低渗气藏渗流机理及产能分析

发布时间：2018-11-11 15:01

【摘要】：在我国低渗气藏分布广泛,其储量在整个天然气储量中占据着相当大的比重。低渗气藏由于其孔喉细微、比表面积大、渗透率低,渗流机理十分复杂,若还是采用常规中高渗气藏的分析方法去评价低渗气藏的产能,导致会导致分析结果往往过于乐观。因此,亟需对低渗气藏的渗流机理和产能进行研究。以低渗气藏的产能为研究目标,在系统调研国内外研究成果的基础之上,深入系统地分析了低渗气藏低渗的渗流机理,包括低速非线性效应、启动压力梯度、应力敏感性以及高速非达西。而目前对于低渗气藏渗流机理的研究多是参照低渗油藏的思路来展开的,没有结合低渗气藏实际的物性特征和渗流规律。导致分析出的结果出现误差。将以上的气藏特殊渗流机理考虑进模型里,建立直井、垂直压裂井和水平井的产能方程。对于直井,分别建立在达西、高速非达西、启动压力梯度、滑脱效应及应力敏感的情况下,稳态和不稳态的产能方程。最终综合考虑多因素,建立稳态产能方程。对于垂直压裂井,分别用线性流+径向流模型和椭圆流模型,考虑有限导流和无限导流情况下,建立产能方程,并对比运算结果。对于水平井,利用椭圆流模型建立综合考虑多因素的产能方程。最终,对影响气井产能的不同参数进行敏感性分析。最后,分析了由于对机理认识不清所导致产能曲线的异常原因,包括启动压力梯度、滑脱效应和应力敏感等,并给出了相应的解决办法。结合低渗气藏的特殊渗流机理,推导出针对低渗气藏渗流特征的一点法产能公式。
[Abstract]:Low permeability gas reservoirs are widely distributed in China, and their reserves occupy a large proportion of the total natural gas reserves. Because of its fine pore throat, large specific surface area, low permeability and complicated percolation mechanism, the low permeability gas reservoir can be used to evaluate the productivity of low permeability gas reservoir if the conventional analysis method of medium and high permeability gas reservoir is adopted, which will lead to too optimistic analysis results. Therefore, it is urgent to study the percolation mechanism and productivity of low permeability gas reservoirs. Taking the productivity of low permeability gas reservoir as the research goal, and on the basis of systematic investigation and research results at home and abroad, the percolation mechanism of low permeability gas reservoir is analyzed in depth and systematically, including low speed nonlinear effect, starting pressure gradient. Stress sensitivity and high speed non-Darcy. At present, the research on the percolation mechanism of low permeability gas reservoir is carried out according to the thinking of low permeability reservoir, and there is no combination of physical characteristics and percolation law of low permeability gas reservoir. The result of the analysis is error. Taking the special percolation mechanism into account, the productivity equations of vertical fracturing wells and horizontal wells are established. For vertical wells, the productivity equations of steady and unsteady state are established under the conditions of Darcy, high speed non-Darcy, starting pressure gradient, slippage effect and stress sensitivity respectively. Finally, considering the multiple factors, the steady productivity equation is established. For vertical fracturing wells, linear radial flow model and elliptical flow model are used to establish productivity equations under the condition of finite and infinite diversion, respectively, and the calculation results are compared. For horizontal wells, an elliptical flow model is used to establish a productivity equation with comprehensive consideration of multiple factors. Finally, sensitivity analysis of different parameters affecting gas well productivity is carried out. Finally, the abnormal causes of productivity curve caused by unclear understanding of the mechanism are analyzed, including starting pressure gradient, slip effect and stress sensitivity, and the corresponding solutions are given. Combined with the special percolation mechanism of low permeability gas reservoir, a one-point productivity formula for percolation characteristics of low permeability gas reservoir is derived.
【学位授予单位】：中国石油大学(华东)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE312;TE328

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