石油与天然气地质 ›› 2019, Vol. 40 ›› Issue (3): 661-668.doi: 10.11743/ogg20190321

• 开发工程 • 上一篇    下一篇

准噶尔盆地吉木萨尔凹陷芦草沟组含油页岩岩石力学特性及可压裂性评价

王小军1, 梁利喜2, 赵龙1, 刘向君2, 秦志军1, 李玮2   

  1. 1. 中国石油 新疆油田分公司 勘探开发研究院, 新疆 克拉玛依 834000;
    2. 西南石油大学 油气藏地质及 开发工程国家重点实验室, 四川 成都 610500
  • 收稿日期:2019-02-12 修回日期:2019-03-16 出版日期:2019-06-28 发布日期:2019-04-26
  • 通讯作者: 梁利喜(1976—),男,博士后、副教授,石油工程岩石力学。E-mail:liangzby@163.com。 E-mail:liangzby@163.com
  • 作者简介:王小军(1973-),男,高级工程师,石油地质。E-mail:wxiaojun@petrochina.com.cn。
  • 基金资助:
    国家基础研究发展计划(973计划)项目(2015CB250906);国家油气重大专项(2016ZX05046-006);中国石油重大科技专项(2017E-0402)。

Rock mechanics and fracability evaluation of the Lucaogou Formation oil shales in Jimusaer sag, Junggar Basin

Wang Xiaojun1, Liang Lixi2, Zhao Long1, Liu Xiangjun2, Qin Zhijun1, Li Wei2   

  1. 1. Exploration and Development Research Institute of Xinjiang Oilfield Company, PetroChina, Karamay, Xinjiang 834000, China;
    2. State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Chengdu, Sichuan 610500, China
  • Received:2019-02-12 Revised:2019-03-16 Online:2019-06-28 Published:2019-04-26

摘要: 页岩油储层具有油气丰度低、渗透能力差、单井无自然产能或自然产能低于工业油流下限、能量衰减快等特点,在水平井或多分支井的基础上实施高效的压裂改造是实现页岩油效益开采的关键。围绕吉木萨尔凹陷芦草沟组含油页岩储层的可压裂性评价,实验测试与理论分析相结合,研究认识了岩石的变形破坏特征、力学强度特性及其纵向分布特征;在芦草沟组页岩储层可压裂性影响因素分析的基础上,建立了可压裂性指数评价方法。结果表明:芦草沟组含油页岩的变形破坏呈现显著的脆性特征,且层理、微裂缝等结构面发育,具备压裂改造形成复杂缝网的内在地质力学条件;芦草沟组页岩储层间存在岩石力学强度、地应力相对较高的隔层,对该类型储集体的压裂过程中在兼顾裂缝网络复杂化的同时还应强化压裂缝对上下储层的沟通能力,实现压裂改造有效体积的最大化;综合脆性指数、水平应力差、层间应力差以及断裂韧性等指标,建立了可同时表征水平井体积压裂缝网形成难易与压裂缝穿越隔层沟通纵向储层能力的可压裂性评价方法;基于微地震压裂监测结果的验证分析表明所建立的可压裂性指数评价方法在以吉木萨尔凹陷油页岩为代表的薄互层状页岩地层中具有较好适用性。

关键词: 脆性, 可压裂性指数, 体积压裂, 岩石力学, 页岩油, 芦草沟组, 吉木萨尔凹陷, 准噶尔盆地

Abstract: The shale oil reservoirs are characterized by low oil and gas abundance,poor permeability,no natural productivity or lower natural production capacity in single wells compared with the lower limit of commercial oil flow,and fast energy decay,etc.The application of efficient volumetric fracturing technique to horizontal or multi-lateral wells is the key to achieving efficient development of shale oils.In order to evaluate the fracability of the shale oil reservoir in the Lucaogou Formation in Jimusaer sag,sufficient experimental and theoretical studies were carried out.The characteristics of deformation and failure,mechanical strength and their lateral variations in the Lucaogou oil-bearing reservoir in Jimusaer sag were recognized.And a new method for evaluating the fracability indexes was established based on the analysis of the factors influencing the shale reservoir fracability in the Lucaogou Formation.The results show that due to the significant brittleness of shale under deformation and the well development of fabric planes such as bedding and micro-fractures,the intrinsic geological and mechanical conditions of the Lucaogou Formation are favorable for the formation of complex fracture networks under fracturing.There are interlayers characterized by high rock mechanical strength and in-situ stress in the Lucaogou shale reservoir.Therefore,to maximize the effective volume of fracturing in such reservoir,the artificial fractures should be designed to increase the connectivity between upper and lower reservoirs,while the fracture networks should be as complicated as possible.Besides,a new fracability evaluation method was established using brittleness index,horizontal stress difference,interlayer stress difference and fracture ductility,which can simultaneously characterize the ability of volumetric fracturing network in horizontal wells and the vertical connectivity of artificial fractures.The analysis based on microseismic fracturing monitoring shows that the fracability index evaluation method is very suitable to evaluate thin alternating shale formations typically shown in the oil shales in Jimusaer sag.

Key words: brittleness, fracability index, volumetric fracturing, rock mechanics, shale oil, Lucaogou Formation, Jimusaer sag, Junggar Basin

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