地面散点式微地震监测技术在昭通国家级页岩气示范区XX平台的应用

Application of the surface scattered-sites microseismic monitoring technology at XX platform of Zhaotong National Shale gas Demonstration Area

微地震监测是评估油气藏压裂效果的一种有效手段,主要包括井中微地震监测和地面散点式微地震监测两种方式。为了了解昭通国家级页岩气示范区XX平台页岩气储层水力压裂过程中的裂缝扩展情况并对压裂效果进行总体评价,指导后续浅层页岩气水力压裂项目的实施,采用了具有可灵活布设、可全平台覆盖、长期监测成本较低等优点的地面散点式微地震监测技术;通过在该示范区太阳构造XX平台的数据采集及处理试验,采用扫描叠加定位算法对微地震事件进行定位,并与该平台同时进行的井中微地震监测成果进行了对比;进而研究分析了散点式微地震监测不同观测孔径、不同检波器道距对定位结果的影响。研究结果表明:(1)较之于井中监测,地面散点式监测在监测时间和监测空间上更加具有优势;(2)观测孔径主要影响定位精度,而道距影响的则是弱信号的定位能力。结论认为,该研究成果验证了地面散点式微地震监测技术在昭通页岩气示范区浅层页岩气压裂效果评估的可行性,为今后微地震动态监测方法在该区的长期应用提供了技术支撑。

Microseismic monitoring is one effective means to evaluate the reservoir fracturing effects and it mainly includes two modes,i.e.,borehole microseismic monitoring and surface scattered-sites microseismic monitoring.In order to understand the fracture propagation situations during the hydraulic fracturing of shale gas reservoir at XX platform of Zhaotong National Shale gas Demonstration Area,evaluate the fracturing effect comprehensively and guide the implementation of the subsequent shallow shale gas hydraulic fracturing project,this paper adopted the surface scattered-sites microseismic monitoring technology which has the advantages of flexible layout,full platform coverage and low long-term monitoring cost.Then,based on the data acquisition and processing experiment at XX platform in Taiyang structure of Zhaotong National Shale Gas Demonstration Area,microseismic events were located by using the scanning superposition location algorithm.And the location results were compared with borehole microseismic monitoring results obtained simultaneously on the same platform.Finally,the influences of different observation apertures and geophone trace spacing in the scattered-sites microseismic monitoring on the results were studied and analyzed.And the following research results were obtained.First,compared with borehole monitoring,the surface scattered-sites monitoring is more advantageous in monitoring time and monitoring space.Second,the observation aperture mainly affects the location accuracy,while the trace spacing affects the location capacity of weak signals.In conclusion,the research results verify the feasibility of the surface scattered-sites microseismic monitoring technology to evaluate the fracturing effect of shallow shale gas in the Zhaotong National Shale Gas Demonstration Area and provide the technical support for the long-term application of microseismic dynamic monitoring method in this area in the future.