大佛寺井田煤—水—甲烷作用研究

发布时间：2018-04-03 20:19

本文选题：大佛寺井田　切入点：低阶煤　出处：《西安科技大学》2017年硕士论文

【摘要】：彬长矿区地处鄂尔多斯盆地南部渭北隆起北缘,为典型侏罗纪低阶煤开采区。选取区内大佛寺井田4#煤储层为研究对象,基于煤层气地质学、界面物理化学、表面活性剂化学等基础理论知识,主要采用大样量煤层气吸附/解吸实验测试和吸附势预测理论分析相结合的方法,通过热力学定量计算与定性分析,从煤储层微观角度研究煤、水、甲烷共存下的固-液-气三相耦合体系,探究相间作用关系,最终揭示煤-水-甲烷作用模式。论文主要获得以下成果和认识:(1)基于Polanyi吸附势理论,以储层温度下的实测数据为依据,建立了考虑“逸度”影响在内的修正的温-压综合吸附预测模型。进而预测了不同类型煤样(空干基煤样、平衡水煤样、不同润湿煤样)在不同温压下的等温吸附/解吸参数,发现实验条件(温压受限)和极限条件(理想温压)下的吸附量和吸附热变化规律不同,可能是温度、压力和润湿剂综合影响下的水分-甲烷作用过程差异所导致。(2)较高的水分、灰分含量,高氧含量以及高惰质组、低镜质组含量,丰富的含氧官能团种类和发育的孔、裂隙是使大佛寺低阶煤煤体亲水良好的内在原因。外因方面,不同类型表面活性剂性质对润湿性影响不同,润湿性由强到弱依次为:正润湿剂、蒸馏水、排采水、负润湿剂。(3)“水分”对甲烷存在置换作用和解吸作用两方面影响。温度、压力和润湿剂综合影响置换解吸效果,置换作用方面,升压促进置换效应,升温则抑制,平衡水样与正润湿样产生甲烷置换正效应,负润湿样产生置换负效应。解吸作用方面,在相对低压段,单位压降更利于甲烷解吸,升压解吸参数减小,低压解吸滞后率大,高压则趋于平缓;升温解吸参数增大,高温解吸滞后则减弱。(4)表面自由能和润湿热的计算证实液态水润湿(加活性剂处理)放出热量可有效促进吸附态甲烷解吸。(5)煤基质中气态水的形成与孔隙结构有关,水分运移主要以液态水润湿和气态水扩散(蒸发)两种形式,气态水对吸附态甲烷形成置换解吸,液态水一定程度上可能利于甲烷的吸附。大佛寺低阶煤煤层气解吸实质是压降传递(能量作用)和汽化水蒸气(置换效应)共同作用的结果。
[Abstract]:Binchang mining area is located in the north edge of Weibei uplift in the south of Ordos Basin, which is a typical Jurassic low rank coal mining area.Taking the coal reservoir of Dafosi mine field as the research object, based on the basic theoretical knowledge of coal bed methane geology, interface physical chemistry, surfactant chemistry and so on,By combining the experimental test of adsorption / desorption of large amount of coal bed methane with the theoretical analysis of adsorption potential prediction, through thermodynamic quantitative calculation and qualitative analysis, coal and water are studied from the microscopic point of view of coal reservoir.The solid-liquid-gas three-phase coupling system under the coexistence of methane is used to explore the interaction relationship between phases and finally reveal the mode of coal-water-methane interaction.Based on the theory of Polanyi adsorption potential and the measured data of reservoir temperature, a modified prediction model of temperature pressure comprehensive adsorption considering the influence of fugacity is established in this paper.Furthermore, the isothermal adsorption / desorption parameters of different types of coal samples (dry coal samples, equilibrium water coal samples, different wetting coal samples) at different temperatures and pressures were predicted.It is found that the variation of adsorption capacity and adsorption heat is different between the experimental conditions (temperature and pressure limitation) and the limit condition (ideal temperature and pressure), which may be temperature.Under the combined influence of pressure and wetting agent, the difference of water-methane interaction process resulted in higher moisture, ash content, high oxygen content, high inertinite group, low vitrinite content, abundant oxygen-containing functional groups and developing pores.Fissures are the internal reasons for the hydrophilicity of low rank coal in Dafosi.In terms of external factors, the properties of different types of surfactants have different effects on wettability. The order of wettability from strong to weak is: positive wetting agent, distilled water, drain water,Negative wetting agent. 3) "moisture" has two effects on methane displacement and desorption.Temperature, pressure and wetting agent comprehensively affect the displacement desorption effect. In the displacement effect, the pressure boosts the displacement effect, the temperature rise is restrained, the balance water sample and the positive wetting sample produce the methane displacement positive effect, the negative wetting sample produces the displacement negative effect.In terms of desorption, the unit pressure drop is more favorable for methane desorption in the relative low pressure section, and the pressure boost desorption parameter decreases, the low pressure desorption hysteresis rate is large, the high pressure desorption hysteresis rate tends to be gentle, and the temperature rise desorption parameter increases.The calculation of surface free energy and moist heat of high temperature desorption hysteresis shows that the heat released by liquid water wetting (plus active agent treatment) can effectively promote the formation of gaseous water in adsorbed methane desorption. 5) the formation of gaseous water in coal matrix is related to pore structure.Water migration is mainly in the form of liquid water wetting and gaseous water diffusion (evaporation). Gaseous water forms displacement desorption of adsorbed methane, and liquid water may be beneficial to methane adsorption to some extent.The desorption of low rank coal bed methane in Dafosi is the result of both pressure drop transfer (energy effect) and vaporized water vapor (displacement effect).
【学位授予单位】：西安科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD712;P618.11

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