致密砂岩凝析气藏反凝析伤害机理及合理开发方式研究

发布时间：2018-07-01 12:09

  本文选题：致密储层 + 凝析气藏　； 参考：《西南石油大学》2015年博士论文

【摘要】：致密砂岩凝析气藏作为非常规油气藏的重要组成部分,在我国油气资源储量及产量构成中占有重要地位,相关研究也已经受到重视。由凝析气藏特殊的相态变化特征可知在衰竭开采过程中,地层压力下降会导致凝析油析出并吸附滞留在储层孔隙孔道中,将对储层渗透性造成不同程度的伤害。致密砂岩凝析气藏储层非均质性强、孔隙度和渗透率低、表面大、毛管压力高,其储层渗透性更易受到反凝析伤害的影响。然而目前针对致密砂岩凝析气藏研究的文献报道还较少,在反凝析伤害机理及合理开发方式等方面存在认识空白,是此类气藏高效开发亟待解决的问题。为此,本文依托致密砂岩全直径岩心,首先在常温低压条件下完成了15组实验,测试了不同初始含水饱和度条件下的水驱气相渗及启动压力梯度,探讨了水锁伤害程度与规律；接着在高温高压条件下进行了7组反凝析伤害评价实验,考虑了不同凝析油含量、不同反凝析区域及不同储层类型等因素,通过对比分析各组反凝析伤害实验结果的差异,揭示了反凝析伤害机理；然后在高温高压条件下开展了针对中、高含凝析油的孔隙型及裂缝-孔隙型致密砂岩凝析气藏在衰竭开发、循环注气、吞吐注气、脉冲注气等方式下的开采动态物理模拟实验18组,以最大限度地获得凝析油采收率为目的并结合矿场实际优选了合理的开发方式；最后推导了考虑应力敏感的裂缝-孔隙型凝析气藏物质平衡方程。通过上述研究取得了一系列对生产实际具有重要指导意义的成果和认识,主要包括：(1)致密砂岩气藏初始含水饱和度对气相渗透率及启动压力梯度均有较大影响。随着初始含水饱和度增加,气相有效渗透率逐渐降低,启动压力梯度逐渐增大；相同初始含水饱和度条件下,随岩石物性变差,启动压力梯度变大。(2)致密砂岩凝析气藏衰竭开发过程中远井区和近井区反凝析伤害程度及差异程度主要受凝析油含量影响。对于相同区域而言,凝析油含量越高,发生反凝析伤害的压力越高,伤害程度更严重。对不同区域而言,当凝析油含量较低时,近井区反凝析伤害程度大于远井区,随着地层压力降低,伤害程度越严重且两个区域差异越大。当凝析油含量较高时,由于凝析油析出量大,达到其临界流动饱和度,远井区与近井区伤害程度基本一致。(3)裂缝发育的致密砂岩储层,相比基质,流体在裂缝中更易流动,凝析油临界流动饱和度更低,气液两相流动导致气相渗透率大幅度降低。裂缝储层反凝析伤害程度比孔隙型储层更严重。压裂可以提高气相渗流能力,但不能降低反凝析伤害程度。(4)对于裂缝欠发育的致密砂岩凝析气藏,衰竭式开采凝析油采收率低,衰竭速度、初始含水饱和度对开发效果影响不大；凝析油含量高的气藏凝析油可流动,凝析油采收率略高；注气可大幅度提高凝析油采收率。(5)裂缝发育的致密砂岩凝析气藏,裂缝与基岩的渗透率级差大,基岩供给不足,衰竭开采凝析油采收率低,注气开发时气窜快,循环注气和吞吐注气效果不理想。(6)考虑现场实际可操作性及工艺要求,针对裂缝欠发育的致密砂岩气藏可考虑前期衰竭开采、后期吞吐注气开发,裂缝发育的致密砂岩凝析气藏建议采用前期衰竭式开采、后期脉冲注气开发。
[Abstract]:As an important component of unconventional oil and gas reservoirs, tight sandstone condensate reservoir plays an important role in the reserves and yield components of oil and gas in China, and the related research has been paid attention to. The special phase change characteristics of condensate gas reservoir can be seen that the decline of formation pressure will lead to the precipitation and retention of condensate oil in the process of depletion mining. In the pore pore channel, the reservoir permeability will be injured in different degrees. The tight sandstone condensate gas reservoir has strong heterogeneity, low porosity and permeability, large surface and high capillary pressure, and the permeability of the reservoir is more vulnerable to the effect of reverse condensate damage. However, there are few literature reports on the study of condensate gas reservoir in tight sandstone. In this paper, we have completed 15 groups of experiments under the condition of normal temperature and low pressure, and tested the water flooding and starting pressure of water flooding under the conditions of different initial water saturation. Gradient, the degree and law of water lock damage are discussed, and 7 groups of anti condensate damage evaluation experiments are carried out under high temperature and high pressure. The factors of different condensate oil content, different reverse condensate region and different reservoir types are considered. By comparing and analyzing the differences of the experimental results of each group of reverse condensate damage, the mechanism of reverse condensate injury is revealed. Under the conditions of high temperature and high pressure, 18 groups of dynamic physical simulation experiments are carried out in the pore type and fractured pore type tight sandstone condensate gas reservoir with high concentration of condensate in failure development, circulation gas injection, gas injection and pulse gas injection, in order to maximize the recovery of condensate oil recovery and to optimize the actual optimization of the field. In the end, a series of important guiding significance for the production practice and understanding are obtained through the above study, which mainly include: (1) the initial water saturation of the tight sandstone gas reservoir to the gas phase permeability and the starting pressure ladder. With the increase of initial water saturation, the effective permeability of gas phase decreases gradually and the starting pressure gradient increases gradually. Under the same initial water saturation conditions, the starting pressure gradient becomes larger with the variation of rock physical property. (2) the extent of reverse Condensate Damage in the far and near well areas of the tight sandstone condensate reservoir failure process. The higher the condensate oil content, the higher the condensate oil content, the higher the pressure of the reverse Condensate Damage and the more serious damage. For different regions, when the content of condensate oil is low, the damage degree of the reverse condensate in the near well area is greater than that in the far well area, and the damage degree is more serious as the formation pressure decreases. The greater the difference between the two regions. When the condensate content is high, the amount of condensate oil is large and its critical flow saturation is reached. The damage degree of the far well area and the near well area is basically the same. (3) the tight sandstone reservoir developed by the fracture is more easy to flow in the crack than the matrix, and the critical flow saturation of the condensate oil is lower, and the gas liquid two phase flow guide is guided. The permeability of gas phase is greatly reduced. The degree of reverse Condensate Damage in fractured reservoir is more serious than that of pore type reservoir. Fracturing can improve the capacity of gas phase seepage, but it can not reduce the degree of reverse condensate damage. (4) for the tight sandstone condensate reservoir under the undeveloped fracture, the failure mode mining condensate oil recovery rate is low, the failure velocity and initial water saturation are open. There is little effect on the effect; the condensate oil with high condensate oil content can flow, the recovery rate of condensate oil is slightly higher, and gas injection can greatly increase the recovery of condensate oil recovery. (5) the tight sandstone condensate gas reservoir with crack development, the permeability difference of the fracture and base rock is large, the bedrock supply is insufficient, the oil recovery recovery is low and the gas injection development is fast in the gas injection development. The effect of circulation gas injection and injection gas injection is not ideal. (6) considering the actual workability and technological requirements of the field, the tight sandstone gas reservoirs with less developed fractures can consider the early failure mining, the late stimulation and puff gas injection development, and the tight sandstone condensate gas reservoirs developed in the fracture development should be exploited in the early stage of depletion type mining and later pulse gas injection development.
【学位授予单位】：西南石油大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TE372
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本文编号：2087733