Error Analysis Of Well Trajectory And Its Visualization Research

Because directional well, horizontal well, extended reach well, multiple target well have been and been being drilled, it is significant to verify the well bore position and its uncertainty. In order to confirm well trajectory uncertainty completely and exactly, this dissertation has set up a relative complete well trajectory error analysis method by taking account of the facet of verification of well site, of well trajectory measurement and of well trajectory survey errors. By use of OOP and OpenGL, the dissertation has achieved to visualize the trajectory and its uncertainty. This dissertation covers such contents: the analysis of geodetic data influence on survey calculation, of survey calculation model error, of measurement theory of ordinary survey tools, of well trajectory measurement uncertainty, the collision probability analysis, the visualization of trajectory and its uncertainty. During the research, several technical fields have been touched, such as the error theory, the drilling engineering technology, the geodetic theory and the visualization technology. The research rout includes theoretical analysis, numerical experiments and on- spot data tests. The dissertation has drawn the following conclusions. The amendment of geodetic data on ordinary survey calculation is very important to the verification of well path position. During the course of amendment, it not only pays attention to keep the survey data and geodetic data of well site in uniform coordinate system, but also considers the variation of two vital parameters (the grid convergence and scale factor) along well path. If not considering this, this kind of error should be treated as certain systematic error. So, the error could be eliminated by use of the amendment method. The error of survey calculation models is a part of the integrated error analysis model of well path. If based on the same original survey data, the model errors of different ordinary survey calculation method would take similar variation tendency. With the development of well trajectory, this kind of error takes linear variation tendency. The more variation of well path's curvature, the more variation this kind of error will take. And the frequency variation of well path's curvature has little impact on this error, but the value variation takes much effect on it. If the survey calculation takes place on the straight well path, the model error of survey calculation could be ignored. The error distribution density function of different ordinary survey calculation could take uniform formula by statistical analysis in relative large sampling space. This dissertation also makes the measurement error analysis model of well path more integrated. Besides including the eliminating method for certain systematic error, the analysis of uncertain systematic error is more comprehensive and also the error of misalignment between survey instrument and well trajectory is regarded as a kind of random error. Based on the existing collision probability analysis method of well trajectories, the research indicates the covariance matrix of well path position uncertainty takes linear variation tendency. According to this conclusion, the interpolation method for well path position uncertainty is founded and able to analyze collision probability between any positions of two well trajectories. During the realization process of visualization of well trajectory and its position uncertainty, a new concept named of"the contour surface of well path position uncertainty"is formed. The innovative points of this dissertation cover the following four aspects. The first is that a revised algorithm for survey calculation is formed by considering the effect of geodetic data. And it lays foundation for ongoing integrated error analysis of well path. The second is that the dissertation carries out comprehensive and systematic analysis of model error of ordinary survey calculation methods. The analysis gains the uniform error distribution density function and covariance matrix for ordinary survey calculation methods. The third is that the original uncertain systematic error analysis model is amended by taking more error sources into account. And the misalignment error is treated as a kind of random error. And an integrated error analysis model is set up. Also on the basis of the above integrated error analysis model, the realization of collision probability analysis between any positions of two well trajectories has been achieved. And the last point is the visualization of well path and its position uncertainty by using OOP and OpenGL. A new concept of"the contour surface of well path position uncertainty"is coined.