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Well bore instability is a technical problem in petroleum exploration and development that has long challenged the oil industry. This problem costs the world oil industry 500 to 600 million dollars every year and is becoming a serious problem in drilling. Qun Ku Qia Ke (QKQK) area's layer of the Tarim oil field was formed during the Carboniferous and Devonian periods, and the lithologic character is complex. There were 200 drilling events in the 5 drilled exploitation wells. The progress of drilling was seriously affected, and the cost increased significantly. Based on the instability and the mineral components of the well's bore hole layer and the physical and chemical properties of the QKQK area, this study researched the chemical mechanism of well bore instability and proposes technical strategies to improve outcomes. The results of field applications showed that anti-sloughing drilling fluid and separate layer drilling fluid met the requirements for drilling engineering in the QKQK area and decreased the risk of drilling accidents. Compared with adjacent wells, the drilling problems at the Qun 5-1H well were reduced by 67.5%, and the economics of the well have increased greatly. The cost of Qun 5-1H drilling was reduced significantly and saved more than 5,400,000 yuan. [ABSTRACT FROM PUBLISHER]

Large Eddy Simulations (LES) of the Sandia Flame D methane diffusion flame are carried out. An extended LES version of the Eddy Dissipation Concept (EDC) model is used as a turbulence combustion closure model. In LES the computational cost is high due to the fine grid resolution and unsteady nature of the governing equations. Using a detailed chemical mechanism in LES with EDC is too expensive, and hence, to reduce computational cost reduced mechanisms are preferred. In this study a number of PSR calculations for methane-air combustion using two reduced methane mechanisms and one detailed methane mechanism are carried out. The reduced mechanisms tend to strongly overpredict the temperature and major species mass fraction in either the lean or the rich mixture zone. Both mechanisms overpredict temperature for lean mixtures. The two reduced methane mechanisms are also studied with LES for the Sandia Flame D. The results of the two reduced mechanisms are compared with the fast chemistry approach and it is observed that in the lean mixture zone of the jet the reduced mechanisms overpredict the temperature and H2O mass fraction. Prediction with fast chemistry approach compared well with the experimental data. The present study emphasize the need of using fast chemistry approach instead of reduced mechanism when using the EDC combustion model. [ABSTRACT FROM AUTHOR]