engleski

A Method for Modeling Directional Behaviour of Bottomhole Assemblies with Downhole Motors

Well path control is one of the most important and very complex drilling phase while drilling deviated or horizontal well. Many authors have put tremendous amount of effort to developed sophisticated computer programs that would enable engineers to understand various mechanisms and variables that affect BHA's behaviour. These include: weight-on-bit, rotary speed, penetration rate, hole inclination and direction, geology and bits. Vast majority of developed programs are based upon finite element methods due to their suitability for computer use. Programs based on finite element methods calculate BHA position and the forces exerted by the BHA on the wellbore. Bit side force and the bit tilt angle with respect to the wellbore centerline are two key parameters for predicting directional response of BHA. One simplification that is being made in all current models is that contacts of BHA with wellbore are being made in stabilizers. Analytical method for calculating side forces as well as contact points is being proposed in this paper. Proposed method is based upon solving statically single or multiple undefined beam depending on number of contact points between drill string and wellbore wall. The proposed method provides the capability to evaluate and to adjust the actual well profile in an interactive, real time mode thus enabling wellpath steering.

Directional Drilling; Wellpath Steering; Bottom Hole Assembly; Bending Moments; Lateral Forces

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