煤层气储层地应力特征及其对压裂效果的影响

发布时间：2019-04-02 15:23

【摘要】：煤储层压裂效果除了与施工措施方面因素有关外,与储层地应力特征也密切相关。文章以国内一商业南部煤层气开发区块为解剖区,探讨了煤储层地应力特征及其对直井压裂效果的影响。研究结果表明,研究区山西组3号煤层的应力状态满足:水平最小主应力(σh)垂向主应力(σv)水平最大主应力(σH)。煤层地应力差异系数(Ki)主要分布在0.26~0.36,随埋深增加,Ki值有略增的趋势。煤层水平方向主应力差(σ_H-σ_h)主要分布在3.2~5 MPa,σ_H-σ_h值每增加1 MPa,相应煤储层压裂改造体积约减少12.5%。煤层σ_H-σ_h值5 MPa时,单井产能较高,而σ_H-σ_h值5 MPa时,单井产能较低。σ_H-σ_h值5 MPa的单井往往其累积产水量也较高,表明较高的σ_H-σ_h值更易于使压裂缝穿透顶底板,增加上下水力缝高,从而引起产水量的增加及天然气的逸散损失。对于具有较高σ_H-σ_h值的煤层气开发区,在重复压裂过程中,宜采用小规模解堵重复压裂,即采用小液量、小排量及低加砂强度的压裂方式。
[Abstract]:The fracturing effect of coal reservoir is not only related to the factors of construction measures, but also closely related to the in-situ stress characteristics of the reservoir. This paper discusses the characteristics of in-situ stress of coal reservoir and its influence on the fracturing effect of straight wells, taking a coal bed methane development block as an anatomical area in south commercial area of China. The results show that the stress state of No. 3 coal seam in Shanxi formation satisfies the following conditions: horizontal minimum principal stress (蟽 h), vertical principal stress (蟽 v), horizontal maximum principal stress (蟽 H). The in-situ stress difference coefficient (Ki) is mainly distributed in 0.26 ~ 0.36, and the Ki value increases slightly with the increase of buried depth. The principal stress difference (蟽 _ H-蟽 _ h) in the horizontal direction of coal seam is mainly distributed in 3.2 ~ 5 MPa, 蟽 _ H-蟽 _ h value, and the corresponding coal reservoir fracturing volume decreases by 12.5% for every 1 MPa, increase of 蟽 _ H-蟽 _ h value. When 蟽 _ H-蟽 _ h value of coal seam is 5 MPa, the productivity of single well is higher than that of 蟽 _ H-蟽 _ h value of 5 MPa, and that of single well of 蟽 _ H-蟽 _ h value of 5 MPa is also higher than that of single well of 蟽 _ H-蟽 _ h value of 5 MPa. It is shown that the higher 蟽 _ H-蟽 _ h value is easier to make the fracturing crack penetrate through the top and floor and increase the height of the upper and lower hydraulic joints, which leads to the increase of water production and the loss of natural gas escape. For coalbed methane development zone with higher 蟽 _ H-蟽 _ h value, small-scale plugging and repeated fracturing should be adopted in the process of repeated fracturing, that is to say, the fracturing mode of small liquid volume, small displacement and low sand-adding strength should be adopted.
【作者单位】：中国石油大学(北京);中国石油长庆油田分公司第十一采油厂;中国石油长庆油田分公司第一输油处;中国石油西部钻探工程有限公司苏里格气田项目经理部;西安石油大学地球科学与工程学院;
【基金】：山东省沉积成矿作用与沉积矿产重点实验室开放基金资助项目(DMSM2017081)
【分类号】：TE377

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