延川南区块2号煤储层顶板封盖能力定量评价

Quantitative Evaluation on the Cap Capability of Reservoir Stratum of No.2 Coal Roof in Yanchuannan Block

引用砂泥比、岩层厚度效应系数、煤层埋深及构造曲率4个地质指标,建立了封盖能力综合指数（SCI）,定量分析了延川南区块2号煤层顶板的封盖能力.研究发现,顶板封盖能力综合指数和煤储层含气量之间具有较高的吻合度.延川南区块2号煤储层顶板SCI值为22.50％ ～ 65.00％,平均值为38.81％,表明其总体封盖能力较强.研究区封盖能力综合指数区域上具有从东向西逐渐增加的趋势,东部地区最低,表明此处顶板封盖能力最弱,间接反映了东部2号煤层具有较低的煤层含气量;在区块中部延1井附近封盖能力综合指数相对较高,且区块西部整体封盖能力综合指数较高,表明这两部分区域围岩封盖能力较强,间接反映了煤储层具有相对较高的含气量.封盖能力综合指数可以作为定量评价煤储层围岩封盖性的有效指标之一.

In order to quantitatively analyze the cap capability of reservoir stratum of No. 2 coal roof in Yanchuannan block,the ratio of sandstone＇s thickness with mudstone＇s, stratum thickness effect quotiety, burial depth and structure curvature were selected as the geolo- gy indexes to build the synthesis cap capability index （SCI） to research it. The results show that the SCI of roof is in agreement with the coalbed methane content. The SCI of No. 2 coal reservoir＇s roof range from 22.50% to 65.00% ,the average is 38.81% ,it implies that the cap capability of Yanchuannan block is strong. The cap SCI indexes increase from east to west,the SCI indexes are lower in the east of the block,it indicates that the cap capacity is weak, which predicates the lower coalbed methane content ;in the middle region, the SCI of Yan 1 well in nearby regions is high,and the synthesis cap capability indexes in western region are higher,which indicate the high combed methane content. The synthesis cap capability can be used as one of the indexes to quantitatively analyze the cap qualification of the coal reservoir＇s wall rock.