摘要
用断裂力学有限元法 ,建立了裂缝宽度预测的有限元模型 ,研究了鄂北塔巴庙地区低渗透砂岩气井中垂直裂缝宽度、裂缝长度及裂缝周围应力变化与压差的关系。结果表明 ,同一井筒压差作用下 ,总能找到某一临界裂缝长度 ,使得应力强度因子达到最大 ,超过这一临界裂缝长度时 ,裂缝的开裂能力减弱 ,要使裂缝继续扩展 ,则必须提高应力强度因子 ,根据岩石的应力强度因子和本研究的断裂力学模型 ,可以确定地层的破裂压力。文中不同压差下的裂缝宽度预测为裂缝屏蔽暂堵完井液中架桥粒子尺寸设计提供了依据。
A finite element model of predicting fracture widths was set up according to the finite element method of fracture mechanics and the relation between the changes,in vertical fracture lengths and widths and in the stresses arround the fractures,and the pressure differences of the low permeability sandstones in the gas wells at Taba region in North E'erduosi Basin was studied by use of the model.The results indicate that by the action of the same wellbore pressure difference,one critical fracture length can be found after all,thus obtaining a maximum stress strength factor;and when the critical fracture length is exceeded,the cracking capability of fractures decreases and the stress strength factor must be enhanced in order to make the fracture cracking be continued.Therefore the formation breakdown pressure may be determined according to the stress strength factor of rocks and the model mentioned above and the fracture width prediction by the action of different pressure drops may provide the basis for the size design of bridging particles in fracture screening temporary plugging completion fluid.
出处
《天然气工业》
EI
CAS
CSCD
北大核心
2003年第3期44-46,共3页
Natural Gas Industry
基金
国家自然科学基金项目资助 (批准号 :5 0 0 74 0 2 5 )
