Quantifying Bottomhole Assembly Tendency Using Field Directional Drilling Data and a Finite Element Model

Abstract

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractPredicting the directional tendency of a bottomhole assembly (BHA) is a key element in improving the efficiency of the directional drilling process. Finite element models attempt to represent the detailed physical interactions between the BHA and wellbore while drilling. However, effective use of such models has been hindered by parameters that are difficult to quantify, particularly the strength of the formation and variations in hole gauge.Details of over 6400 BHA runs made in the Gulf of Mexico from 1994 through 1997 were used in a systematic statistical analysis and combined with intelligent use of the tendency models to yield information that is not readily apparent in single runs of the software. This information can then be used as a predictive tool to minimize the effects of the parameter uncertainties, and to isolate and calibrate those variables to which the models are sensitive. From these studies the most representative values for formation stiffness and hole over-gauge were obtained for various areas within the Gulf region.We describe a methodology using this combination of advanced modeling and statistical analysis to provide more reliable predictions of BHA tendency and to give an indication of the conditions where such predictive techniques can be effectively applied.

Modeling contact of pipes within elliptic and spiralled wellbores using finite element analysis

“…Various models are used in oil industry to estimate the forces on drillpipes [1][2][3][4][5][6]. These tools provide various benefits, such as estimating torsional and axial drag, bending moments, load distribution along the drillpipe and critical buckling loads for a given hole-pipe-wellbore combination.…”

Analysis of steering in horizontal directional drilling installations using down-hole motors

“…Factors identified in oilfield drilling that impact upon the control of steering Previous research undertaken in positional control of downhole assemblies tends to refer to oilfield applications and focus upon the use of PDC bits, which is not felt to be directly relevant to the HDD industry. However, a number of factors have been identified that may be relevant to HDD installations and include; the compressive strength of the rock (Lesso et al, 1999;Hareland et al, 2000); changes in rock strength (both laminations and interbedding within the strata, Boualleg et al, 2006); the dip of the formation (Stockhausen and Lesso, 2003b); the type of down-hole assembly used (Lesso et al, 1999;Studer et al, 2007); the ROP (Ernst et al, 2007;Lesso et al, 1999), the WOB (Lesso et al, 1999;Studer et al, 2007); bit-walk (Liu and Shi, 2002); tool face angle (Lesso et al, 1999;Studer et al, 2007); stabilisers (that amplify the size of dog-legs created by migration away from line and level). Lesso et al (1999) and Studer et al (2007) both developed approaches to investigate the relationship between the apparatus used (within the oilfield industry) and steering response.…”

“…Lesso et al (1999) and Studer et al (2007) both developed approaches to investigate the relationship between the apparatus used (within the oilfield industry) and steering response. Lesso et al (1999) investigated 4600 drives by averaging the steering performance for the drive and then undertaking a cluster analysis. Finite element models were created to predict the behaviour of 'typical' down-hole assemblies (based on the results of the cluster analysis) and the models were used to undertake a parametric study to identify important parameters on steering response (as described above).…”

“…In light of the previous research undertaken on steering control in oilfield drilling, the analysis of control of steering in HDD installations reported in this paper broadly follow the approach undertaken by Lesso et al (1999) and Studer et al (2007). The datasets were broken down into sections and the surveyed values were compared to theoretical values.…”

“…The ratio of actual steering performance against predicted performance was identified for each of the sections to determine the factors that impact upon steering control in HDD installations (following the approach by Lesso et al, 1999;Studer et al, 2007). The study identified a number of factors that impact upon the ability to control steering in HDD, including; the length of slide drilled sections; the distance from the drilling rig to the down-hole assembly; the drill bit type and bend angle of the bent-sub; the geology in which the installation takes place.…”