碳酸盐岩地层的岩性比率预测方法

THE PREDICTING METHOD OF THE LITHOLOGICAL RATIO IN CARBONATE STRATA

实际工作中 ,井间或无井区目的层岩性比率的预测需借助于地震速度资料来实现 ,这对碳酸盐岩地层来讲更是如此。通过对速度谱资料进行倾角和地震—声波速度系统差校正 ,从而得到了可靠的地震原始层序层速度资料。在此基础上 ,建立了岩性预测的地震层序层速度模型及高、低速层压实模型、地质模型、等效模型、数学模型 ,通过这些模型对研究层中高速层的岩性比率进行了定量预测。最后在对研究层进行细分层的基础上 ,根据钻井统计的不同岩类的多少 ,将地层岩性简化为二元结构进行计算并校正 ,从而得到对应于高速层的碳酸盐岩的岩性比率。在塔里木盆地西南地区石炭系地层中 ,预测效果良好。

In the practical operation, especially to the carbonate strata, predicting lithological ratio of the object layer between wells or in no-wells regions is realized with seismic velocity information. This article proofreads the systematic errors between the dip and the seismic-acoustic velocity of the velocity spectrum, and so, the interval velocity information of the original seismic sequence can be dependably gained. On the basis of this, several models are established: lithological predicting models, interval velocity model of the seismic sequence, compaction model of the high and low velocity layers, geological model, equivalence model, mathematical model. The lithological ratio of the studied layers is quantitatively predicted with these models. On the basis of the studied layer being finally divided into many layers, and according to the number of different lithological types, stratigraphical lithology is simplified to binary structure that is calculated and proofread. Carbonate lithological ratio can be gained in corresponding high velocity layers. The predicting effects are very good to Carboniferous strata in southwest Tarim basin.