Feasibility Analysis of Early Gas Monitoring at the Bottom of Marine Riser in Deepwater Drilling

X.H. Wang ； Z.C. Guan ； Y. Tian ； S.Q. Xu

《淡江理工學刊》 21卷4期 (2018/12) Pp. 625-631

https://doi.org/10.6180/jase.201812_21(4).0016

摘要

Gas influx is a phenomenon which causes serious outcome, and consequently the early and accurate detection of gas influx is crucial for deepwater drilling operation security. The detection method outside marine riser (DMOMR) is widely utilized in deepwater drilling as a complement of the traditional wellhead detection method (WDM). In this study, an extended two-fluid model (TFM) is developed to describe the gas-liquid two-phase flow when gas influx occurs and to compare the advantages of the DMOMR and the WDM in marine riser. By comparing the simulation results with the measured data of a well in the Bohai Sea, China, it is demonstrated that this model provides an excellent description for the gas-liquid two-phase flow in marine riser. The tip gas position, overflow and detection time are predicted using this model, and parameters such as water depth, wellbore depth, and formation permeability and equivalent density are controlled to vary respectively. The comparisons present that the DMOMR can detect gas influx in advance than the WDM under most conditions, and the lead time of the DMOMR increases by the increasing water depth and reducing wellbore depth. Moreover, the simulation results agree that the DMOMR has a great advantage in low or medium permeability (＜ 300 mD) formation and lower pressure formation. With the increase of formation permeability and formation equivalent density, the advantage of the DMOMR weakens compared with the WDM.

關鍵字

Deepwater Drilling ； Gas Influx ； Acoustic Detection ； Two-fluid Model ； Numerical Simulation