沁水盆地南部长治区块煤层气田的地应力特征

Geostress Characteristics of Coal Reservoir at Changzhi Block of Southern Qinshui Basin

煤层气的生成、运移及富集等都与地应力的特征有直接的关系,掌握煤储层的应力特征对煤层气田的勘探和开发具有重要意义。基于沁水盆地南部长治区块煤层气开发区18口煤层气井的测井数据,利用带有残余构造应力的Anderson模型,分析垂向应力、最小及最大水平地应力的分布规律。结果表明:垂向应力基本上呈东西走向对称分布,东西部的应力大,中部应力小,数值在15.2~16.5 MPa之间;最小水平主应力自西向东呈现高→低→高→低的分布特点,数值在10.2~19.3 MPa之间;最大水平主应力也是自西向东呈现高→低→高→低的分布,数值在13.0~34.2 MPa之间。研究区东部所受埋深影响大于所受构造影响,而西部受到的构造影响大于其所受的埋深影响。研究区地应力分布规律与煤层气井的产气量存在高度相关性,研究成果可以为煤层气的勘探、开发和安全生产等方面提供参考。

The geostress characteristics of coal reservoir has a close relationship with the generation,migration and enrichment of coalbed gas,and a good understanding of the geostress characteristics is vital for the exploration and development of the gas field.Referring to the logging data at 18 coalbed gas well in Changzhi block of southern Qinshui basin,the distribution of the vertical stress,the minimum and maximum horizontal stresses is evaluated using an Anderson model with residual tectonic stress.The results show that the vertical stress basically presents a symmetric distribution from east to west,and the stresses in the east and west are higher than that in the middle,ranging from 15.2 MPa to 16.5 MPa.The minimum horizontal stress presents a change pattern of high→low→high→low from west to east,and ranges from 10.2 MPa to 19.3 MPa.The maximum horizontal stress presents a similar pattern,and ranges from 13.0 MPa to 34.2 MPa.The results suggest that the influence of the buried depth is bigger than the tectonic influence in the eastern area,whereas the tectonic influence is bigger than that of the buried depth in the western area.This finding indicates that the geostress distribution has a high correlation with the gas output of the coalbed well,and can offer a good data reference for the coalbed gas exploration,development,safe production and etc.