Abstract: In order to reasonably improve the vertical resolution of the compensated neutron log (CNL) in deviated and horizontal well, Monte Carlo simulation was applied to study the vertical geometrical factors of CN241 tool in the well of different deviation angle. The geometrical factor was regarded as response function coefficient, and resolution matching method was used to improve the resolution of the log curves in simulated formation and true formation. The vertical geometrical factors obtained from the simulation data proved that there would be some error when the geometrical factor of vertical well was applied to deviated or horizontal well, and the maximum porosity error could be as high as 10％ when the formation thickness is 40 cm. The results also showed that geometrical factors were different with different deviation angles, therefore the corresponding geometrical factor should be used as response function coefficient when to improve CNL resolution of deviated or horizontal well.

Key words: compensated neutron log, Monte Carlo simulation, geometric factor, vertical resolution