深层气泥岩盖层封闭能力的综合评价——以东濮凹陷杜桥白地区沙河街组三段泥岩盖层为例

COMPREHENSIVE EVALUATION OF SEALING CAPACITY OF CLAYSTONE IN DEEP GAS RESERVOIR──AN EXAMPLE OF Es CLAYSTONE CAPROCK IN DUQIAOBAI AREA IN DONGPU DEPRESSION

谈玉明 任来义 张洪安 张金报 胥菊珍 金振华

Tan Yuming Ren Laiyi Zhang Hong'an Zhang Jinbao Xu Juzhen Jin Zhenhua

通过对东濮凹陷杜桥白地区沙河街组三段深层气盖层泥岩样品实验测试分析和研究,结果表明孔隙度的变化主要受深度和层位的控制;渗透率与深度关系密切,受层位的影响不大,与孔隙度等参数之间也没有明显的相关关系;突破压力随深度加大而增大,但这一趋势并不是十分突出;突破压力与层位的对应关系较明显,E亚段的突破压力最大,E亚段次之,而E则相对较低。为了准确评价盖层封闭能力,选择了孔隙度、渗透率、排替压力、孔径4个盖层评价的指标参数,并根据其重要性的大小分别给予0.1,0.3,0.5和0.1的权系数,以确定东濮凹陷深层气盖层的评价标准:当综合评价的权值大于0.8时,为封闭能力好的1类盖层;当权值为0.6～0.8时,为封闭能力中等的2类盖层;而权值为0.5～<0.6时,为3类盖层;权值为0.3～<0.5时,则为4类盖层;而权值<0.3时则为非盖层。

The result from the experimental analyses of the 3rd member of Shahejie Fm (E) claystone's sealing capacity in the deep gas pools in Duqiaobai area in Dongpu depression shows that the variation in porosity has been controlled by depth and horizons, whereas the permeability has close relation with depth, but it is almost not affected by the horizons, and doesn't have obvious relation with porosity and other related parameters, too. The breakthrough pressure is getting greater with the increase of depth, but this trend is not very prominent. There is a close relation between the breakthrough pressure and the horizons, among which, the E has the biggest breakthrough pressure, then the E comes next, and the E has relatively low breakthrough pressure.For the sake of evaluating the sealing capacity of cap rock accurately, porosity, permeability, displacement pressure, and pore diameter have been selected as the indexes of cap rock evaluation, and weight coefficients of 0.1,0.3,0.5,and 0.1 have respectively been given to them based on their importance,so as to determine the evaluation standards caprocks of deep gas pools in Dongpu depression: when the weight coefficient is larger than 0.8,the cap rock belongs to I type, with good sealing capacity; if it is in the range of 0.6～0.8, the cap rock belongs to type Ⅱ, having moderate sealing capacity; when it is in the range of 0.5～0.55,the cap rock belongs to type Ⅲ; and if it is in the range of 0.3～0.45,the cap rock belongs to type IV; when it is less than 0.3, it is then of non-caprock.

10.11743/ogg20030219