石油学报 ›› 2020, Vol. 41 ›› Issue (9): 1117-1126.DOI: 10.7623/syxb202009008

• 油田开发 • 上一篇    下一篇

页岩储层人工裂缝岩样制备方法及应力敏感性

陈浩1,2, 周涛2, 樊怀才3, 张鉴3, 杨胜来1,4   

  1. 1. 油气资源与探测国家重点实验室 北京 102249;
    2. 中国石油大学(北京)安全与海洋工程学院 北京 102249;
    3. 中国石油西南油气田公司页岩气研究院 四川成都 610021;
    4. 中国石油大学(北京)石油工程学院 北京 102249
  • 收稿日期:2019-09-12 修回日期:2020-05-22 出版日期:2020-09-25 发布日期:2020-09-29
  • 通讯作者: 陈浩,男,1985年10月生,2009年获中国石油大学(北京)石油工程专业学士学位,2015年获得中国石油大学(北京)油气田开发工程专业博士学位,现为中国石油大学(北京)安全与海洋工程学院海洋油气工程系副教授,主要从事油层物理和注气提高采收率的教学和科研工作。
  • 作者简介:陈浩,男,1985年10月生,2009年获中国石油大学(北京)石油工程专业学士学位,2015年获得中国石油大学(北京)油气田开发工程专业博士学位,现为中国石油大学(北京)安全与海洋工程学院海洋油气工程系副教授,主要从事油层物理和注气提高采收率的教学和科研工作。Email:chenhaomailbox@163.com
  • 基金资助:

    国家科技重大专项(2017ZX05037-001、2016ZX05062-002)、中国石油天然气股份有限公司科技重大专项(2016E-0611)和北京市自然科学基金项目(3173044)资助。

Preparation method and stress sensitivity of core samples with hydraulic fractures in shale reservoirs

Chen Hao1,2, Zhou Tao2, Fan Huaicai3, Zhang Jian3, Yang Shenglai1,4   

  1. 1. State Key Laboratory of Petroleum Resource and Prospecting, Beijing 102249, China;
    2. College of Safety and Ocean Engineering, China University of Petroleum, Beijing 102249, China;
    3. Shale Gas Research Institute, PetroChina Southwest Oil&Gas Field Company, Sichuan Chengdu 610021, China;
    4. College of Petroleum Engineering, China University of Petroleum, Beijing 102249, China
  • Received:2019-09-12 Revised:2020-05-22 Online:2020-09-25 Published:2020-09-29

摘要:

应力敏感性是页岩储层的一个重要特性。由于大量天然裂缝和人工裂缝的存在,其渗透率应力敏感性与铺砂浓度密切相关,准确评价页岩人工裂缝的应力敏感性是一个难题。传统应力敏感性的研究多集中在测试和比较基质岩心、天然裂缝岩心及人工裂缝岩心等方面,对于不同铺砂浓度下人工裂缝的应力敏感性研究较少。因此,提出了一种模拟不同铺砂浓度的页岩岩样制备方法,并以四川盆地龙马溪组典型页岩为例,分别进行了变围压和变流压条件下页岩人工裂缝应力敏感性测试。研究结果表明,支撑剂的加入在大幅度提高裂缝导流能力的同时,有效降低了页岩人工裂缝的应力敏感性。且随着铺砂浓度增加,敏感性逐渐减弱,最终趋于不变;低铺砂浓度下(≤1 kg/m2),两种测试方法所得结果基本一致;但高铺砂浓度下(>1 kg/m2),由于存在明显的支撑剂运移现象,变流压测试结果明显高于变围压测试,且随铺砂浓度增加,差异逐渐加大至20%以上。因此,对于高铺砂浓度(>1 kg/m2)页岩人工裂缝应力敏感性的室内评价,为更好地模拟现场实际,应该采用变流压测试方法。

关键词: 页岩气, 人工裂缝, 岩样制备, 应力敏感, 铺砂浓度

Abstract:

Stress sensitivity is an important characteristic of shale reservoirs. Due to the existence of a large number of natural fractures and hydraulic fractures, the stress sensitivity of shale reservoir permeability is closely related to the proppant concentration, and it is a problem to accurately evaluate the stress sensitivity of hydraulic fractures in shales. Traditional studies of stress sensitivity mostly focus on the testing and comparison of matrix cores, natural fracture cores, and hydraulic fracture cores. There are few studies on the stress sensitivity of hydraulic fractures under different proppant concentrations. This paper proposes a method for preparing shale core samples under the simulated proppant concentrations. Taking the typical shale of Longmaxi Formation in Sichuan as an example, the stress sensitivity tests of hydraulic fractures in shales were conducted under variable confining pressure and variable flowing pressure, respectively. The results show that the addition of proppant can greatly improve the fracture conductivity and effectively reduce the stress sensitivity of hydraulic fractures in shales. With the increase of proppant concentration, the sensitivity gradually weakens, and eventually tends to be constant. At low proppant concentrations (≤1 kg/m2), the results of the two test methods are basically consistent. However, at high proppant concentration (>1 kg/m2), due to the obvious migration of proppant, the test results under the variable flowing pressure test are significantly higher than those under the variable confining pressure test; with the increase of proppant concentration, the difference gradually increases to more than 20 % . Therefore, for the laboratory evaluation of the stress sensitivity of hydraulic fractures in shales under high proppant concentrations (>1 kg/m2), the test under variable flowing pressure should be applied to better simulate the actual site.

Key words: shale gas, hydraulic fracture, core sample preparation, stress sensitivity, proppant concentration

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