Day 2 :
China University of Petroleum, China
Xiaohui Wang has her expertise in evaluation and passion in improving the risk assessment in deep water drilling. Her open and contextual evaluation model based on hidden Markov model creates new pathways for improving accuracy of gas cut evaluation. She has built this model after years of experience in research, evaluation and administration in educational institutions.
Gas cut risk assessment is the premise of well control schemes; the evaluation method used is the key technology in the risk assessment process, which directly affects the final effect of well control. In this paper, a gas invasion risk assessment system based on analytic hierarchy process (AHP) and hidden Markov model (HMM) is studied and the feasibility of the system is verified using fifteen actual wells. Firstly, this research starts from the interval judgment matrix and approximates the interval judgment matrix to the general digital judgment matrix. Then it forms an AHP with automatic correction judgment matrix and obtains the approximate weight of each element. Thus, a gas trapping evaluation system based on HMM was established. Realtime dynamic risk assessment was carried out with HMM and its results were compared with the results of AHP. The experimental results show that the method of general digital judgment matrix can be used to solve the problem that the traditional AHP method often results in inconsistency in the measurement of multi-factor weight and improves the accuracy and trust worthiness of the evaluation results. Through the collection of real-time data in the drilling process, the HMM method is used to calculate the risk situation of each node and the monitoring signal data is updated in real time; then the original data is provided for the implementation evaluation system based on the HMM method. Combined with the AHP evaluation results, the degree of the risk can be described more accurately, thus having higher assessment accuracy. The real-time risk assessment method based on HMM and AHP proposed in this research can solve the above problems effectively, thus reducing the harm of gas invasion and save the drilling cost. Recent Publications 1. Yin H, Liu P and Li Q (2015) A new approach to risk control of gas kick in high-pressure sour gas wells. Journal of Natural Gas Science & Engineering 26:142???148. 2. Chen P and Ma T (2014) Research status of early monitoring technology for deep water drilling overflow. J. Acta Petrolei Sinica 35(3):602???612. 3. Hauge E, Aamo O M and Godhavn J M (2013) A novel model-based scheme for kick and loss mitigation during drilling. Journal of Process Control 23(4):463???472. 4. Mcconnell D R, Zhang Z and Boswell R (2012) Review of progress in evaluating gas hydrate drilling hazards. Marine and Petroleum Geology 34(1):209???223. 5. Alhuthali A H, Datta Gupta A and Yuen B (2010) Optimizing smart well controls under geologic uncertainty. Journal of Petroleum Science & Engineering 73(1???2):107???121.
Federal University of Rio de Janeiro, Brazil
Prof. Ricardo A. Medronho is a full professor at the Chem. Eng. Dept. of the Federal Univ. of Rio de Janeiro. He is a specialist in CFD applied to the oil and gas industry and has supervised more than 50 MSc and DSc students.
Accidents related to oil and gas plants are a concern because despite having intermediate frequency of occurrence, the consequences are severe, with intermediate fatality potential and high potential of economic losses. One of the issues noted to this risk is related with electrical facilities and equipment with components operating with flammable products, which can act as source of ignition, generating severe accidents. So, an appropriate hazardous area definition is necessary to avoid these types of accidents in places with explosive atmospheres. This study aims to define a hazardous area of a crude oil pump facility through numeric simulation with computational fluid dynamics (CFD), and compare the results to the recommended practice guidelines used to define the hazardous areas. These guidelines used as reference to define hazardous areas are the NFPA 497 and API 505. For the computational fluid dynamics, the CFD package from Ansys was employed. The comparison of the hazardous areas results based on the guidelines overestimate these areas when compared to the CFD results. It may be concluded that the guidelines are conservative criteria, so the standards are sufficiently safe. Nevertheless, the use of CFD may support projects as an auxiliary tool of risk analysis. Recent Publications 1. Bozek A, Anhalt J and Chin J (2015) The use of infrared emission detection and fugitive emission quantification technologies as a basis for hazardous area classification design. IEEE Transactions on Industry Applications. 51(1):142-147. 2. Nagaosa R S (2014) A new numerical formulation of gas leakage and spread into a residential space in terms of hazard analysis. Journal of Hazardous Materials. 271:266-274. 3. Gomes E G, Medronho R A and Alves J V B (2014) Gas detector placement in petroleum process unit using computational fluid dynamics. International Journal of Modeling and Simulation for the Petroleum Industry. 8:17-24. 4. Zhu Y et al. (2015) Analysis and assessment of the Qingdao crude oil vapor explosion accident: lessons learnt. Journal of Loss Prevention in the Process Industries. 33:289-303.