摘要
煤层气特有的排水采气特性与煤层气区块复杂的地形条件,都极易导致凝析水在煤层气管网低洼处聚集,致使管网压力波动更加明显而频繁,给管网安全运行与维护带来了较大的隐患。为此,基于两相流水力热力相关计算公式,利用管网节点法与大型稀疏矩阵的求解方法,建立了煤层气集输管网的瞬态水力热力计算模型。综合考虑管网所在地区的地形起伏情况,对不同时间条件下的管网各节点参数进行了计算,从而明确了煤层气地面集输系统水力热力参数随时间与集输距离的变化规律。结果表明:(1)各管沿线的质量含气率逐渐下降,持液率不断上升,并受到地形起伏的影响而发生较大波动;(2)积液多存在于管路前端地势低洼处的初始上坡段,并且在管网清管后运行20 h时低点持液率超过高点持液率的1.5倍;(3)随着管路的延长,气相流速不断增大,沿线饱和含水率不断减小;(4)管路全线压力随时间的增加而逐渐下降,在地形起伏明显的地区,受持液率变化的影响,压力也发生了小范围的波动;(5)积液的产生是导致管网压力波动的主要原因。
Due to the particular mode of coalbed methane （CBM） recovery by water drainage and the complex terrain conditions of CBM blocks, condensate water tends to accumulate at the low-lying positions of CBM pipeline, resulting in obvious and frequent pressure fluctuation, and consequently threatening the operation and maintenance of pipeline networks. In this paper, a transient hydraulic and thermal calculation model for CBM surface gathering and transportation pipeline networks was established by using the pipeline network node method and large sparse matrix solution method based on the two-phase hydraulic and thermal calculation equations. Then, the parameters of each node of a pipe network at different time were calculated considering the topographic relief where the pipeline network was located. Accordingly, the relationship of hydraulic and thermal parameters of CBM surface gathering and transportation pipeline networks versus time and gathering and transportation distance were figured out. It is indicated that along the pipe line, mass gas content drops gradually, liquid holdup rises continuously, and they move up and down largely with the relief of landforms; that liquid is mostly accu- mulated at the initial uphill section of low-lying positions at the front end of a pipe line, and the liquid holdup at the low positions is 1.5 times larger than that at higher points 20 hours after the pigging; that with the extension of the pipe line, gas flow rate increases and saturated water content decreases continuously along the pipe line; that pressure along the whole pipeline declines gradually over the time, in the area with obvious topographic relief, the pressure also fluctuates in a small range with the change of liquid holdup; and that liquid accumulation is the main reason for pressure fluctuation of pipeline networks.
出处
《天然气工业》
EI
CAS
CSCD
北大核心
2017年第7期108-114,共7页
Natural Gas Industry
基金
山西省基础研究计划煤层气联合研究基金项目"煤层气地面集输系统优化设计与运行控制"(编号:2014012012)
关键词
煤层气
集输管网
排水采气
瞬态计算
压力特性
管流分析
持液率
管路积液
压力波动
CBM
Gathering and transportation pipeline network
Gas recovery by water drainage
Transient calculation
Pressure characteristics
Conduit flow analysis
Liquid holdup
Liquid accumulation in pipe
Pressure fluctuation
作者简介
高杰，女，1992年生，硕士研究生；主要从事油气地面工程方面的研究工作。地址：（102249）北京市昌平区府学路18号。电话：15652232064。ORCID：0000—0002—0767—9365。E—mail：xiaowu_gaojie@163．com
