Transitioning from Rig to Vessel Based Interventions to Maximize Economic Recovery

As energy markets evolve, the supply mix diversifies, and the push for a net zero energy system accelerates, the competitiveness of oil and gas has become increasingly important. A focus upon the total cost of ownership across the field lifecycle has begun to emerge as a driving factor within subsea oil and gas project evaluation, with greater emphasis on cost-effective operations. Acknowledging that the life of field begins within the engineering, procurement, construction, and installation phase of a project allows the operator to influence through life activities to greatest effect and achieve a balanced optimization of capital and operational expenditure. Intervention is a key activity for maintaining and optimizing a subsea wells performance, from initial installation, through the producing life, and finally during decommissioning. As completion technologies continue to evolve, opportunities emerge for optimization of the systems used to intervene upon subsea wells. One of the largest areas of opportunity is the simplification of a technique to permit operations from a more efficient rig or vessel. This paper explores some of the solutions available today which allow historically rig based activities to be performed from vessels. These include riser based intervention systems, hydraulic intervention solutions, well abandonment technologies, and subsea workover control systems. An evaluation of the presented techniques against alternative approaches is shared, to aid the reader in selecting the optimal solution for an application. Guidance is provided to assist in identifying the key decision criteria, complete with the capabilities and limitations of each solution. The conclusions identify that designing a subsea production system with the flexibility to accommodate life of field activities can deliver reduced total cost of ownership to operators. A key part of this is consideration of optimized intervention techniques which can leverage simpler vessels for deployment and operation. By reducing the vessel specification, broad benefits can be realized including reduced asset day rate, reduced operational duration, and increased asset availability globally. This permits improved scheduling and reduced mobilization costs, in some cases enabling intervention activities which otherwise would not be economical.

In Vitro Bone Cell Behavior on Porous Titanium Samples: Influence of Porosity by Loose Sintering and Space Holder Techniques

A great variety of powder metallurgy techniques can produce biomimetic porous titanium structures with similar mechanical properties to host bone tissue. In this work, loose sintering and space holder techniques, two frequently used metallurgical techniques, are compared to evaluate the influences of porosity (content, size, morphology and wall roughness), mechanical properties (stiffness and yield strength) and in-vitro cellular responses (adhesion and proliferation of myoblasts and osteoblasts). These comparisons are made to achieve the best balance between biomechanical and bifunctional behavior of a partial porous implant for cortical bone replacement. Cell adhesion (filopodia presence) and spreading were promoted on both porous surfaces and fully dense substrates (non-porous control surfaces). Porous scaffold samples designed using 50 vol.% NaCl space holder technique had an improved bioactive response over those obtained with the loose sintering technique due to higher roughness and scaffold pore diameter. However, the presence of large and heterogeneous pores compromises the mechanical reliability of the implant. Considering both scenarios, the substrates obtained with 40 vol.% NH4HCO3 and pore size ranges between 100 and 200 μm provide a balanced optimization of size and strength to promote in-vitro osseointegration.

Technology of Balanced Identification for Selection of Pine Transpiration Mathematical Model

The application of numerical technology for evaluation the correspondence of a mathematical model and experimental data via the balanced (optimization) identification method is demonstrated with comparing various models of pine transpiration. A quantitative measure of the model evaluation is the cross-validation error. Current implementation of the technology allow the researcher to formulate the computing task in a text file, which contains: mathematical model formulas (including differential and/or integration equations); declarations of parameters and/or functions to be identified; data source (with experimental measurements) and additional settings of the numerical method. As a result, the software package returns unknown parameters, functions, and modeling errors. This technology is successfully used to various models in biology, medicine, physics, etc.