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

 

Received: 3 December 2012/Accepted: 29 March 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. The 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

 

REFERENCES

 

Bažant, Z.P., Gettu, R. & Kazemi, M.T. 1991. Identification of nonlinear fracture properties from size effect tests and structural analysis based on geometry dependent R-curves. Int. J. Rock Mech. Min. Sci. 28: 43-51.

Beste, U., Lundvall, A. & Jacobson, S. 2004. Micro-scratch evaluation of rock types-a means to comprehend rock drill wear. Tribology International 37: 203-210.

Chen, L.H. & Labuz, J.F. 2006. Indentation of rock by wedge-shaped tools. J. Rock Mech. Min. Sci. 43: 1023-1033.

Eberhardt, E., Stimpson, B. & Stead, D. 1999. Effects of grain size on the initiation and propagation thresholds of stress-induced brittle fractures. Rock Mech. Rock Eng. 32: 81-99.

Ersoy, A. & Waller, M.D. 1995. Textural characterization of rocks. J. Eng. Geol. 39: 123-136.

Hoseinie, S.H., Ataei, M. & Osanloo, M. 2009. A new classification system for evaluating rock penetrability. Int. J. Rock Mech. Min. Sci 46: 1329-1340.

Hussain, M., Waleed, M., Hassan, E.I. & Abdualzeez, A. 2006. Controls of grain-size distribution on geomechanical properties of reservoir rock-A case study: Cretaceous Khafji Member, Zuluf Field, off shore Arabian Gulf. Marine and Petroleum Geology 23: 703-713.

Koyama, T. & Jing, L. 2007. Effects of model scale and particle size on micro-mechanical properties and failure processes of rocks-A particle mechanics approach. Engineering Analysis with Boundary Elements 31: 458-472.

Mindlin, R.D. 1963. The influence of couple stresses on stress concentrations. Experimental Mech. 3: 1-7.

Palchik, V. 1999. Influence of porosity and elastic modulus on uniaxial compressive strength in soft brittle porous sandstones. Rock Mech. Rock Eng. 32: 303-309.

Robina, H.C., Wongt, K.T. & Chau, P.W. 1996. Microcracking and grain size effect in Yuen Long marbles. Int. J. Rock Mech. Min. Sci. 33: 479-485.

Singh, S.K. 1988. Relationship among fatigue strength, mean grain size and compressive strength of a rock. Rock Mechanics and Rock Engineering 21: 271-276.

Sulem, J. & Cerrolaza, M. 2002. Finite element analysis of the indentation test on rocks with microstructure. Computers and Geotechnics 29: 95-117.

Szwedzicki, T. 1998. Indentation hardness testing of rock. Int. J. Rock Mech. Min. Sci. 35(6): 825-829.

Tanaino, A.S. 2008. Rock drillability classification. PartⅡ: Canonical representation of rock properties in rock classification by fracture resistance. Journal of Mining Science 6: 600-607.

Thuro, K. 1997. Drillability prediction-geological influences in hard rock drill and blast tunneling. Geol. Rundsch. 86: 426-438.

Vernik, L., Bruno, M. & Bovberg, C. 1993. Empirical relations between compressive strength and porosity of siliclastic rocks. Int. J. Rock Mech. Min. Sci. Geomech. Abstr. 30: 677- 680.

Wichtmann, T. & Triantafyllidis, T. 2010. On the influence of the grain size distribution curve on P-wave velocity, constrained elastic modulus Mmax and Poisson's ratio of quartz sands. Soil Dynamics and Earthquake Engineering 30: 757-766.

Yin, H. 1986. Investigation on the application of statistical formation drillability. Paper No. SPE 14848. Society of Petroleum Engineers, Beijing, China, March 17-20. pp. 1-5.

Zhang, X., Zhai, Y.H., Xue, C.J. & Jiang, T.X. 2011. A study of the distribution of formation drillability. Petroleum Science and Technology 29: 149-159.

 

 

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