Tanimoto Kazumasa, Hamada Yohei, Katayama Ikuo
Department of Earth and Planetary Systems Science, Hiroshima University, Higashi-Hiroshima, Hiroshima, 739-8526, Japan.
Japan Petroleum Exploration Co., Ltd., Tokyo, 100-0005, Japan.
Sci Rep. 2024 Nov 28;14(1):29640. doi: 10.1038/s41598-024-80740-4.
In order to examine the rock dependence on drilling performance parameters, such as torque and rate of penetration (ROP), we conducted laboratory drilling experiments using mafic and ultramafic rocks from the Oman ophiolite and the Horoman Complex. Serpentinized peridotite shows approximately twice the ROP (dry conditions: 2.95 ~ 3.85, wet conditions: 8.25 ~ 10.3 × 10 m/min) compared to that of peridotite and mafic samples (dry conditions: 4.75 ~ 6.90, wet conditions: 14.5 ~ 18.3 × 10 m/min) under both dry and wet conditions. This result is likely due to the reduction in fracture strength associated with serpentinization. We compared the laboratory results of drilling parameters with in situ data obtained from IODP Expedition 360 drilling of gabbro and Expedition 399 drilling of serpentinized peridotite, using the equivalent strength method to normalize ROP to the given rotation rate and torque. The calculation results show that the normalized ROP for the serpentinized peridotite formation was systematically higher than that for the gabbro layer, which is in agreement with our experimental results. We propose that the in situ drilling performance parameters can be used to detect the lithological transitions, such as serpentinite.
为了研究岩石对钻进性能参数（如扭矩和钻速（ROP））的依赖性，我们使用阿曼蛇绿岩和幌延杂岩中的镁铁质和超镁铁质岩石进行了实验室钻进实验。与橄榄岩和镁铁质样品相比，蛇纹石化橄榄岩在干燥和潮湿条件下的钻速均约为其两倍（干燥条件下：2.95 ~ 3.85，潮湿条件下：8.25 ~ 10.3×10米/分钟，而橄榄岩和镁铁质样品干燥条件下：4.75 ~ 6.90，潮湿条件下：14.5 ~ 18.3×10米/分钟）。这一结果可能是由于蛇纹石化导致的断裂强度降低。我们使用等效强度法将钻速归一化到给定的转速和扭矩，将钻进参数的实验室结果与国际大洋发现计划（IODP）第360航次辉长岩钻进和第399航次蛇纹石化橄榄岩钻进获得的现场数据进行了比较。计算结果表明，蛇纹石化橄榄岩地层的归一化钻速系统地高于辉长岩层，这与我们的实验结果一致。我们提出，现场钻进性能参数可用于检测岩性转变，如蛇纹岩。
