| The resource of shale gas has many advantages, such as a wide range ofdistribution, abundant reservoirs, long life of exploitation, and so on. Therefore, itgradually becomes the popular direction of the global oil and gas exploration anddevelopment. And a fact has been proved, shale gas reservoirs get a nice prospect ofexploration and development, by actual experience in the exploration anddevelopment at home and abroad. Due to the complex geological characteristics of theshale formations, however, and there are obvious differences of accumulationmechanism and evolution between shale gas reservoirs and conventional reservoirs,combined with the poor stability of shale formations, all these facts cause a greatdifficulty of shale gas well drilling and fracturing construction, and restrict theexploration and development of shale gas resources seriously. In order to ensure thedrilling safety, improve well drilling efficiency and reduce the cost, this thesis isbased on the rock physics, well logging, geology and other disciplines or theories, andthrough combining the research results in the area of shale gas reservoirs andconventional oil and gas reservoir, making full use of logging data, carry out theresearch and analysis of evaluation method of rock mechanics parameters, formationstress and wellbore stability of shale formation, and application examples are given.The thesis is mainly embarked from the conventional logging method, makingthe use of acoustic wave, density logging data to extract shear wave data, and throughthe calculating and debugging of the actual information, it makes sure that thecomputational model of shale formation rock mechanics parameters is analyzed andidentified. And then, based on the research results of rock mechanics parameters, tocomplete the log interpretation and analysis of formation pressure characteristics, andcompare the applicability and reliability of logging interpretation model on stress,combined with the actual logging data of study area and the foreign research result ofshale formation, and complete the validation and determination of stress interpretationmethod applying to the shale formation. By studying the equivalent depth method, theEaton method and the effective stress method, explain the interpretation andprediction method of formation pore pressure. Aiming at wellbore stability problemsof shale gas reservoirs, through deep exploration of wellbore instability mechanism, combined with the analysis on influence factors of wellbore stability, the appropriatefailure criterion of rock strength is selected in this thesis, and the prediction model ofcaving pressure and fracture pressure in the shale formation is established. Accordingto the calculation results of rock mechanics parameters, interpretation results offormation stress and conventional logging data, the prediction model of formationcaving pressure and fracture pressure is validated in this thesis, and providing a strongbasis for evaluation of wellbore stability.Based on the research results above, a set of software modules that apply to theevaluation of shale gas reservoir rock mechanics properties is programmed, and thefeasibility and accuracy of these software modules are verified by launching the welldata of examples in the study area, and it can be seen from the processing results, thecalculation results of the software is accurate, and the application effect is nice.Finally, all these research results provide a strong technical support for loggingevaluation and application of rock mechanics properties of shale gas reservoirs. |
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