Study On Key Technoloies In Scheme Design Of Self-elevating Drilling Unit

With the development of worldwide exploitation for ocean resources, offshore platforms are playing a dominant role in the oil and gas industry for exploration and production of natural resources, which have been designed to operate at various locations with different sea-bed conditions, great water depths and under various sea conditions. Self-elevating drilling unit which was invented in 1950 and used for exploration and extraction of hydrocarbons from the ocean beds is a main structural type of mobile platforms, and it accounts for about 65% of the mobile platform market. Now the world has entered the era of scarce energy gradually, many countries have turned their attention to the ocean, and put a mass of manpower and resources into exploiting marine energy. Self-elevating drilling unit owns the low cost, less steels and conducting drilling operations steadily under different sea conditions so that it becomes the main force in the shallow drilling operations. In recent years, more and more self-elevating drilling unit is designing and building. it needs to develop urgently in the design, construction, inspection and research of the self-elevating drilling unit in our country, especially in the basic design of the marine drilling unit. In our country, there's a big gap in independent designing, the most of the technologies are dependent on foreign country. So developing this field research is needs to increase the capabilities in the marine construction design and the international competition in the marine drilling unit design. It has great significance not only in exploiting the marine resource but also in developing the marine engineer career.To a great extent, the scheme design decides the performance of the final product, creativity, price, the market response speed and efficiency. So it has great theory significance and practical value in researching the key technology of the scheme design about the self-elevating drilling unit, realizing the feasible scheme speedily, technical parameters indicators comprehensive evaluation and the optimal decision-making system. This paper has mainly done the following work:According to the specific circumstances of the scheme design about the self-elevating drilling unit, systems engineering theories and methods are applied to the whole process of the scheme design, advancing the steps in the system analysis of scheme design about the self-elevating drilling unit. According to the Hall' three dimensional structural model and the traits of the scheme design in drilling unit, advancing the three-dimensional structural model system in drilling unit, guiding and realizing scheme design of the self-elevating drilling unit.New type self-elevating drilling unit with multifunction is a trend on the drilling unit design. The methods of formal safety assessment (FSA) is applied to the feasible research of new type self-elevating drilling unit with multifunction, it can prove the possibility of the new function from the aspect of the safety analysis, advance the effective measures to control the risk and point out the problems which should pay more attentions to the process from the design to the operation. It is the precondition of the new type self-elevating drilling unit design with multifunction, it can increasing the new function; moreover, it can improve the safety level effectively. As an example, integrating the methods of formal safety assessment (FSA) is applied to the feasible research of installing the facility platform with self-elevating drilling unit, proving the feasibility and validity of this method, all this is based on applying analysis and summary about operation trait of the self-elevating drilling unit, discussing the working principle and the workflow.In the process of the scheme design about the self-elevating drilling unit, there aren't any mathematical models of the main dimensions, that is applied to the feasible scheme at present. This paper according to the model data have been collected, apply the theories and methods of the system models, separately build the forecast models with the single variable and multivariable on the main dimensions of the self-elevating drilling unit. All this is helpful to analyze and grasp the change rules of the main dimensions factors about the self-elevating drilling unit. According to the known information, design the self-elevating drilling unit; moreover, select the right models to forecast the main dimensions, develop economic demonstration and scheme designs of the drilling unit designs.How to select the optimal one from the feasible schemes is the main problem that it needs to solve during the scheme evaluation of self-elevating drilling unit, there isn't a corresponding evaluation criteria system at present. Combine research task and experts' suggestions of the scheme designs about self-elevating drilling unit, this paper builds a series of scheme evaluation criteria system and studies evaluation method of the self-elevating drilling unit. Base on these, select the optimal scheme with the analysis hierarchy process (AHP) and improved the grey relation analysis (GRA). Primary analysis and practical experience show that the evaluation criteria system and the evaluation method are applicable and reliable. By improving grey relation analysis (GRA), building the grey relation multi-objective combinatorial optimization model is applied to the best scheme of self-elevating drilling unit. To a certain extent, it thinks over the connection of the indices reflecting the objective true nature of the things, and also considers the ship owners' subjective interest and the designers' needs. At the same time, according to design of the self-elevating drilling unit that have been built and used, try to build a series of function level grade evaluation method, that will be reasonable, unabridged, scientific and easy, assess its advanced level. Make use of the known evaluation result, carry out the advanced level grade in the same type platforms, whether the evaluation design has achieved the desired results and improvement direction. It plays an important role in scheme designs of the self-elevating drilling unit for the future.The intelligent scheme design has become a research hotspot on the field of scheme design. On the basis of previous work, the paper studies initially the design theory framework and concrete methods of the intelligence decision support system about the self-elevating drilling unit scheme design, advances the system structure and the specific method of the intelligence decision support system about the self-elevating drilling unit scheme design. Not only does it form the feasible designs, according to the demand to form scheme designs of the self-elevating drilling unit, but also it selects the optimal scheme from the feasible designs under technical economy and ship owners' subjective interest. It will be helpful to improve the design quality of the products, shorten the design circle of the products, make the assessment more reliable. This will provide powerful support tools for designers and decision-makers.