微破裂向量扫描在丰探15井压裂微震实时监测中的应用

浙江油田苏北采油厂于2017-07-28~29对丰探15井近4 km深的泰二段第三段进行了水力压裂,分成试压和主压.我们同时应用微破裂向量扫描(Vector Scanning,VS)实施了地面微震实时监测,目的是评估监测质量、实时监测的可行性、与压裂效果.我们严格执行了安静处布台和有效去噪等应用VS的必要条件,最大限度地提高了信噪比,平均的最小信噪比为2.35%;输出结果可靠.为今后更有效地设计和控制压裂,通过电信网和互联网,我们实施了野外采集数据的实时传输和遥控数据处理解释,观察了每分钟裂缝带的发展;实时监测系统可行.主压的最终X型破裂明显是在试压裂缝的基础上,由试压的300 m长,扩展到400~500 m,并加密了缝网;井域最大主压应力方位被限制在NE(50~80)±5°.本次压裂微震活动有明显的间歇性,较大微震群发生前积累能量所需时间,由初期的10 min内,逐渐延长到最后的百分钟.微震活动由压裂点扩展到远处的顺序清晰,这可能同此井附近的介质较为完整有关.每分钟的压裂微震活动状态一般在5~15 min内可报告给压裂施工团队.通过这次典型的水力压裂微震实时监测,我们验证了:VS的原理可行,且满足其应用的必要条件极为重要.微震实时监测有效地指导了压裂泵注程序的优化,针对监测到的缝网形态及时采取了液性变化、停泵转向等手段,实现了更大的改造体积.

Application to the hydraulic fracture of well FT15 by real-time monitoring using vector processing for microseismic

Subei factory of Zhejiang oil field,China,implemented hydraulic-fracture for the layer T2~3 at a depth close to 4 km,of well FT15 on 07/28~29/2017,for a test and a main stimulation,separately.The Vector Scanning(VS)was used to real-time monitoring the process by distributing the microseismic network on surface,for checking up the monitoring quality,feasibility of real-time monitoring,and fractured effect.We followed strictly the necessary conditions required by VS application,such that the signal-to-noise was satisfied with quality and 2.35%averagely.For better stimulation and its design in future,we transmitted field records automatically to the processing and interpretation center through internet and telecommunication net,minute by minute,and observed the fractures’development.The final fracture net shows an X shape with 400~500 m long and has denser sub-fractures,which is developed based on the test(300 m)the day before;the direction range of in situ maximum principal stress should then be between NE(50~80)±5°.The microseismic activity is apparently intermittent:the earliest activity needs 10 minutes before to accumulate injected energy;and later it becomes,gradually,up to a hundred of minutes.The greater activity each time happens,randomly,in the different one or two orientations at a part of the final net;and in order from stimulation point to far places,maybe due to the relatively homogeneous surrounding rock.The seismicity in each minute can be reported to the hydro-fracturing team in 5~15 minutes.This typical fracturing and its detection show that The VS principle is feasible,and it is very important to satisfy the necessary conditions required by VS.The real-time monitoring helps us to optimize effectively the injection process,such as the adjusting liquidity,stopping pump and changing orientation,etc.,and achieve the greater volume of reservoir stimulation.