METHOD TO DEFINE MAGNETIC AZIMUTH IN WELL INCLINOMETER IN PROCESS OF DRILLING Russian patent published in 2016 - IPC E21B47/22 

FIELD: measurement equipment.

SUBSTANCE: method is based on using readings of projections H_X3, H_Y3, h_Z3 of classic triad of flux gates and two additional field sensors, spaced along the longitudinal axis Z of the inclinometer. As additional flux gates, they use uniaxial field sensors with axes of sensitivity directed along the axis Z, generating accordingly current values pf projections of the summary field h_Z1=H_Z3+H_P1 and h_Z2=H_Z3+H_P2, where H_Z3 - projection of Earth field at inclinometer axis Z, and H_P1, H_P2 - field intensity noise registered by additional sensors 1 and 2, and then they carry out calculation of the values H_Z(1), H_Z(2), H_Z(3), representing three independent realisations of one and the same value of the projection H_Z3, cleaned from magnetic noise impact, in accordance with expressions: H_Z(1)=h_Z1-(h_Z1-h_Z3)/1-K₃₁, H_Z(2)=h_Z2-(h_Z2-h_Z3)/1-K₃₂, H_Z(3)=h_Z1-(h_Z1-h_Z2)/1-K₂₁, where (h_zi-h_zj) characterises difference of readings of primary meters, responsible for local field gradient between sensors i and j, and values are scale coefficients, being permanent values for the entire time of well tunnelling, and which are experimentally determined at the initial stage of drilling works performance, for which purpose a string in assembled form is installed into vertical position with a zenith angle value in the range of (0÷15)° and lowered at such depth, when increment of difference in readings δ(h_Z1-h_Z3) in process of downward string movement does not exceed one-two count units.

EFFECT: expansion of functional possibilities of an inclinometer due to higher accuracy of azimuth generation and provision of inclinometer operability under conditions of arbitrary nature of field distribution in a reading zone.

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