Introducing new powerful methods to analyse BHA behaviour

Abstract TOTAL CFP Research and Development Department has developed powerful programs and methods for the analysis of bottom hole assembly behaviour in rotary drilling. The BHA 2 two-dimensional program, has thoroughly and successfully been used for studies of deviation problems and BHA design in TUNISIA, FRANCE, ALGERIA and ABU DHABI. We have built a correlation method based on the program results and the post-analysis of directional data gathered on site. This method makes it possible to predict the inclination behaviour of a two stabilizer type of BHA. Correlations may be obtained for other types of rotary assemblies if requested. The program results are now more comprehensive due to a plot program which clearly shows how a given BHA deflects within a given hole and under given drilling conditions. The side-forces (efforts exerted at the bit and at every BHA/hole contact) are comprehensively drawn. The influence of every single parameter can be taken individually into account. Plots of the side-forces as a function of: • hole angle, • hole curvature, • weight on bit, • stabilizers undergauge (or wear), • DC's O.D. and DC's inertia, • BHA geometry, • hole overgauge, • etc. can be obtained whatever the BHA and the hole conditions that are considered. This paper presents CFP's programs and methods based on successful operation applications: 1) Optimization of pendulum assemblies for enhanced hole vertically, W.O.B. and ROP. 2) Follow-up of 5500 ft long, 6 deviated phase at 15 degree inclination. 3) Optimization of lock-up BHA'S in 6 hole drilling.