沁南煤层气井排采储层伤害的耦合机理

发布时间：2018-01-05 21:01

本文关键词：沁南煤层气井排采储层伤害的耦合机理　出处：《安徽理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：为了提高对沁水区块煤层气排采伤害的认识,改进排采控制技术,节约生产和管理成本,本论文以沁南煤层气田为研究实例,通过系统收集煤层气井工程数据和排采数据,采集煤层气井产出地层水样和煤岩样,阐明高、中、低产井排采伤害生产表现特征,并同时通过煤储层速敏、贾敏、应力敏感性模拟实验揭示不同排采强度下煤层气井排采储层伤害的发生条件和伤害程度,耦合分析在不同排采阶段煤层气井不同排采伤害的生产特征,揭示速敏、贾敏、应力敏感与煤层气井排采强度之间的内在联系,提出煤层气井排采优化工艺。本次研究取得的主要结论如下： (1)建立了煤层气井排采伤害判别模式：沁南煤层气井前期容易发生速敏效应,中期为贾敏效应(气锁)高发期,后期会发生应力敏感效应。且排采过程中,三类产能井中最易发生的储层伤害为贾敏(气锁),随后为速敏效应,最后为应力敏感。 (2)通过速敏实验得到排水速率超过8m3/d时,速敏效应发生的可能能大大增加。8m3/d的排采速率可以作为一个安全排采界线。同时得到速敏实验时渗透率的四种变化模式：①缓慢下降后在某一点急剧下降；②迅速下降然后在一转折点处开始平稳下降；③渗透率经过一段时间的慢慢变小,后有缓慢上升,最后又缓慢下降；④渗透率呈直线式下降。 (3)证明了排采速率过大容易造成气水相对渗透率的降低,且当排采速率超过8m3/d时,排采速率越大,造成的损失相对渗透率越大。 (4)应力敏感性实验结果表明：①煤样的在有效应力较低的时候,孔隙压力的不断增加(最高至3.5Mpa),煤储层的渗透率的到改善,且当原始渗透率越大,得到的改善结果更明显；②渗透率损耗在有效应力为3.5Mpa前比较大,在有效应力为2.5Mpa或者3.5Mpa之后,渗透率的损耗最高,且有效应力从2.5Mpa增加到9Mpa时,应力敏感性最强；③证明了在孔隙压力低于渗透率变化的临界压力时(实验过程中孔隙压力是从0.8Mpa增加至3.5Mpa),煤储层的渗透率随孔隙压力的增加而变小。模型模拟分析的结果表明低产井后期压敏和速敏效应耦合发生概率较大。
[Abstract]:In order to improve the understanding of coal bed methane (CBM) recovery damage in Qinshui block, improve the drainage control technology, and save production and management costs, this paper takes Qinnan coalbed methane field as an example. By collecting the engineering data of coalbed methane wells and discharging data systematically, collecting the formation water samples and coal rock samples produced by coalbed gas wells, the characteristics of production performance of high, middle and low production wells are expounded, and the speed sensitivity of coal reservoirs is also analyzed. Jia Min, stress sensitivity simulation experiment to reveal the occurrence conditions and damage degree of coalbed methane well drainage reservoir damage under different production intensity, coupled analysis of different production characteristics of coal-bed methane well at different production stage. The relationship between stress sensitivity and recovery strength of coalbed methane wells is revealed, and the optimization technology of coal bed methane well drainage is put forward. The main conclusions of this study are as follows: 1) the model for judging the recovery damage of coalbed methane wells is established: the early stage of Qinnan coalbed methane well is prone to the rate sensitive effect, and the middle stage is the high occurrence period of the Jamin effect (gas lock). The stress sensitivity effect will occur in the later stage, and the reservoir damage in the three types of productivity wells is Jia Min (gas lock, then speed sensitivity, and finally stress sensitivity). 2) the drainage rate is more than 8m3 / d by the speed sensitivity test. It is possible that the speed sensitivity effect can increase the production rate of 8 m3 / d greatly. It can be used as a safe discharge boundary. At the same time, four models of permeability change in the speed sensitivity experiment are obtained:. (1) after a slow decline, a sharp decrease at a certain point; (2) decrease rapidly and then begin to drop steadily at a turning point; (3) the permeability decreases slowly after a period of time, then increases slowly, then decreases slowly; (4) the permeability decreases in a straight line. It is proved that the gas / water relative permeability decreases easily when the production rate is too large, and the loss of relative permeability is greater when the production rate exceeds 8 m3 / d. The results of stress sensitivity experiments show that the pore pressure of the sample of 1 / 1 increases continuously when the effective stress is low (up to 3.5 Mpas, the permeability of coal reservoir is improved. And when the original permeability is larger, the improved results are more obvious. (2) permeability loss is larger before effective stress is 3.5Mpa, and when effective stress is 2.5Mpa or 3.5Mpa, permeability loss is the highest. When the effective stress is increased from 2.5 MPA to 9 MPA, the stress sensitivity is the highest. It is proved that when the pore pressure is lower than the critical pressure of permeability change (the pore pressure is increased from 0.8 MPA to 3.5 Mpa during the experiment). The permeability of coal reservoir decreases with the increase of pore pressure. The results of model simulation show that the coupling probability of pressure sensitivity and velocity sensitivity in the later stage of low production wells is high.
【学位授予单位】：安徽理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE358

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