Abstract Landing large diameter conductor or surface casing strings in deepwater has become a great concern to offshore oil companies, since the dynamic tensile load induced by the heave motion of drillship approaches the capacity of today's landing system. For an accurate prediction of heave induced dynamic tensile load on landing strings and determining the safe margin of deepwater landing operation, a comprehensive mathematical model is proposed in this study. The novelty of this mathematical model lies in that it incorporates the effect of Bottom Hole Assembly (BHA) as well as Guide Base Plate (GBP) which are often neglected by other researchers. The mathematical model proposed in this study is solved with Galerkin's method and its validity is verified by comparing the corresponding results calculated by the numerical method established in a previous research work. The results derived from this model are used to compare with those from existing models to emphasize the important role that BHA and GBP act on heave-induced dynamic response of the landing string assembly. Meanwhile, safe margins of deepwater landing operation derived with/without considering the effect of BHA are presented and compared. At last, sensitivity analysis is carried out to investigate the effect that GBP area and hydrodynamic damping coefficients have on heave-induced dynamic response of the landing string assembly. This study shows that the effect of BHA is essential for an accurate evaluation of the safe margin for deepwater landing operation. By incorporating the effect of BHA, the resonant frequency and stress state of the landing string assembly both have changed; while, the GBP only affects the stress state. Besides, the dynamic tensile load decreases with the increase of GBP area and hydrodynamic damping coefficients in near resonant conditions. This work provides a theoretical guidance to the design of deepwater landing string, which is essential for deepwater drilling operation.

中文翻译：

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深水登陆作业安全裕度评价新数学模型

摘要 由于钻井船的升沉运动引起的动态拉伸载荷接近当今着陆系统的能力，在深水着陆大直径导体或表层套管柱已成为海上石油公司的一个重要问题。为了准确预测登陆管柱上的升沉动态拉伸载荷并确定深水登陆操作的安全裕度，本研究提出了一个综合数学模型。该数学模型的新颖之处在于它结合了其他研究人员经常忽略的井底组件（BHA）和导向底板（GBP）的影响。本研究提出的数学模型用Galerkin'求解 通过比较先前研究工作中建立的数值方法计算的相应结果，验证了 s 方法及其有效性。使用该模型得出的结果与现有模型的结果进行比较，以强调 BHA 和 GBP 对着陆管柱组件的升沉引起的动态响应的重要作用。同时，提出并比较了考虑/不考虑BHA影响的深水登陆作业安全裕度。最后，通过敏感性分析研究GBP面积和水动力阻尼系数对着陆管柱组件升沉动力响应的影响。本研究表明，BHA 的影响对于准确评估深水登陆作业的安全裕度至关重要。通过结合 BHA 的作用，着陆串组件的共振频率和应力状态都发生了变化；而英镑只影响压力状态。此外，在近共振条件下，动态拉伸载荷随着 GBP 面积和流体动力学阻尼系数的增加而减小。这项工作为深水着陆管柱的设计提供了理论指导，这对于深水钻井作业至关重要。