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- Title
Mechanical Properties of Gas Shale During Drilling Operations.
- Authors
Yan, Chuanliang; Deng, Jingen; Cheng, Yuanfang; Li, Menglai; Feng, Yongcun; Li, Xiaorong
- Abstract
The mechanical properties of gas shale significantly affect the designs of drilling, completion, and hydraulic fracturing treatments. In this paper, the microstructure characteristics of gas shale from southern China containing up to 45.1% clay were analyzed using a scanning electron microscope. The gas shale samples feature strongly anisotropic characteristics and well-developed bedding planes. Their strength is controlled by the strength of both the matrix and the bedding planes. Conventional triaxial tests and direct shear tests are further used to study the chemical effects of drilling fluids on the strength of shale matrix and bedding planes, respectively. The results show that the drilling fluid has a much larger impact on the strength of the bedding plane than that of the shale matrix. The impact of water-based mud (WBM) is much larger compared with oil-based mud. Furthermore, the borehole collapse pressure of shale gas wells considering the effects of drilling fluids are analyzed. The results show that the collapse pressure increases gradually with the increase of drilling time, especially for WBM.
- Subjects
OIL shales; DRILLING &; boring; SCANNING electron microscopes; ELECTRON microscopes; SCANNING electron microscopy
- Publication
Rock Mechanics & Rock Engineering, 2017, Vol 50, Issue 7, p1753
- ISSN
0723-2632
- Publication type
Article
- DOI
10.1007/s00603-017-1203-5