应力敏感及液锁对煤层气储层伤害程度实验研究

EXPERIMENTAL STUDY OF DAMAGE OF STRESS AND LIQUID SENSITIVITIES TO COAL-BED GAS RESERVOIR

煤层气成功开发的关键是提高单井产能,而提高日产气量的途径之一是降低各种原因引起的储层伤害。文章研究了有效应力变化及入井液体对储层渗透率的伤害问题。通过实验测定发现,煤层气储层压力敏感性伤害的程度远大于砂岩储层,在有效覆压增加10MPa时,渗透率仅为原始值的20%左右,而气藏砂岩能保持原始渗透率的90%;入井液体饱和度为10%时对储层渗透率伤害超过50%。该研究为进一步认识伤害程度以及采取降低伤害的措施提供了指导意见,文章还提出尝试选择水力冲孔、水力割缝等其它增产措施,以及在各种施工中应尽量控制液体滤失量的建议。

Successful development of coal-bed gas hinges on improvement of single well deliverability by reducing reservoir damage resulted from various factors. Damage of effective stress change and fluids entering the well to reservoir permeability is studied in this paper. Based on experimental study, damage of stress sensitivity to coal-bed gas reservoir is much larger than that to sandstone reservoir. When effective overburden stress increases 10 MPa, permeability of coal-bed gas reservoir is only 20% of its original value, while that of sandstone reservoir is 90% of its original value. When saturation of liquid entering well is 10%, reservoir damage is over 50%. This study provides directive proposals concerning further understanding of reservoir damage and appropriate measures of reducing damage. It is also proposed to carry out other stimulation experiments such as hydraulic punching and slotting and to properly control fluid loss during various operations.