Study Of Key Technology In Drilling Fluid Sampling-While-Drilling System

With the global trend of oil exploitation being transferred offshore, oilfield engineers will have to deal with intricate geological conditions and tough environment that were never met before. Measurement While Drilling (MWD), compared with wireline logging, delivers better performance under such circumstances and shows great potential in well logging practice. As of now, the most advanced technologies related to MWD are in the possession of few giants in oil service business, out of concern for energy security, it is therefore of great significance to put effort into the research of MWD.In response to the urge to sample drilling mud simultaneously while drilling in order to collect relevant geological information and hydrocarbon oil index real-timely, this thesis focuses on the key technologies in the designing of an innovative drilling-mud-sampling-while-drilling system, including the filtration device and the hydraulic device employed to regulate the intake&ejection of mud samples. Prototype design is presented and simulation studies are carried out to help validate its efficiency.Specific contents of each chapter are as follows:In the first chapter, the background information and status quo of MWD research are reviewed in summary, then the main contents and framework of this thesis are presented.In the second chapter, the principle and implementation details of well logging via drilling mud are introduced in the first place, the introduction is followed by an analytic discussion of the key technologies in the sampling system.In the third chapter, a review of the general techniques for solid phase controlling in oil drilling industry is first presented, then the theoretic ground is laid for the purpose of filtering solid-liquid phase mixture more efficiently. Design of the filtration device, which combines sand screen filtration, screw squeezer filtration and centrifugal filtration, is thereafter presented in detail. In the fourth chapter, hydraulic servo system is selected after a brief comparison of several servo systems. Then the design of the hydraulic system for regulating intake and ejection sequences is presented, along with the detailed illustrations of its important components. The type of hydraulic pump to be used in the system is chosen at last according to its specific needs.In the fifth chapter, a simulation model of the hydraulic system is built via AMESim software, and simulations of the system’s working sequences, including its intake and ejection process, are carried out respectively. With respect to the results of the simulations, slight modification is given at last.In the sixth chapter, the research is summarized and future work is elaborated.