資源と素材
Online ISSN : 1880-6244
Print ISSN : 0916-1740
小特集:岩盤 -つくばでの最近の研究-
論文
き裂開口変位計測によるシャットインプレッシャーの評価
竹原 孝山口 勉水田 義明成田 孝石原 治幸
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ジャーナル フリー

2000 年 116 巻 7 号 p. 636-641

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In this paper, a newly developed double packer was introduced. In hydraulic fracturing operation, an opening and closing behavior of a fracture was related to in-situ stress state. A purpose of the new packer was to measure the fracture opening directly. The new packer consisted of two co-axial pipes that move independently. As sealing elements were fixed to each of two pipes, fracture opening could be measure by relative displacements of two co-axial pipes. Two types of sealing elements were examined. One was a rubber and the other was lead. The former was named rubber-seal packer, and the latter is named metal-seal packer.
A conventional double packer, the rubber-seal packer and the metal-seal packer were used in the Kamioka mine in 1998. In this mine, a hydraulic fracturing experiment in order to estimate in-situ stress was done using a borehole that was drilled horizontally from a gallery in 1996. The newly developed packers were used to re-open the pre-existed artificial fracture.
The result of the metal-seal packer experiments showed that relative displacements of two co-axial pipes had a good correlation with the wall expansion that was measured at vicinity of the borehole. It became clear that the metal-seal packer was possible to measure the fracture aperture directly. The shut-in pressure, that is thought to be equivalent to a magnitude of normal stress component, was estimated from the relative displacements of two co-axial pipes. This shut-in pressure estimated from the metal-seal packer agreed well with those from the Muskat method and Hayashi & Haimson method.

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© 2000 by The Mining and Materials Processing Institute of Japan
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