Use of borehole imaging to improve understanding of the in-situ stress orientation of Central and Northern England and its implications for unconventional hydrocarbon resources
Use of borehole imaging to improve understanding of the in-situ stress orientation of Central and Northern England and its implications for unconventional hydrocarbon resources
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DOI：
10.1016/j.marpetgeo.2016.02.012
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发表时间：
2016-05
影响因子：
4.2
通讯作者：
A. Kingdon;M. Fellgett;J. Williams
中科院分区：
文献类型：
--
作者：
A. Kingdon;M. Fellgett;J. Williams
在英国，人们对页岩气潜力产生了新的兴趣，这导致了对英格兰中部和北方石炭纪Bowland-Hodder页岩中碳氢化合物的重新勘探。2010年，在兰开夏郡Preese Hall发生水力压裂诱发地震后，量化英国原地应力方向的实验可用数据库已被证明不足以进行水力压裂的安全规划和监管。因此，本文重新评估了在原地应力方向为英格兰中部和北方完全基于新的解释的高分辨率钻孔成像的应力指标，包括钻孔崩落和钻井引起的拉伸断裂。这些分析证实了先前研究（例如Evans和Brereton，1990年）确定的最大水平原地应力的预期北西北-南东南方向。Evans和Brereton（1990）生成的双测径器数据得出平均SH最大取向为149.87°，圆标准差为66.9°。然而，使用井眼成像而不结合来自较旧的双井径测井工具的结果非常显著地降低了相关的不确定性，平均SH最大取向为150.9°，圆标准差为13.1°。因此，使用高分辨率井眼成像被示出产生更可靠的原地应力取向评估。因此，作者建议，这种成像工具的更高分辨率，因此应被视为一个事实上的标准，在岩石测试之前，在原地应力方向的评估。在英国，在进行任何水力压裂作业之前，应将钻孔成像的使用正式纳入最佳实践或未来的法规，以评估原地应力方向。
New interest in the potential for shale gas in the United Kingdom (UK) has led to renewed exploration for hydrocarbons in the Carboniferous age Bowland–Hodder shales under Central and Northern England. Following an incidence of induced seismicity from hydraulic fracturing during 2010 at Preese Hall, Lancashire, the publically available databases quantifying the in-situ stress orientation of the United Kingdom have shown to be inadequate for safe planning and regulation of hydraulic fracturing. This paper therefore reappraises the in-situ stress orientation for central and northern England based wholly on new interpretations of high-resolution borehole imaging for stress indicators including borehole breakouts and drilling-induced tensile fractures. These analyses confirm the expected north northwest – south southeast orientation of maximum horizontal in-situ stress identified from previous studies (e.g. Evans and Brereton, 1990). The dual-caliper data generated by Evans and Brereton (1990) yields a mean SHmaxorientation of 149.87° with a circular standard deviation of 66.9°. However the use of borehole imaging without incorporation of results from older dual-caliper logging tools very significantly decreases the associated uncertainty with a mean SHmaxorientation of 150.9° with a circular standard deviation of 13.1°.The use of high-resolution borehole imaging is thus shown to produce a more reliable assessment of in-situ stress orientation. The authors therefore recommend that the higher resolution of such imaging tools should therefore be treated as a de-facto standard for assessment of in-situ stress orientation prior to rock testing. Use of borehole imaging should be formally instituted into best practice or future regulations for assessment of in-situ stress orientation prior to any hydraulic fracturing operations in the UK.