Test and Analysis of Mechanical Properties and Failure Patterns for the Deep Brittle Shale Under Complex Load

doi:10.3969/j.issn.1006-6535.2020.04.022

Abstract

Abstract: The deep shale in Zigong, Luzhou and other regions of Sichuan Province are characterized by high hardness, strong brittleness and well-developed bedding fractures, which results in frequent downhole stuck, overflow and other accidents during horizontal well drilling. The drilling fluid plugging performance and mechanical property tests under different confining pressure unloading rates were conducted for the deep brittle shale to clarify the effects of drilling fluid plugging performance and tripping out speed on the mechanical properties of brittle shale and the failure patterns. The test indicates that the drilling fluid plugging performance shows a significant effect on the strength and elastic modulus. The compressive strength and elastic modulus can reach 350 MPa and 16 000 MPa respectively with favorable drilling fluid plugging performance. The compressive strength and elastic modulus are only 40 MPa and 6 000 MPa respectively in case of poor drilling fluid plugging performance. The brittle shale is more likely to be failure under high confining pressure unloading rate. High tripping out speed will result in a sharp decrease of downhole effective liquid column pressure, which will lead to sidewall rock collapse. The shale failure always along the bedding fracture under bottom-hole pressure. This research reveals the mechanical properties and failure patterns of deep brittle shale under complex conditions, which could provide a scientific reference for formulating anti-collapse countermeasures.

Key words: brittle shale, rock mechanics, drilling fluid, wellbore stability, confining pressure, Luzhou Block

CLC Number:

TE242

Fan Yu, Wang Jiajun, Liu Houbin, Wu Pengcheng, Gao Dewei, Wang Xudong. Test and Analysis of Mechanical Properties and Failure Patterns for the Deep Brittle Shale Under Complex Load[J]. Special Oil & Gas Reservoirs, 2020, 27(4): 143-148.

References

[1] 张晨晨,刘滋,董大忠,等.深层海相页岩脆性特征分析与表征[J].新疆石油地质,2019,40(5):555-563.
ZHANG Chenchen,LIU Zi,DONG Dazhong,et al.Brittleness analysis and characterization of deep marine shales[J].Xinjiang Petroleum Geology,2019,40(5):555-563.
[2] 刘厚彬,崔帅,朱达江,等.硬脆性页岩微细观组构及力学性能研究[J].地下空间与工程学报,2019,15(增刊1):34-39.
LIU Houbin,CUI Shuai,ZHU Dajiang,et al.Study on microstructure and mechanical properties of hard brittle shale[J].Chinese Journal of Underground Space and Engineering,2019,15(S1):34-39.
[3] 许杰,刘坤岩,武清钊.焦石坝页岩脆性评价与预测[J].石油物探,2019,58(3):453-460.
XU Jie,LIU Kunyan,WU Qingzhao.Evaluation and prediction of shale brittleness in the Jiaoshiba Area[J].Geophysical Prospecting for Petroleum,2019,58(3):453-460.
[4] 丁乙,刘向君,罗平亚,等.硬脆性泥页岩地层井壁稳定性研究[J].中国海上油气,2018,30(1):142-149.
DING Yi,LIU Xianjun,LUO Pingya,et al.Research on wellbore stability for hard brittle shale[J].China Offshore Oil and Gas,2018,30(1):142-149.
[5] 王翔.鄂尔多斯盆地西部页岩油水平井井壁稳定技术[J].石油地质与工程,2019,33(4):88-91.
WANG Xiang.Wellbore stability technique in horizontal wells for shale oil reservoirs in western Ordos Basin[J].Petroleum Geology and Engineering,2019,33(4):88-91.
[6] 陈卓,邓金根,蔚宝华,等.基于损伤理论的硬脆性泥页岩井壁稳定分析[J].科学技术与工程,2019,19(16):87-94.
CHEN Zhuo,DENG Jingen,YU Baohua,et al.Borehole stability analysis of hard brittle shale based on damage theory[J].Science Technology and Engineering,2019,19(16):87-94.
[7] 刘凯都,刘书杰,文敏.泥页岩渗透水化井壁稳定分析[J].石化技术,2019,26(1):139-140.
LIU Kaidu,LIU Shujie,WEN Min.Analyze of borehole wall stability by the action of physical chemistry[J].Petrochemical Industry Technology,2019,26(1):139-140.
[8] 梁利喜,丁乙,刘向君,等.硬脆性泥页岩井壁稳定渗流-力化耦合研究[J].特种油气藏,2016,23(2):140-143.
LIANG Lixi,DING Yi,LIU Xiangjun,et al.Seepage-mechanochemistry coupling of wellbore stability in hard brittle shale[J].Special Oil & Gas Reservoirs,2016,23(2):140-143.
[9] DARLEY H C H.A laboratory investigation of borehole stability[J].Journal of Petroleum Technology,1969,21(7):883-892.
[10] 赵虎,司西强,王善举,等.钻井液对页岩井壁的稳定性能评价方法探讨[J].石油工业技术监督,2019,35(2):12-15.
ZHAO Hu,SI Xiqiang,WANG Shanju,et al.Discussion on evaluation methods for stabilizing effect of drilling fluid on shale well wall[J].Technology Supervision in Petroleum Industry,2019,35(2):12-15.
[11] 贾梦瑶,唐洪明,陆燕萍,等.川南地区龙马溪组页岩有机质非均质性研究[J].特种油气藏,2019,26(6):29-34.
JIA Mengyao,TANG Hongming,LU Yanping, et al.Heterogeneity of organic matter in the Longmaxi Shale Formation of southern Sichuan Basin[J].Special Oil & Gas Reservoirs,2019,26(6):29-34.
[12] 郝海洋,李勇,宋继伟,等.黔西南地区煤系地层井壁稳定技术探讨[J].探矿工程(岩土钻掘工程),2019,46(7):8-13,33.
HAO Haiyang,LI Yong,SONG Jiwei,et al. Wellbore stabilization techniques in coal-bearing formation in southwestern Guizhou[J].Exploration Engineering(Rock & Soil Drilling and Tunneling),2019,46(7):8-13,33.
[13] 熊健,黄林林,刘向君,等.高温影响下页岩岩石的声学特性实验研究[J].西南石油大学学报(自然科学版),2019,41(6):35-43.
XIONG Jian,HUANG Linlin,LIU Xiangjun,et al.An experiment study on the effect of high temperature on the acoustic properties of the shale[J].Journal of Southwest Petroleum University(Science & Technology Edition),2019,41(6):35-43.
[14] 吴铭.泥页岩储层岩石力学特性及其脆性评价[J].中国石油和化工标准与质量,2019,39(3):170-171.
WU Ming.Rock mechanical properties and brittle evaluation of shale reservoirs[J].China Petroleum and Chemical Standard and Quality,2019,39(3):170-171.
[15] 张景轩,范晓,陈波,等.硬脆性页岩断裂韧性二维数值模拟研究[J].复杂油气藏,2019,12(1):73-80.
ZHANG Jingxuan,FAN Xiao,CHEN Bo,et al.Two-dimensional numerical simulation of fracture toughness of hard brittle shale[J].Complex Hydrocarbon Reservoirs,2019,12(1):73-80.
[16] 衡帅,李贤忠,刘晓,等.直剪条件下页岩裂缝扩展演化机制研究[J].岩石力学与工程学报,2019,38(12):2438-2450.
HENG Shuai,LI Xianzhong,LIU Xiao,et al.Study on the mechanisms of fracture propagation in shale under direct shear conditions[J].Chinese Journal of Rock Mechanics and Engineering,2019,38(12):2438-2450.
[17] 刘卫东,朱晓虎,蒋文海,等.页岩微裂缝模拟实验评价[J].钻采工艺,2019,42(2):104-107.
LIU Weidong,ZHU Xiaohu,JIANG Wenhai,et al.Experimental simulation and evaluation of shale microcracks[J].Drilling & Production Technology,2019,42(2):104-107.
[18] 张宜.页岩气储层脆性评价方法研究现状[J].探矿工程(岩土钻掘工程),2019,46(7):51-56.
ZHANG Yi.Research status of shale gas reservoir brittleness evaluation method[J].Exploration Engineering(Rock & Soil Drilling and Tunneling),2019,46(7):51-56.
[19] 姜瑞忠,刘秀伟,崔永正,等.非稳态窜流多段压裂水平井井底压力分析[J].油气地质与采收率,2019,26(5):86-95.
JIANG Ruizhong,LIU Xiuwei,CUI Yongzheng,et al.Bottomhole pressure analysis of multistage fractured horizontal well during unsteady crossflow[J].Petroleum Geology and Recovery Efficiency,2019,26(5):86-95.
[20] 王洪峰,李晓平,王小培,等. 多井干扰试井技术在克深气田勘探开发中的应用[J].油气地质与采收率,2018,25(1):100-105.
WANG Hongfeng,LI Xiaoping,WANG Xiaopei,et al. Application of multi-well interference test technology in exploration and development of Keshen Gasfield[J].Petroleum Geology and Recovery Efficiency,2018,25(1):100-105.