Formation rock failure mode and its recognition method under high pressure squeezing condition in horizontal wells

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Dinah Dickerson
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1 01 36 Vol. 36 No. 5 5 Journal of China University of Petroleum Oct TE A doi /j. issn Formation rock failure mode and its recognition method under high pressure squeezing condition in horizontal ells DONG Chang-yin 1 LIU Chun-miao WU Long 3 FENG Sheng-li 4 ZHANG Xiao-bin 1 LONG Jia-jia 1 1. School of Petroleum Engineering in China University of Petroleum Qingdao China. Supervision Branch Company CNOOC Energy Resources Development Company Limited Tianjin China 3. Changqing Branch Institute of Research Institute of Drilling and Production Engineering Chuanqing Drilling and Exploration Company Limited Xi an China 4. Research Institute of Drilling and Production Engineering Qinghai Oilfield Dunhuang China Abstract For the horizontal ell in unconsolidated sandstone reservoir to formation rock failure patterns ere put forard one of hich is the pattern of fracture initiation and extension another is plastic compaction packing. The process and mechanism of outside-casing plastic packing in horizontal ell ere analyzed. Based on the formation stress and rock strength distribution near ellbore a formation rock failure recognition model as developed. With the model the critical failure floing pressure profile along the ellbore trajectory as calculated and the initial breakdon point position as determined. The results sho that the rock failure pattern depends on formation stress distribution rock strength and job parameters. With bottom hole pressure increasing rock ould be broken don by the failure pattern of plastic compaction packing hen radial principal stress achieves rock anti-compressing strength firstly. Contrarily if the ellbore tangential stress overcomes the rock anti-tensile strength firstly the rock fracturing occurs. Under the high pressure squeezing conditions the strong consolidated rock ith high strength tends to be broken don by fracturing pattern and the unconsolidated rock ith lo strength is more easily to failure by the pattern of plastic compaction packing. Due to the nonuniformity of formation stress and rock strength a- long ellbore the critical broken pressures of to failure patterns sho nonhomogeneity along horizontal ellbore trajectory AA09Z

106 01 10 Key ords horizontal ells outside casing gravel packing rock failure pattern plastic compaction packing

2 Key ords horizontal ells outside casing gravel packing rock failure pattern plastic compaction packing recognition model Fig. 1 Typical curve of high pressure squeezing gravel packing AB BC

3 σ 1 = σ r 3 CF σ = 1 σ + θ σ z CD σ θz θz MPa. DE. 1 3 σ 1 σ 7-8 σ r = r r p +σ + xx σ yy 1- r ( r ) +σ - xx σ yy 1+ 3r4 r -4r ( 4 r ) cos θ +δ [ a 1-υ r 1-1-υ ( r ) - φ ] p -p p. σ θ = - r r p +σ + xx σ yy 1+ r ( r ) -σ - xx σ yy 1+ 3r4 ( r ) cos θ a 1-υ +δ 4 1-υ 1+r [ ( r ) - φ] p -p p. σ z = σ zz -υ [ σ - xx σ yy r ( r ) cos θ+4σ xy r ( r ) sin θ ] + δ [ a 1-υ -φ 1-υ ] p -p p. σ xx = σ v σ yy = σ H sin β+σ h cos β σ zz = σ H cos β+σ h sin β. r m θ rad σ r σ θ σ z MPa r m p MPa p p MPa υ a Biot δ φ σ xx σ yy σ zz MPa σ v σ H σ h MPa β rad r = r σ 1 σ σ 3 σ - θ σ z +4σ θz 槡 σ 3 = 1 σ + θ σ z - 1 槡 σ - θ σ z +4σ θz. 1 1 max σ 1 σ σ c. σ c MPa σ 3 <0 σ 3 σ t. 3 σ t MPa 3 Fig. Flo chart of formation failure mode recognition

4 m kg /m km Fig. 4 Variation of principal stress ith bottom hole pressure in tight sandstone MPa 3 σ MPa σ MPa 3 σ MPa σ 1 45 MPa MPa 3 1 /10 Fig. 3 Variation of principal stress ith bottom hole pressure in unconsolidated sandstone 3 σ MPa σ 1 5 MPa σ p MPa σ MPa MPa. 1 ~. km MPa 6 ~ MPa 3 4. km

5 ~ 57 MPa 3 J MPa. 1 km DONG Chang-yin JIA Bi-xia ZHANG Ying-chun et al. Mechanism of gravel-packing in highly deviated ells 3 MPa. 1 J. Journal of China University of Petroleum Edition of km Natural Science Fig. 5 4 WANG Wei-zhang YAN Xiang-zhen. Numerical simulation of packing zone morphology ith high pressure gravel- Critical breaking pressure distribution packing sand-prevention technology in unconsolidated along horizontal ellbore sandstone J. Journal of Weifang University J YAN Xiang-zhen WANG Wei-zhang YANG Xiu-juan et 3 al. Analytical solution of high-pressure squeezing problems at stratum near ell J. Journal of China University of Petroleum Edition of Natural Science J WEI Ya-min WANG Ai-ping DONG Chang-yin et al. Ne model for critical sanding pressure dradon prediction in horizontal ells based on characteristic break radi- 4 us J. Journal of China University of Petroleum Edition of Natural Science J DONG Chang-yin WANG Ai-ping. Distribution of plastic stress near ellbore and prediction of sanding radius for 1 M. sanding horizontal ells J. Journal of China University of Mining & Technology J. J LU Bao-ping BAO Hong-zhi. Advances in calculation DONG Chang-yin ZHANG Zong-yuan ZHANG Qi et methods for rock mechanics parameters J. Petroleum Drilling Techniques al. An integral model for productivity evaluation of sand control horizontal oil ells J. Petroleum Geology & Oilfield Developed in Daqing J CHEN Mian CHEN Zhi-xi HUANG Rong-zun. Hydraulic fracturing of highly deviated ells J. Journal of the University of Petroleum China Edition of Natural Science J

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