鄂尔多斯盆地大牛地气田盒3段河道砂岩相控储层预测

Facies-constrained reservoir prediction of P_1h_3 channel sandstone in Daniudi gasfield,the Ordos Basin

鄂尔多斯盆地大牛地气田二叠系下石盒子组盒3段属于典型的河流相沉积,由于地震属性预测受地震分辨率限制,造成河道砂体储层预测的多解性。应用高分辨率层序地层学,对盒3段目的层进行了沉积相展布规律研究,认清了盒3段顶界面地震反射层Tf9是一个在全区有近似等时地质意义的反射界面,盒3段上砂组的厚度与Tf9平均振幅的统计关系符合调谐振幅原理,从而优选出盒3段砂岩的振幅敏感属性。通过地震相、测井相及沉积微相综合分析,认为盒3段振幅敏感属性平面图与其沉积相展布规律一致,通过相关分析能较好地预测出砂岩发育的有利区。在D66井附近目标区的实践表明,砂岩预测结果与实钻吻合率达90%。由此表明,以沉积相、沉积特征约束地震属性预测能实现对复杂地质体的准确预测和描述。

The reservoirs of the 3^rd member of the Permian Lower Shihezi Formation （P1h^3） in the Daniudi gas field in the Ordos Basin are typical fluvial deposits. As reservoir prediction with seismic attributes is constrained by seismic resolution ,uncertainty occurs in the prediction of channel sandstone reservoirs. High-resolution sequence stratigraphy is applied in this paper to figure out the distribution pattern of sedimentary facies of the targets in P1h^3. It has been made clear that the seismic reflector on the top of P1h^3 （T9^f） has the geologic significance of an approximate isochronous surface in the whole study area. The relationship between the thickness of the upper sandstone interval in P1h^3 and the average amplitude of T9^f conforms to the principle of tuning amplitude. Thus, the amplitude attributes that are sensitive to the sandstone in the P1h^3 are optimized. According to integrated analyses of seismic facies,logging facies and sedimentary mierofacies,it is thought that the plan view of sensitive amplitude attribute of P1h^3 is consistent with the distribution pattern of sedimentary facies. Favorable zones for sandstone development could be predicted through relevant analysis. Application in area near the D66 well shows that 90% of the prediction matches the real drilling results. Therefore, under the constraints of sedimentary microfacies and sedimentary characteristics, seismic attributions can be used to accurately predict and characterize complex reservoirs.