Abstract:

In the drilling operation, wellbore stability mostly occurs in the mudstone and shale section. The rock mechanics parameters obtained from the test can be used to well carry on the wellbore stability and the mechanical properties analysis, the mudstone triaxial creep test carried on the triaxial rock mechanics testing aircraft is introduced in detail, according to the result of the test, by applying the nonlinear regression method, the constitutive equation and its creep coefficient description distortion is obtained, the creep rule and the creep pressure of mudstone is analyzed to provide the scientific basis. Meanwhile, in the view of the calculation formula of safe drilling fluid density deadline required by different undergauge rate, corresponding drilling fluid density is calculated.

Key words: creep test, mudstone, constitutive equation, drilling fluid density