基于腐蚀实验与寿命预测的页岩气井套管生产安全风险研究

发布时间：2018-01-11 16:14

本文关键词：基于腐蚀实验与寿命预测的页岩气井套管生产安全风险研究　出处：《重庆科技学院》2015年硕士论文　论文类型：学位论文

【摘要】：由于套管的损坏，，油气田的正常生产会受到严重影响。目前，套管损坏问题研究已成为国内外石油天然气开采中急需解决的重要问题之一。油气井自身技术和所处环境都十分复杂，目前，尚未找到有效的预防套管损坏的方法。套管损坏后再采取补救措施，不仅耗时费力，而且效果也不甚理想。长久以来，普遍认为引起套管损坏的因素可大致分为腐蚀因素、工程因素、地质因素、开发因素四大类。其中，由腐蚀因素造成套管强度降低而损坏的事故频频发生。因此，研究套管腐蚀损坏机理和对套管实际使用中的腐蚀情况进行监测预测具有重要的理论意义和实用价值。本文以中国西南某页岩气开采区块一期产建区为工程依托，针对采用套管进行生产具有的安全风险，考虑到页岩气井具体的生产工艺和特点，在国内外研究基础之上，通过系统地分析和研究气田复杂井况下套管腐蚀损坏的各种因素和机理，设计出合理可行的现场挂片实验的方法，研究页岩气井套管的腐蚀与磨损情况，在此基础上，通过数学方法对页岩气井的套管腐蚀速率进行预测，进而对套管的安全性和使用寿命进行评价和预测。论文主要工作与取得成果如下：（1）对引起套管损坏的腐蚀因素进行了分类分析，主要分析了酸性物质、盐性物质、硫化氢、细菌与磨损对套管的腐蚀的影响。介绍了均匀腐蚀和局部腐蚀两种常用的套管腐蚀模型和腐蚀速率预测模型。对CO2浓度、流速、温度、氯离子、碳酸根离子、硫酸根离子和钙镁离子对套管腐蚀的影响规律及其作用机理进行了分析，为对套管使用寿命进行预测和安全评价提供了基础。（2）对该页岩气区块的页岩气组分和出水水质、压力温度产量、井身结构和套管设计等各个方面的情况进行分析，为现场挂片实验的设计和套管寿命预测提供了基础。分析表明：1）页岩气组分中的CO2和地层出水中所含的阳离子（Ca2+、Mg2+）与阴离子（Cl－、HCO3、SO24）含量均会对套管腐蚀情况造成影响；2）项目采用套管完井的井身结构方案，生产套管采用外径为139.7mm，材质为TP110T，壁厚为12.34mm的套管。（3）为了客观准确地分析该页岩气区块页岩气井的腐蚀状况，本论文设计出一种合理可行的现场挂片实验方法，即从已经试采的25口井中选择n口井进行挂片实验研究，然后通过数学方法和计算机技术对实验数据进行分析，将实验结果推广到其他未测试井中。（4）挂片实验过程中，监测对温度、流速、压力等腐蚀影响因素，并测量不同测试井的CO2浓度和各种阳离子（Ca2+、Mg2+）与阴离子（Cl－、、）含量，采用多元回归分析或者神经网络进行定量关系的数学拟合，得到各种影响因素与腐蚀速率的定量关系。从工程安全的角度，确定出不同阶段各项影响因素的可能达到的最不利值，通过计算得出相应阶段的可能最大腐蚀速率。根据相应的腐蚀速率和腐蚀时间，则可以评定套管腐蚀损伤等级，并对套管的腐蚀寿命和剩余强度进行预测。
[Abstract]:Due to casing damage, the normal production of oil and gas fields will be seriously affected. At present, the problem of casing damage has become one of the important problems of domestic and international oil and gas exploration needs to be resolved. Its oil and gas technology and environment are very complex. At present, the effective method for preventing casing damage has not been found. After casing damage to take remedial measures, not only time-consuming, and the effect is not ideal. For a long time, generally believe that the factors causing casing damage can be divided into corrosion factors, engineering factors, geological factors, development factors in four categories. Among them, the corrosion factors of casing strength reduce damage caused by accidents occur frequently. Therefore, research the damage mechanism of casing corrosion and the actual use of casing corrosion has important theoretical significance and practical value for monitoring and forecasting.
In this paper, Chinese southwest a shale gas block a production building area based on the project, the production of casing safety risk, considering the production process and the specific characteristics of shale gas, both at home and abroad on the basis of the study, through a variety of factors and the mechanism of systematic analysis and Research on gas field under complex well conditions of casing corrosion damage the design method is reasonable and feasible field test, and the wear corrosion of shale gas well casing, on this basis, predicted by the mathematical method of casing corrosion rate of shale gas, and the safety and service life of the casing for evaluation and prediction. The main work and achievements are as follows:
(1) to cause corrosion of casing damage is analyzed, the main analysis of the acidic substances, substances, salt of hydrogen sulfide, affecting bacteria and wear corrosion of the casing. The uniform corrosion and local corrosion of two kinds of commonly used model of casing corrosion and corrosion rate prediction model. The concentration of CO2, flow rate. Temperature, chloride, bicarbonate ions, and the mechanism of influence of casing corrosion of sulfate ion and magnesium ions were analyzed to predict and provide the basis for safety evaluation on the service life of the casing.
(2) the group of shale gas shale gas blocks and effluent water quality, temperature and pressure of production, by the analysis of well structure and casing design and other aspects of the situation, provide the basis for the design and life prediction for casing field immersion test. The results show that: 1) cation containing components in shale gas CO2 and formation water in (Ca2+, Mg2+) and anion (Cl, HCO3, SO24) content will affect the casing corrosion; 2) project by wellbore casing completion, the production casing diameter is 139.7mm, the material is TP110T, the wall thickness of 12.34mm tube.
(3) in order to objectively and accurately analyze the corrosion status of shale gas blocks in shale gas wells, this paper designs a reasonable and feasible field test method, namely n wells hanging experiments from the production has 25 wells, and then through the experimental data on mathematical methods and computer technology analysis the experimental results, will be extended to other non test wells.
(4) test process, monitoring of temperature, velocity, pressure and other factors affecting the corrosion, and measure the different test wells and CO2 concentration of various cations (Ca2+, Mg2+) and anions (Cl,,) content, mathematical fitting relationship determined by multiple regression analysis and neural network, quantitative the relationship between the various influencing factors and corrosion rate. From the engineering safety point of view, to determine the different stages of the various influencing factors may reach the most disadvantageous value, the maximum possible corrosion rate of the corresponding period of the calculated. According to the corrosion rate and corrosion time, can damage assessment level of casing corrosion, and corrosion life of casing and the residual strength prediction.

【学位授予单位】：重庆科技学院
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE931.2

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