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基于全直径岩心的页岩层理缝流体流动非均衡性实验
Experimental study on flow heterogeneity of shale bedding fractures based on full-diameter cores
【摘要】 采用全直径页岩岩心,保留原始天然层理缝,基于自主设计的全直径岩心实验装置,在不同闭合压力、注入流量下对层理缝在4个径向方位的流动能力非均衡性进行评价。研究表明,层理面的表面分布形态影响层理缝导流能力,在不同闭合压力、不同注入流量条件下,4个径向方位的流动能力差异明显,裂缝表面粗糙度越大,流动能力随闭合压力的变化幅度越大。对于未支撑层理缝,随着闭合压力增加,存在4个径向方位上流动能力均差百分比逐渐增大的现象,在埋深较大的岩样中特征更为明显,表明随着闭合压力增加,层理缝内流动非均衡性存在增大的趋势。铺置支撑剂后,在较低闭合压力下受到裂缝粗糙面自支撑、支撑剂失稳与非均匀铺置综合影响,流动非均衡性在相同闭合压力下大于未铺置支撑剂时,但随着闭合压力增加,支撑剂逐渐压实稳定,流动非均衡性逐渐缓解。
【Abstract】 A self-designed full-diameter core experimental facility was used to evaluate the flow heterogeneity of bedding fractures at four radial directions under different closure pressures and injection rates, using full-diameter cores retaining original natural bedding fractures.The distribution morphology of bedding surface affects the conductivity of bedding fractures, and the flow capacity of bedding fractures in four radial directions varies greatly with the closure pressure and injection rate. The rougher the fracture surface, the greater the flow capacity varies with the closure pressure. For unsupported bedding fractures, the mean percentage error(MPE) of the conductivity in four radial directions increase gradually with the increase of the closure pressure. This phenomenon is especially prominent in deep rock samples. It is indicated that the flow heterogeneity of bedding fractures tends to increase with the closure pressure. When proppant is placed in the fracture, at a low closure pressure, due to the combined effects of self-support of rough fracture surface, proppant instability and uneven proppant placement, the flow heterogeneity is greater than that when proppant is not placed at the same closure pressure; however,with the increase of the closure pressure, the proppant becomes compact and stable, and the flow heterogeneity is mitigated gradually.
【Key words】 shale; full-diameter core; bedding fracture; conductivity; heterogeneity; fracturing;
- 【文献出处】 石油勘探与开发 ,Petroleum Exploration and Development , 编辑部邮箱 ,2023年05期
- 【分类号】P618.13
- 【下载频次】199