A Method of Modeling the Directional Behavior of Bottomhole Assemblies Including Those With Bent Subs and Downhole Motors

Abstract

This peper was prepared for presentation atthe 1986 lADC/SPE Drilling Conference held in Dallas, TX, FebruaW ID-12, 1986. Thie paper was aeleclad for preaerltationby an IADCLSPEProgram Committee followingreview of informationcontained In an abstractsubmittedby the autfror(s).Contents of the papar, as presentad, have not been reviewad by the 60.Sefy of Petroleum Engineera or InternationalAseocia:.m of Drilling Contrsc:ora&ndare subject to correctionby !he author(a).The matcxial,as presented, doas not necessarily reflect any positionof the IADC; r SPE, itsof. ficere, or members. Papers presented al lADC/SPE meetings are subject to publicationby Editorial Committees of the IADC and SPE. Permissionto copy la restrictedto an abstract of oot more than 300 words. Illustrationsmay not be copied. The abstrsct ehouldcontain mnspicuous acknowledgment of where and bv whom the oaoer is Dreaented. Write Publications Manager, SPE, ABSTRACT Thie paper presents an analytical model that has succeeafully predicted the inclination directional behavior of rotary drilling bottomhole assemblies, including aeaemblies that contain bent subs and downhole motors. The model has been installed as part of the Engineering Simulator for Drilling (ESD), and ccmbinea the effects on directional behavior of bottomhole assembly configuration, hole geometry, rock drillability, bit type and operating parameters such as bit hydraulics, weight-on-bit and rotary speed. The model combines previous work dealing with bottomhole aasembly analysis and bit mechanics (including side-cutting behavior), with original work defining the manner by which bits directionally penetrate.The model's computation echeme depends on a microcode version of a finite element bottomhole assembly behavior program running on an array processor. The system provides solutions of the finite element routine every one to aix seconds. Solutions are required at this frequency in order to obtain stable directional predictions at 30 times faster than real time.The paper also shcws that comparisons of the model results with field data are good in areas where formation affects are benign. Comparisons of model predictions with field reeults in areas of significant formation directional affects are also shown. These comparison are useful in quantifying the effect of the dip and strike on directional behavior, and in defining areaa where future work is needed._References_and illustrations at end of paper. Q&a"""

Finite Element for Simulating BHA-Casing-Rock Interactions

“…The implementation of the above geometrically nonlinear finite element formulation for the analysis of BHA Model problems consists of the following main steps: Model Property: A steel material will be used with mass density = 7800 kg/m 3 ; Young's modulus = 209×10 9 ; Poisson's ratio = 0.3. Where for Rock material the mass density = 2000 kg/m 3 modulus = 30×10 9 ; and Poisson's ratio = 0.2;…”

“…In 1953, the pioneering work was developed by Lubinski and Woods and Williamson and Lubinski [1] with the same model. Many analytical and numerical models exist which are designed to analyze Bottom hole assemblies and/or predict wellbore trajectories [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. There are four basic mathematical models used for BHA analysis; the analytical model, FEM, finite difference model and weighted residuals.…”

Analysis of Spiraled-Borehole Data by Use of a Novel Directional-Drilling Model

“…Spiral holes may lead to poor-quality formation-evaluation results-from both logging while drilling (LWD) and wirelinebecause the quality of data from shallow depth-of-investigation devices (such as density, microresistivity, or imagining logs) is impeded (Gaynor et al 2001). During cementing, zonal isolation may be compromised by channeling and variable casing standoff (Chen et al 2002).…”

“…After this pioneering work, numerous publications have been devoted to this topic (Murphey and Cheatham 1966;Millheim et al 1978;Brett et al 1986;Ho 1986;Jogi et al 1988;Maouche 1999). Few authors have recognized, however, that the formulation of a directional-drilling model requires coupling the equations governing the deformation of the drillstring to the bit/ rock-interface laws.…”