摘要
岩石弹性力学性质是储层水力压裂裂缝起裂的重要力学约束,解译弹性力学性质与煤层破裂压力间的数学关系对于气井压裂设计有一定作用。以沁水盆地郑庄区块51口煤层气井为对象,利用声波时差、体密度测井数据反演了近井煤岩弹性力学参数(弹性模量E、剪切模量G、体积模量K、泊松比v)值,计算了表征煤岩破裂实际耗能情况指标——破裂压力当量(P_t)值。通过数学回归发现:中低弹性模量软煤中弹性力学参数(E、G、K)与P_t呈线性正相关关系;对于高弹性模量(E>6GPa)硬煤,发育天然大裂隙煤层P_t较低且随模量(E、G、K)降低而增高(煤粉的堵塞效应),而致密煤层P_t随煤岩模量增大而快速升高。煤岩泊松比(v)与P_t间的关系则不同,高弹性模量硬煤P_t随煤岩泊松比(v)增大而快速升高,而中低模量软煤P_t先随v减小而升高(煤岩脱水效应),后与v呈正相关关系。
The elastic mechanical property of rock is a mechanical constraint for the fracture initiation in hydraulic fracturing.51 coalbed methane wells in Zhengzhuang blocks of Qinshui Basin are taken as the object in this paper, the parameters of elasticity mechanics ( Young' s modulus E , shear modulus G , bulk modulus K ‘Poisson's ratio v) of No.3 coal near wellbore were calculated based on the acoustic, density logging data, and meanwhile the values of equivalent fracture pressure ( P,) which represent energy consumption were figured out.Based on regression?two patterns of relationship between the elastic mechanical parameters (E 9 K ) and P t were proposed.In soft coal with medium and low modulus, there is a positive correlation between them, for high-modulus hard coal. P t is low when the coal develops natural fracture and P, increases with the decrease of parameters (E,G.K) with the blockage effect of coal fines, whereas P, increases rapidly with the increase of parameters (E ,G , K ) when the coal is stiffness.The relationship between v and PI in coal is inversely related to above.Pt increases rapidly with the increase of v in high modulus hard coal .while in medium and low modulus soft coal P( increases with the decrease of v firstly by the extrusion effect of pore water in coal,and then it is positively correlated with p.
作者
陈立超
王生维
Chen Li-chao;Wang Sheng-wei(School of Mining and Technology in Inner Mongolia University of Technology ,Hohhot 010051,China;State Key Laboratory of Coal and CBM Co-mining in Jinchen Anthracite Mining Group,Jincheng 048204,China;Faculty of Earth Resources in China University of Geosciences,Wuhati 430074 ,China)
出处
《天然气地球科学》
EI
CAS
CSCD
北大核心
2019年第4期503-511,共9页
Natural Gas Geoscience
基金
国家科技重大专项(编号:2016ZX05067001-007)
山西省煤层气联合研究基金(编号:2016012007)
甘肃省油气资源重点实验室开放基金(编号:SZDKFJJ20160606)
内蒙古自然科学基金(编号:2016MS0402)
内蒙古高等学校科学研究项目(编号:NJZY16090)联合资助
关键词
煤储层
弹性力学性质
破裂压力当量
水力压裂
裂缝起裂机制
郑庄区块
沁水盆地
Coal reservoir
Elastic mechanical properties
Equivalent fracture pressure
Hydraulic fracturing
Fracture initiation mechanism
Zhengzhuang block
Qinshui Basin
