Prediction And Application Of Stratum Trinomial Pressure In DWYY

Based on the basic theory of rock mechanics ,this thesis decides the formula of stress distribution around the well bore in inclined hole. The formulas of fracture pressure and collapse pressure were concluded according to Culon-morper rule and the Minimum Main Stress Destroy rule. We did studies about the correlation of logging data and mechanics parameters of stratum by doing experiments so that the theory of fracture pressure and collapse pressure can become practical. The multi-correlation of the time differences of press wave and shear wave, density and clay content and the correlation of dynamic parameters and static parameters were established in order to do preparation for conventional logging data being used in engineering. In order to complete the single-layer-based stress explanation, we built the single-layer-based stress model in form of combined springs and concluded the involved formulas. The technology about how to analyze the stability of well bore by auto-adaptation was developed and the methods on how to decide the primitive strength of stratum within certain mud system by reverse analyzing drilling data. As the result , the accuracy of prediction of collapse pressure was improved.On the basis of above theory researches, the software to predict the profile of Pore Pressure,Fracture Pressure and Collapse Pressure (PP,FP and CP) of stratum was developed by VB6.0. The software can do such jobs as processing the logging data file ,building the data file of well bore profile ,defining indexes, doing calculation for the pressure profile and designing the mud density. Considering pore pressure profile, fracture pressure profile and collapse pressure profile at the same time, we created the new method of optimum design for well bore structure and edited relevant software, which can do optimum design for well bore structure on the basis of PP,FP and CP profiles and some relevant design parameters and provide the depth of different kinds of casings. Following is what we have achieved:1,The formulas of fracture pressure and collapse pressure.2,Single-layer-based stress model and the methods of describing stress.3,Auto-adaptation-oriented method of analyzing the stability of well bore and PP,FP and CP profiles according to such data as drilling, stratum and measurement.4,New method of optimum design for well bore structure on the basis of PP,FP and CP profiles considering flow parameters and dynamic characteristics.5,The model of correlation between logging parameters and mechanics parameters by simulation experiments in laboratory.6,The software of prediction of PP,FP and CP profiles and software of optimum design for well bore structure.This technology is a practical drilling engineering technique ,which is suitable for the geologic characteristics in peripheral area of Daqing. It uses conventional logging data to calculate and predict PP,FP and CP of stratum. The new solutions for measuring the PP,FP and CP of the finished wells and predicting the ones for awaiting to be drilled wells have been found. The challenges of predicting the PP,FP and CP in peripheral area of Daqing have been overcome by doing core experiments and verifying the practicability of this technology. It is important for improving the level of geologic designs of drilling and guiding drilling.