Numerical Simulation of Casing Stress during Multi-stage Fracturing Based on Stage Finite Element Method

Year 2018, , 20 - 24, 27.11.2018

Xueli Guo , Jun Lı Gonghui Lıu Hui Yan

https://doi.org/10.22399/ijcesen.418035

Abstract

During multi-stage hydro-fracturing operation, casing deformation issues have widely occurred in the Changning-Weiyuan National Shale Gas Demonstration Area, which dramatically reduce the productions of shale gas wells. It is important to access the influence of multiple factors on casing during fracturing operations. In this paper, a stage-finite-element method is presented to establish three-dimensional physical and finite element casing-cement sheath-formation (CCF) models during volume fracturing processes. It considers the influences of initial stress and displacement state at and near the wellbore. Loads from the initial stress field, fracturing pressure, and transient temperature changes are incorporated in the models. Cement channelling, cement elastic modulus, casing eccentricity, and fracturing pump rate are also the variables taken into account. Sensitivity analyses are conduced to reveal which one has the greatest influence on casing stress. The results indicate that casing stress is highly affected by cement channelling. Low casing stress can be guaranteed by high cement sheath modulus and optimal fracturing pressure. Casing transient temperature is significantly reduced by the large pump rate, then a certain thermal stress generating in the casing. Among all of the factors, casing eccentricity has a minor influence on casing stress.

Keywords

Stage finite element method, Casing stress, Fracturing, Cement channelling, Transient temperature

References

• Reference1 Lv Z., Wang L., Deng S., et al. China Shale Gas Exploration: Early Sichuan Basin Longmaxi Shale Gas Stimulation and Completion Case Study, SPE/IADC Middle East Drilling Technology Conference & Exhibition. Society of Petroleum Engineers, Dubai 2013, DOI:10.2118/166746-MS.
• Reference2 Sugden C., Johnson J., Chambers M., et al. Special Considerations in the Design Optimization of High Rate, Multistage Fractured Shale Wells, IADC/SPE Drilling Conference, and Exhibition. Society of Petroleum Engineers, San Diego ,2012, DOI:10.2118/151470-MS.
• Reference3 Zhou C., Wu X., Li H., et al. Influence of In-situ Stress Distribution on Selection of Fracturing Fluid Backflow Technology, Acta Physica Polonica A, 130(2016) 347-351. DOI: 10.12693/APhysPolA.130.347.
• Reference4 Davies R. J., Almond S., Ward R. S., et al. Oil and gas wells and their integrity: Implications for shale and unconventional resource exploitation, Marine and Petroleum Geology, 56(2014) 239-254. DOI:10.1016/j.marpetgeo.2014.03.001.
• Reference5 Rocha-Valadez T., Mentzer R. A., Hasan A. R., et al. Inherently safer sustained casing pressure testing for well integrity evaluation, Journal of Loss Prevention in the Process Industries, 29(2014) 209-215, DOI:10.1016/j.jlp.2014.02.012.
• Reference6 Yan W., Zou L., Li H., et al. Investigation of Casing Deformation during Hydraulic Fracturing in High Geo-stress Shale Gas Play, Journal of Petroleum Science and Engineering, 150(2016) 22-29, DOI: 10.1016/j.petrol.2016.11.007.
• Reference7 Lin T., Yu H., Lian Z., et al. Numerical simulation of the influence of stimulated reservoir volume on in-situ stress field, Journal of Natural Gas Science and Engineering, 36(2016) 1228-1238, DOI: 10.1016/j.jngse.2016.03.040.
• Reference8 Zhang, W., Eckert, A., Liu, X. Numerical Simulation of Micro-Annuli Generation by Thermal Cycling. 51st U.S. Rock Mechanics/ Geomechanics Symposium, American Rock Mechanics Association. San Francisco, 2017. ID: ARMA-2017-0354.
• Reference9 B. Nagy, International Conference on Computational and Experimental Science and Engineering (ICCESEN 2014), 25-29 October 2014 Antalya-Turkey. DOI: 10.12693/APhysPolA.128.B-314.
• Reference10 M. Koru and O. Serçe. Experimental and Numerical Determination of Casting-Mold Interfacial Heat Transfer Coefficient in the High Pressure Die Casting of A-360 Aluminum Alloy 130(2016) 453-458. DOI: 10.12693/APhysPolA.130.453.
• Reference11 F. Kulalı, I. Akkurt, N. Özgür, International Conference on Computational and Experimental Science and Engineering (ICCESEN 2015), 14-19 October 2015 Antalya-Turkey. DOI: 10.12693/APhysPolA.130.496.
• Reference12 O. Ipek, M. Kan, B. Gurel, International Conference on Computational and Experimental Science and Engineering (ICCESEN 2015), 14-19 October 2015 Antalya-Turkey. DOI: 10.12693/APhysPolA.132.580.
• Reference13 Gao C, Xie L.Z., Xie H.P., et al. 2017. Estimation of the equivalent elastic modulus in shale formation: Theoretical model and experiment[J]. Journal of Petroleum Science and Engineering, 151:468-479. DOI: 10.1016/j.petrol.2016.12.002.