ABSTRACT

Dual wellhead suction bucket foundation plays an important role in joint mining and production improvement. In order to ensure safe operation, the bearing capacity mechanism and wellhead stability need to be studied. In this paper, the mechanical model of riser and dual wellhead suction bucket foundation is established through theoretical research, and the finite element software Ansys and Abaqus are used for analysis. By loading the model wellhead load, the ultimate bearing capacity of dual wellhead suction bucket foundation is obtained. Through the sensitivity analysis of buried depth, soil parameters and other factors, the influence law of different factors on the bearing capacity of suction bucket foundation is obtained. Based on the hydrologic environment and actual construction parameters in the deep-water area of the South China Sea, the wellhead stability of dual wellhead suction bucket foundation under drilling conditions is analyzed, in order to provide some guidance for the actual operation.

INTRODUCTION

With the development of offshore oil exploration and exploitation in deep-water. The traditional drilling and injection well construction method can no longer meet the needs of deep-sea oil and gas exploitation. As a new well construction technology proposed by Norway, It was noted (Spanjarrd,2016; Tjelta,2001; Liu Z,2021) that suction bucket foundation surface well construction technology has better adaptability. Through a large number of investigations and studies, it is found(Li W,2020; Yan W,2015;Wu X,2020) that whether the dual wellhead suction bucket foundation is stable mainly depends on the vertical load and lateral load it bears. Tian D discovered(2017) that the shape of sand and related parameters also have great influence on the stability of wellhead. In terms of bearing capacity of suction bucket foundation, (Allersma,1999) found that the bearing capacity of suction bucket foundation varies greatly with different soil types. In deep-water drilling, the environmental loads and stress values of the equipment required for deep-water oil and gas production are analyzed, and then the vertical and lateral loads of suction bucket foundations are analyzed(Cheng G,2013) When the finite element model is established to analyze the mechanical properties of suction bucket foundation, the horizontal load and bending moment of riser, BOP, LMRP and other equipment subjected to environmental load can be taken as the boundary conditions. It is also noted (Monajemi,H,2009; Li S,2020) that it is necessary to prevent the lateral load and vertical load on the pile from exceeding its own horizontal and vertical bearing capacity.

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