Risk Analysis Of Coring Engineering For Hydrate-bearing Strata

Coring is an important data source of natural gas hydrate (NGH) exploration anddevelopment. The risk and uncertainty of coring engineering in deep water area is even moresignificant for the not maturity of technology and tool equipment, so risk prediction andanalysis is essential for risk control because of the uncertainty of coring engineering. It willcontribute to avoid risk effectively and improve the coring operation success rate and corerecovery.This paper provided the definition of marine hydrates coring project risk; elaborated thecontent of risk assessment; analyzed the features and main sources of coring engineering riskand formulated the measurement level and scope of risk index on the base of theory of projectrisks related research at home and abroad for reference. It is beneficial to understand thecoring project risk better and formulate effective measures.Combined with the characteristics of coring engineering, risk factors and events arerecognized and analyzed effectively; risk assessment system and mathematic model areestablished. Using Monte Carlo simulation method as well as AHP, risk of coring engineeringis analyzed and calculated. With the consideration of various uncertainly risk factors,combination sampling method is applied to get quantized risk probability distribution.Meanwhile, according to the simulation results, risk index of each factor is available whichquantizes its corresponding contribution to the risk of engineering. Hence, risk factors orevents with high index can be found based on analysis of probability, which is helpful in riskmanagement of coring engineering and promoting success ratio and core recovery. Studiesshow that this method is good at evaluation effectiveness and its prediction results arereasonable. Finally, risk analysis software of coring engineering is complied with VisualBasic6.0programming language.On the one hand, this study discussed the risk analysis of coring engineering for hydrate-bearing strata theoretically, on this basis it offered new technological approaches forestablishing new evaluation methodology and supplied decision basis for risk management;on the other hand, the study did the foundational research work for subsequent hydrate coringproject evaluation.