考虑煤层气藏地解压差的物质平衡储量计算方法  

Reserves calculation method with a material balance equation considering the difference between initial coal seam pressure and critical desorption pressure

作　　者：胡素明[1] 李相方[1] 胡小虎[2] 任维娜[1] 孔冰[1] 胥珍珍[3] 孙晓辉[3] 范坤[3] 

机构地区：[1]中国石油大学石油工程学院,北京102249 [2]中国石化石油勘探开发研究院,北京100083 [3]塔里木油田公司勘探开发研究院,新疆库尔勒841000

出　　处：《煤田地质与勘探》2012年第1期14-19,共6页Coal Geology & Exploration

基　　金：国家重点基础发展计划(973计划)项目(2009CB219606);国家科技重大专项(2011ZX05038-4)

摘　　要：以往的煤层气藏物质平衡法未考虑地解压差问题,对此进行了改进,提出了新方法。首先对煤层的原始吸附气含量采用临界解吸压力(而非前人采用的原始地层压力)下的Langmuir方程进行表征;然后通过近似化和线性化处理,将基本物质平衡方程转化为视平均储层压力(P/Z*)和累积产气量(GP)的直线方程。该直线在直角坐标系横坐标上的截距为原始地质储量,在纵坐标上的截距为视临界解吸压力(而非前人的视原始地层压力)。运用该物质平衡法,计算Eclipse建立的一个煤层气藏模型的储量,发现误差仅为0.35%。这表明在参数准确的情况下Langmuir体积和压力、原始割理孔隙度和某些时刻的平均地层压力等在数模中可准确获知,该方法是准确可靠的。The pressure difference between initial coal seam pressure and critical desorption pressure was neglected in previous material balance methods.Therefore,a modified method has been presented in this paper.In the deri-vation,the initial gas content is expressed as a Langmuir＇s equation about the critical desorption pressure,rather than the initial coal seam pressure.Finally,a linear material balance equation of the pseudo average reservoir pressure（P/Z＊） versus cumulative gas production（Gp） is obtained,whose intercept on horizontal axis yields the initial gas reserves,and intercept on vertical axis gives the pseudo critical desorption pressure,instead of the pseudo initial reservoir pressure.By using this method to evaluate a simulated reservoir,its reserves can be ob-tained with an error less than 0.35%,which indicates the method is reliable when the Langmuir＇s volume and Langmuir＇s pressure,average reservoir pressure,initial cleat porosity are accurate.

关 键 词：煤层气 物质平衡法 地质储量 含气量 地解压差 

分 类 号：TE33[石油与天然气工程—油气田开发工程]