Dynamic risk assessment approach of riser recoil control failure during production test of marine natural gas hydrate

Abstract

The marine natural gas hydrate is considered to have huge resource potential in the South China Sea, and a sixty‐day production test has been successfully conducted in 2017. As the crucial and most vulnerable connection of floating platform and subsea wellhead, the risers are of paramount importance in safe production test of the hydrate. Due to harsh environment and the possible drive off and drift off events induced by failure of dynamic positioning system of the platform, the unplanned emergency disconnect of risers is an integral preventive measure to avoid accidents and secure the well. Once the disconnect occurs, the huge potential energy stored in the riser column will release and consequently cause violent axial recoil, which will cause serious consequences if the recoil control fails. This paper presented a quantitative risk assessment approach on the basis of dynamic Bayesian networks to dynamically predict the risk of riser recoil control failure during production test of hydrate. By using the proposed method, the dynamic failure risk of the riser recoil control was figured out, and the most contributory factors were identified. The practical application of the proposed methodology was demonstrated through a case study. Results indicated that the probability of riser recoil control failure can be significantly decreased within one year through equipment repair, and the failure and repair rates of shutoff valves and main air isolation valves are the most contributory factors. Some corresponding safety control measures were proposed to further mitigate the risk of riser recoil control failure during the production test of hydrate.

Risk assessment for yachting tourism in China using dynamic Bayesian networks

“…The Fuzzy Analytical Hierarchy (FHA) method is often used to calculate the risk index affecting the safety risk factors of yachting tourism [ 30 , 31 ]. The disadvantage of this method is the subjectivity of the evaluation result and problems in dealing with uncertain information in the analysis [ 34 ]. Fault Tree Analysis (FTA) [ 57 , 58 ] is often used to calculate the probability of maritime accident risk factors, but its evaluation results cannot reflect real-time dynamic information [ 59 ].…”

“…Yachting tourism has obvious seasonal characteristics. DBNs can consider uncertain information and risks, and make prediction and diagnostic analyses over time, which are widely used in the risk analysis of maritime accidents [ 34 ]. For example, Fan, Zheng, and Luo employed a BN model to examine the effectiveness of port state surveillance inspections and to gauge the level of ships’ safety at different times [ 35 ].…”

Numerical simulation of the stress field and fault sealing of complex fault combinations in Changning area, Southern Sichuan Basin, China

“…In contrast, when a section is in a tensile stress environment, the sealing performance of the section is poor, and a fault opens, becoming a channel for oil and gas escape. [21][22][23][24][25][26][27][28][29] In the quantitative evaluation of fault sealing, obtaining the stress value on the fault plane is the key to solving the problem. At present, the most intuitive and accurate method to obtain the stress value is to measure the crustal stress by field hydraulic fracturing tests, but this method is restricted by the location and number of well points, and the measured in situ stress is not the normal stress on the fault plane.…”

Management and Production Engineering Review

“…Today, Bayesian Network (BN) represents another area of research. It is widely used in many applications for system performance evaluation, risk analysis, diagnosis and prediction analysis, and maintenance (Weber et al, 2012;Chang et al,2019). Reasoning from probabilistic graphical models facilitates dealing with both diagnosis and prediction problems.…”

“…In another study, (Wang, et al, 2017) established a stochastic deterioration model for multi-element systems under a conditional maintenance strategy (CBM). A quantitative risk assessment approach based on DBN that dynamically predicts the risk of riser recoil control failure during production test of marine natural gas hydrate was presented by (Chang et al, 2019).…”