Finite difference method and transfer matrix method were used to get spectrum response curve of unit impulse function signal to research the spectrum characteristics of acoustic traveling though the drill string. Similarities and differences of the two methods were discussed through analysis of spectrum curve get from the two approaches. The results show that: The distribution of band-pass and band-stop get by the two calculating methods is basically the same, some transmission coefficient of finite difference method is less than 1, is not completely transmission phenomenon. Analysis of the reason for this is that the transfer matrix method is an analytic method, finite difference method is a numerical algorithm. From the calculation precision of speaking, analytic algorithm is higher than that of numerical algorithm. But to verify the reliability of two methods needs based on laboratory experiment or field test.

No abstract

Considering the uncertainty and randomness of casing loadings and geometry sizes, performance parameters in deep wells, a kind of calculation method of probability distribution of casing external loading and collapse strength was established. Based on the Monte-Carlo method, the probability distribution of casing strength was simulated under non-uniform external loading conditions. With strength-load interference theory, the calculation method of casing safety reliability was obtained, which can analyzes reliabilities of different types of casing strings subjected different loadings in the dangerous section, and a regional relationship between casing reliabilities and safety factors is established. Results show that when casing reliabilities collapse strengths are in the range of 0.5-1.0, the related safety factors locate from 1.0 to 1.25. Safe reliability analysis can provide references for casing strength designs in deep and super deep wells.

Wellbore temperature is significant to well program and safety drilling for deep water drilling operations. On the basis of transient heat transfer mechanisms involved in deep water drilling among wellbore and formation and sea water, wellbore temperature profile, especially near sea bed and sensitivities to drilling fluid circulating duration, inlet temperature, water depth, water temperature, riser insulation and drilling fluid specific heat capacity have been analyzed via this model. Analysis show that deep-water wellbore temperature is much lower than a land well, the temperatures above sea bed normally ranges 10-30°C, and decreases with increased circulating duration; temperature at both outlet and bottom hole decreases drastically with increased water depth, and heat generation must be considered into estimating wellbore temperature profile especially one at bottom hole.

Magnetic guidance drilling technology is use of magnetic guidance instrument measuring the distance between the signal source and the location of the instrument, and it is used to control the well trajectory to connect or parallel the target layer. And it is an effective supplement of the existing steering drilling technology. At present, the magnetic guidance drilling technology is mainly applied to drill horizontal wells in pairs for the super heavy recovery, CBM horizontal connected wells, underground soluble minerals, relief well and so on. This paper introduces the data processing and the related software development of the active magnetic measuring instrument.