Directional/complex wells

Magnetic Referencing and Real-Time Survey Processing Enable Tighter Spacing of Wells

Wellbore position is computed from survey measurements taken by a measurement-while-drilling (MWD) tool in the bottomhole assembly (BHA).

jpt-2016-05-fig1magneticref1.jpg
FIg. 1—A comparison of the EOU at a standard deviation of 2.79 for 95% confidence for the tool codes MWD (green) and MWD+IFR1+SAG (red). The actual drilled wellbore trajectory is with 95% confidence within the EOU of the selected surveying method.

Wellbore position is computed from survey measurements taken by a measurement-while-drilling (MWD) tool in the bottomhole assembly (BHA). The MWD tool uses accelerometers and magnetometers to measure the Earth’s gravitational and geomagnetic fields. Knowing the direction of these two fields and using them as a frame of reference enable drillers to calculate inclination and direction (azimuth) of the wellbore. Local high-resolution in-field referencing (IFR) models have been produced for the Permian Basin that significantly improve the accuracy of MWD azimuth measurements.

Ellipse of Uncertainty (EOU)

Numerous error sources are associated with MWD-survey measurements, and each error source contributes in some form to the magnitude of uncertainty that propagates along the computed wellbore trajectory.

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