http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
- 中文 을 입력하시려면 zhongwen을 입력하시고 space를누르시면됩니다.
- 北京 을 입력하시려면 beijing을 입력하시고 space를 누르시면 됩니다.
RISS 인기검색어
- 검색키워드
- 저자 : Pawel A. Nawrocki (검색결과 3 건)
- 무료
- 기관 내 무료
- 유료
-
Alterations of breakdown and collapse pressures due to material nonlinearities
Nawrocki, Pawel A. Techno-Press 2009 Geomechanics & engineering Vol.1 No.2
Breakdown pressures obtained from the classic, linear elastic breakdown model are compared with the corresponding pressures obtained using a nonlinear material model. Compression test results obtained on sandstone and siltstone are used for that purpose together with previously formulated nonlinear model which introduces elasticity functions to address nonlinear stress-strain behaviour of rocks exhibiting stress-dependent mechanical properties. Linear and nonlinear collapse pressures are also compared and it is shown that material nonlinearities have significant effect on both breakdown and collapse pressures and on tangential stresses which control breakdown pressure around a borehole. This means that the estimates of ${\sigma}_H$ made using linear models give stress values which are different than the real values in the earth. Thus the importance of a more accurate analysis, such as provided by the nonlinear models, is emphasised. It is shown, however, that the linear elastic model does not necessarily over-predict borehole stresses and the opposite case can be true, depending on rock type and test interpretation.
-
-
Zili Qi,Pawel A. Nawrocki,Dong Wang 한국자원공학회 2013 Geosystem engineering Vol.16 No.1
Since rock formations are always saturated by fluids, the coupled poroelastic models were developed to conduct wellbore stability analysis. The analysis based on this theory allows us to consider phenomena such as well communication with rock formation, change of pore pressure profile, pore pressure dissipation, etc. This article presents the analytical solution of one coupled poroelastic model and then departs to consider two common drilling scenarios, which are under-balanced drilling (UBD) and over-balanced drilling (OBD). Obtained results show that the phenomena of time-dependent delayed failure and failure initiation taking place not only at the wellbore wall but also inside the formation can be predicted by virtue of the coupled model. Moreover, these two phenomena are different for the two drilling scenarios mentioned above. Regarding the (UBD), the borehole stability status will get enhanced with time due to the poroelastic effect in the formation. On the contrary, the borehole stability status will get worse, and time-delayed failure may happen for the OBD.
연관 검색어 추천
이 검색어로 많이 본 자료
활용도 높은 자료
