LFS低渗致密凝析气藏渗流及储层伤害研究

发布时间：2018-03-07 21:40

本文选题：低渗致密　切入点：凝析气藏　出处：《西南石油大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着我国石油工业勘探开发的进展,越来越多的低渗致密凝析气藏被发现,该类型气藏兼具低渗致密气藏与凝析气藏的开发难点,因其具有更为复杂的渗流规律、油气相态变化以及颇高的市场价值等特点,逐渐成为国内外学者研究的热点。本文从低渗致密气藏与凝析气藏两个角度,运用动态分析、模拟实验和数值模拟相结合的研究方法,进行了低渗致密凝析气藏生产动态特征分析及动态储量计算,低渗致密储层不同渗流和伤害机理以及凝析气藏反凝析伤害的实验研究。在动态分析和实验研究基础上,开展了近井带相态及油气相渗透率变化、多种渗流机理对产能影响以及压裂解除储层伤害效果的数值模拟研究。得到以下结论及认识:(1)实际低渗致密凝析气藏生产动态特征分析得到,气藏发生反凝析后,气油比突高,油压明显降低,产量递减更快,气油比随生产时间的延长呈"驼峰型";递减及动态储量计算得到,总体上动态储量在854～5000×104m3,动态平均渗透率0.06～0.7mD,比测井解释和岩石渗透率高,说明存在微裂缝和压裂影响。(2)低渗致密储层储渗物性、核磁共振和扫描电镜实验研究表明:目标区块平均孔隙度4.92%,平均渗透率0.16mD,属于典型低孔、特低渗透致密气藏;岩心大孔隙空间内可动水饱和度有限,不可动水饱和度与驱替压差在一定范围内呈负韵律相关性;孔缝间连通性较差,岩心微粒的胶结方式主要有填充式胶结和衬垫式胶结。(3)低渗致密储层应力敏感、启动压力梯度和近井地层液锁实验研究表明:渗透率应力敏感强,随净应力的增大,渗透率降低速度先快后慢,最高应力敏感性损害率平均超过80%;启动压力梯度不明显;水锁伤害程度评价为强水锁效应,岩心含水饱和度高于80%时,损失80%以上。(4)凝析气藏渗流及伤害相关实验研究表明:PVT相态研究得到目标气藏属于低密度高含凝析油型凝析气藏,露点压力31.7MPa;反凝析现象对平衡气相渗透率伤害严重,后期伤害可达约85%;不同衰竭速度模拟实验中,衰竭速度快携带凝析油能力强,增大渗流通道,可使凝析油气采收率略高;含水衰竭试验得到含水既复杂了多相渗流,又可占据狭小孔道的双重作用。(5)通过近井带相态及油气相渗透率变化研究得到结论:近井带30m范围压力极易低于露点压力,形成反凝析现象。近井周围气相相对渗透率急剧降低,反凝析使得气相流动能力下降,近井下降约40～50%。(6)不同渗流及伤害机理对产能影响研究表明:对于未压裂直井应力敏感、水锁和反凝析伤害都很大,应力敏感的伤害最大约34.95%,水锁伤害次之约21.78%,反凝析伤害较大约14.37%。压裂作业可以有效降低反凝析和水锁伤害程度,但对应力敏感伤害的改善较少。
[Abstract]:With the development of petroleum exploration and development in China, more and more condensate gas reservoirs with low permeability have been found. The characteristics of phase change and high market value of oil and gas have gradually become a hot topic for scholars at home and abroad. In this paper, the dynamic analysis is used from the two angles of low permeability tight gas reservoir and condensate gas reservoir. With the combination of simulation experiment and numerical simulation, the production dynamic characteristics and dynamic reserve calculation of low permeability dense condensate gas reservoir are analyzed. Experimental study on different percolation and damage mechanism of low permeability tight reservoir and reverse condensate damage of condensate gas reservoir. On the basis of dynamic analysis and experimental study, the changes of near well zone phase state and oil and gas phase permeability are carried out. Numerical simulation study on the effect of various percolation mechanisms on productivity and the effect of fracturing to remove reservoir damage. The following conclusions and understandings are obtained: by analyzing the production characteristics of practical low permeability dense condensate gas reservoirs, the gas and oil ratio is higher after the reverse condensate occurs in the gas reservoir. The oil pressure is obviously reduced, the production decline is faster, the gas-oil ratio is "hump type" with the prolonging of production time, and the dynamic reserves are 8545000 脳 104m3, the dynamic average permeability is 0.060.7mD, which is higher than that of log interpretation and rock permeability. The results of NMR and SEM experiments show that the average porosity of the target block is 4.92 and the average permeability is 0.16mD, which belongs to typical low-porosity and ultra-low permeability tight gas reservoir. In the pore space of the core, the movable water saturation is limited, the unmovable water saturation and the displacement pressure difference are negatively correlated in a certain range, and the connectivity between the pores is poor. The cementing methods of core particles are mainly filled cementing and padding cementing. The stress sensitivity of low permeability tight reservoir is mainly found. The experimental study on starting pressure gradient and liquid lock in near-well formation shows that permeability stress is sensitive and the net stress increases with the increase of net stress. The maximum stress sensitivity damage rate is above 80 on average; the starting pressure gradient is not obvious; the water lock damage degree is evaluated as a strong water lock effect, and the water saturation of the core is higher than 80%. Experimental study on percolation and damage of condensate gas reservoir with loss of more than 80% indicates that the target gas reservoir belongs to low density and high condensate bearing condensate gas reservoir with dew point pressure of 31.7MPa, and reverse condensate phenomenon has serious damage to equilibrium gas phase permeability. In the simulation experiment of different exhaustion velocity, the ability of fast carrying condensate oil is strong and the oil recovery factor of condensate oil can be slightly higher by increasing the seepage channel. The dual action of occupying a narrow pore channel. 5) through the study of the phase state of the near well zone and the change of the permeability of the oil and gas facies, it is concluded that the pressure of the near well zone in the range of 30 m is easily lower than that of the dew point pressure. The reverse condensate phenomenon is formed. The relative permeability of the gas phase around the near well decreases sharply, the reverse condensate reduces the gas phase flow capacity, and the drop of the near well is about 40 ~ 50%. The research on the effect of different seepage flow and damage mechanism on the productivity shows that the stress is sensitive to the stress of the unfractured straight well. The damage of water lock and reverse condensate is very great, the damage of stress sensitivity is about 34.95%, the damage of water lock is about 21.78, and the damage of back condensate is about 14.37.The fracturing operation can effectively reduce the degree of back condensate and water lock damage, but the improvement of stress sensitive injury is less.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE372

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