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Background
Published in Jie Zhang, Chuanjun Han, Rubber Structures in Oil and Gas Equipment, 2022
A blowout preventer (BOP) is one of the core equipment for the well control operation, which can ensure the safe and normal operation of oil and gas drilling engineering. In drilling operation, when the liquid column pressure in the well is less than the formation pressure, blowout may occurs. The blowout preventer can quickly close the wellhead to prevent blowout accidents. While, the blowout preventer also plays an important role in underbalanced drilling, pressure operation and other processes [20]. The blowout preventer failure causes serious environment pollution and life threatening. The rubber core is one of the key components of the blowout preventer. The rubber core performance determines the sealing performance of the blowout preventer and the oil and gas exploitation progress.
Survey on reliability analysis of dynamic positioning systems
Published in Ships and Offshore Structures, 2023
Fang Wang, Liang Zhao, Yong Bai
Position loss may occur on DP MODUs while connected to a subsea well (Figure 3). In normal operations, a MODU should be positioned within a green zone inside the yellow limit. When the vessel loses the capability to maintain position by means of thruster force, she may have an excursion beyond the yellow or even the red limit. This condition is denoted drive-off or drift-off event, which is generic to all DP vessels. If the vessel passes the yellow limit, the drilling operation must be stopped and the driller starts to prepare for disconnection. If the vessel passes the red limit, emergency disconnection must be initiated in order to disconnect the riser/LMRP (lower marine riser package) and shut in the well. Failure of disconnection may result in damage of the riser, wellhead, or BOP (blowout preventer). This could cause significant financial losses and vessel downtime, and in the worst case could escalate into a subsea blowout.
Delay-feedback-based recoil control for deepwater drilling riser systems
Published in International Journal of Systems Science, 2022
Yan-Dong Zhao, Yue-Ting Sun, Bao-Lin Zhang, Dawei Zhang
The emergency disconnection of a deep riser system is presented by Figure 1, where a tensioner is mounted between the drilling platform and the riser, a lower marine riser package (LMRP) and a subsea blowout preventer (BOP) are installed at the bottom of the riser. If an emergency disconnection is required, a connector between the BOP and LMRP will be unlocked. In this case, the drilling mud inside riser will discharge and seawater will enter the riser through the refill valve. Consequently, the recoil response of the riser system occurs. To mitigate the response, it is significant to establish a recoil model of the riser system. In fact, the recoil response of riser system is related to the multiple dynamic behaviours of the drilling platform, riser and tensioner. Also, it is affected by external disturbances, such as the friction resistance induced by the seawater and drilling mud discharge.
Calculation method for the vertical bearing capacity of a riser-surface casing composite pile
Published in Ships and Offshore Structures, 2021
In recent years, the cost of offshore oilfield exploitation has gradually increased in the Bohai Sea. The tasks of some old platforms have become increasingly heavy, and the exploitation difficulty has continued to increase (Wang et al. 2019). The bearing capacity design of some jacket platforms can no longer meet the increasing demands of the exploitation tasks. Furthermore, to improve economic benefits, in addition to the conventional large oil fields, increasingly marginal, low-capacity, and inefficient block oil fields, including small marginal oil fields, need to be developed (Yang 2003; Permata and Hatzignatiou 2011; Carpenter 2014; Zhao et al. 2016). To save development costs, some simple platform structures have been developed. Whether involving a traditional jacket platform or a simple platform, the indispensable part of the platform structure is the oil well. The oil wells of offshore platforms generally include risers and surface casings. The riser is a steel pipe that runs from the offshore drilling platform to the shallow seabed during the drilling process. Its main function is to isolate the well from seawater, form a circulation channel for drilling fluid, and provide structural support for the Christmas tree and blowout preventer. The surface casing is usually used to isolate the well from the shallow surface water layer and the shallow complex bottom layer.