Abstract: The conclusions developed from computer numerical simulation of pa-
eked hole assembly ace of theoretical and practical importance.The results
from simulation can be used as a guide in vertical and directional dril
ing.Fundamental formulae of finite element method in analyzing bottom
hole assembly are given in appendix A.The computer program is v-ritten
in "FORTRAN".All data are input into computer nith0 question and ans-
wer"format.Tabulated data or plot of displacement of bottom hole assem-
bly can be selected at users s will.
It is proved by simulation that the hehavior of bottom hole assernbly
not only depends on bit side force.Both the bit side force and the resul-
taut should be considered in analysis of bottom hole assembly.Three
general types of assembly.holding，building and dropping-aro simu-
lated.Comparison of the results ith field measurements of drilled hole
angles is presented.The computer simulation with the factors of a parti-
cular formaton could be helpful in predicting well trajectary，designing
a proper assembly and determining the Sveight on bit，