›› 2019, Vol. 40 ›› Issue (3): 1-1.doi: 10.7657/XJPG20190317

• 论文 •    

煤层气井排采参数影响因素及优化方法

彭泽阳,李相方,孙政   

  1. (中国石油大学(北京)? 石油工程学院,北京? 102249)
  • 出版日期:2019-06-01 发布日期:1905-07-17

Influencing Factors and Optimization Methods of Drainage Parameters in CBM Wells

PENG Zeyang, LI Xiangfang, SUN Zheng   

  1. (1.School of Petroleum Engineering, China University of Petroleum, Beijing 102249, China)
  • Online:2019-06-01 Published:1905-07-17

摘要: 为进一步认识煤层气井排采影响因素,从煤层气储集层生产过程中可能出现的伤害出发,分析排采过程中各种伤害的机理,将伤害分为储集层应力敏感、近井地带伤害、煤粉运移和压降传递4个方面。根据最小化机理伤害的原则,针对煤层气不同生产阶段的压降速率进行理论研究和探讨,进而提出煤层气排采参数的优化方法。结果表明,在煤层气井生产初期,适当提高排采速度在不会引起严重的应力敏感效应的前提下,不仅能够有效增加排液效果,也能降低由于压裂作业对近井地带造成的伤害;而在煤层气井生产的中后期,建议采用间或增大压差的方式解放圈闭气,提高产量。对于易产煤粉储集层,在井底压力略大于临界解吸压力时,加大压差快速排水,不仅有助于已产出煤粉的排出,也能使气水两相流区域尽快出现,阻止储集层远端水的快速产出,达到抑制煤粉的目的。

Abstract: In order to further understand the factors affecting the production of coalbed methane(CBD) wells, the possible damage mechanisms in the production process of coalbed gas wells including reservoir stress sensitivity, near-bore zone damage, pulverized coal migration and pressure drop transmission are analyzed. Based on the principle of minimizing the above mechanism damages, the pressure drop rates in different stages of coalbed methane production are studied theoretically in this paper and then the optimization method of coal seam gas well drainage is put forward. The results show that in the early stage of CBM production, the appropriate increase of production rate will not cause serious stress sensitivity effect, and not only the drainage effect can be effectively improved, but the damage to near-bore areas can be decreased; in the middle-late CBM production stage, it is suggested that the occasional increase of pressure difference should be adopted to release the trapped gas and improve production. For the reservoirs producing pulverized coal easily, when the bottom pressure of the well is slightly greater than the critical desorption pressure, increasing pressure difference for rapid drainage can promote the expulsion of the produced pulverized coal and make the gas-water two phase flow area appear as soon as possible, and the aims to prevent the rapid water production from the far-end of the reservoir and to suppress the pulverized coal can be realized

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