低渗致密砂岩气体滑脱流动机理研究

发布时间：2018-01-09 11:38

本文关键词：低渗致密砂岩气体滑脱流动机理研究　出处：《断块油气田》2017年03期 　论文类型：期刊论文

【摘要】：以苏里格气田盒8段低渗致密砂岩为研究对象,开展了常规条件下(出口端为大气压)和回压条件下的气体滑脱流动实验。结果表明:无回压条件下,相对高渗岩样的气测渗透率与平均压力倒数关系符合Klinkenberg模型,对于相对低渗且孔隙半径更小的岩样,则需要采用二次曲线模型描述;当施加回压时,气体滑脱随回压的增大而减弱,达到临界回压时,气测渗透率趋于稳定,但该临界值随岩样渗透率的减小而增大。分析认为,Knudsen数(Kn数)能综合反映渗透率(平均孔隙半径)和气体压力(回压)对气体滑脱程度的影响。高压压汞表明,研究区块渗透率越低的岩样,具有更小的孔隙半径,从而具有更大的Kn数,产生更强的气体滑脱;增大回压有助于减小分子平均自由程,从而减小Kn数,弱化甚至消除气体滑脱效应。
[Abstract]:Taking the low permeability tight sandstone in Bo8 section of Sulige gas field as the research object, the gas slippage flow experiments under conventional conditions (atmospheric pressure at outlet end) and backpressure conditions are carried out. The results show that there is no backpressure condition. The reciprocal relationship between gas permeability and average pressure of relatively high permeability rock samples is in line with Klinkenberg model. For rock samples with relatively low permeability and smaller pore radius, the quadratic curve model should be used to describe the rock samples. When the back pressure is applied, the gas slippage weakens with the increase of the back pressure, and when the critical pressure is reached, the gas measured permeability tends to be stable, but the critical value increases with the decrease of the rock sample permeability. Knudsen number and Kn number can comprehensively reflect the influence of permeability (mean pore radius) and gas pressure (back pressure) on the degree of gas slippage. High pressure mercury pressure shows that the lower the permeability of the studied block is, the lower the rock sample is. With a smaller pore radius, it has a larger Kn number, resulting in stronger gas slippage. Increasing the back pressure can reduce the average free path of the molecule, decrease the Kn number, weaken or even eliminate the gas slippage effect.
【作者单位】：中国石油长庆油田分公司苏里格气田研究中心;低渗透油气田勘探开发国家工程实验室;
【基金】：国家科技重大专项“鄂尔多斯盆地大型低渗透岩性地层油气藏开发示范工程”(2016ZX05050)
【分类号】：TE31
【正文快照】： 0引言气体在多孔介质中的流动存在气体滑脱现象。通常,岩石孔隙直径越小,气体滑脱现象越显著[1-2]。对于致密砂岩气等非常规资源,由于储层微纳米级孔隙发育,气体的滑脱行为及其对渗透率和气体产出过程的影响备受重视[3]。1941年Klinkenberg[4-5]实验证实了气体滑脱效应,并给出

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