利用测井资料预测岩石II型断裂韧性 的方法研究

 根据直缝巴西圆盘(SNBD)试验获取应力强度因子的计算原理，设计组建一套岩石II型断裂韧性测试系统，测定20块取自WG油田岩石试样的II型断裂韧性。基于试验数据，分析II型断裂韧性和围压、抗拉强度的关系，建立利用测井资料预测断裂韧性的模型。利用H341井声波测井、密度测井和伽马测井资料预测水平地应力和抗拉强度，结合建立的断裂韧性模型成功预测II型断裂韧性连续值，并在压裂实践中得到验证。该方法解决了现场压裂作业缺少断裂韧性全井筒连续数据的难题。

STUDY ON PREDICTION METHOD OF FRACTURE TOUGHNESS OF ROCK MODE II BY LOGGING DATA

According to the theory of computing stress intensity factor by straight-notched Brazilian disc(SNBD) specimens，a set of experimental equipment is designed and constructed to test fracture toughness of rock mode-II. 20 rock specimens are prepared from pay zone and barrier layer between 1 500 and 2 000 m in WG oil field，China，and the tests are conducted successfully. Based on the experimental results，the relationship among fracture toughness of mode II，confining pressure and tensile strength is analyzed with the least square method，and the prediction model of fracture toughness of mode II is established by the geophysical logging data. Finally，the fracture toughness mode II is predicted，which is verified in field application by combining the KIIc prediction mode with the horizontal in-situ stress and tensile strength prediction based on acoustic logging，density logging and GR logging data from Well H341. The method is beneficial for solving the lack of continuous fracture toughness mode II along the well bore in field hydraulic fracturing operation.