Dynamics of ocean cables with local low-tension regions

A general set of 3-D dynamic field equations for a cable segment is derived based on the classical Euler-Kirchhoff theory of an elastica. The model includes flexural stiffness to remove the potential singularity when cable tension vanishes and can be reduced to the equations for a perfectly flexible cable. A hybrid model and a solution scheme by direct integration are then proposed to solve the oceanic cable/body system with a localized low-tension region. Numerical examples demonstrate the capability and validity of the formulation and the numerical algorithm.     

Impact Compressive Creep Characteristics of Simulative Soil for Deep-Sea Sediment

The impact load (equivalent impact height) applied to deep-sea sediment by a walking mining machine was first deduced by the energy conservation principle, and the simulative soil was prepared based on the deep-sea sediment collected from the Pacific C-C mining area. The self-designed impact compressive creep tests of the simulative soil were conducted under different ground stresses and impact heights, in order to determine impact compressive creep parameters using a K-H rheological model. Test results show that the impact compressive creep curves have three similar creep stages (transient creep, unstable creep, and stable creep) to static compressive creep curves, where the transient creep deformation and total deformation at the unstable creep stage decrease with the impact load. Among the three impact compressive creep parameters (K₁, K₂, β) of the simulative soil, K₁ is first increased with impact height and finally fluctuated to a certain stable value, while K₂ and β are approximately linearly increased with impact height. The maximum subsidence of the mining machine under a specific designed ground stress and walking velocity predicted by the impact compressive creep constitutive equation can be used for safety assessment of the mining machine.     

埃及Bakr—Amer油田古近系Eoc组储层特征

储层特征研究是评价碳酸盐岩储层物性、寻找油气富集区和落实剩余油分布的基础,通过对区域构造、地层和沉积特征的研究,利用统计和数学方法对Bakr-Amer油田Eoc储层物性、储集空间类型和控制因素进行了分析,认为受构造运动影响,储层在深部残余厚度大,但物性相对也较差,以压实、胶结和溶蚀作用为主。高部位残余厚度小,但受风化、淋滤和构造运动的影响,裂缝发育,储层物性好,以压实和溶蚀作用为主。     

瓦斯煤层裸露面蠕变失稳的时间预测研究

通过对煤体蠕变特性的分析,提出采用五元粘弹塑流变模型能很好地描述煤体的蠕变特征。在考虑煤层瓦斯的作用下,得到了含瓦斯的煤蠕变状态方程。由于揭开的煤层裸露面由原来的三向受力变为二向受力,在合适的条件下煤体会产生蠕变。而煤体在双向受压时,裸露面方向的应变为拉应变,当裸露面方向的煤体的拉应变大于煤体破坏时的拉应变时,煤体将产生蠕变失稳。从而可以预测煤体蠕变失稳的时间。研究成果可以解释揭煤工程岩体失稳。     

On the external pressure capacity of deepwater sandwich pipes with inter-layer adhesion conditions

Sandwich pipes (SP), a composite structure consisting of two concentric steel tubes and a polymeric or cement-based core has been proposed to be well-insulated and withstand high installation and operational loads in deepwater oil and gas field. In the paper, the post-buckling responses and pressure capacity of sandwich pipes filled with the solid polypropylene annular were investigated. The degree of the inter-layer adhesion condition between the core layer and the surrounding pipes was modeled by the contact surfaces adopting different maximum shear strength values to allow the relative displacement between the layers. The effects such as inter-layer adhesion interactions, thickness-to-radius ratios, the core thickness, the material parameters, the relative initial ovality directions and the inelastic anisotropy on the collapse pressure of SPs were discussed. More than 2000 finite element (FE) models of the sandwich pipes with practical configurations were constructed and analyzed using the programming language Python within the FE software package ABAQUS. Based on the FE results, a simplified equation was developed and recommended for the collapse pressure calculation of sandwich pipes with the polypropylene annular.     

Seismic characterization of switching platform geometries and dominant carbonate producers (Miocene,Las Negras,Spain)

The primary goals of seismic interpretation and quantification are to understand and define reservoir architecture and the distribution of petrophysical properties. Since seismic interpretation is associated with major uncertainties, outcrop analogues are used to support and improve the resulting conceptual models. In this study, the Miocene carbonates of Cerro de la Molata (Las Negras, south‐east Spain) have been selected as an outcrop analogue. The heterogeneous carbonate rocks of the Cerro de la Molata Platform were formed by a variety of carbonate‐producing factories, resulting in various platform morphologies and a wide range of physical properties. Based on textural (thin sections) and petrophysical (porosity, density, carbonate content and acoustic properties) analyses of the sediments, eleven individual facies types were determined. The data were used to produce synthetic seismic profiles of the outcrop. The profiles demonstrate that the spatial distribution of the facies and the linked petrophysical properties are of key importance in the appearance of the synthetic seismic sections. They reveal that carbonate factory and facies‐specific reflection patterns are determined by porosity contrasts, diagenetic modifications and the input of non‐carbonate sediment. The reflectors of the seismograms created with high‐frequency wavelets are coherent with the spatial distribution of the predefined facies within the depositional sequences. The synthetic seismograms resulting from convolution with lower frequency wavelets do not show these details – the major reflectors coincide with: (i) the boundary between the volcanic basement and the overlying carbonates; (ii) the platform geometries related to changes in carbonate factories, thus sequence boundaries; and (iii) diagenetic zones. Changes in seismic response related to diagenesis, switching carbonate producers and linked platform geometries are important findings that need to be considered when interpreting seismic data sets.     

THERMODYNAMIC PROPERTIES AND ROLE OF THERMALS IN THE STRATUS-TOPPED BOUNDARY LAYER

From results of two large-eddy simulation of stratus-topped boundary layer,the structure,thermodynamic prop-erties and role of thermals are investigated by using conditional sampling methods,which divided the thermals into thewarm/moist,cool/dry,warm/dry and cool/moist events.The results show that the main turbulent circulation in thestratus-topped boundary layer is composed of the warm/moist updraft and cool/dry downdraft.Below entrainmentregion,the warm/moist updrafts and cool/dry downdrafts are,respectively,positively and negatively buoyant andcontribute most to total fluxes and variances.Evaporative cooling has important effect on the structure and thermodynamic properties of thermals instratus-topped boundary layer.     

重质碳酸钙表面改性及充填丁苯橡胶试验研究

重质碳酸钙是一种重要的无机矿物填料，经过表面改性，可以将其由普通填料变成性能优越的功能填料。本次研究选用鄂西优质重质碳酸钙为试验样品，采用干法表面化学改性方法对重质碳酸钙实施了改性，通过测定改性重质碳酸钙的活化率、湿润接触角、固液悬浮体的粘度、白度及表面化学成分对其性能进行考察，并对改性效果进行评价。在丁苯橡胶中的应用试验显示，改性重质碳酸钙充填丁苯橡胶的性能良好，其应用前景广阔。