论文部分内容阅读
GS凹陷深层上古生界煤系地层具有生烃能力,圈定出该套地层分布对凹陷油气评价意义重大。在缺少地震资料的情况下,依靠少量的钻井、地质资料,尝试利用电磁-重力联合建模约束反演圈定深层目标。首先根据三维大地电磁反演结果和已知钻井地质资料建立初始地质模型;再结合地层密度和重力异常特征,利用重力交互反演修正优化初始地质模型;然后对该模型进行大地电磁资料的电性约束反演,并进行拟合差评估,获得最优地质模型;最后将该地质解释方案与位于凹陷中部的一条地震剖面进行综合分析,确定地震剖面深层反射就是上古生界。该套烃源层主要分布于凹陷深部位,最大厚度达800m。实测资料处理结果表明,电磁-重力联合建模约束反演可以逐步降低单一地球物理方法的多解性,提高对深部地层的识别能力。非地震与地震结果相互印证,展示了电磁-重力联合建模约束反演技术在研究类似盆地深层目标中具有较好的应用潜力。
The deep Paleozoic coal measures strata in the GS depression have hydrocarbon generation ability, and it is of great significance to evaluate the distribution of this set of strata for the evaluation of oil and gas in the depression. In the absence of seismic data, relying on a small amount of drilling and geological data, attempt to use the electromagnetic-gravity modeling constrained inversion to delineate deep targets. Firstly, the initial geologic model was established based on the results of 3D magnetotelluric inversion and known drilling geological data. Combined with the characteristics of formation density and gravity anomalies, the initial geologic model was modified and optimized by gravity inversion. Then, Constraint inversion is performed and the fitting difference is evaluated to obtain the optimal geological model. Finally, a comprehensive analysis of the geological interpretation scheme and a seismic section located in the middle of the depression shows that the deep reflection of the seismic section is the Upper Paleozoic. The set of hydrocarbon source layer is mainly distributed in the deep depression, the maximum thickness of 800m. The measured data processing results show that the electromagnetic-gravity combined modeling constrained inversion can gradually reduce the multi-solution of the single geophysical method and improve the recognition ability of the deep strata. The mutual proof of non-seismic and seismic results shows that the EMG-GRT inversion technique has good potential in the study of deep targets in similar basins.