Patent ID: 11940590
Assignee: CHINA UNIVERSITY OF PETROLEUM (EAST CHINA)
Field: Measurement (Instruments)
Classification: CPC G  E  Y | IPC E  G

Claim 6:
7. The fast forward method for gamma-ray logging of highly-deviated and horizontal well according to claim 6, wherein in step S13, the obtaining a bilateral function fitting expression of the one-dimensional equivalent longitudinal contribution coefficient by using a double exponential model is specifically implemented by: fitting the one-dimensional equivalent longitudinal contribution coefficient in the following manner:
normalizing the gamma source intensity density of the formation/o, and fitting a gamma-ray flux Φr0z of the surface source of the formation at a distance of z from the center of the detector in the effective detection space under the condition of the straight well to the detector to obtain a double-exponential function fitting model:

gz=Aebz+Cedz 

where A, C, b and d are fitting coefficients; and
calculating a natural gamma flux of the surface source (at a vertical distance of z from the center of the detector along the well axis under the condition of the straight well) at the center of the gamma detector by using the double-exponential function fitting model in the effective detection space, and normalizing the natural gamma flux such that the sum of the natural gamma-ray fluxes gz of the surface sources (at different distances from the center of the detector along the well axis) at the center of the gamma-ray detector is 1, and then the one-dimensional equivalent longitudinal contribution coefficient is obtained.