页岩气开发中地面微地震监测系统的优化设计研究

发布时间：2018-05-30 02:07

本文选题：微地震定位 + 震源扫描算法　；参考：《成都理工大学》2015年硕士论文

【摘要】：在页岩气开发中,一般通过水力压裂产生人工裂缝,以提高这些低渗透、致密储层中的油气的开采效率。对水压裂效果的评估一般是通过监测所产生的微地震来实现的。微地震监测是目前储层压裂中最精确、最及时、信息最丰富的监测手段之一。在水力压裂微地震定位中,监测系统的选取直接决定了定位的精度和可定位事件的数量,并最终影响对压裂效果的评估。本文主要针对地面监测系统进行研究。基于地面监测系统采集的数据具有信噪比低、识别难度大、数据量大等特点,一般采用震源扫描算法进行微地震事件的定位。探讨微地震定位过程中震源扫描算法的基本原理,定位的流程及关键技术参数的选取。采用R=3.0作为识别微地震事件的门槛值。建立均匀各向同性的三维速度模型,设计一系列理论监测系统和实际监测系统,模拟微地震事件,合成具有不同信噪比水平的微地震信号。通过对合成数据进行定位,分析定位结果,总结归纳地面监测系统的优化设计原则。通过对理论监测系统的检波器的布设方式、布设范围以及布设间距等因素展开讨论,得到了部分地面监测系统的优化设计原则,并结合实际的监测系统的综合分析进行验证。发现微地震定位的效果与监测系统的覆盖范围,分支数目,检波器间距,以及震源位置等因素有直接关系。初步总结出以下几点地面监测系统的优化设计原则:检波器数目基本相同时,应采用星状布设方式;在一定范围内,适当增大检波器布设的范围,增加分支数目,适当增大检波器间距,可以在节约成本的基础上得到较好的定位效果;监测系统布设范围的半径,应该与震源深度的大小相当,或略大于震源深度;若已知震源分布的大致区域,监测系统的检波器应该侧重于该区域布设等。最后,本研究对理论监测系统和实际监测系统的定位结果,结合几何误差和走时误差的角度进行了分析总结。
[Abstract]:In shale gas development, artificial fractures are generally produced by hydraulic fracturing to improve the oil and gas recovery efficiency in these low permeability and tight reservoirs. The evaluation of water fracturing effect is usually achieved by monitoring microearthquakes. Microseismic monitoring is one of the most accurate, timely and informative monitoring methods in reservoir fracturing. In hydraulic fracturing micro-seismic location, the selection of monitoring system directly determines the positioning accuracy and the number of locatable events, and ultimately affects the evaluation of fracturing effect. This paper mainly studies the ground monitoring system. Based on the features of low signal-to-noise ratio (SNR), high difficulty in recognition and large amount of data collected by the ground monitoring system, the focal scanning algorithm is generally used to locate micro-seismic events. This paper discusses the basic principle of focal scanning algorithm, the flow of location and the selection of key technical parameters in the process of micro-seismic location. RG3. 0 is used as the threshold to identify microseismic events. A homogeneous isotropic 3D velocity model is established and a series of theoretical and practical monitoring systems are designed to simulate microseismic events and synthesize microseismic signals with different signal-to-noise ratio (SNR) levels. By locating the synthetic data and analyzing the positioning results, the optimal design principles of the ground monitoring system are summarized. Based on the discussion of the layout mode, range and spacing of the geophone in the theoretical monitoring system, the optimum design principles of some ground monitoring systems are obtained and verified by the comprehensive analysis of the actual monitoring system. It is found that the effect of microseismic location is directly related to the coverage of the monitoring system, the number of branches, the spacing of geophone, and the location of the source. The optimization design principles of the ground monitoring system are summarized as follows: when the number of geophone is basically the same, the stellate arrangement should be adopted; within a certain range, the range of geophone layout should be enlarged and the number of branches should be increased. If the distance between geophone is increased properly, better positioning effect can be obtained on the basis of saving cost, the radius of the monitoring system should be equal to the depth of the source, or a little larger than the depth of the source. If the area of source distribution is known, the geophone of the monitoring system should focus on the location of the region. Finally, the positioning results of the theoretical monitoring system and the practical monitoring system are analyzed and summarized, combining the geometric error and the travel time error.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE37

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