页岩气藏表观渗透率和综合渗流模型建立  

Establishment of apparent permeability model and seepage flow model for shale reservoir

作　　者：张烈辉[1] 单保超 赵玉龙[1] 郭晶晶[1] 唐洪明[1] 

机构地区：[1]油气藏地质及开发工程国家重点实验室.西南石油大学,成都610500

出　　处：《岩性油气藏》2017年第6期108-118,共11页Lithologic Reservoirs

基　　金：国家自然科学基金项目"致密气藏储层干化;提高气体渗流能力的基础研究"(编号:51534006);"多场多尺度耦合作用下页岩气藏体积压裂水平井非线性渗流理论研究"(编号:51404206);"页岩气储层纳米尺度非均质性研究"(编号:51674211);"基于边界元法的页岩气藏缝网多段压裂水平井不稳定渗流理论研究"(编号:5170427)联合资助

摘　　要：页岩储层结构复杂,多尺度效应明显,存在黏性流动、滑脱效应、Knudsen扩散以及表面扩散等多重运移机制。利用Knudsen数划分流态,绘制了考虑真实气体效应的流态图版。考虑多重运移机制,建立了页岩气藏表观渗透率模型;在此基础上综合考虑吸附解吸以及溶解气扩散影响,建立了页岩气藏多重介质不稳定渗流数学模型,明确了不同运移机制对页岩气藏非稳态产能的影响。结果表明:不同运移机制之间既相互联系又相互制约;Knudsen扩散和表面扩散均通过改变表观渗透率大小,对生产中期阶段的气体流动能力产生重要影响;溶解气和吸附气均是页岩气的重要赋存形式,是开发过程中自由气的补充,对气井生产中晚期非稳态产能具有显著影响;溶解气与吸附气能够增加气藏的累产气量,减缓气藏压力的下降速度。Multi-scaled effects of gas seepage behavior,such as slippage effect,Knudsen diffusion and surface diffusion,can lead to non-Darcy flow in shale formation. A flow chart considering real gas effects was plotted according the value of Knudsen number,and a comprehensive apparent permeability model was established considering different flow mechanisms. Flux contribution of slip viscous flow,Knudsen diffusion and surface diffusion were discussed under different pore radii and pressure conditions. Using the apparent permeability model,a comprehensive flow continual equation was built considering adsorption/desorption effect and dissolved gas diffusion in Kerogen. The results show that nonlinear flow effect is obvious in low pressure and small pore conditions. The main mass transfer mechanism is different under different conditions. Knudsen and surface diffusion mainly affect the middle flow period through changing the apparent permeablity. Dissolved gas in Kerogen and adsorbed gas are important occurrence of shale gas and supplement of free gas during reservoir development,and they have a significant influence on unstable productivity during middle-later flow period. Dissolved gas and adsorbed gas can increase the cumulative gas production,slow down gas reservoir pressure drop.

关 键 词：页岩气 表观渗透率 滑脱效应 Knudsen扩散 表面扩散 吸附解吸 溶解气 

分 类 号：TE312[石油与天然气工程—油气田开发工程]