A Comprehensive Modeling Analysis of Borehole Stability and Production-Liner Deformation for Inclined/Horizontal Wells Completed in a Highly Compacting Chalk Formation
- Kenji Furui (ConocoPhillips) | Giin-Fa Fuh (ConocoPhillips) | Nabeel A. Abdelmalek (ConocoPhillips) | Nobuo Morita (Waseda University)
- Document ID
- Society of Petroleum Engineers
- SPE Drilling & Completion
- Publication Date
- December 2010
- Document Type
- Journal Paper
- 530 - 543
- 2010. Society of Petroleum Engineers
- 1.14 Casing and Cementing, 5.8.7 Carbonate Reservoir, 5.3.4 Integration of geomechanics in models, 3 Production and Well Operations, 3.2.4 Acidising, 4.1.2 Separation and Treating, 2.2.2 Perforating
- Compaction, 3D finite element model, Wellbore stability, Chalk, Liner deformation
- 3 in the last 30 days
- 1,310 since 2007
- Show more detail
- View rights & permissions
|SPE Member Price:||USD 10.00|
|SPE Non-Member Price:||USD 30.00|
Numerous casing and production-liner deformation/failure problems have been reported in high-porosity chalk formations in both the overburden and the reservoir sections, causing costly operation problems that prevent workovers and recompletions. This paper presents the results of studies performed to investigate stability of an openhole, cemented liner and uncemented-liner completions in a highly compacting chalk formation. The effects of critical cavity dimensions caused by various acid-stimulation techniques were also investigated.
On the basis of the review of historical caliper-survey data, we ascertain that axial-compression collapse is a major liner-deformation mechanism in the reservoir zones. Axial-compression collapse has been found in both low-angle wells (also in buildup sections of horizontal wells) and horizontal laterals. The casing deformation in low-angle sections is a result of reservoir compaction (i.e., change in the vertical formation strain), while the deformation in horizontal sections is primarily induced by increased axial loading because of cavity deformation. The current completion practice using cluster perforations and high-volume acid treatments causes vertically enlarged cavities, resulting in poor radial constraint.
A series of laboratory triaxial tests was performed on selected reservoir chalk samples to measure the stress/strain and failure behavior of the chalk formation considering a wide range of porosity and water saturation and different levels of confining pressures. Using the chalk-failure criteria and constitutive relations developed from the analysis of laboratory triaxial-compression-test data, a 3D nonlinear poroelastic/plastic finite-element-method (FEM) model was developed for the openhole stability analysis. The simulation results show that the abnormally high ductility of chalks after pore collapse around a borehole could actually enhance borehole stability, with a magnitude beyond expectation.
In this study, analytical and numerical models are also developed for evaluating cavity-induced axial- compression collapse of production liners. Model results indicate that the risk of the cavity-induced axial- compression collapse substantially increases for short perforated intervals stimulated with large acid treatments. However, increasing the perforation-interval lengths along the entire liner axis results in more-uniform acid distribution and will greatly reduce the chance of axial-compression collapse caused by localized cavity deformation. On the basis of these analysis results, key completion design criteria and stimulation strategies were developed for wells completed in highly compacting chalk reservoirs to reduce risk of casing and liner mechanical problems.
|File Size||3 MB||Number of Pages||14|
Fuh, G-F., Morita, N., and Furui, K. 2009. Modeling Analysis of Sand-ScreenCollapse Resistance Under Geotectonic Load. Paper SPE 124388 presented atthe SPE Annual Technical Conference and Exhibition, New Orleans, 4-7 October.doi: 10.2118/124388-MS.
Morita, N., Doi, T., and Kinoshita, T. 2005a. Stability of an Open Hole Completedin a Limestone Reservoir With and Without Acid Treatments. SPE J. 10 (2): 105-114. SPE-77776-PA. doi: 10.2118/77776-PA.
Morita, N., Kasahara, Y., Hikida, H., and Ito, Y. 2005b. Collapse Resistance of TubularStrings Under Geotectonic Load. Paper SPE 95691 presented at the SPE AnnualTechnical Conference and Exhibition, Dallas, 9-12 October. doi:10.2118/95691-MS.
Joint Chalk Research Phase IV: Project 4.1 Review of Rock Mechanical Data.1996. Final report, Job No. 160 09163, Danish Geotechnical Institute,Copenhagen, Denmark (5 November 1996).
Sneddon, I.N. and Lowengrud, M. 1970. Crack Problems in the ClassicalTheory of Elasticity, 20-30. New York: SIAM Series in Applied Mathematics,John Wiley & Sons.
Yudovich, A., Chin, L.Y., and Morgan, D.R. 1989. Casing Deformation in Ekofisk.J Pet Technol 41 (7): 729-734. SPE-17856-PA. doi:10.2118/17856-PA.