力学与实践 ›› 2019, Vol. 41 ›› Issue (4): 398-404.DOI: 10.6052/1000-0879-18-449

• 应用研究 • 上一篇    下一篇

致密油储层毛细管力自发渗吸模型分析 1)

杨柳*, †,2), 赵逸清**, 蒋荣敏††, 张旭辉, 鲁晓兵   

  1. *中国矿业大学(北京)深部岩土力学与地下工程国家重点实验室,北京 100083;
    中国科学院力学研究所流固耦合系统力学重点实验室,北京 100190;
    **新疆油田公司勘探开发研究院开发所,新疆克拉玛依 834000;
    ††塔里木油田公司油气工程研究院,新疆库尔勒 841000
  • 发布日期:2019-08-26
  • 作者简介:2) 杨柳,讲师,主要从事岩石与流体相互作用方面的研究工作。E-mail:shidayangliu@cumtb.edu.cn
  • 基金资助:
    1) 国家自然科学青年基金资助项目(11702296)。

SPONTANEOUS CAPILLARY IMBIBITION MODEL IN TIGHT OIL RESERVOIRS 1)

YANG Liu*,†,2), ZHAO Yiqing**, JIANG Rongmin††, ZHANG Xuhui, LU Xiaobing   

  1. *State Key Laboratory for Geomechanics and Deep Underground Engineering, China University of Mining and Technology (Beijing), Beijing 100083, China;
    Key Laboratory for Mechanics in Fluid Solid Coupling Systems, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China;
    **Exploration and Development Research Institute of Xinjiang Oilfield Company, Karamay 834000, Xinjiang, China;
    ††Oil and Gas Engineering Research Institute of Tarim Oilfield Company, Korla 841000, Xinjiang, China
  • Published:2019-08-26

摘要: 部分致密油井压后关井一段时间,压裂液返排率普遍低于30%,但是致密油气井产量反而越高,这与压裂液毛细管力渗吸排驱原油有关。然而,致密油储层致密,物性差,渗流机理复杂,尚没有形成统一的自发渗吸模型。本文基于油水两相非活塞式渗流理论,建立了压后闷井期间压裂液在毛细管力作用下自发渗吸进入致密油储层的数学模型,采用数值差分方法进行求解,并分析了相关影响因素。结果显示渗吸体积、渗吸前缘移动距离与渗吸时间的平方根呈线性正相关关系,与经典Handy渗吸理论模型预测结果一致,说明毛细管力自发渗吸模型可靠性较高。数值计算结果表明毛细管水相扩散系数是致密储层自发渗吸速率的主控参数,毛细管水相扩散系数越高,自发渗吸速率越大。毛细管水相扩散系数随着含水饱和度先增加后减小;随着束缚水饱和度、油相和水相端点相对渗透率增加而增加;随着相渗特征指数、油水黏度比和残余油饱和度增加而减小。该研究有助于深入认识致密油储层压裂液渗吸机理,对优化返排制度、提高致密油井产量具有重要意义。

关键词: 致密油, 毛细管力, 自发渗吸, 水相扩散系数

Abstract: The fracturing construction shows that the lower flowback efficiency is often accompanied with a high production in tight oil reservoirs, which may be due to the spontaneous imbibition of the fracturing fluid. However, the tight oil reservoir has poor physical properties with a complex permeable mechanism. A spontaneous imbibition model for tight oil reservoirs is desirable. Based on the oil-water flow theory, a mathematical model of the spontaneous imbibition is established. The numerical difference method is used to solve the equations and analyze the influencing factors. The results show that the imbibition volume and the imbibition front position of the tight oil reservoir are linear functions of the square root of time, as is consistent with the prediction of the classical Handy imbibition model. It indicates that the imbibition model is reliable. The numerical results show that the phase diffusion coefficient is the main control parameter of the imbibition rate and has a positive correlation with the imbibition rate. The phase diffusion coefficient increases first and then decreases with the water saturation; it increases with the increase of the irreducible water saturation, and the relative endpoint permeability of the oil and the water; it decreases with the increase of the permeability characteristic index, the oil-water viscosity ratio and the residual oil saturation. The results of this paper can help to understand the fracturing fluid imbibition mechanism in the tight oil reservoirs, and can be used for optimizing the flowback regime and improving the production of the tight oil.

Key words: tight oil, capillary pressure, spontaneous imbibition, phase diffusion coefficient

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