【作者】 孙英杰；

【导师】 宋维琪；

【作者基本信息】 中国石油大学 ， 地球探测与信息技术， 2008， 硕士

【摘要】 微地震技术是一种十分先进的裂缝监测技术,具有效率高、成本低等特点,目前已被广泛应用于监测油田生产动态。但在实际的油藏开发过程中,产生的微地震事件都很微弱,给准确反演微震源位置带来很大困难。针对这一情况,本文主要对微地震震源反演方法进行了研究。首先利用射线追踪方法实现复杂模型正演模拟,并建立复杂度不同的速度模型,分析不同速度模型下的波谱特征,以有效的指导实际资料处理和反演。论文采用了限定拾取范围、拾取初至的波谷(峰)等一系列措施,使得拾取结果更加可靠。采用极大值法、直方图法以及矢端曲线法对检波器的偏振角进行求取,较为准确的求得了偏振角,用于微地震事件的识别、检波器的一致性处理、以及最终的微震源定位。结合实际微地震三分量记录和数据采集方式的特点,论文设计了三分量独立调节的震源速度联合反演方法。通过模型和部分微震资料反演试算,揭示出双井观测下微地震资料垂向坐标易收敛、水平方向搜索源位置发散的特点。结合声波测井资料建模和射孔资料约束,设计了适合于井中观测微地震资料的联合反演方法。在正演基础上,研究设计了垂向位置变量和速度变量采用普通搜索、水平方向位置变量采用优选信赖域计算的方法。在可能的信赖域中,通过联合反演找出最优者,再在被找出的这个信赖域中,利用搜索法计算,直到解出最优解,同时在步长大小、精度控制、反演速度改进方面给出了适应微地震特色的说明。算法通过理论和实际资料计算,证明是可行的,多个微地震事件联合反演的结果表明,论文中基于正演模拟迭代的、不同寻优方法有机联合的反演方法,克服了单一反演方法的弊端,反映了裂缝的真实位置。更多还原

【Abstract】 Micro-seismic technique is an advanced technique for fracture monitoring, which has been used to monitor oil-field production performance because of its high efficiency and low cost. However, in the actual process of oil reservoir exploitation, the information of micro-seismic generated is relatively weak, which brings great difficulty for locating the source accurately by inversion. To resolve this problem, a source inversion method in view of micro-seismic is studied in this paper.First, forward modeling of complicated geologic condition is carried out by ray tracing procedure, and then velocity models in different media are built to analyze the characteristics of wave spectrums in them, in order to guide the inversion process using actual data effectively. A series of measures, such as limiting picking range and picking first arrival peak, are taken in the paper, which making the picking results more dependable. Polarizing angles of the geophones are discriminated correctly by the methods of maximum, histogram and vector curve, which are used to identify the true micro-seismic events, do geophone community process and source location.Combining with three-component record and field data acquisition means of the actual micro-seismic data, a cooperative inversion method with three components being separately regulated is designed. With the trial inversion of some models and partly micro-seismic data, the results show that, the inversion of the micro-seismic data, obtained through the double drillings observation system, can constringe the solution to the right place easily in vertical direction, but diverge in horizontal direction. Combined with the model based on acoustic logging information and the restriction of perforating data, a cooperative inversion method suit for micro-seismic data observed in log is gained. On the basis of the forward modeling, vertical position variable and velocity are calculated by normal search method, but horizontal variable is computed by searching trust region. The optimum trust region is found out by means of combined inversion, and then the solution is searched and found out in the region. The explanation of some parameters, such as step length, precision and inversion velocity are also given, based on the distinguishing feature of micro-seismic data. The combined inversion method is verified feasible by the theory models and practical data. The cooperative inversion results of multi micro-seismic events show that, the inversion method based on forward modeling iteration and organic combination of various optimization methods overcomes the faults of single inversion method, reflects the real fracture location effectively.更多还原