Applying the vantage PDMS to jack-up drilling ships

The plant design management system （PDMS） is an integrated application which includes a database and is useful when designing complex 3-D industrial projects. It could be used to simplify the most difficult part of a subsea oil extraction project-detailed pipeline design. It could also be used to integrate the design of equipment, structures, HVAC, E-ways as well as the detailed designs of other specialists. This article mainly examines the applicability of the Vantage PDMS database to pipeline projects involving jack-up drilling ships. It discusses the catalogue （CATA） of the pipeline, the spec-world （SPWL） of the pipeline, the bolt tables （BLTA） and so on. This article explains the main methods for CATA construction as well as problem in the process of construction. In this article, the authors point out matters needing attention when using the Vantage PDMS database in the design process and discuss partial solutions to these questions.

Study on General Performance of Jack-up Under Elevated Condition

Method of checking for jack-up elevated performance including leg structure strength, fixation system or jacking system beating capacity, pre-load requirements, spud can beating capacity and overturning stability is suggested in this paper. As an example, a jack-up with truss legs is analyzed by finite element analysis method. This paper may be helpful to the rig owners, operators and designers.

Soil-Structure Interaction Analysis of Jack-up Platforms Subjected to Monochrome and Irregular Waves

As jack-up platforms have recently been used in deeper and harsher waters, there has been an increasing demand to understand their behaviour more accurately to develop more sophisticated analysis techniques. One of the areas of significant development has been the modelling of spudean performance, where the load-displacement behaviour of the foundation is required to be included in any numerical model of the structure. In this study, beam on nonlinear winkler foundation （BNWF） modeling--which is based on using nonlinear springs and dampers instead of a continuum soil media--is employed for this purpose. A regular monochrome design wave and an irregular wave representing a design sea state are applied to the platform as lateral loading. By using the BNWF model and assuming a granular soil under spudcans, properties such as soil nonlinear behaviour near the structure, contact phenomena at the interface of soil and spudcan （such as uplifting and rocking）, and geometrical nonlinear behaviour of the structure are studied. Results of this study show that inelastic behaviour of the soil causes an increase in the lateral displacement at the hull elevation and permanent unequal settlement in soil below the spudcans, which are increased by decreasing the friction angle of the sandy soil. In fact, spudeans and the underlying soil cause a relative fixity at the platform support, which changes the dynamic response of the structure compared with the case where the structure is assumed to have a fixed support or pinned support. For simulating this behaviour without explicit modelling of soil-structure interaction （SSI）, moment- rotation curves at the end of platform legs, which are dependent on foundation dimensions and soil characteristics, are obtained. These curves can be used in a simplified model of the platform for considering the relative fixity at the soil- foundation interface.

Dynamic Analysis Method of Offshore Jack-up Platforms in Regular and Random Waves

A jack-up platform, with its particular structure, showed obvious dynamic characteristics under complex environmental loads in extreme conditions. In this paper, taking a simplified 3-D finite element dynamic model in extreme storm conditions as research object, a transient dynamic analysis method was proposed, which was under both regular and irregular wave loads. The steps of dynamic analysis under extreme conditions were illustrated with an applied case, and the dynamic amplification factor （DAF） was calculated for each response parameter of base shear, overturning moment and hull sway. Finally, the structural response results of dynamic and static were compared and analyzed. The results indicated that the static strength analysis of the Jack-up Platforms was not enough under the dynamic loads including wave and current, further dynamic response analysis considering both computational efficiency and accuracy was necessary.

Design of A Bionic Spudcan and Analysis of Penetration and Extraction Performances for Jack-up Platform

The mechanisms of soil structure interaction have drawn much attention in the past years in the installation and operation of jack-up platform. A bionic spudcan produced by biomimetic of egg and snail shell is proposed, and the performance of the penetration and extraction are analyzed by numerical method. The geometric contour of egg and snail shell is measured, and its mathematical model is established respectively. According to the structure of existing spudcan of jack-up platform, three kinds of typical biomimetic spudcan are designed. Furthermore, numerical analysis models of biomimetic spudcan are established respectively to study the soil structure interaction mechanism in the process of penetration and extraction, and contrastive analysis of resistance characteristics are carried out. To conclude, the results show that the biomimetic spudcan facilitates the platform installation, and it is also beneficial to the improvement of the bearing capacity of spudcan.

Prediction Methods of Spudcan Penetration for Jack-up Units

Jack-up units are extensively playing a successful role in drilling engineering around the world, and their safety and efficiency take more and more attraction in both research and engineering practice. An accurate prediction of the spudcan penetration depth is quite instrumental in deciding on whether a jack-up unit is feasible to operate at the site. The prediction of a too large penetration depth may lead to the hesitation or even rejection of a site due to potential difficulties in the subsequent extraction process; the same is true of a too small depth prediction due to the problem of possible instability during operation. However, a deviation between predictive results and final field data usually exists, especially when a strong-over-soft soil is included in the strata. The ultimate decision sometimes to a great extent depends on the practical experience, not the predictive results given by the guideline. It is somewhat risky, but no choice. Therefore, a feasible predictive method for the spudcan penetration depth, especially in strata with strong-over-soft soil profile, is urgently needed by the jack-up industry. In view of this, a comprehensive investigation on methods of predicting spudcan penetration is executed. For types of different soil profiles, predictive methods for spudcan penetration depth are proposed, and the corresponding experiment is also conducted to validate these methods. In addition, to further verify the feasibility of the proposed methods, a practical engineering case encountered in the South China Sea is also presented, and the corresponding numerical and experimental results are also presented and discussed.

The Calculating Model of Structural Analysis for Jack-Up Rig Legs

The selection or establishment of structural calculating model is a matter of primary importance in structural analysis. By analysing the irrationality of the calculating models used by some research organizations at home and abroad in structural analyses for truss jack-up rig legs, this paper introduces a new calculation model which is more reasonable. This model can simulate better the load situation of a rig reflecting more precisely the effects of the leg loads caused by the spring support of gearboxes of the jacking system and the secondary bending moment raised by hull displacement under extreme conditions. The rig conversion was completed in 1989. In July 1991 the rig safely stood the frontal hitting of Typhoon with the wind speed of 52 m / s, which shows that the checking on the structure is correct.

Study on the Design Method of the Jack-up＇s X-Type Cantilever Allowable Load Nephogram

The extending of a cantilever and transverse moving of a drilling floor enable the jack-up to operate in several well positions after the Jack-up has pitched. The cantilever allowable load nephogram is the critical reference which can evaluate the jack-up's drilling ability, design the cantilever structure and instruct a jack-up manager to make the operations safe. The intent of this paper is to explore the interrelationships between the cantilever position, drilling floor and the loads including wind force, the stand set-back weight etc., through analyzing the structure and load characteristics of the x-type cantilever and the simplified mechanics model with the restriction of the maximum moment capacity of the cantilever single side beam. Referring to several typical position designs load values, the cantilever allowable load nephogram is obtained by using the suitable interpolation method. The paper gives a method for cantilever allowable load design, which is proved reliable and effective by the calculation example.

Discussion on Key Points of Wind Load of Jack-up Unit

The anti-overturning ability and structure safety of jack-up unit in in-place condition are often affected by environment loads, especially wind load. According to the MODU rule, the projected area method is used for calculating the wind load. However, the calculated results are conservative and not good for structure optimization design. In this paper, a 400 ft jack-up is studied as an example. Based on the wind tunnel test and numerical simulation method, some key points of wind load calculation, such as shielding effect, lift effect and shape coefficient of component, are discussed. The study shows that the points mentioned above, which are ignored in the MODU rule calculation, result in the conservative result.

Uplift Resistance Calculation and Sensitive Analysis of Jack-up Wind Installation Vessels

The uplift resistance calculation is an important basis for the construction decisions of the jack-up wind installation vessel and the design of the jacking system,and determines the operation risk and reliability in the installation process of the wind turbine. The influence factors of the pile shoe's penetration depth and uplift resistance are analyzed,and the calculation model and flow of the uplift resistance are given. Based on a construction example,the influence rules are analyzed for the change of the pile shoe's structural parameters on the penetration depth and uplift resistance.The analysis results show that the penetration depth is more sensitive to the width of the pile shoe,and the height has greater influence on the uplift resistance than the length and width of the spud. With the increase of the height,the uplift resistance may increase rapidly.Although the decreases of the length,width and height of the pile shoe may reduce the uplift resistance,the penetration depth may increase in the meantime. This will increase the pulling pile time and reduce the construction efficiency. So the parameters of the pile shoe should be optimized according to the adaptable geology condition so as to obtain the optimal uplift resistance and working efficiency.

Collision Analysis Between Spudcan and Seabed During the Process of Jack-up Platform Lowering Jack-up Legs

In the leg-lowering process,the offshore jack-up platform is in a floating state,and the spudcan may collide with the seabed due to the platform motion in waves,thereby threatening the safety and stability of the platform.This paper first analyzed the hydrodynamic response of a jack-up platform under different sea states.Then a finite-element model was established which considered the material and geometrical nonlinearity in the structure and the nonlinear interaction between soil and structure to investigate the collision response between the spudcan and seabed during lowering jack-up legs.The results show that the dynamic response of the platform decreases and gradually tends to be stable as the wave period increases.The motion response of the platform reach the largest value when the wave period is 8 s and the wave direction is 0°.The collision angle between the spudcan and seabed has a large influence on the collision response,while the velocity of leg-lowering has little influence on the collision response.The collision response is also significantly affected by soil conditions.For clay,the increase in undrained shear strength and Young’s modulus will increase the impact force.

Comparative Analysis of a Jack-up Drilling Unit with Different Leg Systems

The jack-up unit is one of the best drilling platforms in offshore oil fields with water depth shallower than 150 meters.As the most pivotal component of the jack-up unit,the leg system can directly affect the global performance of a jack-up unit.Investigation shows that there are three kinds of leg structure forms in the world now:the reverse K,X,and mixing types.In order to clarify the advantage and defects of each one,as well as their effect on the global performance of the jack-up unit,this paper commenced to study performance targets ofa deepwater jack-up unit with different leg systems(X type,reverse K type,and mixing type).In this paper a typical leg scantling dimension and identical external loads were selected,detailed finite element snalysis(FEA)models were built to simulate the jack-up unit's structural behavior,and the multi-point constraint(MPC)element together with the spring element was used to deal with the boundary condition.Finally,the above problems were solved by comparative analysis of their main performance targets(including ultimate static strength,dynamic response,and weight).

Jack-up日费对钻修井机具比选的敏感性分析

低油价下大量自升式钻井平台(Jack-up)资源处于闲置状态,在油服公司为降低损失,允许Jack-up日费有较大谈判空间的情况下,对于推荐采用固定式钻修井机具开发的油气田,有必要反算出与推荐方案投资相平衡的Jack-up日费,从而与油服公司谈判,以不高于平衡日费的条件租赁Jack-up,达到降低开发成本的目的。通过研究Jack-up日费对油气田开发各组成费用的影响,得出了油气田开发投资随日费变化的计算方法,对海上油气田开发的钻修井机具选择具有重要的指导意义。

砂土中桩靴插桩对临近筒型基础的影响研究

通过物理模型试验和有限元法研究砂土中风电安装船桩靴插桩对临近筒型基础的影响。首先通过物理模型试验,验证有限元模型的合理性,初步确定桩靴在砂土中贯入的影响范围大致在2.5倍桩靴直径。基于有限元CEL方法进一步研究桩靴和筒型基础的净距与桩靴直径之比(S/D)对筒型基础在位稳定性的影响。结果表明:筒型基础的倾斜率、最大竖向位移以及筒壁应力随着S/D的增大而逐渐减小,插桩过程中,靠近桩靴一侧的筒裙和分舱板应力远大于远离桩靴一侧的筒型基础应力,且筒顶的土压力远小于筒底土压力。

基于实际预压载作业的自升式平台环境载荷图谱绘制新思路

The environmental load chart is an important technical support required for the jack-up drilling platform to facilitate its adaptation to different operating waters and ensure the safety of operation.This chart is a crucial part of the platform operation manual.The chart data are closely related to external factors such as water depth,wind,wave,and current conditions of the working water,as well as to the structural characteristics of the platform itself and the number of variable loads.This study examines the platform state under extreme wind,wave,and current conditions during preloading.In addition,this study focuses on the difference between the ultimate reaction force of the pile leg during preloading and the reaction force of the pile leg without considering any environmental load before preloading.Furthermore,the relationship between the difference and the new reaction force of the pile leg caused by the combination of different environmental conditions is established to facilitate the construction of a new form of environmental load chart.The newly formed chart is flexible and simple;thus,it can be used to evaluate the environmental adaptability of the platform in the target well location and provides the preloading target demand or variable load limit according to the given environmental constraints.Moreover,the platform can perform personalized preloading operations,thereby improving its capability to cope with complex geological conditions,such as reducing punch-through risks.This condition reduces the load on jacking system devices and increases its service life.

一种海洋自升式修井平台船型分析

针对渤海海域油气开发中自升式修井平台的船型设计,进行系统分析。从桩腿数量维度出发,考虑波流载荷、风载荷和平台重力的共同作用,通过有限元数值模拟软件,建立自升式修井平台的仿真模型,计算不同方向角下平台的波流载荷、桩腿位移和抗倾力矩等评价指标,综合对比分析三桩腿和四桩腿两种不同船型的设计特点,以揭示各自在平台方案、预压载能力和稳定性等方面的特点。研究结果发现,四桩腿平台在舱内设备布置、预压载能力和抗倾稳性方面具有明显优势,特别是在单桩失效情况下,四桩腿平台的稳定性和安全性更高。研究结论对自升式修井平台的设计优化具有重要的指导意义,为进一步提升平台的安全性和高效性提供理论依据。

多跨预应力混凝土连续梁整体平移改造施工关键技术

宿迁古黄河老桥为(22.5+3×30+22.5)m四幅分离式连续梁桥,两侧为非机动车道桥,中间为机动车道桥。由于该桥位于生态保护区且梁体质量良好,为满足迎宾大道二期快速化改造需要,采取在不中断交通的前提下,通过交通导改先后将西侧和东侧机动车道桥分别往两侧整体平移3.25 m,再于中间修建新桥的改造方案。结合桥位处水文地质情况,采用在非机动车道桥外侧设置“钢板桩+过水钢管”围堰进行无水条件下的基础墩身拼宽施工。改造施工时,根据单侧机动车道桥支座处顶升荷载及梁底空间选配布置顶升千斤顶和步履器;通过有限元计算确定梁体顶升与平移施工过程中各支点竖向和横向位移偏差控制指标,采用PLC液压同步控制系统操控步履器与千斤顶交替顶升与平移,既能保证梁体整体顶升与平移的精度又能有效控制梁体应力突变;待梁体平移到设计位置后,拆除步履器和顶升千斤顶,复原垫石、支座及挡块。

网衣对自升式桁架网箱结构响应的影响

自升式桁架网箱凭借便于将养殖箱体下潜入水的结构特性,为更好地适应深远海养殖极端环境提供了一种选择。网衣作为桁架网箱关键部件,通过纲绳系缚于桁架管上,在外部环境载荷作用下可能会对网箱主体结构强度产生影响。针对一种自升式桁架网箱,基于SESAM/GeniE建立其有限元分析模型,分析了在有无网衣及不同网衣参数条件下的网箱主体结构响应。结果表明:网衣对网箱主体结构响应评估存在较大影响,尤其在流速较高时,网衣阻力大幅增加,直接影响网箱桩腿受力和桁架利用系数(Utilization factor,UF)值,证明在校核网箱主体结构强度时不可忽略网衣的作用;不同网目群化比下,网衣对自升式深海网箱整体结构响应评估结果影响不大,在网箱主体结构响应仿真计算中可以考虑使用较大的网衣群化比来提升计算效率;网衣系缚纲绳数量变化对网箱主体结构的响应评估基本无影响,但增加系缚纲绳可以有效减少纲绳受力。

黏土中大直径钢圆筒在桩靴贯入时的稳定性研究

某在建水下生产系统附近有自升式平台的频繁桩靴插拔作业,采用了大直径薄壁钢圆筒作为水下生产系统的保护结构,因此钢圆筒在自升式平台桩靴插拔过程中的受力与变形备受关注。开展了离心模型试验,揭示了桩靴贯入过程导致的钢圆筒受力与变形规律;进而应用经离心试验验证的耦合欧拉与拉格朗日数值模拟方法,开展了筒-靴不同相对位置工况下,桩靴贯入对钢圆筒稳定性的影响分析。结果表明:桩靴贯入导致的筒壁附加应力及位移随筒-靴间距的增加而衰减,其衰减程度随筒靴间距的增加而减小,且由于筒靴间距的不同,钢圆筒对应存在两种受力模式。筒靴间距为2倍桩靴直径时,筒身附加应力可达110 MPa,表明桩靴对钢圆筒的影响距离可达2倍桩靴直径以上。

自升式平台桩靴周围土体冲刷机制及数值模拟

为了评估自升式平台插桩后桩靴周围土体受波流-海流作用局部冲刷的安全性,基于计算流体动力学通过数值模拟建立波流作用下的桩靴周围土体局部冲刷的三维有限元数值模型,通过求解Navier-Stokes方程,准确模拟桩靴周围流场变化情况;基于现场作业场址参数和实际海况条件下建立适用于自升式平台桩靴周围土体局部冲刷的工程分析方法,将数值结果与试验结果进行对比;讨论自升式平台在不同入泥深度和作业周期下桩靴周围土体局部冲刷问题。结果表明:波流共同作用下自升式平台桩靴入泥深度对桩靴周围土体局部冲刷深度具有较大影响,当桩靴入泥深度越小时,桩靴周围越容易发生局部冲刷;基于桩靴不同入泥深度工况针对性地制定冲刷防护措施,降低桩靴周围土体局部冲刷深度,有效降低工程作业风险。