performance and application of the existing fracturing pump are investigated and analyzed deeply, and the technical development of fracturing pump at home and abroad is understood, grasped and studied in a comprehensive and systematic way. Through the study of valve box failure mode, failure criterion and comprehensive field failure data analysis, it is concluded that fatigue cracking is the most important and dangerous failure mode of valve box. (2) the chemical composition of valve box material is tested. Metallographic observation and hardness test a series of physical and chemical tests. The examination of chemical composition shows that there are many corrosion resistant and wear resistant alloy elements in the valve box material, which plays a certain role in alleviating the bad service conditions such as easy corrosion and wear of the valve box. The metallographic observation shows that the heat treatment process of the valve box is more reasonable. The matrix structure of the material is tempering Soxhlet and ferrite without any inherent defects such as inclusions, tissue segregation, porosity, etc. The hardness test shows that the working medium has corrosive effect on the valve box material. The hardness of the material near the surface of the inner cavity of the valve box is obviously decreased, and the corrosion defects are easily formed and the crack initiation is induced. (3) the fracture surface of the failure valve box is analyzed qualitatively, and it is determined that the crack of the valve box is caused by fatigue. The macroscopic observation shows that the cracks in the valve box are discontinuous growth, and the linear cracks are the most. The microscopic morphology analysis revealed that the fatigue fringes on the fracture surface propagated in a brittle manner. (4) the finite element model of valve box was established to predict the fatigue life by introducing the methods of whole life, crack initiation, crack propagation, etc. The simulation results show that the prediction results of crack initiation are in good agreement with the actual damage of the valve box, that is, the intersecting line of the inner cavity of the valve box and the cone of the valve seat hole are the weak area of fatigue, and the peak value of stress concentration of the valve box is close to the fatigue limit. The high alternating stress of the valve box is the direct cause of the fatigue damage of the valve box. (5) the measures and effects to improve the fatigue life of the valve box, such as self-strengthening technology, surface machining precision and material selection, are discussed. The research shows that self-reinforcing and shot peening technology can effectively improve the fatigue life of valve box. It is suggested that the materials with high strength and good toughness should be used as the valve box blank. (6) through the testing of tensile mechanical properties of valve box material, the routine fatigue test is carried out. The basic mechanical properties of valve box material, S-N curve and the effect of corrosion on fatigue life were obtained through corrosion fatigue test and so on. The test data show that corrosion can reduce fatigue life by about 50% at 613Mpa stress level. In a word, the failure mode, failure mechanism and failure reason of valve box are determined by the research work in this paper. The prediction method of different fatigue life of valve box is established. The measures to improve the fatigue life of valve box are discussed from the aspects of valve box material selection, structure improvement and manufacturing strengthening technology. Some new ideas and research methods are provided for the development of fracturing pump valve box. Therefore, the research work of this paper has certain practical application value.
【學位授予單位】：西南石油大學
【學位級別】：碩士
【學位授予年份】：2012
【分類號】：TH322

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相關(guān)期刊論文 前1條

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本文編號：2121788