非常规油气开采过程中的可相变多孔介质物理模型研究及参数识别

Physical model study and parameter recognition of phase-change porous medium during the production of unconventional oil and gas

高彦芳 任战利 丁帅伟 陈勉 金衍

GAO Yanfang REN Zhanli DING Shuaiwei CHEN Mian JIN Yan

西北大学地质学系 大陆动力学国家重点实验室 中国石油大学(北京)石油工程学院

Department of Geology, Northwest University, Xi’an 710069, Shaanxi, China State Key Laboratory of Continental Dynamics, Xi’an 710069, Shaanxi, China College of Petroleum Engineering, China University of Petroleum (Beijing), Beijing 102249, China

对于某些非常规油气储层以及极地、冰川和冻土地层，油气钻采过程中发生伴随着相变现象的骨架组构演化。为研究油气相变-骨架演化过程中的储层孔隙度和含油饱和度动态变化规律，以油砂储层为例，通过沥青熔化系数、流体排出系数和水的可注性系数，分沥青相变-孔隙塌陷和沥青相变-孔隙扩容两种情况建立可相变多孔介质物理模型，给出了不同定量系数下沥青熔化-孔隙塌陷/扩容的8个应用图版，并根据实验和现场监测数据对物理模型参数进行了识别和分析。研究表明，在沥青相变-孔隙塌陷过程中，随着沥青熔化系数增加，孔隙度和含油饱和度降低，有效孔隙度和有效含油饱和度增加；随着流体排出系数增加，孔隙度和有效孔隙度降低，含油饱和度增加，有效含油饱和度不变。在沥青相变-孔隙扩容过程中，随着水的可注性系数增加，孔隙度和有效孔隙度增加，含油饱和度和有效含油饱和度降低。油砂储层微压裂过程中有效孔隙度及孔隙度最大增加幅度分别为6.18%和1.53%，仅为室内实验条件下的12%左右。

Skeleton fabric evolution associated with phase change phenomenon occurs in the process of oil and gas drilling and production in some unconventional reservoirs and the Arctic, glacial and permafrost formations. In order to study the dynamic change laws of reservoir porosity and oil saturation in the process of oil and gas phase change-skeleton evolution, this paper took an oil sand reservoir as the example to establish a physical model of phase-change porous medium for two scenarios, i.e., asphalt phase change-pore collapse and asphalt phase change-pore expansion, respectively, by means of asphalt melting coefficient, fluid drainage coefficient and water injectability coefficient. In addition, eight application charts of asphalt melting-pore collapse/expansion at different quantitative coefficients were prepared. Then, the parameters of the physical model were recognized and analyzed based on experimental and field measurement data. It is indicated that in the process of asphalt phase change-pore collapse, porosity and oil saturation decrease and effective porosity and effective oil saturation increase with the increase of asphalt melting coefficient; while porosity and effective porosity decrease, oil saturation increases and effective oil saturation is unchanged with the increase of fluid drainage coefficient. In the process of asphalt phase change-pore expansion, porosity and effective porosity increase and oil saturation and effective oil saturation decrease with the increase of water injectability coefficient. The maximum increase amplitude of effective porosity and porosity in the micro-fracturing process of oil sand reservoir are 6.18% and 1.53%, respectively, which are only about 12% of laboratory experimental results.

10.13639/j.odpt.2021.05.012