Sains Malaysiana 43(1)(2014): 81–87

Effect of Grain Size and Grain Content on the Hardness and Drillability of Rocks

(Kesan Saiz Butiran dan Kandungan Butiran terhadap Kekerasan dan Kebolehgerudian Batuan)

MOU YANG¹, YINGFENG-MENG¹*, GAO LI, LIN HAN¹& YUFEI-LI²

  ¹State Key Laboratory of Oil and Gas Geology and Exploration, Southwest Petroleum University

610500. Chengdu, P.R. China

²Gas Production Engineering Research Institute of Southwest, 618300 Guanghan, P.R. China

Diserahkan: 3 Disember 2012/Diterima: 29 Mac 2013

ABSTRACT

It is well-known that the characteristics of hardness and drillability are influenced by microstructure of rock. In this study, rock properties were analyzed on grain size and grain content. Coarse-grain and fine-grain sandstones were tested under successive indentation condition. Eighteen groups of sandstone and shale were employed for the drillability test. Indentation tests results showed that grain size influenced the low point of residual hardness, the crushing depth and volume and grain content influenced the peak point of hardness. Drillability values of shale increased with increasing contents of clay and quartz. Meanwhile, drillability values of sandstone increased with increasing content of quartz, but decreased with increasing content of clay. Therefore, these preliminary studies show great potential applications for selecting suitable bit type and formulating drilling program as a function of rock microstructure and crushing rock method for bit in the oil drilling.

Keywords: Drillability; grain content; grain size; hardness; successive indentation

ABSTRAK

Adalah diketahui sifat kekerasan dan kebolehgerudian batuan dipengaruhi oleh mikrostruktur batuan. Dalam kajian ini, saiz butiran dan kandungan butiran beberapa batuan dianalisis. Batu pasir bersaiz butiran kasar dan halus diuji dengan keadaan pelekukan berterusan. Lapan belas kumpulan batu pasir dan syal digunakan untuk ujian kebolehgerudian. Ujian pelekukan menunjukkan saiz butiran mempengaruhi kekerasan baki titik rendah, kedalaman kehancuran dan isi padu manakala kandungan butiran mempengaruhi kekerasan titik tinggi. Nilai kebolehgerudian syal meningkat dengan peningkatan kandungan lempung dan kuartz. Untuk batu pasir, nilai kebolehgerudian meningkat dengan peningkatan kandungan kuartz, tetapi menyusut dengan peningkatan kandungan lempung. Hasil kajian awal ini menunjukkan keupayaan tinggi kaedah ini dalam pemilihan mata gerudi yang sesuai dan merancang kaedah penggerudian sebagai fungsi mikrostruktur batuan dan kaedah penghancuran batuan untuk penggerudian minyak.

Kata kunci: Kandungan butiran; kebolehgerudian; kekerasan; pelekukan berketerusan; saiz butiran

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*Corresponding author; email: cwctmyf@vip.sina.com