© Effects Of Confining Pressure And Temperature On Mixed- Mode (I-II) Fracture Toughness Of A Limestone Rode Al-Shayea, NA; Khan, K; Abduljauwad, SN PERGAMON-ELSEVIER SCIENCE LTD, INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES; pp: ; Vol: 37 King Fahd University of Petroleum & Minerals Summary Studying fracture toughness behavior at elevated temperatures and cofining pressures is valuable for a number of practical situations such as hydraulic fracturing used to enhance oil and gas recovery from a reservoir, and the disposal or safe storage of radioactive waste in underground cavities. Mixed-mode (I-II) fracture toughness under simulated reservoir conditions of high temperature and confining pressure was studied using straight notched Brazilian disk (SNBD) specimens under diametrical compression. Rock samples were collected from a limestone formation outcropping in the Central Province of Saudi Arabia. Tests were conducted under an effective confining pressure (sigma(3)) Of UP to 28 MPa (4000 psi), and a temperature of up to 116 degrees C. The results show a substantial increase in fracture toughness under confining pressure. The pure mode-I fracture toughness (K-IC) increased by a factor of about 3.7 under a sigma(3) of 28 MPa compared to that under ambient conditions. The variation of K-IC was found to be linearly proportional to sigma(3) The pure mode-II fracture toughness (K-IIC) increased by a factor of 2.4 upon increasing sigma(3) to 28 MPa. On the other hand, K-IC at 116 degrees C was only 25% more than that at ambient conditions. Some ductile behavior was displayed by the rock samples at a high temperature and confining pressure. (C) 2000 Elsevier Science Ltd. All rights reserved. References: Copyright: King Fahd University of Petroleum & Minerals;

© ABE H, 1979, INT J NUMER ANAL MET, V313, P79 ABOUSAYED AS, 1978, VDI BER, V33, P819 ALMEIDA LCR, 1998, P 8 C INT ASS ENG EN, V1, P351 ATKINSON C, 1982, INT J FRACTURE, V18, P279 AWAJI H, 1978, J ENG MATER-T ASME, V100, P175 BARTON CC, 1982, P 23 US S ROCK MECH, P145 CUTLER RA, 1983, J TEST EVAL, V11, P3 FOWELL RJ, 1994, INT J ROCK MECH MIN, V31, P571 GOODMAN RE, 1989, INTRO ROCK MECH HOAGLAND RG, 1973, ROCK MECHANICS, V5, P77 KRISHNAN GR, 1998, INT J ROCK MECH MIN, V35, P195 LIM IL, 1994, INT J ROCK MECH MIN, V31, P265 MEREDITH PG, 1983, THESIS U LONDON MITCHELL JK, 1993, FUNDAMENTALS SOIL BE MULLER W, 1986, PAGEOPH, V124, P694 PERKINS TK, 1966, SOC PETROL ENG J, P308 POWERS LF, 1963, GEOLOGY ARABIAN PENI RUMMEL F, 1982, P 1 JAP US S FRACT M, P495 SANCHEZ J, 1979, THESIS U PITTSBURGH SCHMIDT RA, 1976, EXPL MECH, V16, P161 SCHMIDT RA, 1977, INT J ROCK MECH MIN, V14, P289 SHETTY DK, 1986, J AM CERAM SOC, V69, P437 SHLYAPOBERSKY J, 1985, P 26 US S ROCK MECH, P539 SIH GC, 1968, FRACTURE ADV TREATIS, V2 THALLAK S, 1993, INT J ROCK MECH MIN, V30, P831 VASARHELYI B, 1997, ROCK MECH ROCK ENG, V30, P59 WHITTAKER BN, 1992, ROCK FRACTURE MECH P For pre-prints please write to: Copyright: King Fahd University of Petroleum & Minerals;