基于压缩感知谱反演算法及其在随钻过程中的应用

Spectral inversion algorithm based on compressive sensing and its applications while drilling

在超高温高压环境下的深海钻井过程中,受关键层位、尤其是薄弱层(弱抗张力地层)影响,加上缺乏海上超高温高压薄弱层精准快速识别及关键层位精准卡层技术方法,以致钻井事故频发,是海上超高温高压油气勘探开发亟待解决的重要问题.随钻过程中高精度地震数据的应用,作为钻井过程实时监测的手段,能够有效提供钻头前方精细地质构造信息.本文在谱反演提高分辨率技术基础上,提出了基于压缩感知L0范数算法的谱反演算法,并形成完整的提高分辨率技术流程.该方法能够相对保幅保真地实现地震数据的有效拓频,识别薄弱层及实现随钻地震高精度关键层位综合预测.方法在南海西部油田深层的随钻实际数据分析中,有效识别了钻头前方薄弱层、关键地层、储层深度等关键信息,结果与钻后测井资料吻合,验证了方法有效性,为南海西部油田超高温高压钻井的风险评估提供依据.

In the process of deep water drilling,the key strata,especially weak layers(formation with low tensile strength)under ultra-high temperature and pressure environment are big problems.What′s more,the lack of accurate and rapid identified technology against offshore ultra-high temperature and pressure weak layers has led to frequent drilling accidents,which is an important problem to be solved in offshore ultra-high temperature and pressure oil and gas exploration and development.The application of high-precision seismic data,as a real-time monitoring basic data while drilling,can effectively provide detailed geological structure information ahead of the bit.Based on the spectral inversion technology to enhance resolution,this paper proposes a spectral inversion algorithm via compressive sensing L0 norm algorithm,and form a complete technical process workflow to enhance resolution.This method can realize effective extension frequency of seismic data with relative amplitude preservation and fidelity,in order to identify weak layers and realize comprehensive prediction of high precision key layers by seismic data processing and analysis while drilling.Application of actual data in the deep layer of the West South China Sea oilfield,this method effectively identifies key information such as weak layers,key formations,and reservoir depth ahead of the bit.The results were consistent with the logging data after drilling,which verified the effectiveness of the method and provided a basis for the risk assessment of ultra-high temperature and pressure drilling in the western South China Sea oilfield.