Research on risk assessment and prevention methods of shallow water flow hazards in deep-water and shallow areas

Abstract:

With the continuous increase in global energy demand, offshore oil & gas resources, especially deep-water oil & gas
resources, have become new development hotspots. The deep-water oil & gas resources are characterized by high reserves, great  
potential and low exploration rates, but they are also accompanied by shallow geological hazards and other problems that onshore  
drilling works have never faced. Shallow water flow (SWF) is a common geological hazard, which is essentially the over-pres
sured sand section developed in the deep water and shallow areas and mainly formed by rapid deposition and unbalanced  
compaction in the formation. SWF hazards have large destructive power and wide distribution areas, which have influence on  
the borehole, casing and wellhead, and can seriously damage the integrity of the wellbore. In this paper, the concept, harm, and  
main causes of SWF hazards are firstly expounded. Then the identification and prediction technology, risk assessment methods,  
prevention, and control measures of SWF hazards are summarized. Finally, risk assessment and comprehensive prevention  
methods are put forward. It is concluded that the identification and prediction methods of SWF hazards mainly include logging  
and reflection seismic methods. Among these, the reflection seismic method is adopted more commonly in practice, which recog
nizes the overpressure sand body by the abnormal fluctuations of the value of V p / V s . At present, the risk assessment of the SWF  
hazards places more emphasis on the pre-drilling prediction and qualitative judgment but lacks quantitative analyses. However,  
experimental and numerical simulation studies have been constantly filling this gap in recent years. The prevention and control  
operations of SWF hazards include well control measures and working fluid system optimization. Based on current work of the  
risk prediction and assessment of the SWF hazards, a new risk assessment system is proposed and then combined with disaster  
prevention measures in this study, proposing a dynamic hazard prevention method. This hazard prevention method reasonably  
plans the drilling operations in SWF areas, combines the risk assessment scheme with the response mechanism, and continuously  
optimizes the drilling scheme during the drilling operation to improve the flexibility of drilling operations and enhances the  
hazard prevention ability. Finally, the development trends of SWF hazard prevention are examined. It is considered that basic  
research into the flow failure mechanism of the SWF hazards, the development of geophysical identification technology, as well  
as the application of artificial intelligence technology (AIT) will be the research emphases in the future.


Key words:geological hazard; shallow water flow; hazard prevention methods; risk assessment; machine learning

Received: 2020-05-11

Corresponding Authors:linb_cupb@163.com

Cite this article:申屠俊杰, 林伯韬. 深水浅层浅水流灾害风险评价与防灾方法研究. 石油科学通报, 2021, 03: 451-464 SHENTU Junjie, LIN Botao, LU Ji. Research on risk assessment and prevention methods of shallow water flow hazards in deep-water and shallow areas. Petroleum Science Bulletin, 2021, 03: 451-464.

URL: