页岩气水平井地质导向钻进中的储层“甜点”评价技术

随钻自然伽马探测手段在四川盆地涪陵国家级页岩气产能示范区水平井导向实践中暴露出储层特征显示不明确、"甜点"层钻遇率低的问题。为此,通过研究该区页岩标志层、"甜点"层的岩性、物性及含气性特征,建立其与已测量的自然伽马值的对应关系,总结得出了该区页岩储层"甜点"判别方法,以此作为LWD随钻地质导向轨迹实时控制的依据。焦页14-3HF井的现场试验结果表明,实钻水平段1 540 m,"甜点"钻遇率和储层钻遇率均为100%,优质"甜点"钻遇率达93.6%,单井完井测试平均无阻流量达到103.24×10~4 m~3/d,取得了非常好的效果。结论认为,该储层"甜点"层判别和识别技术能够更好地指示钻头在"甜点"层中钻进,有利于全面发挥地质导向技术在页岩气水平井钻井中的技术优势。

Sweet spot evaluation technology in the geosteering drilling of shale gas horizontal wells

When GR detection while drilling was applied in the geosteering drilling of horizontal wells in the Fuling National Shale Gas Productivity Demonstration Region, Sichuan Basin, reservoir characteristics were not definitely presented and the drilling ratio of “sweet spot” layers was low. In view of this, the corresponding relationship between the lithology, physical properties and gas potential of “sweet spot” layers and shale markers in this block and the measured values was established. Then, the discrimination method for “sweet spot” in shale reservoirs in this block was developed and taken as the basis for the real-time control of LWD geosteering trajectory. Field test of this method was conducted in Well Jiaoye 14-3HF. It is shown that the actual horizontal section is 1 540 m long, drilling ratios of sweet spots and reservoirs are both 100%, drilling ratio of high-quality sweet spots is 93.6%, average AOF (absolute open flow) of single-well completion test is 103.24×10⁴ m³/d. It is concluded that this “sweet spot” layer discrimination and identification technology can better guide the drilling of bits in “sweet spot” layers and it is favorable for the geosteering technology to fully exert its technical advantages in the drilling of shale gas horizontal wells.