深煤层水力波及压裂技术及其在沁南地区的应用

发布时间：2018-04-22 11:17

本文选题：沁水盆地 + 深煤层　；参考：《天然气工业》2017年10期

【摘要】：为提高深部煤层的煤层气产能,针对其地质特征提出了在深煤层实施多口直井同步水力波及压裂的技术思路。首先基于边界元位移不连续法建立了多裂缝诱导应力数学模型,模拟深煤层诱导应力场分布,分析水力波及压裂复杂缝网形成的可能性,然后采用离散元方法研究应力干扰的裂缝网络延伸情况及其影响因素,最后通过三轴压裂实验和现场应用效果验证了其可行性。结果表明:(1)水力波及压裂技术能增大应力干扰面积和应力干扰强度,促使水平主应力差的减小甚至诱导局部区域的地应力方向发生改变,有利于沟通煤岩中发育的面、端割理,从而形成大规模高效复杂的裂缝网络;(2)水力波及压裂有利于复杂缝网形成的条件包括较小的初始水平主应力差、低泊松比、较小井距、低压裂液黏度、高缝内净压力等;(3)真三轴物理模拟实验结果显示,水力波及压裂技术能够充分沟通煤岩天然裂隙,形成由人工裂缝、面割理和端割理组成的复杂裂缝网络。进而提出了一套深煤层多井同步水力波及压裂工艺优化设计方法,在沁水盆地南部柿庄北地区深煤层选取了5口直井进行先导性试验,裂缝监测及排采数据表明,水力波及压裂井产生的波及体积较大,裂缝网络复杂;较之于常规压裂井,水力波及压裂井不仅见气更早,产量、套压较高且稳定,而且所形成的区域压力降波及邻井,可大幅增加实施井及邻井产量。
[Abstract]:In order to improve the productivity of coal bed methane in deep coal seam, the technical thinking of synchronous hydraulic wave fracturing in multiple straight wells in deep coal seam is put forward according to its geological characteristics. Firstly, based on the boundary element discontinuity method, a mathematical model of induced stress of multiple fractures is established, and the distribution of induced stress field in deep coal seam is simulated, and the possibility of formation of complex fracture network by hydraulic and fracturing is analyzed. Then discrete element method is used to study the fracture network extension of stress interference and its influencing factors. Finally, the feasibility of the method is verified by triaxial fracturing experiment and field application. The results show that hydraulic wave fracturing technology can increase the area of stress interference and the intensity of stress interference, promote the decrease of horizontal principal stress difference and even induce the change of the direction of in-situ stress in local area, which is helpful to communicate the developed surface and end cleavage in coal and rock. Therefore, the conditions conducive to the formation of complex fracture network by hydraulic sweep fracturing include small initial horizontal principal stress difference, low Poisson ratio, small well spacing and low pressure fracturing viscosity. The results of physical simulation experiments show that hydraulic and fracturing techniques can fully communicate the natural fractures of coal and rock and form a complex fracture network composed of artificial fracture, surface cleat and end cleat. Furthermore, a set of optimization design method of synchronous hydraulic wave fracturing technology for deep coal seam is put forward. Five vertical wells are selected in the deep coal seam in the south of Qinshui Basin to carry out pilot tests. The data of fracture monitoring and drainage show that: 1. Compared with the conventional fracturing wells, the hydraulic and fracturing wells not only see gas earlier, produce higher and stable casing pressure, but also form regional pressure drop and spread to adjacent wells, while hydraulic and fracturing wells have larger sweep volume and complex fracture network, which are not only earlier in gas production, but also more stable than those in conventional fracturing wells. Can greatly increase the production of implementation wells and adjacent wells.
【作者单位】：中联煤层气有限责任公司;中国海洋石油有限公司;"油气藏地质及开发工程"国家重点实验室·西南石油大学;
【基金】：国家科技重大专项“增产改造材料研制及完井工艺研究”(编号:2011ZX05042-002-001)
【分类号】：TE37

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