蒸发混相驱提高挥发油采收率影响因素数值模拟分析

影响挥发油藏蒸发混相驱采收率的因素大致分为地质因素和工程因素两类。地质因素主要是油藏纵向非均质性和油层厚度 ,其中前者的影响十分显著。油藏纵向非均质用韵律、垂向渗透率对数正态分布均值和变异系数、垂向渗透率与水平渗透率比值等 4个参数来描述 ;工程因素包括井距、注入方式 (注气或气水交替 )、溶剂注入量、气水交替频率、射孔位置等。研究结果如下 :①应认真筛选注气蒸发混相驱的油藏 ,反韵律地层不适宜开展注气混相驱 ;②不同非均质程度的正韵律地层 ,垂向渗透率与水平渗透率比值对其混相驱采收率的影响规律不同 ;③射孔位置对提高波及效率意义重大 ;④正交试验结果表明各因素对蒸发混相驱采收率的影响程度不同 ,可用多元线性回归公式给予定量的综合评价。

A numerical simulation analysis on influence factors in vaporizing miscible flooding to enhance the recovery of volatile reservoirs

The factors that influence vaporizing miscible flooding recovery of the volatile oil reservoirs can mainly be divided into two sorts, i.e., geologic fa ctors and engineering factors. The former includes vertical heterogeneity in res ervoirs and thickness of net pay. Vertical heterogeneity is a quite significant influence factor, described in this paper with sedimentary rhythm, vertical hete rogeneity logarithm normal distribution mean, variation coefficient and the rati o of vertical permeability over horizontal permeability, K v/ K h. The later includes well spacing, injection mode (gas injection or gas alternating wa ter injection), solvent cumulative injection amount and the alternating frequenc y, etc. The following conclusions have been presented: Firstly, to perform vapor izing miscible flooding, it is essential to screen the suitable volatile reservo irs. Those reservoirs with reverse sedimentary rhythm are not suitable for this kind of development scheme. Secondly, for differently heterogeneous reservoirs d eveloped by vaporizing miscible flooding, the effects that K v/ K h has on their recoveries form different trends and principle. Thirdly, changing perf oration position has significant influence on sweep efficiency of vaporizing mis cible flooding. Lastly, two multivariate linear regression formulas are developed to quantify the influences, which those significant factors have on the miscible fl ooding recovery.