PROCEDURE DETERMINING RHEOLOGICAL CHARACTERISTICS OF DRILLING FLUID IN PROCESS OF DRILLING Russian patent published in 2002 - IPC

FIELD: quality inspection while drilling holes for oil and gas. SUBSTANCE: mechanical drilling is stopped, starting effort is formed in hole while it is continued to be washed with change of flow rate of drilling fluid with simultaneous fixing of discharge pressure of drilling fluid in drill pipe string in correspondence with mathematical inequality. Obtained data are used to plot graph of dependence of discharge pressure of drilling fluid on flow rate of drilling fluid, straight line is extrapolated to crossing with coordinate axis of discharge pressure. Discharge pressure of drilling fluid is found by value of cut off segment. Value of discharge pressure is within limits of laminar mode of flow of drilling fluid. Weighted average of values of dynamic stress of displacement ( with due account of depth of hole ) and of plastic viscosity are found by mathematical formulas. EFFECT: increased accuracy and timeliness of determination of rheological characteristics in process of drilling. 2 dwg