下寺湾油田长7油层组页岩气储层敏感性实验

由于延长组长7油层组页岩气储层微裂缝页理发育，且基质型页岩与裂缝型页岩并存，所以在开发过程中储层易受到伤害。敏感性评价实验是研究储层伤害的重要手段之一，但这一实验目前主要针对基质型页岩进行研究。考虑到页岩储层往往需要进行压裂才能生产，且基质型页岩与裂缝型页岩的伤害机理有所不同，所以将裂缝型页岩的岩心流动实验和基质型页岩的压力脉冲衰减法实验相结合，来研究长7油层组页岩气储层的敏感性伤害机理。结果表明：该页岩储层具有强应力敏感、中等强度碱敏、中等偏弱水敏和中等偏弱速敏等特征。对比发现：在除应力敏感性评价实验外的其他各项实验中，裂缝型页岩的伤害程度均高于基质型页岩，主要是由于裂缝的存在使外来流体与地层的作用面积增大，从而造成更大的伤害；在应力敏感性评价实验中，基质型页岩应力敏感性强于微裂缝型页岩，但略低于裂缝型页岩。该研究成果可为页岩气的高效开发提供依据。

Sensitivity experiment of shale gas reservoir of Chang 7 reservoir in Xiasiwan oilfield

There are many microcracks and lamellations developed in Chang 7 shale gas reservoir, and matrix shale and fractured shale coexist, so the reservoirs are easily damaged during the development process. Sensitivity evaluation experiment is one of the important means to explore reservoir damage, however, the current experiment mainly focuses on the matrix shale. Considering that shale reservoirs often need fracturing before the shale gas can be produced, and the damage mechanism of matrix shale is different from that of fractured shale, the core flow experiment of fractured shale and the pressure pulse attenuation experiment of matrix shale were combined to study the sensitive damage mechanism of Chang 7 shale gas reservoir. The results show that the shale reservoir has the characteristics of strong stress sensitivity, medium alkali sensitivity, moderately weak water sensitivity, and moderately weak velocity sensitivity. It is found that the damage degree of fractured shale is higher than that of matrix shale in all kinds of experiments except stress sensitivity evaluation experiment. The main reason is that the presence of fractures increases the area of interaction between external fluid and formation, thus causing greater damage. Overall, the stress sensitivity of matrix shale is stronger than that of micro-fractured shale, but slightly lower than that of fractured shale. The research results can provide a basis for efficient development of shale gas.