[M-IS08] 地球掘削科学

[MIS08-P08] In-situ rock physical properties established from continuous drilling parameters: invaluable datasets to analyse state of drilling and rock strength

Wspanialy Adam¹、斎藤 実篤¹、MOE KYAW¹、*山田 泰広¹ (1.海洋研究開発機構　海洋掘削科学研究開発センター)

キーワード：岩石強度、エネルギー、等価強度、掘削トルク

Surface drilling parameters are excellent datasets to understand in-situ physical properties of the rock. We here present some results from land-based drilling experiments at Atsugi and Boso, Japan. We have acquired large surface drilling datasets together with approximately 100 m of continuous cores. Methods such as Specific Energy (SE) and Equivalent Strength (EST) have been used here to analyse drilling process and physical characteristic of the rock. Results from subsequent core scratching experiments enabled very good correlation and validation of the calculated SE/EST with the measured Unconfined Compressive Strength (UCS). Our field results also demonstrate that the calculated SE/EST successfully detect fractures in the formation, show developing drilling dysfunctions such as vibration, and bit balling. The results also indicate that the frequency and amplitude of the SE/EST oscillations may be used in detecting lithological changes of the drilled rock medium.