基于启动压力梯度与应力敏感的致密气藏多层多级渗流模型  

Multi-stage and multi-layer percolation model of tight gas reservoir based on pressure gradient and stress sensitivity

作　　者：田冷[1,2] 李鸿范 马继翔 谢全 顾岱鸿[1,2] 任效星 

机构地区：[1]中国石油大学(北京)石油工程教育部重点实验室,北京102249 [2]中国石油大学(北京)石油工程学院,北京102249 [3]中国石油长庆油田分公司,陕西西安751500 [4]华北油田勘探开发研究院,河北任丘062552 [5]Department of Petroleum Engineering,Curtin University

出　　处：《天然气地球科学》2017年第12期1898-1907,共10页Natural Gas Geoscience

基　　金：国家自然科学基金(编号:U1562102);国家科技重大专项(编号:2016ZX05047005-001)联合资助

摘　　要：致密砂岩气藏具有储层物性差、非均质性强、渗流规律复杂以及开发难度大的特征,因此基于非均质层多级渗流实验,建立多层多级渗流模型,弄清各层渗流规律对该类气藏气井合理压裂设计与压力保持至关重要。首先,进行了滑脱效应、启动压力梯度以及应力敏感3类实验,实验结果表明:储层有效渗透率介于(0.01~1.0)×10-3μm2之间,当气藏压力高于10MPa时,滑脱效应对生产影响程度在3%以内,可忽略;致密气藏单相气体渗流不存在启动压力梯度现象,而两相渗流则存在;对于高含水饱和度储层,为气水两相渗流,由于毛管力作用,宏观表现为启动压力现象;与基质岩心相比,微裂缝岩心的渗透率应力敏感性更强,应力敏感滞后程度也更强。然后,考虑启动压力梯度与应力敏感效应,建立了多层多级渗流模型。最后,利用无因次拟压力和无因次时间的关系曲线进行了模型参数敏感性分析。研究认为,层间参数主要影响晚期阶段,裂缝地层系数之比k越大,晚期压力降越大;另外层内参数中变形介质拟渗透率模数、介质弹性储容比和启动拟压力梯度均影响过渡与晚期阶段,因此合理保持压力对致密气藏开发后期尤为重要。Tight reservoir with poor phy neity result in the difficulty in the deve neity and the establishment of a multi- sical property, complex seepage characteristics and strong heteroge- lopment,so the study of reservoir horizontal and vertical heteroge- layered and multi-stage （different scales） seepage model based on multi-stage seepage experiments in heterogeneous layers is essential for improving oil recovery. Firstly, three kinds of experiments are carried out：Slippage effect, starting pressure gradient and stress sensitivity. Experimental results show：when the reservoir effective permeability is between 0.01 × 10.3μm2 and 1.0 × 10 3μm2 and the gas reservoir pressure is higher than 10MPa,the effect of slippage effect on the production is less than 3 % which can be ignored;there is no starting pressure gradient in single gas flow in tight gas reservoir;for the gas-water two-phase seepage in high water saturation reservoirs,due to the role of capil- lary force,the macro performance of the reservoir is the starting pressure phenomenon;compared with the matrix core, the stress sensitivity of the micro-crack core permeability is stronger and stress-sensitive lag is also stronger.Then,considering the starting pressure gradient and the stress sensitivity, the Multi-Layered and Multi-Stage seepage model of tight sandstone gas reservoir is established.Finally, the sensitivity analy- sis of model parameters was carried out by using the relationship between dimensionless quasi-pressure and dimensionless time.Research shows：the interlayer parameters mainly affect the later stage,the larger the ratio of the formation coefficient of the fracture, the greater the later pressure drop, so the fracturing scale is uniform when the production is in several layers, otherwise the pressure between the layers differentiates significantly,likely to cause a single layer of gas overriding and gas flow;in addition,the permeability mod- ulus of the deformed medium, the elasticity ratio of the medium and the starting pressure gr

关 键 词：致密气藏 启动压力梯度 应力敏感 多层多级渗流模型 

分 类 号：TE312[石油与天然气工程—油气田开发工程]