DAS井地联合勘探实例分析——以长庆油田环县三维井地联采为例

DAS joint VSP and 3D surface seismic:A case study on HX3D in the Changqing oilfield

光纤分布式声波传感(DAS)技术因其耐高温高压和高密度全井段采集等技术优势使得井地联合勘探技术更加高效,在井驱参数提取及井旁成像等方面具有广泛的应用前景,但目前该技术面临记录数据的信噪比偏低、单分量数据波场分离困难、地面激发点稀疏造成照明不均匀和成像质量欠佳等技术难题。为此,系统分析了长庆油田珠60井的套管外DAS-VSP井地联采数据的采集质量及对处理结果的影响、DAS单分量波场特征及反射波分离、井驱参数提取、井地联合多次波分析、3D-VSP成像的技术优势和不足等,形成了高效初至拾取及井驱参数提取、单分量保真波场分离、扩展面元VSP CDP成像等一系列技术成果,提出了下一步的研究重点是将高密度优势转化为高信噪比,进一步提高波场分离保真度,并在处理中尽可能克服激发点稀疏的影响,以实现3D-VSP的精确成像,最终实现井地联合成像,这些结果对于今后的DAS井地联合勘探具有非常积极的指导意义。

Optical fiber distributed acoustic sensing(DAS)technology makes downhole-surface joint exploration more efficient because of its high temperature,high pressure resistance,and high-density whole-wellbore acquisition.It has been widely used in well-driven parameter estimation and near-well imaging,but it currently faces technical problems such as low signal-to-noise ratio,difficult wavefield separation due to one-component(1C)data,inhomogeneous illumination,and unsatisfactory imaging caused by sparse shot points.In this study,many issues were investigated,such as the acquisition quality and its influence on the processing of DAS VSP data with cemented fiber,separation of DAS 1C wavefield,well-driven parameter extraction,multiple reflection analysis,and technical advantages and weakness of 3D-VSP imaging.A series of technical achievements were presented,such as efficient first break picking,refined well-driven parameter extraction,high-fidelity 1C wavefield separation,and extended bin VSPCDP imaging.It has been pointed out that the emphases would achieve high S/N data from high-density raw data,further improving the wavefield separation fidelity,and overcoming the effect of shot point sparsity as much as possible in the processing,realizing 3D-VSP precision imaging,and finally achieving joint borehole and surface imaging.This understanding has very positive guidance for DAS joint VSP and surface seismic exploration in the future.