渗透性对不同煤层气井产气影响研究

发布时间：2018-06-21 00:16

本文选题：煤层气井 + 储层压力　；参考：《西安科技大学》2015年硕士论文

【摘要】：煤层气开采研究主要有两个重要环节,其一是最大限度使煤储层中吸附态甲烷脱离煤基质表面,成为游离气,即煤层气解吸;二是使储层中转化为游离态的甲烷气体最大限度产出,即煤层气排采。而在生产中,后者往往对前者起着促进作用,因为煤层气解吸需要储层压力降低至临界解吸压力之下,目前采用的手段主要是排水降压,若压降漏斗不能向外延伸,煤储层压力降亦不能有效向远处传递,煤储层压力降将受到限制,煤层气亦不能解吸出来。通过对大佛寺井田煤层气井排采过程中储层压降特征、影响半径变化规律及产气量控制模型建立的研究,将对开采区煤层气的开发具有参考价值。本文主要利用渗流力学原理,分析了煤层气垂直井与水平井随排采进行储层压降特征和压力分布规律。用地下水动力学原理,以导水系数表征煤储层渗透性,建立其与煤储层在排采过程中的影响半径计算模型。在研究大佛寺储层孔、裂隙及渗透率特征基础上,利用研究区典型垂直井和水平井的历史排采资料,进行了排采阶段划分,通过模型计算煤层气井不同排采阶段导水系数,然后根据Jacob公式计算垂直井影响半径,利用等面积转化得到水平井渗流边界,最后根据煤层气吸附解吸特征及压降规律建立了气井产气模型并应用于大佛寺井田。分析大佛寺井田垂直井和水平井产气模型结果,两者的计算结果与实际排采相近。煤层气直井排采曲线表现出“驼峰式”,最终计算产气量稳定在2200 m3/d左右;水平井排采曲线呈“单峰式”,计算结果显示最高产气量为34000 m3/d,排采曲线产气量随着井底流压的降低而增加,产气先增大再减小,符合煤层气井产气规律。产气模型在大佛寺井田中能很好的应用,并利用预测曲线对大佛寺井田煤层气井排采工作制度提出调整建议,以提高煤层气井的产气量和延长稳产时间。
[Abstract]:There are two important links in the study of coalbed methane production. One is to make the adsorbed methane in the coal reservoir escape from the coal matrix surface to become free gas, that is, the coal bed methane desorption; The second is the maximum production of methane gas which is converted to free state in the reservoir, that is, coal bed methane exhaust production. In production, the latter often plays a promoting role in the former, because the coalbed methane desorption requires the reservoir pressure to be lowered below the critical desorption pressure. The main means used at present are drainage and pressure reduction, if the pressure drop funnel cannot extend outwards, The pressure drop of coal reservoir can not be effectively transmitted to the distance, the pressure drop of coal reservoir will be restricted, and the coal bed methane can not be desorbed. The study on the characteristics of reservoir pressure drop, the law of influence radius change and the establishment of gas production control model in coalbed methane well of Dafosi mine field will be of reference value to the development of coalbed methane in mining area. Based on the principle of percolation mechanics, this paper analyzes the pressure drop characteristics and pressure distribution of coal bed methane vertical well and horizontal well with production. Based on the principle of groundwater dynamics, the permeability of coal reservoir is characterized by water conductivity coefficient, and the calculation model of influence radius between coal reservoir and coal reservoir in the process of discharging production is established. Based on the study of the pore, fissure and permeability characteristics of Dafosi reservoir, based on the historical production discharge data of typical vertical wells and horizontal wells in the study area, the stage of production discharge is divided, and the water conductivity coefficients of coal bed gas wells in different production stages are calculated by the model. Then the influence radius of vertical well is calculated according to Jacob's formula, and the seepage boundary of horizontal well is obtained by equal area transformation. Finally, according to the characteristics of coalbed methane adsorption and desorption and the law of pressure drop, the gas production model of gas well is established and applied to Dafosi well field. The gas production model results of vertical well and horizontal well in Dafosi mine field are analyzed. The production curve of coal bed methane vertical well shows "hump type", and the final calculated gas production is about 2200 m3 / d, while the horizontal well drainage curve shows "single peak" type. The results show that the maximum gas yield is 34000 m3 / d, and the gas production increases with the decrease of bottom hole flow pressure, and the gas production first increases and then decreases, which accords with the gas production law of coalbed methane wells. The model of gas production can be applied well in the Dafosi mine field, and some suggestions are put forward to adjust the work system of coal bed methane well drainage and production in Dafosi mine field by using the prediction curve, in order to increase the gas production rate of the coal bed gas well and prolong the stable production time.
【学位授予单位】：西安科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE37

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